iupac-nist solubility data series. 90. hydroxybenzoic acid

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IUPAC-NIST Solubility Data Series. 90. Hydroxybenzoic Acid Derivatives inBinary, Ternary, and Multicomponent Systems. Part I. Hydroxybenzoic

Acids, Hydroxybenzoates, and Hydroxybenzoic Acid Salts in Water andAqueous Systems

Ayako Goto, Editor a)

University of Shizuoka, Shizuoka 422-8526, Japan

Hiroshi Miyamoto, EditorNiigata University, Niigata 950-2181, Japan

Mark Salomon, EditorMaxPower, Inc., 141 Christopher Lane, Harleysville, Pennsylvania 19438

Rensuke Goto, EvaluatorUniversity of Shizuoka, Shizuoka 422-8526, Japan

Hiroshi Fukuda, EvaluatorKitasato University, Kanagawa, 252-0373, Japan

Erich Königsberger, Compiler and Lan-Chi Königsberger, CompilerMurdoch University, Murdoch, Western Australia WA6150, Australia

�Received 13 October 2010; accepted 8 November 2010; published online 22 February 2011�

The solubility data for well-defined binary, ternary, and multicomponent systems ofsolid-liquid type are reviewed. One component, which is 2-, 3-, and 4-hydroxybenzoicacids, 4-hydroxybenzoate alkyl esters �parabens�, or hydroxybenzoic acid salts, is in thesolid state at room temperature and another component is liquid water, meaning that all ofthe systems are aqueous solutions. The ternary or multicomponent systems include or-ganic substances of various classes �hydrocarbons of several structural types, halogenatedhydrocarbons, alcohols, acids, ethers, esters, amides, and surfactants� or inorganic sub-stances. Systems reported in the primary literature from 1898 through 2000 are compiled.For seven systems, sufficient binary data for hydroxybenzoic acids or parabens in waterare available to allow critical evaluation. Almost all data are expressed as mass and molefractions as well as the originally reported units, while some data are expressed as molarconcentration. © 2011 American Institute of Physics. �doi:10.1063/1.3525876�

Key words: Aqueous systems; hydroxybenzoic acid; hydroxybenzoic acid salt; paraben; salicylic acid;solubility.

CONTENTS

1. Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.1. Scope of the volume. . . . . . . . . . . . . . . . . . . 31.2. Experimental methods. . . . . . . . . . . . . . . . . . 41.3. Procedure used in critical evaluation. . . . . . 5

2. Hydroxybenzoic Acids, Parabens, and

a�Electronic mail: [email protected]
© 2011 American Institute of Physics.
0047-2689/2011/40„1…/013101/130/$47.00 013101

aded 22 Feb 2011 to 132.163.193.247. Redistribution subject to AIP lic

Hydroxybenzoic Acid Salts in Binary Aqueous

Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.1. Hydroxybenzoic acid–water systems. . . . . . 5

2.1.1. Critical evaluation of the solubilityof hydroxybenzoic acids. . . . . . . . . . 52.1.1.1. Salicylic acid

�2-hydroxybenzoic acid�. . . . 52.1.1.2. 3-Hydroxybenzoic acid. . . . 112.1.1.3. 4-Hydroxybenzoic acid. . . . 13

2.2. Paraben–water systems. . . . . . . . . . . . . . . . . 18

J. Phys. Chem. Ref. Data, Vol. 40, No. 1, 2011-1

ense or copyright; see http://jpcrd.aip.org/about/rights_and_permissions

013101-2 GOTO ET AL.

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2.2.1. Critical evaluation of the solubilityof parabens. . . . . . . . . . . . . . . . . . . . . 182.2.1.1. Methylparaben. . . . . . . . . . . 182.2.1.2. Ethylparaben. . . . . . . . . . . . . 232.2.1.3. Propylparaben. . . . . . . . . . . . 272.2.1.4. Butylparaben. . . . . . . . . . . . . 30

2.3. Solubility of hydroxybenzoic acid salt–water systems. . . . . . . . . . . . . . . . . . . . . . . . 332.3.1. Singly substituted hydroxybenzoic

acid salts. . . . . . . . . . . . . . . . . . . . . . . 332.3.1.1. 2-Hydroxybenzoic acid

salts. . . . . . . . . . . . . . . . . . . . 332.3.1.2. 3-Hydroxybenzoic acid

salts. . . . . . . . . . . . . . . . . . . . 362.3.1.3. 4-Hydroxybenzoic acid

salts. . . . . . . . . . . . . . . . . . . . 372.3.2. Dihydroxybenzoic acid salts. . . . . . . 39

2.3.2.1. 2,3-Dihydroxybenzoic acidsalts. . . . . . . . . . . . . . . . . . . . 39






3. Hydroxybenzoic Acids, Parabens, andHydroxybenzoic Acid Salts in TernaryAqueous Systems. . . . . . . . . . . . . . . . . . . . . . . . . 633.1. Hydroxybenzoic acid–water–organic

compound systems. . . . . . . . . . . . . . . . . . . . 633.1.1. Salicylic acid. . . . . . . . . . . . . . . . . . . 63

3.1.1.1. Halides. . . . . . . . . . . . . . . . . 633.1.1.2. Alcohols. . . . . . . . . . . . . . . . 643.1.1.3. Ketones and acids. . . . . . . . . 693.1.1.4. Organic salts. . . . . . . . . . . . . 703.1.1.5. Amides. . . . . . . . . . . . . . . . . 793.1.1.6. Carbohydrates. . . . . . . . . . . . 803.1.1.7. Aromatic compounds. . . . . . 813.1.1.8. Heterocyclic compounds. . . 87

3.1.2. 3-Hydroxybenzoic acid. . . . . . . . . . . 913.2. Parabens and hydroxybenzoic acid salt–

water–organic compound systems. . . . . . . . 913.2.1. Methylparaben. . . . . . . . . . . . . . . . . . 91

3.2.1.1. Alcohols. . . . . . . . . . . . . . . . 913.2.1.2. Amides. . . . . . . . . . . . . . . . . 933.2.1.3. Carbohydrate. . . . . . . . . . . . . 1003.2.1.4. Polyethylene glycol

derivative. . . . . . . . . . . . . . . 1003.2.1.5. Aromatic compound. . . . . . . 101

3.2.2. Ethylparaben. . . . . . . . . . . . . . . . . . . . 1023.2.2.1. Alcohols. . . . . . . . . . . . . . . . 1023.2.2.2. Carbohydrate. . . . . . . . . . . . . 103
3.2.2.3. Organic salt. . . . . . . . . . . . . . 103
J. Phys. Chem. Ref. Data, Vol. 40, No. 1, 2011


3.2.2.4. Polyethylene glycolderivatives. . . . . . . . . . . . . . . 104

3.2.3. Propylparaben. . . . . . . . . . . . . . . . . . . 1063.2.3.1. Alcohols. . . . . . . . . . . . . . . . 1063.2.3.2. Carbohydrate. . . . . . . . . . . . . 1063.2.3.3. Polyethylene glycol

derivative. . . . . . . . . . . . . . . 1073.2.4. Butylparaben. . . . . . . . . . . . . . . . . . . . 107

3.2.4.1. Alcohols. . . . . . . . . . . . . . . . 1073.2.4.2. Carbohydrate. . . . . . . . . . . . . 1083.2.4.3. Organic salt. . . . . . . . . . . . . . 1083.2.4.4. Polyethylene glycol

derivatives. . . . . . . . . . . . . . . 1093.2.5. Alkylparabens. . . . . . . . . . . . . . . . . . . 110

3.2.5.1. Alcohol. . . . . . . . . . . . . . . . . 1103.2.6. Benzylparaben. . . . . . . . . . . . . . . . . . 112

3.2.6.1. Alcohol. . . . . . . . . . . . . . . . . 1123.2.6.2. Carbohydrate. . . . . . . . . . . . . 113

3.2.7. 2-Hydroxybenzoic acid salts. . . . . . . 1133.2.7.1. Alcohol. . . . . . . . . . . . . . . . . 113

3.3. Hydroxybenzoic acid–water–inorganiccompound systems. . . . . . . . . . . . . . . . . . . . 1163.3.1. Salicylic acid. . . . . . . . . . . . . . . . . . . 116

3.3.1.1. Inorganic salts. . . . . . . . . . . . 1163.3.2. 3-Hydroxybenzoic acid. . . . . . . . . . . 1223.3.3. 4-Hydroxybenzoic acid. . . . . . . . . . . 122

4. Hydroxybenzoic Acids and Parabens inMulticomponent Aqueous Systems. . . . . . . . . . . 1234.1. Hydroxybenzoic acid–water–organic

compound–inorganic compound systems... 1234.1.1. 4-Hydroxybenzoic acid. . . . . . . . . . . 123

4.2. Hydroxybenzoic acid–water–inorganiccompound �1�–inorganic compound �2�systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1234.2.1. 3-Hydroxybenzoic acid. . . . . . . . . . . 1234.2.2. 4-Hydroxybenzoic acid. . . . . . . . . . . 124

4.3. Hydroxybenzoic acid and paraben–water–urea–inorganic compound systems. . . . . . . . 1244.3.1. Salicylic acid. . . . . . . . . . . . . . . . . . . 1244.3.2. 3-Hydroxybenzoic acid. . . . . . . . . . . 1264.3.3. 4-Hydroxybenzoic acid. . . . . . . . . . . 1274.3.4. Methylparaben. . . . . . . . . . . . . . . . . . 127

4.4. Hydroxybenzoic acid and paraben–water–urea–inorganic compound �1�–inorganiccompound �2� systems. . . . . . . . . . . . . . . . . 1284.4.1. 4-Hydroxybenzoic acid. . . . . . . . . . . 1284.4.2. Methylparaben. . . . . . . . . . . . . . . . . . 1284.4.3. Ethylparaben. . . . . . . . . . . . . . . . . . . . 1294.4.4. Propylparaben. . . . . . . . . . . . . . . . . . . 1294.4.5. Butylparaben. . . . . . . . . . . . . . . . . . . . 129

5. References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

List of Tables

1. List of hydroxybenzoic acids,hydroxybenzoates and hydroxybenzoic acid
salts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

IUPAC-NIST SOLUBILITY DATA SERIES. 90 013101-3

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2. List of compiled sheets for solutes in aqueousbinary, ternary, and multicomponent systems. . . 4

3. Analytical methods of solutes in aqueoussystems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4. Summary of experimental solubility data ofsalicylic acid in water. . . . . . . . . . . . . . . . . . . . . . 5

5. Observed data and recommended valuescalculated according to Eq. �1� for salicylicacid in water. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

6. Summary of experimental solubility data of3-hydroxybenzoic acid in water. . . . . . . . . . . . . . 11

7. Observed data and recommended valuescalculated according to Eq. �1� for3-hydroxybenzoic acid in water. . . . . . . . . . . . . . 12

8. Summary of experimental solubility data of4-hydroxybenzoic acid in water. . . . . . . . . . . . . . 14

9. Observed data and recommended valuescalculated according to Eq. �1� for4-hydroxybenzoic acid in water. . . . . . . . . . . . . . 15

10. Summary of experimental solubility data ofmethylparaben in water. . . . . . . . . . . . . . . . . . . . . 18

11. Observed data and recommended valuescalculated according to Eq. �1� formethylparaben in water. . . . . . . . . . . . . . . . . . . . . 19

12. Summary of experimental solubility data ofethylparaben in water. . . . . . . . . . . . . . . . . . . . . . 24

13. Observed data and recommended valuescalculated according to Eq. �1� forethylparaben in water. . . . . . . . . . . . . . . . . . . . . . 24

14. Summary of experimental solubility data ofpropylparaben in water. . . . . . . . . . . . . . . . . . . . . 27

15. Observed data and recommended valuescalculated according to Eq. �1� forpropylparaben in water. . . . . . . . . . . . . . . . . . . . . 28

16. Summary of experimental solubility data ofbutylparaben in water. . . . . . . . . . . . . . . . . . . . . . 30

17. Observed data and recommended valuescalculated according to Eq. �1� forbutylparaben in water. . . . . . . . . . . . . . . . . . . . . . 31

List of Figures

1. Fitting curve of Eq. �1� and the observed datafor salicylic acid in water.. . . . . . . . . . . . . . . . . . 7

2. Fitting curve of Eq. �1� and the observed datafor 3-hydroxybenzoic acid in water.. . . . . . . . . . . 12

3. Fitting curve of Eq. �1� and the observed datafor 4-hydroxybenzoic acid in water.. . . . . . . . . . . 15

4. Fitting curve of Eq. �1� and the observed datafor methylparaben in water.. . . . . . . . . . . . . . . . . 19

5. Fitting curve of Eq. �1� and the observed datafor ethylparaben in water.. . . . . . . . . . . . . . . . . . . 24

6. Fitting curve of Eq. �1� and the observed datafor propylparaben in water.. . . . . . . . . . . . . . . . . . 28

7. Fitting curve of Eq. �1� and the observed data
for butylparaben in water.. . . . . . . . . . . . . . . . . . . 31

1. Preface

1.1. Scope of the volume

This volume reviews experimentally determined solubility

data for well-defined binary, ternary, and multicomponent

systems in which one component is a hydroxybenzoic acid,

hydroxybenzoate or hydroxybenzoic acid salt. The solutes

are as follows: hydroxybenzoic acid corresponds to 2-, 3-,

and 4-hydroxybenzoic acids. 4-hydroxybenzoic acid alkyl

ester �paraben� corresponds to methyl-, ethyl-, propyl-,

butyl-, isobutyl-, hexyl- heptyl-, octyl-, decyl-, dodecyl-, and

benzyl esters. Monohydroxybenzoic acid salts correspond to

lithium, sodium, potassium, rubidium, cesium, and silver

salts, and 2,3-, 2,4-, 2,5-, 2,6-, 3,4-, and 3,5- dihydroxyben-

zoic acid salts correspond to cerium, dysprosium, erbium,

europium, gadolinium, holmium, neodymium, lanthanum,

lutetium, praseodymium, samarium, terbium, thulium, ytter-

bium, and yttrium salts. All of the solutes are in the solid

state at room temperature. The list of the solutes is shown in

Table 1. The goal of the search is to include all published

data for systems designated in the title.

Hydroxybenzoic acids and related compounds are impor-

tant substances closely related to daily life. Among the com-

piled sheets of the solutes, those for salicylic acid are the

most numerous. Salicylic acid is a phytohormone and it is a

key ingredient in many skin-care products for the treatment

of acne, psoriasis, etc. For example, it has been used in

shampoos because of its effect on skin cells. The solubilities

of the parabens which have a chemical structure of

4-hydroxybenzoic acid ester have been frequently reported.

They are widely used as preservatives in the cosmetic, phar-

maceutical, and food industries. They are used primarily for

their bacteriocidal and fungicidal properties and can be

found in shampoo, shaving gels, toothpaste, etc. The para-

bens have been considered to be safe because of their low

toxicity profile and their long history of safe use. However, a

few recent controversial studies have begun to challenge this

view. At the present time, it is reported that parabens are

practically nontoxic.1–3 However, further research is neces-

sary to determine the safety of parabens from the point of

view of the precautionary principle. Therefore, it is important

to give the solubility data concerning the hydroxybenzoic

acid and the derivatives from the viewpoint of future human

health. The solubilities, as well as partition coefficients for

parabens in water or aqueous solutions containing a surfac-

tant at various temperatures, have been reported in several

papers by Goto4–10 from the period 1977–1986 and the be-

havior of the parabens in pharmaceuticals and cosmetic bases

has been thermodynamically studied.



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TABLE 1. List of hydroxybenzoic acids, hydroxybenzoates and hydroxyben-zoic acid salts

Solute

Hydroxybenzoicacid

2-Hydroxybenzoic acid �salicylic acid, 2HA�,3-hydroxybenzoic acid �3HA�, 4-hydroxybenzoic acid�4HA�

HydroxybenzoateEster of hydroxybenzoic acid �paraben�: methyl ester�methylparaben, MP�, ethyl ester �ethylparaben, EP�,propyl ester �propylparaben, PP�, butyl ester�butylparaben, BP�, isobutyl ester �isobutylparaben�, hexyester �hexylparaben�, heptyl ester �heptylparaben�, octylester �octylparaben�, decyl ester �decylparaben�, dodecylester �dodecylparaben�, and benzyl ester �benzylparaben�

Hydroxybenzoicacid salt

2-Hydroxybenzoic acid salt: lithium, sodium, potassium,rubidium, cesium, and silver salts3-hydroxybenzoic acid salt: lithium, sodium, potassium,rubidium, and cesium salts4-hydroxybenzoic acid salt: lithium, sodium, potassium,rubidium, cesium, and silver salts2,3-hydroxybenzoic acid salt: cerium, dysprosium,erbium, europium, gadolinium, holmium, neodymium,lanthanum, lutetium, praseodymium, samarium, terbium,thulium, ytterbium, and yttrium salts2,4-dihydroxybenzoic acid salt: cerium, dysprosium,erbium, europium, gadolinium, holmium, neodymium,lanthanum, lutetium, praseodymium, samarium, terbium,thulium, and ytterbium salts2,5-dihydroxybenzoic acid salt: cerium, dysprosium,erbium, europium, gadolinium, holmium, neodymium,lanthanum, lutetium, praseodymium, samarium, terbium,thulium, and ytterbium salts2,6-dihydroxybenzoic acid salt: dysprosium, erbium,gadolinium, holmium, lutetium, terbium, thulium, andytterbium salts3,4-dihydroxybenzoic acid salt: cerium, dysprosium,erbium, europium, gadolinium, holmium, neodymium,lanthanum, lutetium, praseodymium, samarium, terbium,thulium, ytterbium, and yttrium salts3,5-dihydroxybenzoic acid salt: cerium, dysprosium,erbium, europium, gadolinium, holmium, neodymium,lanthanum, lutetium, praseodymium, samarium, terbium,thulium, and ytterbium salts

In Part I of this volume, all of the systems are aqueoussolutions. However, the ternary or multicomponent systemsinclude organic substances of various classes �hydrocarbonsof several structural types, halogenated hydrocarbons, alco-hols, acids, ethers esters, amides, and surfactants� or inor-ganic substances.

An exhaustive search of the chemical literature publishedprior to 2001 found solubility data for eight categories ofsystems, as shown in Table 2. From these, 307 compilationsheets were prepared. Most compilations present the solubil-ity data for one system as reported in one publication. Forsome original publications, which reported very limited data
for several systems, those data are grouped into a single


compilation. This volume includes solid-liquid equilibriumof aqueous binary, ternary, and multicomponent systems. Thelist of binary, ternary, and multicomponent systems is shownin Table 2. This is the result of an exhaustive search of thechemical literature using Chemical Abstracts.

TABLE 2. List of compiled sheets for solutes in aqueous binary, ternary, andmulticomponent systems

SoluteBinarysystems

Ternarysystems

Multicomponentsystems

Hydroxybenzoic acid �HA� 21 72 10Hydroxybenzoic acid ester �HAE� 31 58 5Hydroxybenzoic acid salt �HAS� 102 6 0

In some original sources, solubility data were reported asincidental or ancillary information to other studies. If, forthis or other reasons, details concerning experimental meth-ods, source and purity of materials, or estimated errors werebrief or absent, correspondingly short entries appear in thecompilations, sometime with the note “No further detailswere reported” or “not stated.”

For convenience of comparison of experimental data,compilers and the evaluators of this volume, as far as pos-sible, expressed all initial results in mass percent and molefraction as well as in the units reported in the original source.Conversions, where they were made, are clearly attributed tothe compiler. Some units require numerical data for the den-sity of pure components and/or the mixtures. Definitions ofmass percent and mole fraction as well as their relation toother units of solubility are given in the Introduction to theSolubility Data Series.11

1.2. Experimental methods

Most solubility measurements of binary, ternary, and mul-ticomponent systems containing each solute have been madefrom 260.3 to 486.2 K at atmospheric pressure. Samples ofliquid phases at equilibrium are analyzed by various meth-ods. The solubility measurements of hydroxybenzoic acidsfor binary, ternary, and multicomponent systems are mainlycarried out by titration in which the sample solution wastitrated with alkali solution such as NaOH or Ba�OH�2 solu-tion using p-nitrophenol, phenolphthalein, or Congo Red asan indicator. The solubility measurement of hydroxybenzoicacid salts in binary, ternary, and multicomponent systemswas carried out mainly by gravimetry and the syntheticmethod. The basic approach to solubility measurement ofhydroxybenzoates for binary, ternary, and multicomponentsystems is UV spectroscopy, but gravimetry is used in lim-ited systems. Table 3 lists various methods for measurement
of the solubilities.


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TABLE 3. Analytical methods of solutes in aqueous systems

Methoda

Binary system Ternary systemMulticomponent

systemTotal

numberaHAb HAEc HASd HA HAE HAS HA HAE

Spectroscopy 6 27 31 2 53 0 10 5 134Titration 6 0 0 46 1 0 0 0 53Gravimetry 3 0 53 9 5 5 0 0 75Synthetic method 4 0 15 6 0 0 0 0 25Other methode 0 1 3 1 0 1 0 0 6

aThe total number of sheets does not correspond with the sum of the different methods because some sheets contain plural analytical methods and some sheetsfor references whose methods are not described clearly are not counted.

bHA: Hydroxybenzoic acid.cHAE: Hydroxybenzoic acid ester.dHAS: Hydroxybenzoic acid salt.e
Other methods include thermometry, and measurement of radioisotopes, potential difference, HPLC, and vapor pressure.
System pressure at the solution temperature is seldom re-ported because it is assumed that the effect of pressure isminor. Sources of error in these methods include gravita-tional effects and impurities in materials whose solubilitiesare determined.

1.3. Procedure used in critical evaluation

A critical evaluation was prepared for each system forwhich multiple independent reports of solubility are avail-able. In evaluating the available data, the evaluators haveconsidered the data quality of individual original sources tothe extent that can be established from the content �andomissions� of those reports and by comparing the resultsobtained independently in more than one laboratory. Severalaspects of the solubility data have been considered: purity ofsubstances, date of experiment, experience of the research-er�s�, and previous publications.

Data are recommended if the results of independentgroups closely agreed with each other and the evaluator hasno doubt of the adequacy of the experimental and computa-tional procedures used. Data determined by an inadequate orill-defined method are rejected.

Where two or more reliable compilations were found for asystem, a critical evaluation was carried out. This was pos-sible for only seven systems of hydroxybenzoic acid �sali-cylic acid, 3-, and 4-hydroxybenzoic acid� and parabens�methyl-, ethyl-, propyl-, and butylparabens� in water in therange from 273.2 to 474.5 K.

Data for the solubility of the hydroxybenzoic acids and theparabens in water can be treated as a function of absolutetemperature. Data for the solubility of the hydroxybenzoicacids and the alkyl esters were fitted to Eq. �1�,12–14

ln x1 = A/T + B ln T + C . �1�

The equation parameters are presented in the criticalevaluations and were statistically calculated by the least-squares method so that the smoothing equation gives smallerstandard deviations than any other tested equation, such asthe equation

ln x1 = A/T + C . �2�


The solubilities calculated by the proposed equation arepresented in the figures and tables, whose values are recom-mended.

A complete guide to the preparation and use of compila-tions and evaluations for the IUPAC-NIST Solubility DataSeries can be found in the article11 jointly published byIUPAC and NIST. These procedures were applied to all thedata sources4–10,15–84 compiled here.

Of particular interest for the present volume are the un-common use of the symbols � for mass concentration and �for volume fraction. These symbols, defined in Ref. 11, areoften found in the pharmaceutical literature, particularly inthe older literature.

2. Hydroxybenzoic Acids, Parabens, andHydroxybenzoic Acid Salts in Binary

Aqueous Systems

2.1. Hydroxybenzoic acid–water systems

2.1.1. Critical evaluation of the solubility ofhydroxybenzoic acids

2.1.1.1. Salicylic acid „2-hydroxybenzoic acid…

Components: Evaluators:�1� Benzoic acid, 2-hydroxy-�salicylic acid; o-hydroxybenzoicacid�; C7H6O3; �69-72-7��2� Water; H2O �7732-18-5�

Ayako Goto, University ofShizuoka, Shizuoka, Japan;Rensuke Goto, University ofShizuoka, Shizuoka, Japan;Hiroshi Miyamoto, NiigataUniversity, Niigata, Japan;Hiroshi Fukuda, KitasatoUniversity, Tokyo, Japan

Critical EvaluationTABLE 4. Summary of experimental solubility data of salicylic acid in water

T /K 102c1 /mol dm−3 102m1 /mol kg−1 104x1 Analytical method Reference

273.2 0.670 1.20a Titration �Ba�OH�2� 15273.2 0.899 1.62a Gravimetry 16278.2 0.935 1.68a Gravimetry 16283.15 1.99 Titration �NaOH� 12




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TABLE 4. Summary of experimental solubility data of salicylic acid inwater—Continued


283.2 0.979 1.76a Gravimetry 16283.2 0.950 1.71a Titration �Ba�OH�2� 17285.3 1.01 1.82a Titration �Ba�OH�2� 15287.7 1.21 No information 18 and

19288.2 1.33 2.40a Gravimetry 16293.2 1.45 2.61a Gravimetry 16293.2 1.33 2.40a Titration �Ba�OH�2� 17293.2 1.60 2.90a Titration and

Gravimetry20

293.2 1.40 2.50a Titration �NaOH� 21293.3 1.32 Titration �KOH� 22296.2 1.48 2.67a Titration �Ba�OH�2� 15298.04 1.60 2.88 Titration �Ba�OH�2� 23298.15 3.33 Titration �NaOH� 12298.2 1.60 2.90a Titration �alkali

solution�24

298.2 1.60 2.90 Gravimetry 25298.2 1.64 Titration �NaOH� 26298.2 1.63 Gravimetry 27298.2 1.63 Titration �Ba�OH�2� 27298.2 1.80 3.24a Gravimetry 16298.2 1.61 Gravimetry 28298.2 1.62 Gravimetry 29298.2 1.60 Titration �Ba�OH�2� 30298.2 1.53 Electrometry 31298.2 1.79 Not stated 18 and

19298.2 1.90 Not stated 32298.2 1.61 Titration �alkali

solution�33

298.2 1.62 Titration �NaOH� 34298.3 1.60 Titration �NaOH� 35298.7 1.491 Spectrophotometry 36299.6 1.71 Titration �NaOH� 37301.0 1.80 Not stated 32301.2 3.12 Not stated 38301.3 1.79 3.22a Titration �Ba�OH�2� 15301.4 1.78 Not stated 32301.5 1.78 Not stated 32302.3 1.85 Not stated 32303.2 2.16 3.89a Gravimetry 16303.2 1.89 3.41a Titration �Ba�OH�2� 17303.2 2.2 4.0a Titration,

Gravimetry20

303.2 1.99 No information 18 and19

303.2 2.14 3.85a Spectrophotometry 39303.7 2.13 Not stated 32303.8 2.20 Titration �NaOH� 40307.15 4.41 Titration �NaOH� 12307.6 2.21 3.98a Titration �Ba�OH�2� 15307.97 2.324 4.18 Gravimetry,

Volumetry�Ba�OH�2�

23

308.2 2.55 4.59a Gravimetry 16310.2 1.81 Spectrophotometry 36311.9 2.60 4.68a Titration �Ba�OH�2� 15



TABLE 4. Summary of experimental solubility data of salicylic acid inwater—Continued


313.2 3.02 5.44a Gravimetry 16313.2 2.86 5.17a Titration �Ba�OH�2� 17317.15 5.73 Titration �NaOH� 12317.2 6.00a Titration �Ba�OH�2� 17318.15 6.77 Titration �NaOH� 12318.2 3.56 6.41a Gravimetry 16318.2 2.75 Gravimetry 36320.15 6.72 Titration �NaOH� 12321.8 3.70 6.66a Titration �Ba�OH�2� 15323.15 8.43 Titration �NaOH� 12323.2 4.65 8.37a Gravimetry 15323.2 7.30a Synthetic method 41323.2 4.29 7.76a Titration �Ba�OH�2� 17324.15 7.85 Titration �NaOH� 12325.15 8.47 Titration �NaOH� 12327.15 9.34 Titration �NaOH� 12328.15 9.65 Titration �NaOH� 12328.2 5.43 9.77a Gravimetry 16329.2 4.98 8.96a Titration �Ba�OH�2� 15329.2 9.41a Synthetic method 41330.65 11.1 Titration �NaOH� 12331.2 11.1a Titration �Ba�OH�2� 17333.2 6.58 11.8a Gravimetry 16333.2 6.26 11.4a Titration �Ba�OH�2� 17334.65 13.1 Titration �NaOH� 12336.2 13a Titration �Ba�OH�2� 17337.2 7.21 13.0a Titration �Ba�OH�2� 15338.2 8.01 14.4a Gravimetry 16339.15 14.9 Titration �NaOH� 12339.2 8.47 15.2a Titration �Ba�OH�2� 15342.0 17a Titration �Ba�OH�2� 17343.2 10.1 18.1a Gravimetry 16348.2 12.7 22.8a Volumetry

�Ba�OH�2�15

348.2 12.9 23.2a Gravimetry 16353.2 16.4 29.4a Gravimetry 16353.2 26.9a Synthetic method 41358.2 20.8 37.3a Gravimetry 16363.2 28.1 50.4a Gravimetry 16368.2 38.5 68.9a Gravimetry 16373.2 58.8 104.7a Gravimetry 16

aThe mole-fraction solubilities were calculated based upon m1 /mol kg−1 or

w1.

Solubilities of salicylic acid in water were reported in 28

publications. The measurements were carried out from

273.2 to 373.2 K. The solubilities of salicylic acid in water

are shown in Table 4, in which mole fraction and molar

concentration are used as units. The measurement was car-

ried out mainly by titration and gravimetry, as shown in

Table 4.

Data for the solubility of salicylic acid in water ex-

pressed in mole fraction can be treated as a function of ab-

solute temperature. They were fitted to Eqs. �1� and �2� given



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in Sec. 1.3. The data points very closely agree with Eq. �1� in

the whole range of temperature, as shown in Fig. 1, but they

deviate from Eq. �2� in the range of higher and lower tem-

peratures. The equation parameters were derived by multiple

regression analysis using SPSS based on Eq. �1�, with the

following results:

Multiple correlation coefficient: 0.997

Sample size: 68

p-value �F test�: 0.000

Constants: A=13810�890, B=56.35�2.81, C=

−375.5�19.0

White circles in Fig. 1 represent the observed data and

the black line corresponds to calculated values according to

Eq. �1� �ln x1=13810 /T+56.35 ln T−375.5�. The observed

data fit closely with the calculated line in the range of

273.2–373.2 K, with the multiple correlation coefficient of

0.997, as shown in Fig. 1. Therefore, the calculated value at

each measured temperature is reasonably considered as a rec-

ommended value in the whole range of temperature.

Table 5 shows typical observed data in the range of

273.2–373.2 K selected from among the sources in Table 4,

and the recommended values calculated from Eq. �1� at each

temperature.

FIG. 1. Fitting curve of Eq. �1� and the observed data for salicylic acid inwater.


TABLE 5. Observed data and recommended values calculated according toEq. �1� for salicylic acid in water

T /K 104x1�obs� 104x1�rec�

273.2 1.62 1.48278.2 1.68 1.66283.2 1.76 1.88285.3 1.82 1.99288.2 2.4 2.16293.2 2.5 2.52296.2 2.67 2.77298.2 2.9 2.96301.2 3.12 3.28303.2 3.41 3.52307.15 4.41 4.07308.2 4.59 4.23311.9 4.68 4.87318.2 6.41 6.25320.15 6.72 6.77321.8 6.66 7.25323.2 7.76 7.69328.2 9.77 9.52329.2 9.41 9.95331.2 11.1 10.86333.2 11.8 11.87336.2 13.0 13.59337.2 13.0 14.22338.2 14.4 14.89339.2 15.2 15.59342 17.0 17.75343.2 18.1 18.77348.2 23.2 23.80353.2 29.4 30.31358.2 37.3 38.77363.2 50.4 49.79368.2 68.9 64.19373.2 104.7 83.04

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Water; H2O; �7732-18-5�

15J. Walker and J. K. Wood, J.Chem. Soc. Trans. 73, 618�1898�.

Variables: Prepared by:t / °C=0.0 to 75.0 A. Goto and H. Miyamoto

Solubility of salicylic acid in water

Temperature Observed solubility Calculated solubility

t / °CS �author�a

g�1� /100 g�2�100w1

�compiler�100m1 /mol kg−1

�compiler�S �author�b

g�1� /100 g�2�100m1 /mol kg−1

�compiler�

0.0 0.092 0.092 0.67 0.090 0.6512.1 0.1395 0.139 1.01 0.139 1.0123.0 0.204 0.204 1.48 0.205 1.4828.1 0.247 0.246 1.79 0.246 1.7834.4 0.305 0.304 2.21 0.309 2.2438.7 0.359 0.358 2.60 0.360 2.6148.6 0.511 0.508 3.70 0.513 3.71




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Temperature Observed solubility Calculated solubility

t / °CS �author�a

g�1� /100 g�2�100w1


�compiler�S �author�b

g�1� /100 g�2�100m1 /mol kg−1

�compiler�

56.0 0.688 0.683 4.98 0.669 4.8464.0 0.996 0.986 7.21 — —66.0 1.17 1.16 8.47 — —75.0 1.76 1.73 12.7 — —

aIn the original paper, the solubility was given as grams per hundred grams of solvent.bThe solubility was calculated from the equation log10 S=0.015 56t−1.0458 reported by the author, where the solubility S �symbol given in the original paper�was given as grams per hundred grams of solvent and t is the temperature in degrees Centigrade.

Auxiliary Information

Method/Apparatus/Procedure:Both saturation and supersaturation methods were used to obtain thesaturated solutions. The solutions were usually agitated by stirrers drivenby a small turbine, but at the higher temperatures, equilibrium wasreached with only occasional agitation by hand. The salicylic acidsolutions obtained were titrated directly with barium hydroxide solutionusing Congo Red as an indicator, after previously diluting with water. Thebarium hydroxide solution was standardized with pure succinic acid usingphenolphthalein as an indicator.

Source and Purity of Materials:No information was given.

Estimated Errors:Nothing specified.


16E. Savarro, Atti accad. sci.Torino 48, 948 �1914� �Chem.Abs. 8, 340 �1914��.

Variables: Prepared by:t / °C=0 to 100 A. Goto and H. Miyamoto


Temperature Solubility

t / °C Original dataa100w1


�compiler�

0 1.24 0.124 0.8995 1.29 0.129 0.93510 1.35 0.135 0.97915 1.84 0.184 1.3320 2.00 0.200 1.4525 2.48 0.248 1.8030 2.98 0.298 2.1635 3.51 0.351 2.5540 4.16 0.416 3.0245 4.89 0.489 3.5650 6.38 0.638 4.6555 7.44 0.744 5.4360 9.00 0.900 6.5865 10.94 1.094 8.00870 13.75 1.370 10.06







�compiler�

75 17.55 1.755 12.9380 22.09 2.209 16.3585 27.92 2.792 20.7990 37.35 3.735 28.0995 50.48 5.048 38.49

100 75.07 7.507 58.76

aIn the original paper, the solubility was given as grams per 1000 grams of

solution.


Method/Apparatus/Procedure:The solubility of salicylic acid in water was determined in Pawlewski’sapparatus �B. Pawlewski, Ber. Dtsch. Chem. Ges. 32, 1040 �1899��. Thesalicylic acid content was determined by using the standardized sodiumhydroxide solution. The water and salicylic acid were placed in the testtube. The tube was equipped with a condenser and a siphon glass tubeand connected with a weighing bottle equipped with a condenser. Theapparatus was placed into a large thermostated glass beaker to mix thewater and salicylic acid, and air was bubbled through the mixture. Afterequilibrium was established, the saturated solution in the tube was filteredinto the weighing tube through the siphon tube equipped with a cottonwool filter. The apparatus was removed from the large beaker, cooledand/or dried, and the bottle was weighed. Salicylic acid was determinedgravimetrically after evaporation of the solvent.

Source and Purity of Materials:Salicylic acid was recrystallized before use.

Estimated Errors:Solubility: precision of �1.5%.Temperature: nothing specified.

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3: �69-72-7��2� Water; H2O; �7732-18-5�

41S.V. Sidgwick and E.K.Embank, J. Chem. Soc. 1921,979.




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Temperaturea Solubility

t / °C�solid�

t / °C�liquid� 100w1

100x1

�compiler�

159.0 100.0 100.0131.8 89.75 53.32119.5 80.00 34.28109.5 67.0 65.40 19.78107.2 86.4 48.18 10.82106.7 89.1 34.02 6.30105.6 87.2 16.82 2.57101.4 77.3 8.02 1.12

97.9 5.27 0.72080.0 2.026 0.269056.0 0.717 0.094150.0 0.557 0.0730

aCritical solution temperature; 89.5 °C

Two transition points of temperature �solid� and tem-

perature �liquid� were observed in the limited range, as

shown in the above table, in which �solid� and �liquid� were

indicated by the authors. These phenomena were explained

by the authors that the solution, supersaturated with respect

to the solid, separates into two liquid phases before crystal-

lization begins. Temperature �solid� corresponds to that for

transition from liquid to two phases, and temperature �liquid�corresponds to that for transition from two phases to solid.


Method/Apparatus/Procedure:The solubility was determined synthetically. Weighed quantities of theacid and the solvent were enclosed in bulbs, which were sealed andheated in a suitable bath. The thermometers had been compared with astandard instrument, and all readings were corrected.

Source and Purity of Materials:The preparation and purification methods were described elsewhere �J.Walker and J.K. Wood, J. Chem. Soc. 117, 40 �1920��. The m.p. ofsalicylic acid was 89.5 °C.



17C.R. Bailey, J. Chem. Soc.Trans. 126, 1951 �1925�.





t / °C 100w1

100x1

�compiler�102c1 /mol kg−1

�compiler�

10.0 0.131 0.0171 0.95020.0 0.184 0.024 1.3330.0 0.261 0.0341 1.8940.0 0.395 0.0517 2.8650.0 0.592 0.0776 4.2960.0 0.864 0.114 6.0


Method/Apparatus/Procedure:The mixtures of salicylic acid and water were stirred in a thermostat. Bothsupersaturation and undersaturation methods were used. When equilibriumhad been attained, the solution was sucked off through a side tube withfilter into a stoppered flask and weighed, transferred to a measuring flask,and made up to a known volume. Salicylic acid was directly estimatedwith barium hydroxide solution using p-nitrophenol as an indicator.

Source and Purity of Materials:Commercial salicylic acid was recrystallized from water four times. Thephysiologically pure salicylic acid was dissolved in a hot mixture ofphenol and water, and the solution was slowly cooled. After the productwas recrystallized twice, the m.p. of the purified product was 158.7 °C.When allowance was made for stem distillation, the m.p. was increased to160.4 °C.



18S.S. Doosaj and W.V. Bhagwat,J. Indian Chem. Soc. 10, 225�1933�19W.V. Bhagwat and S.S. Doosaj,J. Indian Chem. Soc. 10, 477�1933�.

Variables: Prepared by:t / °C=14.5, 25.0, and 30.0 A. Goto and H. Miyamoto



t / °C �1 /g dm−3102c1 /mol dm−3

�compiler�

14.5 1.667 1.20725.0 2.478 1.79430.0 2.743 1.986



013101-10 GOTO ET AL.

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Method/Apparatus/Procedure:No information was given.




38P.G. Desai and A.M. Patel, J.Indian Chem. Soc. 12, 131�1935�.

Variables: Prepared by:t / °C=28 A. Goto and H. Miyamoto



t / °C 104x1

28 3.118


Method/Apparatus/Procedure:Water was saturated with salicylic acid in a series of flasks, which werekept revolving on a wheel in an air thermostat at 28 °C for 48 h. In orderto avoid any error due to the absorption of the solute by the filter paper, afresh saturated solution was filtered through it before the solution used forthe estimation of the acid was passed through. A suitable amount of thefiltrate was titrated against barium hydroxide solution usingphenolphthalein as an indicator. The stock solution of barium hydroxidewas titrated against a standard solution of succinic acid.

Source and Purity of Materials:Water whose conductivity was checked was used throughout the work.Salicylic acid was twice recrystallized.

Estimated Errors:Solubility: the error was less than 0.5%.Temperature: nothing specified.


32W.V. Bhagwat, J. Indian Chem.Soc. 16, 235 �1939�.

Variables: Prepared by:t / °C=25–30.5 A. Goto and H. Miyamoto




Temperature Solubilitya

t / °C �1 /g dm−3102c1 /mol dm−3

�author�

25 2.581 1.89627.8 2.479 1.79528.2 2.461 1.78228.3 2.461 1.78229.1 2.551 1.84730.5 2.935 2.125

a�1 value was described by H. Stephen and T. Stephen, Solubilities of Inor-

ganic and Organic Compounds, Vol. 2 part 1 �Pergamon Press, Oxford,

1979�, p. 194. In the original paper, c1 was given as “Normality” units.


Method/Apparatus/Procedure:No information was given.




36D.M. Altwein, J.N. Delgado,and F.P. Cosgrove, J. Pharm. Sci.54, 603 �1965�.

Variables: Prepared by:t / °C=25.5, 37.0, and 45.0 A. Goto and H. Miyamoto



t / °C 102c1 /mol dm−3

25.5 1.49137.0 1.81045.0 2.751


Method/Apparatus/Procedure:Definite quantities of salicylic acid �2 g at 25.5 and 37.0 °C, 2 and 2.5 gat 45.0 °C� and 50 ml of water were placed in 100 ml volumetric flasks.The flasks were stoppered and the mixtures were shaken in a thermostatfor 12 h at 25.5, 37.0, and 45.0 °C. 1 ml volumetric pipettes equippedwith twine were used. Aliquot quantities were removed from thedissolution fluids, diluted to the proper concentration, and assayedspectrophotometrically for the amount of acid at 236 m�. All of thesamples and controls were run in triplicate.

Source and Purity of Materials:Salicylic acid was of Baker analyzed reagent. The melting point of theacid was 159 °C.



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Estimated Errors:Solubility: nothing specified.Temperature: precision �0.2 °C.


12A. Apelblat and E. Manzurola,J. Chem. Thermodyn. 21, 1005�1989�.

Variables: Prepared by:T /K=283.15–339.15 A. Goto, R. Goto, and H.

Miyamoto



T /K 103x1

283.15 0.1998298.15 0.3333307.15 0.4411317.15 0.5725318.15 0.6772320.15 0.6720323.15 0.7425324.15 0.7854325.15 0.8474327.15 0.9339328.15 0.9645330.65 1.108334.65 1.306339.15 1.490



Method/Apparatus/Procedure:The solubility measurements were performed as described by A. Apelblatand E. Manzurola, J. Chem. Thermodyn. 19, 317 �1987�. Suspended inexcess, solid was dissolved in distilled water by stirring for 10 h indouble-wall tubes thermostated by circulating water. The stirring wasfollowed by gravitational settling overnight. The weighed samples ofsaturated solutions were titrated with solutions of NaOH, standardizedwith potassium hydrogen phthalate. Phenolphthalein was used as anindicator.

Source and Purity of Materials:Salicylic acid was obtained from Sigma. Sodium hydroxide and potassiumhydrogen phthalate were obtained from Merck.

Estimated Errors:Solubility: nothing specified.Temperature: precision �0.01 K.

2.1.1.2. 3-Hydroxybenzoic acid

Components: Evaluators:�1� Benzoic acid, 3-hydroxy-�m-hydroxybenzoic acid�;C7H6O3; �99-06-9��2� Water; H2O �7732-18-5�

Ayako Goto, University ofShizuoka, Shizuoka, Japan;Rensuke Goto, University ofShizuoka, Shizuoka, Japan;Hiroshi Miyamoto, NiigataUniversity, Niigata, Japan;Hiroshi Fukuda, KitazatoUniversity, Tokyo, Japan

Critical EvaluationTABLE 6. Summary of experimental solubility data of 3-hydroxybenzoic acid in water


286.5 0.048 4 0.0871a Titration �Ba�OH�2� 15288.2 0.510 0.0913a Gravimetry 16292.0 0.061 0 0.1110a Titration �Ba�OH�2� 15297.5 0.076 3 0.137a Titration �Ba�OH�2� 15298.2 0.0531 Titration �alkali solution� 33303.2 0.050 6 0.0910a Titration �alkali solution� 39304.1 0.099 91 0.180a Titration �Ba�OH�2� 15309.4 0.129 0.233a Titration �Ba�OH�2� 15323.2 0.302 0.519a Gravimetry 16324.2 0.229 0.411a Titration �Ba�OH�2� 15342.2 0.471 0.841a Synthetic method 41352.8 0.791 1.40a Synthetic method 41357.8 1.25 2.199a Synthetic method 41366.5 2.44 4.214a Synthetic method 41371.5 3.71 6.257a Synthetic method 41383.0 7.20 11.5a Synthetic method 41407.2 17.6 24.0a Synthetic method 41474.5 — 100.0a Synthetic method 41

aThe mole-fraction solubilities were calculated based upon m1 /mol kg−1 or w1.



013101-12 GOTO ET AL.

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The critical evaluation was carried out as described inSec. 2.1.1.1 for salicylic acid in water:

The number of publications: 5The range of temperature: 286.5–474.5 KThe unit: mass percent, mole fraction, and molar concen-

trationAnalytical methods: synthetic method, and titrationData in Table 6 for the solubility of 3-hydroxybenzoic

acid in water expressed by mole fraction were fitted to Eqs.�1� and �2� given in Sec. 1.3. The data points very closelyagree with Eq. �1� in the range from 286.5 to 371.5 K, asshown in Fig. 2, where the data above 373.2 K were ex-cluded to compare with the result of salicylic acid, but theydeviate from Eq. �2� in the range of higher and lower tem-perature. Multiple regression analysis according to Eq. �1�yielded the following results:

Multiple correlation coefficient: 0.990Sample size: 14p-value �F test�: 0.000Constants: A=18 410�6794, B=72.43�20.91, C=

−485.7�141.9White circles in Fig. 2 represent the observed data and

the black line corresponds to calculated values according toEq. �1� �ln x1=18 410 /T+72.43 ln T−485.7�. The observeddata fit closely with the calculated line in the range of286.5–371.5 K, with the multiple correlation coefficient of0.990, as shown in Fig. 2. Therefore, the calculated value ateach measured temperature is reasonably considered as a rec-ommended value in the whole range of temperature.

Table 7 shows typical observed data in the range of286.5–371.5 K and the recommended values calculatedfrom Eq. �1� at each temperature.

TABLE 7. Observed data and recommended values calculated according toEq. �1� for 3-hydroxybenzoic acid in water

T /K 104x1�obs� 104x1�rec�

286.5 0.0871 0.0882288.2 0.0913 0.0927292.0 0.111 0.1043297.5 0.137 0.1256303.2 0.091 0.1551304.1 0.180 0.1606

FIG. 2. Fitting curve of Eq. �1� and the observed data for 3-hydroxybenzoicacid in water.



TABLE 7. Observed data and recommended values calculated according toEq. �1� for 3-hydroxybenzoic acid in water—Continued

T /K 104x1�obs� 104x1�rec�

309.4 0.233 0.1991323.2 0.519 0.3701324.2 0.411 0.3883342.2 0.841 0.981352.8 1.40 1.775357.8 2.199 2.373366.5 4.214 3.986371.5 6.257 5.410

Components: Original Measurements:�1� Benzoic acid, 3-hydroxy-�m-hydroxybenzoic acid�;C7H6O3; �99-06-9��2� Water; H2O; �7732-18-5�

15J. Walker and J.K. Wood, J.Chem. Soc. Trans. 73, 618�1898�.

Variables: Prepared by:t / °C=13.3–51.0 A. Goto and H. Miyamoto

Solubility of 3-hydroxybenzoic acid in water

Temperature Observed solubilitya,b Calculated solubilityc

t / °COriginal

dataa100w1

�compiler�m1 /mol kg−1

�compiler�100S


�compiler�

13.3 0.668 0.554 0.048 4 0.671 0.048 618.8 0.843 0.836 0.061 0 0.842 0.061 024.3 1.054 1.043 0.076 31 1.057 0.076 5330.9 1.380 1.361 0.099 91 1.388 0.100 536.2 1.787 1.756 0.129 4 1.727 0.125 051.0 3.167 3.070 0.229 3 3.180 0.230 2

aIn the original paper, the solubility was given as grams per hundred gramsof water.bThe w1 value was calculated by the compiler.cThe solubility is calculated from the equation log10 S=0.017 93t−0.4118,where S �symbol given in the original paper� is the solubility by weight andt is the temperature in degrees Centigrade.


Method/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 15 for thesalicylic acid–water system in Sec. 2.1.1.1.




16E. Savarro, Atti Accad. Sci.Torino 48, 948 �1914� �Chem.Abs. 8, 340 �1914��.

Variables: Prepared by:t / °C=15 and 50 A. Goto and H. Miyamoto



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Temperature Solubilitya,b

t / °C Original data100w1


�compiler�

15 7.00 0.700 0.051050 40.0 4.00 0.3017

aIn the original paper, the solubility was given as grams per 1000 g of water.bThe value w1 was calculated by the compiler.


Method/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 16 for thesalicylic acid–water system in Sec. 2.1.1.1. 3-Hydroxybenzoic acid wasdetermined gravimetrically after evaporation of the solvent.

Source and Purity of Materials:3-Hydroxybenzoic acid was recrystallized.

Estimated Errors:Solubility: precision �1.5%.Temperature: nothing specified.

Components: Original Measurements:�1� Benzoic acid, 3-hydroxy-�m-hydroxybenzoic acid�; C7H6O3; �99-06-9��2� Water; H2O; �7732-18-5�

41S.V. Sidgwick and E.K.Embank, J. Chem. Soc.1921, 979.

Variables: Prepared by:t / °C=69–201.3 A. Goto and H. Miyamoto



t / °C 100w1

m1 /mol kg−1

�compiler�100x1

�compiler�

69 6.11 0.471 0.84179.6 9.85 0.791 1.4084.6 14.70 1.248 2.19993.3 25.22 2.442 4.21498.3 33.85 3.705 6.257

109.8 49.85 7.197 11.48134.0 70.80 17.55 24.02201.3 100.0 — 100.0



Source and Purity of Materials:The preparation and purification methods were described by J. Walker andJ.K. Wood, J. Chem. Soc. 117, 40 �1920�. Melting point of3-hydroxybenzoic acid was 201.5 °C.




39H. Nogami, T. Nagai, and K.Ito, Chem. Pharm. Bull. 14, 351�1966�.

Variables: Prepared by:t / °C=30 A. Goto, R. Goto, and H.

Miyamoto



t / °C %a102m1 /mol kg−1

�compiler�

30 0.768 5.06

aThe compiler assumed that “%” should be read “mass %.”


Method/Apparatus/Procedure:The rotating disk method, as described by H. Nogami, T. Nagai, and A.Suzuki, Chem. Pharm. Bull. 14, 329 �1966�, was employed. Everyexperiment was carried out under the following conditions: the solution of100 ml at 30 °C; the disk of 3 cm diameter compressed under3 tons cm−2; the rotating velocity of disk at 100 r.p.m. The concentrationof 3-hydroxybenzoic acid was determined according to UV absorptionmethod. The optical density of 3-hydroxybenzoic acid was determined at231 and 290 nm.

Source and Purity of Materials:3-Hydroxybenzoic acid was of the purest reagent grade.


2.1.1.3. 4-Hydroxybenzoic acid

Components: Evaluators:�1� Benzoic acid, 4-hydroxy-�p-hydroxybenzoic acid�;C7H6O3; �99-96-7��2� Water; H2O; �7732-18-5�

Ayako Goto, University ofShizuoka, Shizuoka, Japan;Rensuke Goto, University ofShizuoka, Shizuoka, Japan;Hiroshi Miyamoto, NiigataUniversity, Niigata, Japan;Hiroshi Fukuda, KitasatoUniversity, Tokyo, Japan



013101-14 GOTO ET AL.

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Critical EvaluationTABLE 8. Summary of experimental solubility data of 4-hydroxybenzoic acid in water


278.15 0.0159 0.0286a Titration �NaOH� 13284.15 0.0228 0.0411a Titration �NaOH� 13285.9 0.0222 0.0400a Titration �Ba�OH�2� 15288.2 0.032 0.0576a Gravimetry 16289.15 0.0299 0.0538a Titration �NaOH� 13293.15 0.0374 0.0673a Titration �NaOH� 13293.2 0.0347 Spectrophotometry 42294.1 0.0356 0.0641a Titration �Ba�OH�2� 15298.15 0.0489 0.0880a Titration �NaOH� 13298.2 0.0335 Spectrophotometry 43 and 44298.2 0.0427 Titration �alkali solution� 33298.35 0.0451 Titration �NaOH� 35303.15 0.0634 0.114a Titration �NaOH� 13303.2 0.0529 0.0952a Spectrophotometry 39307.15 0.0812 0.146a Titration �NaOH� 13307.6 0.0715 0.129a Titration �Ba�OH�2� 15312.15 0.103 0.185a Titration �NaOH� 13312.6 0.0877 0.158a Titration �Ba�OH�2� 15316.15 0.139 0.249a Titration �NaOH� 13319.2 0.131 0.236a Titration �Ba�OH�2� 15321.15 0.180 0.324a Titration �NaOH� 13323.2 0.216 0.38a Gravimetry 16324.1 0.177 0.317a Synthetic method 41326.15 0.244 0.43a Titration �NaOH� 13327.8 0.198 0.356a Titration �Ba�OH�2� 15329.2 0.239 0.429a Synthetic method 41330.15 0.333 0.596a Titration �NaOH� 13333.4 0.317 0.569a Synthetic method 41335.15 0.429 0.766a Titration �NaOH� 13336.2 0.361 0.646a Synthetic method 41338.3 0.399 0.713a Synthetic method 41340.15 0.567 1.02a Titration �NaOH� 13341.4 0.468 0.83a Synthetic method 41345.15 0.727 1.29a Titration �NaOH� 13348.9 0.740 1.32a Synthetic method 41353.3 0.977 1.72a Synthetic method 41362.8 1.77 3.09a Synthetic method 41370.2 3.03 5.17a Synthetic method 41382.7 6.32 10.2a Synthetic method 41387.2 7.83 12.4a Synthetic method 41410.7 18.0 24.5a Synthetic method 41440.2 41.7 42.9a Synthetic method 41486.2 100.0a Synthetic method 41

a −1
The mole-fraction solubilities were calculated based upon m1 /mol kg or w1
The critical evaluation was carried out as described inSec. 2.1.1.1. for salicylic acid in water:


trationAnalytical methods: synthetic method, and titrationData in Table 8 for the solubility of 4-hydroxybenzoic

acid in water expressed by mole fraction were fitted to Eqs.�1� and �2� given in Sec. 1.3. The data points very closely
agree with Eq. �1� in the range from 286.5 to 371.5 K, as


shown in Fig. 3, where the data above 373.2 K were ex-cluded to compare with the result of salicylic acid, but theydeviated from Eq. �2� in the range of higher and lower tem-perature. Multiple regression analysis according to Eq. �1�gave the following results:

Multiple correlation coefficient: 0.997Sample size: 34p-value �F test�: 0.000Constants: A=8381�2073, B=44.07�6.52, C=

−290.9�44.1


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the black line corresponds to calculated values according toEq. �1� �ln x1=8381 /T+44.07 ln T−290.9�. The observeddata fit closely with the calculated line in the range of278.15–370.2 K, with the multiple correlation coefficient of0.997, as shown in Fig. 3. Therefore, the calculated value ateach measured temperature is reasonably considered as a rec-ommended value in the whole range of temperature.

Table 9 shows typical observed data in the range of278.15–370.2 K selected from among the sources in Table 8,and the recommended values calculated from Eq. �1� at eachtemperature.

TABLE 9. Observed data and recommended values calculated according toEq. �1� for 4-hydroxybenzoic acid in water

T /K 104x1�obs� 104x1�rec�

278.15 0.0286 0.0298284.15 0.0411 0.0404285.9 0.04 0.0442288.2 0.0576 0.0498293.15 0.0673 0.0645324.1 0.317 0.350327.8 0.356 0.432329.2 0.429 0.467294.1 0.0641 0.0678298.15 0.088 0.0841303.2 0.0952 0.110307.15 0.146 0.137312.15 0.185 0.180312.6 0.158 0.185316.15 0.249 0.225319.2 0.236 0.266321.15 0.324 0.297324.1 0.317 0.350327.8 0.356 0.432329.2 0.429 0.467330.15 0.596 0.493333.4 0.569 0.593336.2 0.646 0.695338.3 0.713 0.783341.4 0.836 0.935345.15 1.29 1.16348.9 1.32 1.44353.3 1.72 1.85362.8 3.09 3.20370.2 5.17 4.91

FIG. 3. Fitting curve of Eq. �1� and the observed data for 4-hydroxybenzoicacid in water.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-�p-hydroxybenzoic acid�;C7H6O3; �99-96-7��2� Water; H2O; �7732-18-5�

15J. Walker and J.K. Wood, J.Chem. Soc. Trans. 73, 618�1898�.



Temperature Observed solubilitya Calculated solubilityb

t / °COriginal

data100w1


�compiler�100S


�compiler�

0.0 — — — 0.160 0.011612.7 0.307 0.306 0.0222 0.310 0.022420.9 0.492 0.490 0.0356 0.476 0.034534.4 0.987 0.977 0.0715 0.963 0.069739.4 1.211 1.197 0.08767 1.244 0.0900646.0 1.815 1.782 0.1314 1.766 0.127954.6 2.740 2.667 0.1984 2.768 0.2004

aIn the original paper, the solubility was given as grams per hundred gramsof solvent. The value w1 was calculated by the compiler.bThe solubility was calculated from the equation log10 S=0.0227t−0.079 72, where S �symbol given in the original paper� is the solubility byweight and t is the temperature in degrees Centigrade.






16E. Savarro, Atti Accad. Sci.Torino 48, 948 �1914� �Chem.Abs. 8, 340 �1914��.

Variables: Prepared by:t / °C=15 and 50 A. Goto and H. Miyamoto



t / °C Original data100w1


�compiler�

15 4.4 0.44 0.03250 29.8 2.98 0.216

aIn the original paper, the solubility was given as grams per 1000 g of water.The value w1 was calculated by the compiler.



013101-16 GOTO ET AL.

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Method/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 16 for thesalicylic acid–water system in Sec. 2.1.1.1. The 4-hydroxybenzoic acidwas determined gravimetrically after evaporation of the solvent.

Source and Purity of Materials:4-Hydroxybenzoic acid was recrystallized.

Estimated Errors:Solubility: precision �1.5%.Temperature: nothing specified.


41S.V. Sidgwick and E.K.Embank, J. Chem. Soc. 1921,979.




t / °C 100w1

100x1

�compiler�

50.9 2.38 0.31756.0 3.20 0.42960.2 4.20 0.56963.0 4.75 0.64665.1 5.22 0.71368.2 6.07 0.83675.7 9.28 1.3280.1 11.85 1.72389.6 19.66 3.09397.0 29.47 5.168

109.5 46.60 10.22114.0 51.95 12.36137.5 71.30 24.47167.0 85.20 42.88213.0 100.0 100.0


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 41 for thesalicylic acid–water system in Sec. 2.1.1.1.

Source and Purity of Materials:The preparation and purification methods were described by J. Walker andJ.K. Wood, J. Chem. Soc. 117, 40 �1920�. Melting point of4-hydroxybenzoic acid was 213.0 °C.







Miyamoto



t / °C %a102m1 /mol kg−1

�compiler�

30 0.735 5.29

aThe compiler assumed that “%” should be read “mass %.”


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 39 for thesalicylic acid–water system in Sec. 2.1.1.1. The optical density of4-hydroxybenzoic acid was determined at 250 nm.

Source and Purity of Materials:4-Hydroxybenzoic acid was of the purest reagent grade.



42T.C. Corby and P.H. Elworthy,J. Pharm. Pharmacol. 23, Suppl,39S �1971�.




t / °C 102c1 /mol dm−3

20 0.0347


Methods/Apparatus/Procedure:The solubility was determined as described by P.H. Elworthy and F.J.Lipscomb, J. Pharm. Pharmacol. 20, 790 �1968�. The solution was assayedby ultraviolet spectroscopy.

Source and Purity of Materials:4-Hydrdoxybenzoic acid �BDH Ltd., Lab. reagent� was recrystallized fromdistilled water and dried overnight at 40 °C in a vacuum overphosphorous pentaoxide; m.p. 214 °C.

Estimated Errors:Not stated.



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43P.L. Wu and A. Martin, J.Pharm. Sci. 72, 587 �1983�82A. Martin, P.L. Wu, Z. Liron,and S. Cohen, J. Pharm. Sci. 74,638 �1985�.




t / °C x1 c1 /mol dm−3

25 0.000 60 0.0335


Methods/Apparatus/Procedure:A suitable amount of water was introduced into screw-capped vialscontaining an excess amount of solute. After being sealed with severalturns of electrical tape, the vials were submerged in water at 25 °C andshaken at 100 cpm for 24 h in a constant-temperature bath. Afterequilibrium had been attained, the saturated solutions were transferred to asyringe and filtered by a filter of pore size �1 �m. The solutions wereassayed using a spectrophotometer. The solubility of the solute wasdetermined at least six times.

Source and Purity of Materials:The 4-hydroxybenzoic acid �Matheson Coleman Bell, Norwood, OH� wasrecrystallized from aqueous ethanol and dried at 105 °C overnight.A pure grade of dioxane �Mallinckrodt Chem. Works, St. Louis, MO� wasused as received.

Estimated Errors:Solubility: The experimental variation in solubility was �3% in replicatesamples.Temperature: precision �0.1 °C.


44A Martin, P.L. Wu, and A.Beerbower, J. Pharm. Sci. 73,188 �1984�.


Miyamoto


Temperature Solubilityt / °C 104x1

25 6.0



Methods/Apparatus/Procedure:The mole fraction solubility x1 of 4-hydroxybenzoic acid was determinedas described by A. Beerbower, A. Martin, and P.L. Wu, J. Pharm. Sci. 73,179 �1984�. A suitable amount of water was introduced into screw-cappedvials containing an excess amount of the solute. After being sealed withseveral turns of plastic tape, the vials were submerged in water at 25 °Cand shaken. After equilibrium had been attained, each vial was removed,wiped dry, and analyzed. The solutions were transferred to a syringe andfiltered using a filter of pore size �1 �m. After suitable dilution, thesolutions were assayed using a spectrophotometer. The solubility wasdetermined at least six times.

Source and Purity of Materials:4-Hydroxybenzoic acid was obtained from Matheson, Coleman and Belland the acid was recrystallized from aqueous alcohol and dried at 105 °C.Melting point measured by a hot-stage method is 486.85 K.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy�p-hydroxybenzoic acid�;C7H6O3; �99-96-7��2� Water; H2O �7732-18-5�

13A. Apelblat and E. Manzurola,J. Chem. Thermodyn. 29, 1527�1997�.


Miyamoto


Temperature Observed solubility Calculated solubilitya

T /K m1 /mol kg−1

278.15 0.0159 0.0161284.15 0.0228 0.0223289.15 0.0299 0.0294293.15 0.0374 0.0368298.15 0.0489 0.0488303.15 0.0634 0.0649307.15 0.0812 0.0816312.15 0.1027 0.1090316.15 0.1385 0.1375321.15 0.1804 0.1842326.15 0.2438 0.2471330.15 0.3330 0.3127335.15 0.4286 0.4202340.15 0.5666 0.5652345.15 0.7269 0.7606

aThe author reported the fitting equation ln�m1 / �mol kg−1��=−275.673

+7891.58�T /K�−1+43.384 ln�T /K�. The solubility was calculated from the

fitting equation by the compiler.



013101-18 GOTO ET AL.

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Methods/Apparatus/Procedure:The solubility measurements were performed as described by A. Apelblatand E. Manzurola, J. Chem. Thermodyn. 19, 317 �1987�. Suspended inexcess, solid was dissolved in distilled water by stirring for 10 h indouble-wall tubes thermostated by circulating water. The stirring wasfollowed by gravitational settling overnight. Weighed samples of saturatedsolutions were titrated with solutions of NaOH, standardized withpotassium hydrogen phthalate. Phenolphthalein was used as an indicator.

Source and Purity of Materials:4-Hydroxybenzoic acid was obtained from Aldrich. The purity of thereagent was more than 0.99 mass % fraction and was used without furtherpurification.


2.2. Paraben–water systems

2.2.1. Critical evaluation of the solubility ofparabens

2.2.1.1. Methylparaben

Components: Evaluators:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O3

�99-76-3��2� Water; H2O �7732-18-5�

Ayako Goto, University ofShizuoka, Shizuoka, Japan;Rensuke Goto, University ofShizuoka, Shizuoka, Japan;Hiroshi Fukuda, KitasatoUniversity, Tokyo, Japan

Critical EvaluationTABLE 10. Summary of experimental solubility data of methylparaben inwater


273.15 1.09 Spectrophotometry 45273.2 1.14a Spectrophotometry 46278.15 1.27 Spectrophotometry 45278.2 1.34a Spectrophotometry 46283.15 1.54 Spectrophotometry 45283.2 1.59a Spectrophotometry 46288.15 1.79 Spectrophotometry 45288.2 0.831 Spectrophotometry 47288.2 1.85 Spectrophotometry 48288.2 1.90a Spectrophotometry 46293.15 2.15 Spectrophotometry 45293.2 2.27a Spectrophotometry 46288.2 0.997 Spectrophotometry 47288.2 1.26 Spectrophotometry 49298.15 2.67 Spectrophotometry 45298.2 1.14 Spectrophotometry 47298.2 1.45 Spectrophotometry 50298.2 1.49 Gravimetry 51298.2 1.60 Spectrophotometry 52298.2 1.610 HPLC analysis 53298.2 1.90 3.419b Spectrophotometry 54298.2 2.46 Spectrophotometry 55298.2 2.61 Spectrophotometry 56298.2 2.70 Spectrophotometry 44



TABLE 10. Summary of experimental solubility data of methylparaben inwater—Continued


298.2 2.72a Spectrophotometry 46298.2 2.86 Spectrophotometry 48298.2 2.60a Spectrophotometry 57300.2 1.45 Spectrophotometry 5298.2 1.65 Spectrophotometry 58300.2 3.04a Spectrophotometry 59303.15 3.12 Spectrophotometry 45303.2 1.56 Not reported 60303.2 1.66 Spectrophotometry 61303.2 3.24 Spectrophotometry 56303.2 3.28a Spectrophotometry 46303.2 3.30a Spectrophotometry 57308.15 3.74 Spectrophotometry 45308.2 3.97a Spectrophotometry 46308.2 4.01a Spectrophotometry 56308.2 4.11a Spectrophotometry 57310.15 4.05 Spectrophotometry 45313.15 4.53 Spectrophotometry 45313.2 4.80a Spectrophotometry 46313.2 4.92 Spectrophotometry 56313.2 6.83 Spectrophotometry 48313.2 4.61a Spectrophotometry 57318.15 5.63 Spectrophotometry 45318.2 5.83a Spectrophotometry 46323.15 6.83 Spectrophotometry 45323.2 7.08b Spectrophotometry 46323.2 7.55 Spectrophotometry 48328.2 8.60a Spectrophotometry 46331.5 9.83a Spectrophotometry 46331.65 9.37 Spectrophotometry 45

aThe mole-fraction solubilities were calculated based on m1 /mol kg−1 or w1.bThe molar fraction was calculated from w1, but the value was not used forthe evaluation.

Solubilities of methylparaben in water were reported in19 publications. The measurements were carried out from273.15 to 331.65 K. The solubilities are shown in Table 10,in which mass percent and mole fraction as well as molarconcentration are expressed as units. The measurements werecarried out mainly by spectroscopy, as shown in Table 10.

Data of the solubility of methylparaben in water ex-pressed by mole fraction can be treated as a function of ab-solute temperature. They were fitted to Eqs. �1� and �2� givenin Sec. 1.3. The data points very closely agree with Eq. �1� inthe whole range of temperatures, as shown in Fig. 4, but theydeviate from Eq. �2� in the range of higher and lower tem-perature. The equation parameters were derived by multipleregression analysis using SPSS based on Eq. �1�, with thefollowing results:






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273.2–331.5 K selected from among the sources in Table 10


temperature.

TABLE 11. Observed data and recommended values calculated according toEq. �1� for methylparaben in water

T /K 104x1�obs� 104x1�rec�

273.2 1.14 1.09278.2 1.34 1.30283.2 1.59 1.55288.2 1.85 1.86293.2 2.27 2.24298.2 2.70 2.70300.2 3.04 2.91303.2 3.24 3.26308.2 3.97 3.95310.15 4.05 4.26313.2 4.8 4.79318.2 5.83 5.82323.2 7.08 7.09328.2 8.6 8.65331.5 9.83 9.86

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O3;�99-76-3��2� Water; H2O; �7732-18-5�

5A. Goto, F. Endo, and K. Ito,Chem. Pharm. Bull. 25, 1165�1977�.

Variables: Prepared by:t / °C=27 A. Goto

FIG. 4. Fitting curve of Eq. �1� and the observed data for methylparaben inwater.


Solubility of methylparaben in water


t / °C 103c1 /mol dm−3

27 1.45


Methods/Apparatus/Procedure:The excess paraben was put in glass stoppered flasks containing 10 mlwater. The flasks were then shaken at 27�0.1 °C in an incubator �Taiyoincubator, M-I type� to attain equilibrium. After a given volume of thesupernatant was diluted adequately with water, the concentration of theparaben in the solution was determined by measuring the absorbance at256 nm �HITACHI 101 Spectrophotometer�.

Source and Purity of Materials:Methylparaben is of reagent grade. The water was used after treatment ofdistilled water by ion exchange and distillation from an all-Pyrex glassdistillation apparatus.



57K.S. Alexander, B. Laprade,J.W. Mauger, and A.N. Paruta, J.Pharm. Sci. 67, 624 �1978�.

Variables: Prepared by:t / °C=25–40 A. Goto, R. Goto, and H.

Miyamoto



t / °C 105x1

25 26.030 33.035 41.140 46.1



013101-20 GOTO ET AL.

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Methods/Apparatus/Procedure:Solubility was determined by a method previously described �P.A.Schwartz and A.N. Paruta, J. Pharm. Sci. 65, 252 �1976��. The paraben, inan amount in excess of its solubility, was placed in screw-capped glassvials with water. After equilibrium solubility was attained by at least 24 hof continuous rotation, each of six sample vials was removed insuccession for assay. A filtered aliquot of the saturated solution waspipetted into tared containers, weighed, and appropriately diluted forspectrophotometer assay with 95% ethanol to give a final concentration ofsolute in the range of 1–5 �g /ml. All pipets were prewarmed to preventthermal precipitation, and each had a pledget of fiberglass wrapped aroundits tip to act as a filter. The spectrophotometer was calibrated for parabenat its wavelength of maximum absorbance, at concentrations up to15 �g /ml in 95% ethanol. A least-squares method was used to determinethe statistical significance ��=0.0001� of the linear relationship betweenabsorbance and concentration. The spectrophotometer was Cary model 16,Cary Instruments, Monrovia, CA.

Source and Purity of Materials:Methylparaben: Lot 14, Matheson, Coleman and Bell.The solute was within 1 °C of the literature melting-point value.

Estimated Errors:Temperature: precision �0.2 °C.


50S.H. Yalkowsky and S.C.Valvani, J. Pharm. Sci. 69, 912�1980�.


Miyamoto



t / °C −log10 sobs

102c1 /mol dm−3

�compiler�

25 1.84 1.45

aThe solubility s was given as moles per liter.


Methods/Apparatus/Procedure:Solubility of methylparaben was determined by UV spectrophotometer�G.L. Flynn and S.H. Yalkowsky, J. Pharm. Sci. 61, 838 �1972��. Amoderate excess of the paraben was placed in an appropriately sizedstoppered flasks, water was added to the capacity of the flask, and theflask was placed in a 37 °C shaker bath and agitated gently for 6–8 days.An appropriately sized sample for the paraben was removed via awarmed, glass-wool-tipped pipet and appropriately diluted for analysis. Aminimum dilution of 100% �50–100 ml� was used to preventcrystallization at ambient temperature. The absorption maximum at285 nm was measured and compared with a simultaneously preparedstandard. The standard solutions were prepared by dissolving accuratelyweighed samples �10 or 1.0 mg� of each compound in 10 ml of 95%ethanol. In each case, there were diluted 100-fold with de-ionized waterand assayed using 1 or 10 cm cells, respectively.



Source and Purity of Materials:No information of source and purification of the materials were reported.The m.p. of methylparaben was 131 °C


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester; �methylp-hydroxybenzoate;methylparaben�; C8H8O3;�99-76-3��2� Water; H2O; �7732-48-5�

56R.E. Lindstrom and C.H. Lee,J. Pharm. Pharmacol. 32, 245�1980�.


Miyamoto



t / °C 104x1

25 2.6130 3.2435 4.0140 4.92


Methods/Apparatus/Procedure:The solubility of the methylparaben in water was determined at varioustemperatures in the range 25–41.36 °C according to the proceduredescribed in Ref. 80. The solubility was analyzed using a Beckmann DUspectrophotometer.

Source and Purity of Materials:Not stated.




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60C. McDonald and C.Richardson, J. Pharm. Pharmacol.33, 38 �1981�.


Miyamoto



t / °C102c1 /mol dm−3

�compiler�

30 1.56


Methods/Apparatus/Procedure:Not stated.




61S.H. Yalkowsky, S.C. Valvani,and T.J. Roseman, J. Pharm. Sci.72, 866 �1983�.


Miyamoto



t / °C log10 s1

102c1 /mol cm−3

�compiler�

30 −1.78 1.66

a In the original paper, s is the solubility in moles per liter.


Methods/Apparatus/Procedure:An excess amount of solute was allowed to equilibrate with water in asealed vial for 24 h at 300 °C. After equilibration, the samples werefiltered through either a 0.22 �m porous or a 1.2 �m silver membranefilter which was preequilibrated at 30 °C. Analysis of the filtrate wasperformed using UV spectrophotometry.


Source and Purity of Materials:Methylparaben of purest grade was obtained from commercial sources�Aldrich, Eastman and Fluka� and was used as received.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate,methylparaben�; C8H8O3;�99-76-3��2� Water; H2O; �7732-18-5�

46D.J.W. Grant, M. Mehdizadeh,A.H.-L. Chow, and J.E.Fairbrother, Int. J. Pharm. 18, 25�1984�.


Miyamoto



T /K 104x1 �compiler�

273.2 1.14278.2 1.34283.2 1.59288.2 1.90293.2 2.27298.2 2.72303.2 3.28308.2 3.97313.2 4.80318.2 5.83323.2 7.08328.2 8.60331.2 9.83

aThe solubility was calculated from the regression equation at round tem-

peratures by the compiler.


Methods/Apparatus/Procedure:A small amount of the solid solute, in excess of the solubility limit, wasplaced with 10 cm3 of water in a borosilicate glass test tube, which wasequilibrated in a thermostatic water bath. The content of each tube wasagitated by means of glass rod stirrers. To obtain temperatures belowroom temperature, the water bath was kept in a cold room at 4 °C.Saturation was achieved within 72 h at 15–25 °C and within 120 h at0–10 °C. The solubility above 25 °C was determined by agitating inconical flasks placed in a thermostatic shaking incubator for 24 h. Foranalysis the sample solutions were withdrawn through a warm Pasteurpipette containing a glass wool plug. At different time intervals, triplicatesamples were removed. Solubility was determined by UV spectroscopy.

Source and Purity of Materials:The methylparaben was supplied by B.D.H. Chemicals, Toronto and wasrecrystallized from toluene to constant melting point. The water wasdouble-distilled in an all-glass apparatus.




013101-22 GOTO ET AL.

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Results were analyzed from the observed data with the

equation ln x1sat=−�a /R��1 /T�+ �b /R�ln T+C, where R is the

gas constant.

Temperature Regression coefficients �with statistics�

t / °C na−a /RK−1 sb tc b /R sb tc C

0.0–58.3 13 6520 752 9.0 32.86 2.42 13.6 −217.3Correlation coefficient

ln x1sat vs ln T

rln x1

sat vs ln Tr

Multipler2

−0.996 0.998 1.000

a Number of mean data points.bStandard deviation of the regression coefficient.c Student’s t-value; all significant at the 5% level.

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben� C8H8O3;�99-76-3��2� Water; H2O; �7732-18-5�

44A. Martin, P.L. Wu, and A.Beerbower, J. Pharm. Sci. 73,188 �1984�.


Miyamoto



t / °C 104x1

25 2.7


Methods/Apparatus/Procedure:The mole fraction solubilities x1 of methylparaben were determined asdescribed by A. Beerbower, A. Martin, and P.L. Wu, J. Pharm. Sci. 73,179 �1984�. A suitable amount of water was introduced into screw-cappedvials containing an excess amount of the solute. After being sealed withseveral turns of plastic tape, the vials were submerged in water at 25 °Cand shaken. After equilibrium had been attained, each vial was removed,wiped dry, and analyzed. The solutions were transferred to a syringe andfiltered using a filter of pore size �1 �m. After suitable dilution, thesolutions were assayed using a spectrophotometer. The solubility wasdetermined at least six times for each solvent.

Source and Purity of Materials:Methylparaben �Tenneco Chemical Inc.� was used. The m.p. measured bya hot-stage method is 399.65 K.

Estimated Errors:Solubility: errors were below 3%.Temperature: precision �0.2 °C.




59J.T. Rubino and E.K. Obeng, J.Pharm. Sci. 80, 479 �1991�.


Miyamoto



t / °Cx1

�compiler�

27 0.000 304


Methods/Apparatus/Procedure:The solubility of methylparaben was determined by placing an excessamount of the paraben in 4 ml screw-capped vials with water and rotatingin a temperature-controlled water bath at 27 °C for 72 h. The saturatedsolutions were filtered through a 0.5 �m solvent-resistant filter. A weighedaliquot of the filtrate was diluted with HPLC grade ethanol and assayedspectrophotometrically.

Source and Purity of Materials:Methylparaben of high purity was obtained from Sigma ChemicalCompany and used as received from the supplier. The m.p. was 131 °Cand the value agreed with that described in Ref. 46.

Estimated Errors:Solubility: the variation of triplicate experiments was �5%.Temperature: �0.2 °C.


47A.E. Beezer, S. Forster, W.-B.Park, and G.J. Rimmer,Thermochim. Acta 178, 59�1991�.

Variables: Prepared by:T /K=288.2, 293.2, and 298.2 A. Goto, R. Goto, and H.

Miyamoto



T /K c1 /mol dm−3

288.2 8.31�10−3

293.2 9.97�10−3

298.2 1.14�10−2



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Methods/Apparatus/Procedure:The measurement of solubility was similar to that described by A.E.Beezer, W.H. Hunter, and D.E. Storey, J. Pharm. Pharmacol. 35, 350�1983�. Absorbance measurements were made at 258 nm.

Source and Purity of Materials:The methylparaben was the gift of Apin Chemicals Ltd. �Abingdon, GreatBritain� and was used as received. The purity was specified as 99.5%.Ethanol was of Anala R grade.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate,methylparaben�; C8H8O3;�99-76-3��2� Water; H2O; �7732-18-5�

45R. J. Prankerd, Int. J. Pharm.84, 233 �1992�.


Miyamoto



T /K 104x1

273.15 1.0877278.15 1.2667283.15 1.5433288.15 1.7856293.15 2.1537298.15 2.6670303.15 3.1238308.15 3.7432310.15 4.0503313.15 4.5298318.15 5.6349323.15 6.8287331.15 9.3746

aUnpublished data provided by D. J. W. Grant and M. Mehdizadeh were

used to fit the theoretical equation. Analysis procedure was given in the

original paper. Also, see Ref. 46.


Methods/Apparatus/Procedure:The solubilities of the paraben were determined by agitating the materialsin conical flasks placed in a thermostatic shaking incubator. Saturationwas then achieved within 24 h. For analysis each sample of solution ofthe paraben was quickly withdrawn through a warm Pasteur pipettecontaining a glass plug to act as a filter. At different time intervals,triplicate samples were removed, weighed, and analyzed and the meancomposition was determined at saturation. The solubility was determinedby a spectrophotometer at 257 nm.46





53F. Giordano, R. Bettini, C,Donini, A. Gazzanig, M.R. Caira,G.G.Z. Zhang, and D.J.W. Grant,J. Pharm. Sci. 88, 1210 �1999�.


Miyamoto



t / °C102c1 /mol dm−3

�compiler�

25 1.610


Methods/Apparatus/Procedure:The solubility was determined by equilibrating the liquid phase with aknown weight of the paraben in powdered form at 25.0�0.5 °C withagitation. A 5 day period had previously been shown to affordequilibrium. The three independent sets of experiments were performed onthe paraben. After equilibration at 25.0�0.5 °C, the suspension wasfiltered through a 0.22 �m Millipore filter. The filtrate, after appropriatedilution with the mobile phase, was assayed. The sample of solutionappropriately diluted with the mobile phase �methanol /0.04M ammoniumacetate, 55:45, v:v� was analyzed with an HPLC system �LC-19AS,Shimadzu, Japan�; detector �UV-vis, SPD-10 A, Shimadzu� at =256 nm:column �C-18 Bondapak, Waters, Milford, MA� 10 �m, 3.9�300 nm;flow rate of 0.8 ml min−1. Peak integration was performed with a C-R6Achromatopac �Shimadzu, Japan�. Linearity of response in the0–20 mg ml−1 concentration range was assessed from plots of peak areaagainst concentration.

Source and Purity of Materials:Methylparaben was obtained from Sigma Company �St. Louis, MO� andwas used as received. Organic solvents were of chromatographic gradepurity. Double-distilled water was used for solubility experiments.

Estimated Errors:Temperature: �0.5 °C.

2.2.1.2. Ethylparaben

Components: Evaluators:�1� Benzoic acid, 4-hydroxy-,ethyl ester �ethylp-hydroxybenzoate;ethylparaben�; C9H10O3

�120-47-8��2� Water; H2O �7732-18-5�




013101-24 GOTO ET AL.

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Critical EvaluationTABLE 12. Summary of experimental solubility data of ethylparaben inwater

T /K 102c1 /mol dm−3 104x1 Analytical method Reference

273.15 0.424 Spectrophotometry 45273.2 0.401a Spectrophotometry 46278.15 0.480 Spectrophotometry 45278.2 0.458a Spectrophotometry 46283.15 0.557 Spectrophotometry 45283.2 0.531a Spectrophotometry 46288.15 0.650 Spectrophotometry 45288.2 0.623a Spectrophotometry 46288.2 0.275 Spectrophotometry 47293.15 0.789 Spectrophotometry 45293.2 0.739a Spectrophotometry 46293.2 0.337 Spectrophotometry 47298.15 0.992 Spectrophotometry 45298.2 0.638 Spectrophotometry 51298.2 0.887a Spectrophotometry 46298.2 0.603 Spectrophotometry 50298.2 0.409 Spectrophotometry 47298.2 0.96 Spectrophotometry 57300.2 0.62 Spectrophotometry 58300.2 0.54 Spectrophotometry 5300.2 1.02a Spectrophotometry 59303.15 1.03 Spectrophotometry 45303.2 0.631 Spectrophotometry 61303.2 1.07a Spectrophotometry 46303.2 1.22 Spectrophotometry 57308.15 1.35 Spectrophotometry 45308.2 1.31a Spectrophotometry 46308.2 1.49 Spectrophotometry 57310.15 1.56 Spectrophotometry 45313.15 1.71 Spectrophotometry 45313.2 1.62a Spectrophotometry 46313.2 1.72 Spectrophotometry 57318.15 2.11 Spectrophotometry 45318.2 2.02a Spectrophotometry 46323.15 2.73 Spectrophotometry 45323.2 2.53a Spectrophotometry 46328.15 3.32 Spectrophotometry 45328.2 3.19 Spectrophotometry 46331.2 3.76 Spectrophotometry 46331.65 3.93 Spectrophotometry 45

aThe mole-fraction solubilities were calculated based on m1 /mol kg−1 or w1.

The critical evaluation was carried out as described inSec. 2.2.1.1 for methylparaben in water:

The number of publications: 10The range of temperature: 273.15–331.65 KThe unit: mole fraction and molar concentrationAnalytical methods: spectrophotometryData in Table 12 for the solubility of ethylparaben in

water expressed by mole fraction were fitted to Eqs. �1� and�2� given in Sec. 1.3. The data points very closely agree withEq. �1� in the whole range of temperatures, as shown in Fig.5, but they deviate from Eq. �2� in the range of higher andlower temperatures. Multiple regression analysis accordingto Eq. �1� produced the following:

Multiple correlation coefficient: 0.998



Sample size: 32

p-value �F test�: 0.000

Constants: A=12550�1411, B=53.35�4.69, C=

−355.4�31.5










273.2–331.2 K selected from among the sources in Table 12


temperature.

TABLE 13. Observed data and recommended values calculated according toEq. �1� for ethylparaben in water

T /K 104x1�obs� 104x1�rec�

273.2 0.401 0.407278.2 0.458 0.470283.2 0.531 0.548288.2 0.623 0.646293.2 0.739 0.769298.2 0.887 0.925300.2 1.02 0.998308.2 1.31 1.37310.15 1.56 1.49313.2 1.72 1.69318.2 2.02 2.09323.2 2.53 2.61328.2 3.19 3.28331.2 3.76 3.77

FIG. 5. Fitting curve of Eq. �1� and the observed data for ethylparaben inwater.



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Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,ethyl ester �ethylp-hydroxybenzoate;ethylparaben�; C9H10O3

�120-47-8��2� Water; H2O; �7732-18-5�



Solubility of ethylparaben in water


t / °C 103c1 /mol dm−3

27 5.4


Methods/Apparatus/Procedure:All procedures were identical to those given in the compilation of Ref. 5for the methylparaben–water system in Sec. 2.2.1.1.

Source and Purity of Materials:Ethylparaben was of reagent grade. Water was purified by distillation fromdeionized water.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,ethyl ester �ethylp-hydroxybenzoate;ethylparaben�; C9H10O3;�120-47-8��2� Water; H2O; �7732-18-5�



Miyamoto



t / °C 105x1

25 9.630 12.235 14.940 17.2


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 57 for themethylparaben–water system in Sec. 2.2.1.1.


Source and Purity of Materials:Ethylparaben: Lot EX665. Matheson, Coleman, and Bell.The solute was within 1 °C of the literature melting point value.





Miyamoto



t / °C log10 sobs

103c1 /mol dm−3

�compiler�

25 �2.22 6.03

aThe solubility s was given as moles per liter.


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 50 for themethylparaben–water system in Sec. 2.2.1.1

Source and Purity of Materials:No information on source and purification of the materials were reported.The m.p. of ethylparaben was 116 °C.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,ethyl ester �ethyl4-hydroxybenzoate;ethylparaben�; C9H10O3;�120-47-8��2� Water; H2O; �7732-18-5�



Miyamoto



t / °C log10 s1

103c1 /mol cm−3

�compiler�

30 −2.20 6.31

aIn the original paper, s is the solubility in moles per liter.



013101-26 GOTO ET AL.

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Source and Purity of Materials:Purest grade ethylparaben was obtained from commercial sources�Aldrich, Eastman, and Fluka� and was used as received.




Variables: Prepared by:T /K=273.2–331.2 A. Goto and H. Miyamoto



T /K 105x1a

273.2 4.01278.2 4.58283.2 5.31288.2 6.23293.2 7.39298.2 8.87303.2 10.7308.2 13.1313.2 16.2318.2 20.2323.2 25.3328.2 31.9331.2 37.6

aThe solubility was calculated from the regression equation at round tem-peratures by the compiler.


Methods/Apparatus/Procedure:The details of the solubility measurements were identical to those given inthe compilation of Ref. 46 for the methylparaben–water system in Sec.2.2.1.1. The solubility was determined by UV spectroscopy.

Source and Purity of Materials:Ethylparaben was supplied by B.D.H. Chemicals, Toronto, and wasrecrystallized from toluene to constant melting point. The water wasdouble-distilled in an all-glass apparatus.


Results were analyzed from the observed data with thesat
equation ln x1 =−�a /R��1 /T�+ �b /R�ln T+C.



t / °C na−a /RK−1 sb tc b /R sb tc C

0.00–58.5 14 13 977 1832 7.6 58.04 6.09 9.5 −386.9

Correlation coefficientln x1

sat vs 1 /Tr

ln x1sat vs ln T

rMultiple

r2

−0.990 0.993 0.998

aNumber of mean data points.bStandard deviation of the regression coefficient.cStudent’s t-value; all significant at the 5% level.

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,ethyl ester �ethylp-hydroxybenzoate acid;ethylparaben�; C9H10O3;�120-47-8��2� Water; H2O; �7732-18-5�



Miyamoto



t / °Cx1

�compiler�

27 0.000 102



Source and Purity of Materials:Ethylparaben of high purity was obtained from Sigma Chemical Companyand used as received. The m.p. was 116 °C and the value agreed with thatreported in Ref. 46.

Estimated Errors:Solubility: the variation among triplicate samples was �5%.Temperature: �0.2 °C.






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T /K 105x1

273.15 4.238278.15 4.800283.15 5.566288.15 6.499293.15 7.891298.15 9.918303.15 10.323308.15 13.554310.15 15.606313.15 17.140318.15 21.125323.15 27.312328.15 33.191331.15 39.329

aUnpublished data provided by D.J.W. Grant and M. Mehdizadeh were usedto fit the theoretical equation. Analysis procedure was given in the originalpaper. Also, see Ref. 46.





2.2.1.3. Propylparaben

Components Evaluators:�1� Benzoic acid, 4-hydroxy-,propyl ester �propylp-hydroxybenzoate;propylparaben�; C10H12O3;�94-13-3��2� Water; H2O �7732-18-5�


Critical EvaluationTABLE 14. Summary of experimental solubility data of propylparaben inwater


273.15 0.132 Spectrophotometry 45273.2 0.137a Spectrophotometry 46278.15 0.159 Spectrophotometry 45278.2 0.161a Spectrophotometry 46283.15 0.193 Spectrophotometry 45283.2 0.194a Spectrophotometry 46288.15 0.225 Spectrophotometry 45288.2 0.235a Spectrophotometry 46288.2 0.211 Spectrophotometry 48288.2 0.205 Spectrophotometry 47293.15 0.272 Spectrophotometry 45


TABLE 14. Summary of experimental solubility data of propylparaben inwater—Continued


293.2 0.29a Spectrophotometry 46293.2 0.241 Spectrophotometry 47298.15 0.318 Spectrophotometry 45298.2 0.286 Gravimetry 51298.2 0.257 Spectrophotometry 50298.2 0.361a Spectrophotometry 46298.2 0.332 Spectrophotometry 48298.2 0.257 Spectrophotometry 47298.2 0.37 Spectrophotometry 57300.2 0.22 Spectrophotometry 58300.2 0.436a Spectrophotometry 59303.15 0.407 Spectrophotometry 45303.2 0.21 Not stated 60303.2 0.447 Spectrophotometry 61303.2 0.455a Spectrophotometry 46303.2 0.44 Spectrophotometry 57308.15 0.552 Spectrophotometry 45308.2 0.581a Spectrophotometry 46308.2 0.55 Spectrophotometry 57310.15 0.628 Spectrophotometry 45313.15 0.852 Spectrophotometry 45313.2 0.707 Spectrophotometry 48313.2 0.747a Spectrophotometry 46313.2 0.73 Spectrophotometry 57318.15 0.950 Spectrophotometry 45318.2 0.971 Spectrophotometry 46323.15 1.29 Spectrophotometry 45323.2 1.27a Spectrophotometry 46323.2 1.17 Spectrophotometry 48328.2 1.68a Spectrophotometry 46

aThe mole-fraction solubilities were calculated based upon m1 /mol kg−1 orw1.

The critical evaluation was carried out as described inSec. 2.2.1.1 for methylparaben in water:


trationAnalytical methods: spectrophotometry and gravimetryData in Table 14 for the solubility of propylparaben in

water expressed by mole fraction were fitted to Eqs. �1� and�2� given in Sec. 1.3. The data points very closely agree withEq. �1� in the whole range of temperatures, as shown in Fig.6, but they deviate from Eq. �2� in the range of higher andlower temperatures. Multiple regression analysis accordingto Eq. �1� gave the following results:

Multiple correlation coefficient: 0.997Sample size: 33p-value �F test�: 0.000Constants: A=17 660�2103, B=72.80�7.04, C=


the black line corresponds to calculated values according toEq. �1� �ln x1=17 660 /T+72.80 ln T−484.3�. The observed


013101-28 GOTO ET AL.

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273.2–328.2 K selected from among the sources in Table 14,


temperature.

TABLE 15. Observed data and recommended values calculated according toEq. �1� for propylparaben in water

T /K 104x1�obs� 104x1�rec�

273.2 0.137 0.135278.2 0.161 0.158283.2 0.194 0.189288.2 0.235 0.229293.2 0.29 0.281298.2 0.361 0.351303.2 0.44 0.444308.2 0.581 0.567310.15 0.628 0.626313.2 0.73 0.733318.15 0.95 0.955318.2 0.971 0.958323.2 1.27 1.263328.2 1.68 1.68

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,propyl ester �propylp-hydroxybenzoate;propylparaben�; C10H12O3;�94-13-3��2� Water; H2O; �7732-18-5�



Miyamoto

FIG. 6. Fitting curve of Eq. �1� and the observed data for propylparaben inwater.



Solubility of propylparaben in water


t / °C 105x1

25 3.730 4.435 5.540 7.3



Source and Purity of Materials:Propylparaben: Lot PX 1910, Matheson, Coleman, and Bell.The solute was within 1 °C of the literature melting point value.







t / °C log10 sobs

103c1 /mol dm−3

�compiler�

25 −2.59 2.57

aIn the original paper, s is the solubility in moles per liter.



Source and Purity of Materials:No information on source and purification of the materials was reported.The m.p. of propylparaben was 96 °C.




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60C. McDonald and C.Richardson, J. Pharm. Pharmacol.33, 38 �1981�.


Miyamoto



t / °C102c1 /mol dm−3

�compiler�

30 0.21


Methods/Apparatus/Procedure:Not stated.








t / °C log10 s1

103c1 /mol cm−3

�compiler�

30 −2.35 4.47



Source and Purity of Materials:Propylparaben of purest grade was obtained from commercial sources�Aldrich, Eastman, and Fluka� and was used as received.








T /K 105x1a

273.2 1.37278.2 1.61283.2 1.94288.2 2.35293.2 2.90298.2 3.61303.2 4.55308.2 5.81313.2 7.47318.2 9.71323.2 12.7328.2 16.8

aThe solubility was calculated from the regression equation at round tem-




Source and Purity of Materials:The propylparaben was supplied by B.D.H. Chemicals, Toronto, and wasrecrystallized from toluene to constant melting point. The water wasdouble-distilled in an all-glass apparatus.



equation ln x1sat=−�a /R��1 /T�+ �b /R�ln T+C.



013101-30 GOTO ET AL.

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t / °C na−a /RK−1 sb tc b /R sb tc t

0.00–55.0 13 16 194 4501 3.6 67.81 15.05 4.5 −450.9

Correlation coefficient

ln x1sat vs 1 /T

rln x1

sat vs ln Tr

Multipler2

−0.988 0.991 0.992







T /K 105x1

273.15 1.3175278.15 1.5880283.15 1.9307288.15 2.2486293.15 2.7195298.15 3.1817303.15 4.0655308.15 5.5164310.15 6.2766313.15 8.5245318.15 9.5012323.15 12.9076

aUnpublished data provided by D.J.W. Grant and M. Mehdizadeh were used

to fit the theoretical equation. Analysis procedure was given in the original

paper. Also, see Ref. 46.







2.2.1.4. Butylparaben

Components: Evaluators:�1� Benzoic acid, 4-hydroxy-,butyl ester �butylp-hydroxybenzoate;butylparaben�; C11H14O3;�94-26-8��2� Water; H2O; �7732-18-5�


Critical EvaluationTABLE 16. Summary of experimental solubility data of butylparaben inwater


273.15 0.0986 Spectrophotometry 45273.2 0.103a Spectrophotometry 46278.15 0.110 Spectrophotometry 45278.2 0.121a Spectrophotometry 46283.15 0.138 Spectrophotometry 45283.2 0.143a Spectrophotometry 46288.15 0.163 Spectrophotometry 45288.2 0.169a Spectrophotometry 46288.2 0.0704 Spectrophotometry 47293.15 0.196 Spectrophotometry 45293.2 0.107 Spectrophotometry 42293.2 0.202a Spectrophotometry 46293.2 0.0835 Spectrophotometry 47298.15 0.229 Spectrophotometry 45298.2 0.0747 Gravimetry 51298.2 0.129 Spectrophotometry 50298.2 0.242a Spectrophotometry 46298.2 0.105 Spectrophotometry 47298.2 0.23 Spectrophotometry 57300.2 0.12 Spectrophotometry 58300.2 0.11 Spectrophotometry 5303.15 0.255 Spectrophotometry 45303.2 0.117 Spectrophotometry 61303.2 0.292a Spectrophotometry 46303.2 0.289a Spectrophotometry 61303.2 0.32 Spectrophotometry 57308.15 0.350 Spectrophotometry 45308.2 0.353a Spectrophotometry 46308.2 0.4 Spectrophotometry 57313.2 0.47 Spectrophotometry 57

aThe mole-fraction solubilities were calculated based on m1 /mol kg−1 or w1.

The critical evaluation was carried out as described inSec. 2.2.1.1:

The number of publications: 10The range of temperature: 273.15–313.2 KThe unit: mole fraction, and molar concentrationAnalytical methods: gravimetry, and spectrophotometryData in Table 16 for the solubility of butylparaben in

water expressed by mole fraction were fitted to Eqs. �1� and�2� given in Sec. 1.3. The data points closely agree with Eq.�1� in the whole range of temperatures, as shown in Fig. 7,but they deviate from Eq. �2� in the range of higher andlower temperature. The results of multiple regression analy-
sis according to Eq. �1� were as follows:


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the black line corresponds to calculated values according toEq. �1� �ln x1=15130 /T+62.77 ln T−419.0�. The observeddata fit closely with the calculated line in the range of273.2–313.2 K, with the multiple correlation coefficient of0.994, as shown in Fig. 7. Therefore, the calculated value ateach measured temperature is reasonably considered as a rec-ommended value in the whole range of temperature.

Table 17 shows typical observed data in the range of273.2–313.2 K selected from among the sources in Table 16and the recommended values calculated from Eq. �1� at eachtemperature.

TABLE 17. Observed data and recommended values calculated according toEq. �1� for butylparaben in water

T /K 104x1�obs� 104x1�rec�

273.2 0.103 0.101278.2 0.121 0.117283.2 0.143 0.137288.2 0.169 0.163293.2 0.202 0.196298.2 0.242 0.238303.2 0.292 0.293308.2 0.353 0.364313.2 0.47 0.456

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,butyl ester �butylp-hydroxybenzoate;butylparaben�; C11H14O3;�94-26-8��2� Water; H2O; �7732-18-5�



FIG. 7. Fitting curve of Eq. �1� and the observed data for butylparaben inwater.


Solubility of butylparaben in water


t / °C 103c1 /mol dm−3

27 1.1


Methods/Apparatus/Procedure:The procedure was identical to that given in the compilation of Ref. 5 forthe methylparaben–water system in Sec. 2.2.1.1. The measurement wascarried out by spectroscopy.

Source and Purity of Materials:Butylparaben was of reagent grade. Water was purified by distillation fromde-ionized water.





Miyamoto



t / °C 105x1

25 2.330 3.235 4.040 4.7



Source and Purity of Materials:Butylparaben: J.T. Baker Chemical Co.The solute was within 1 °C of the literature melting point value.




013101-32 GOTO ET AL.

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Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,butyl ester �butylp-hydroxybenzoate;butylparaben� C11H14O3;�94-26-8��2� Water; H2O; �7732-18-5�





t / °C log10 sobs

103c1 /mol dm−3

�compiler�

25 −2.89 1.29



Source and Purity of Materials:No information of source and purification of the materials were reported.Melting point of butylparaben was 68 °C.







t / °C log10 s1

103c1 /mol dm−3

�compiler�

30 −2.93 1.17

a In the original paper, s is the solubility in moles per liter.





Source and Purity of Materials:Butylparaben of purest grade was obtained from commercial sources�Aldrich, Eastman, and Fluka� and was used as received.







T /K 105x1a

273.2 1.03278.2 1.21283.2 1.43288.2 1.69293.2 2.02298.2 2.42303.2 2.92308.2 3.53

a The solubility was calculated from the regression equation at round tem-




Source and Purity of Materials:The butylparaben was supplied by B.D.H. Chemicals, Toronto, and wasrecrystallized from toluene to constant melting point. The water wasdouble-distilled in an all-glass apparatus.



equation ln x1sat=−�a /R��1 /T�+ �b /R�ln T+C.



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t / °C na−a /RK−1 sb tc b /R sb tc t

0.00–35.0 8 7813 7399 1.1 37.15 25.52 1.5 −248.5Correlation coefficient

ln x1sat vs 1 /T

rln x1

sat vs 1 /Tr

Multipler2

−0.993 0.994 0.991



45R.J. Prankerd, Int. J. Pharm.84, 233 �1992�.




T /K 105x1

273.15 0.9860278.15 1.0976283.15 1.3819288.15 1.6332293.15 1.9596298.15 2.2862303.15 2.5485308.15 3.5017

aUnpublished data provided by D.J.W. Grant and M. Mehdizadeh were used

to fit the theoretical equation. Analysis procedure was given in the original

paper. Also, see Ref. 46.






2.3. Solubility of hydroxybenzoic acid salt–watersystems

2.3.1. Singly substituted hydroxybenzoic acid salts

2.3.1.1. 2-Hydroxybenzoic acid salts

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-,monolithium salt �lithiumsalicylate�; C7H5O3Li; �552-38-5��2� Water; H2O; �7732-18-5�

62N.V. Sidgwick and E.K.Ewbank, J. Chem. Soc. 1922,1844.

Variables: Prepared by:T /K=270.94–411.2 H. Miyamoto

Solubility of lithium salicylate in water


Solid phaseat / °C 100w1 100x1

−2.26 10.17 1.396 A−5.56 20.62 3.145 A

−12.82 35.83 6.525 A−8.5 45.25 9.365 B−1.0 49.04 10.74 B

9.0 52.45 12.12 C3.5b 52.96 12.34 B

10.0 52.96 12.34 C28.5 56.50 15.41 C32.0 57.50 15.98 C38.5 59.67 17.22 C52.0b 64.18 20.13 C60.0b 66.56 21.87 C73.0 66.56 21.87 D

113.0 71.46 26.04 D

aA=ice; B=lithium salicylate hexahydrate; C=lithium salicylate monohy-drate; D=lithium salicylate anhydride.bMetastable point.


Methods/Apparatus/Procedure:The content of the salt was determined by evaporating to dryness. At hightemperatures, the solubility measurements were made synthetically, byenclosing weighed quantities of the salt and water in small tubes andobserving the temperatures at which the last crystals disappeared on slowwarming. The components of the solid phases were determined by directanalysis and/or the residue method. The amount of water in each phasewas estimated by drying at 100 °C.

Source and Purity of Materials:Lithium salicylate was made by precipitating lithium sulfate solution withbarium salicylate.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-,monosodium salt �sodiumsalicylate�; C7H5O3Na; �54-21-7��2� Water; H2O; �7732-18-5�




013101-34 GOTO ET AL.

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Variables: Prepared by:t / °C=−0.77–137.0 H. Miyamoto

Solubility of sodium salicylate in water



−0.77 4.94 0.581 A−0.77 13.15 1.675 A−5.04b 21.18 2.935 A−1.5 20.06 2.746 B

9.0 29.61 4.519 B12.5 35.03 5.718 B15.2 40.48 7.107 B17.5 44.40 8.242 B20.0 50.00 10.11 B47.5 55.10 12.08 C78.5 59.32 14.09 C

114.0 64.16 16.77 C137.0 67.95 19.27 C

aA=ice; B=sodium salicylate hexahydrate; C=sodium salicylate anhydride.bMetastable point.


Methods/Apparatus/Procedure:See the compilation of Ref. 62 for the system lithium salicylate–water.

Source and Purity of Materials:Sodium salicylate was prepared by neutralizing salicylic acid with thecorresponding hydroxide or carbonate.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-,monopotassium salt �potassiumsalicylate�; C7H5O3K; �578-36-9��2� Water; H2O; �7732-18-5�



Solubility of potassium salicylate in water



−1.82 10.49 1.185 A−3.47 18.82 2.316 A−6.52 31.15 4.422 A−8.00 35.80 5.394 A

0 44.08 7.464 B9.0 49.19 8.450 B

24.0 53.33 10.46 B28.5 55.82 11.45 B61.0 61.31 13.95 C

103.8 68.97 18.53 C108.5 70.20 19.42 C



Solubility of potassium salicylate in water



138.2 74.80 23.29 C

a A=ice; B=potassium salicylate monohydrate; C=potassium salicylate an-

hydride.



Source and Purity of Materials:Potassium salicylate was prepared by the same method as sodiumsalicylate.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-,monorubidium salt �rubidiumsalicylate�; C7H5O3Rb;�45749-39-1��2� Water; H2O; �7732-18-5�



Solubility of rubidium salicylate in water



−1.62 12.34 1.127 A−3.69 23.48 2.424 A−6.34 33.81 3.968 A−8.82 42.77 5.706 A

−13.17 53.40 8.488 A8.0 64.85 12.99 B

21.5 68.15 14.77 B27.0 69.84 15.79 B49.0 74.97 19.53 B73.0 77.96 22.26 B88.0 79.89 24.34 B

134.0 86.36 33.88 B

aA=ice; B=rubidium salicylate monohydrate.



Source and Purity of Materials:Rubidium salicylate was prepared by neutralizing salicylic acid with thecorresponding hydroxide or carbonate. Rubidium carbonate was preparedfrom a specimen of the alum. The salt obtained was testedspectroscopically, and found to be free from other alkali metals.



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Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-,monocesium salt �cesiumsalicylate�; C7H5O3Cs;�15092-48-2��2� Water; H2O; �7732-18-5�



Solubility of cesium salicylate in water



−1.83 16.08 1.264 A−4.24 30.97 2.907 A−8.08 47.71 5.740 A−3.5 65.70 11.32 B

4.5 68.24 12.53 B20.5 74.59 16.37 B33.0 80.07 21.13 B41.5 83.35 25.03 C54.0 85.67 28.50 C67.5 89.91 37.28 C84.3 92.80 46.00 D

107.0 94.33 52.58 D

aA=ice; B=cesium salicylate monohydrate; C=cesium salicylate hemihy-

drate; D=cesium salicylate anhydride.bMetastable point.



Source and Purity of Materials:Cesium salt was made from a specimen of American pollucite. Thecesium salt was tested spectroscopically, and found to be free from otheralkali metals.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-,silver salt �silver salicylate�;C7H6O3Ag; �528-93-8��2� Water; H2O; �7732-18-5�

63I. M. Kolthoff, J.J. Lingane,and W.D. Larson, J. Am. Chem.Soc. 60, 2512 �1938�.

Variables: Prepared by:t / °C=25 H. Miyamoto


Solubility of silver salicylate in water


t / °C 103c1 /mol dm−3

25 4.42


Methods/Apparatus/Procedure:Saturated solution of the silver salt was prepared in conductance cellsthrough which a stream of previously dried nitrogen, saturated with thevapor of the solvent, was led to provide stirring. When the conductancehad become constant, samples of the saturated aqueous solutions werewithdrawn and analyzed for silver by the potentiometric method. Thesolubilities in ethanol and methanol were determined by the conductancemethod. The conductance cells were of the type used by I.M. Kolthoffand A. Willman, J. Am. Chem. Soc. 56, 1008 �1934�. Their cell constantswere determined in the usual way. The specific conductance of methanolat 25 °C varied from 2.9 to 5.0 and the range in the corresponding valuesfor ethanol was from 0.4�10−4 to 1.2�10−4 cm−1 �−1. The conductanceof the alcohol was subtracted from the observed specific conductancewhere necessary.

Source and Purity of Materials:Ethanol and methanol were refluxed over silver oxide, distilled, anddehydrated with magnesium. The water content of methanol ranged from0% to 0.03%, while that of ethanol varied from 0.01% to 0.07%. Thesilver salt of the acid was precipitated from solution of the correspondingsodium salt with a slight excess of silver nitrate. The precipitates werewashed and recrystallized from hot water. The product was washed withwater, then with ethanol, and air dried.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-,silver salt �silver salicylate�;C7H6O3Ag; �528-93-8��2� Water; H2O; �7732-18-5�

64N.A. Izmailov and V.S.Chernyi, Zh. Fiz. Khim. 34, 319�1960� �Russ. J. Phys. Chem.�Engl. Transl.� 34, 149 �1960��.


Solubility of silver salicylate in water


t / °C 103m1 /mol kg−1

25 4.38



013101-36 GOTO ET AL.

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Methods/Apparatus/Procedure:The solubility determination of the silver salt used the radioactive isotope110Ag. The silver salt with solvent was placed in a tube, sealed, andplaced in an air thermostat. Equilibrium was reached in 16–18 h. Thesolution removed from the tube was centrifuged. The samples werewithdrawn by a micropipette and run on to a disk of filter paper, dried,and sealed in tracing cloth or Cellophane. The prepared specimens werefound on a cylindrical counter and their radioactivity was measured. Themethods of preparing saturated solutions, sampling, and the radioactivemeasurement are described by N.A. Izmailov and V.S. Chernyi, Zh. Fiz.Khim. 34, 127 �1960�; Russ. J. Phys. Chem. �Engl. Transl.� 34, 59 �1960�.The concentration of silver salicylate was analyzed for the silver content.

Source and Purity of Materials:The silver salt of salicylic acid was prepared from silver nitrate labeledwith radioactive 110Ag and the sodium or potassium salts of the acid.

Estimated Errors:Solubility: relative accuracy is 1%–3% at a confidence limit of 0.95.Temperature: precision �0.5 °C.


Components: Original Measurements:�1� Benzoic acid, 3-hydroxy-,monolithium salt �lithium3-hydroxybenzoate�; C7H5O3Li;� ��2� Water; H2O; �7732-18-5�



Solubility of lithium 3-hydroxybenzoate in water



−4.41 16.02 2.33 A−10.78 29.58 4.99 A−17.67 39.97 7.68 A

10.0 52.53 13.46 B74.5 55.04 14.68 B

104.0 58.47 16.52 B122.0 61.86 18.57 B

aA=ice; B=lithium 3-hydroxybenzoate anhydride.


Methods/Apparatus/Procedure:The synthetic method was used. The experimental details were given inthe compilation of Ref. 62 for the lithium salicylate–water system in Sec.2.3.1.1.

Source and Purity of Materials:Lithium salt of 3-hydroxybenzoic acid was made by precipitating lithiumsulfate solution with the barium salt of the corresponding acid.




Components: Original Measurements:�1� Benzoic acid, 3-hydroxy-,monosodium salt �sodium3-hydroxybenzoate�; C7H5O3Na;�7720-19-6��2� Water; H2O; �7732-18-5�



Solubility of sodium 3-hydroxybenzoate in water



−3.21 14.68 1.899 A−8.85 30.53 4.71 A

−17.52 45.16 8.48 A10.0 58.78 13.82 B

110.0 64.61 17.94 B147.5 69.75 20.60 B

aA=ice; B=sodium 3-hydroxybenzoate anhydride.



Source and Purity of Materials:Sodium salt of 3-hydroxybenzoic acid was prepared by neutralizing3-hydroxybenzoic acid with the corresponding hydroxide or carbonate.


Components: Original Measurements:�1� Benzoic acid, 3-hydroxy-,monopotassium salt �potassium3-hydroxybenzoate�; C7H5O3K;�17361-85-2��2� Water; H2O; �7732-18-5�



Solubility of potassium 3-hydroxybenzoate in water



−2.41 12.39 1.43 A−5.06 22.25 2.775 A−8.59 31.34 4.46 A

−19.92 49.39 9.07 A10.0 59.04 12.85 B33.5 61.94 14.27 B95.0 69.60 18.98 B

136.8 75.02 23.52 B

a
A=ice; B=potassium 3-hydroxybenzoate anhydride.


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Source and Purity of Materials:Potassium salt of 3-hydroxybenzoic acid was prepared by neutralizing3-hydroxybenzoic acid with the corresponding hydroxide or carbonate.


Components: Original Measurements:�1� Benzoic acid, 3-hydroxy-,monorubidium salt �rubidium3-hydroxybenzoate�; C7H5O3Rb;� ��2� Water; H2O; �7732-18-5�



Solubility of rubidium 3-hydroxybenzoate in water



−2.23 14.92 1.399 A−6.41 32.13 3.690 A

−13.69 48.88 7.184 A+B14.0 50.61 7.658 B32.5 54.94 8.982 B45.0 60.02 10.83 B64.0 65.04 13.10 C88.0 70.45 16.17 C

105.0 74.49 19.11 C130.0 79.91 24.35 C

aA=ice; B=rubidium 3-hydroxybenzoate monohydrate; C=rubidium

3-hydroxybenzoate anhydride.



Source and Purity of Materials:Rubidium salt of 3-hydroxybenzoic acid was prepared by neutralizing theacid with the corresponding hydroxide or carbonate. Rubidium carbonatewas prepared from a specimen of the alum. The salt obtained was testedspectroscopically and found to be free from other alkali metals.



Components: Original Measurements:�1� Benzoic acid, 3-hydroxy-,monocesium salt �cesium3-hydroxybenzoate�; C7H5O3Cs;� ��2� Water; H2O; �7732-18-5�



Solubility of cesium 3-hydroxybenzoate in water



−1.97 16.98 1.348 A−4.92 32.84 3.160 A−9.65 48.52 5.919 A

−18.50 63.15 10.25 A10.0 77.10 18.34 B19.0 78.52 19.61 B29.0 81.70 22.95 B35.0 84.45 26.60 B40.0 86.35 29.67 B41.5b 87.88 32.60 C73.0 89.88 37.21 C

126.5 93.42 48.64 C

aA=ice; B=cesium 3-hydroxybenzoate monohydrate; C=cesium

3-hydroxybenzoate anhydride.bMetastable point.



Source and Purity of Materials:Cesium salt of 3-hydroxybenzoic acid was made from a specimen ofAmerican pollucite. The cesium salt was tested spectroscopically, andfound to be free from other alkali metals.



Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,monolithium salt �lithium4-hydroxybenzoate�; C7H5O3Li;�61937-89-1��2� Water; H2O; �7732-18-5�





013101-38 GOTO ET AL.

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Solubility of lithium 4-hydroxybenzoate in water



−0.98 5.04 0.659 A−2.37 9.81 1.341 A−5.23 17.88 2.650 A−9.28 25.96 4.199 A

−12.62 b 31.54 5.488 A12.5 30.84 5.280 B

0 30.92 5.299 B85.0 31.96 5.557 B

113.0 35.00 6.308 B

aA=ice; B= lithium 4-hydroxybenzoate anhydride.bMetastable point.



Source and Purity of Materials:Lithium salt of 4-hydroxybenzoic acid was made by precipitating lithiumsulfate solution with the barium salt of the corresponding acid.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,monosodium salt �sodium4-hydroxybenzoate�; C7H5O3Na;�114-63-6��2� Water; H2O; �7732-18-5�



Solubility of sodium 4-hydroxybenzoate in water



−0.77 5.075 0.597 A−2.07 10.43 1.293 A

7.0 19.65 2.678 B24.0 31.47 4.914 B36.5 41.32 7.342 B39.0b 45.61 8.623 B43.0 45.61 8.623 C

107.5 50.51 10.30 C163.0 54.93 12.06 C

aA=ice; B=sodium 4-hydroxybenzoate pentahydrate; C=sodium

4-hydroxybenzoate anhydride.bMetastable point.





Source and Purity of Materials:Sodium salt of 4-hydroxybenzoic acid was prepared by neutralizing4-hydroxybenzoic acid with the corresponding hydroxide or carbonate.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,monopotassium salt �potassium4-hydroxybenzoate�; C7H5O3K;�13639-20-8��2� Water; H2O; �7732-18-5�



Solubility of potassium 4-hydroxybenzoate in water



−1.43 8.04 0.821 A−3.24 15.55 1.848 A15.8 29.91 4.184 B25.8 35.50 5.355 B43.0 45.71 7.932 B64.4 56.70 11.82 B70.5 59.34 12.99 B86.8 63.01 14.84 C

129.5 64.95 15.94 C

aA=ice; B=potassium 4-hydroxybenzoate trihydrate; C=potassium4-hydroxybenzoate anhydride.


Methods/Apparatus/Procedure:The synthetic method was used. The details were given in the compilationof Ref. 62 for the lithium salicylate–water system in Sec. 2.3.1.1.

Source and Purity of Materials:Potassium salt of 4-hydroxybenzoic acid was prepared by neutralizing theacid with the corresponding hydroxide or carbonate.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,monorubidium salt �rubidium4-hydroxybenzoate�; C7H5O3Rb;� ��2� Water; H2O; �7732-18-5�





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Solubility of rubidium 4-hydroxybenzoate in water



−1.17 9.92 0.883 A−2.47 17.47 1.685 A−4.22 26.22 2.798 A17.5 35.66 4.297 B45.0 45.95 6.441 B68.0 55.73 9.248 B94.0 64.95 13.04 C

120.5 74.00 18.72 C127.0 75.92 20.33 C

aA=ice; B=rubidium 4-hydroxybenzoate monohydrate; C=rubidium4-hydroxybenzoate anhydride.



Source and Purity of Materials:Rubidium salt of 4-hydroxybenzoic acid was prepared by neutralizing theacid with the corresponding hydroxide or carbonate. Rubidium carbonatewas prepared from a specimen of the alum. The salt obtained was testedspectroscopically and found to be free from other alkali metals.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,monocesium salt �cesium4-hydroxybenzoate�; C7H5O3Cs;� ��2� Water; H2O; �7732-18-5�

62N.V. Sidgwick and E.K.Ewbank, J. Chem. Soc.1922, 1844.


Solubility of cesium 4-hydroxybenzoate in water



−1.56 4.34 1.103 A−2.42 20.38 1.677 A−4.27b 29.57 2.723 A

3.5 29.57 2.723 B27.5 40.80 4.395 B49.0 50.07 6.268 B75.5 60.36 9.222 C90.3 65.35 11.17 C

107.5 70.67 13.85 C118.0 73.84 15.84 C136.0 79.88 20.93 C

aA=ice; B=cesium 4-hydroxybenzoate monohydrate; C=cesium4-hydroxybenzoate anhydride.b
Metastable point.



Source and Purity of Materials:Cesium salt of 4-hydroxybenzoic acid was made from a specimen ofAmerican pollucite. The cesium salt obtained was tested spectroscopically,and found to be free from other alkali metals.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,silver salt �silver4-hydroxybenzoate�; C7H5O3Ag;� ��2� Water; H2O; �7732-18-5�

64N.A. Izmailov and V.S.Chernyi, Zh. Fiz. Khim. 34, 319�1960� �Russ. J. Phys. Chem.�Engl. Transl.� 34, 149 �1960��.


Solubility of silver 4-hydroxybenzoate in water


t / °C 103m1 /mol kg−1

25 9.43


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 64 for thesilver salicylate–water system of the paper by the authors in Sec. 2.3.1.1.

Source and Purity of Materials:The silver salt of 4-hydroxybenzoic acid was prepared from silver nitratelabeled with radioactive 110Ag.

Estimated Errors:Solubility: relative accuracy is 1%–3 % at a confidence limit of 0.95.Temperature: precision �0.5 °C.

2.3.2. Dihydroxybenzoic acid salts

2.3.2.1. 2,3-Dihydroxybenzoic acid salts

Components: Original Measurements:�1� Cerium2,3-dihydroxybenzoate;C21H15O12Ce; � ��2� Water; H2O; �7732-18-5�

65A. Kula and W. Brzyska, PolishJ. Chem. 74, 45 �2000�.

Variables: Prepared by:T /K=293 H. Miyamoto



013101-40 GOTO ET AL.

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Solubility of cerium 2,3-dihydroxybenzoate in water


T /K 103c1 /mol dm−3

293 0.9


Methods/Apparatus/Procedure:The solubility of cerium 2,3-dihydroxybenzoate in water at 293 K underisothermal condition was determined by a Specord M-40spectrophotometer, using arsenazo III.

Source and Purity of Materials:The complex of Ce�III� with 2,3-dihydroxybenzoic acid was obtained bydissolving the freshly precipitated Ce�III� carbonate in a solution of2,3-dihydroxybenzoic acid and crystallizing at room temperature. Theprecipitates formed were filtered off, washed with water, and dried at303 K to a constant mass. The composition of the prepared complex wasdetermined by elemental analysis, by ignition of the complex to the oxideand from a TG curve. The Ce�III� complex was prepared as a crystallinesolid with a molar ratio of metal to organic ligand of 1:3 and formulaCe�C6H3�OH�2COO�3.


Components: Original Measurements:�1� Dysprosium2,3-dihydroxybenzoatetetrahydrate;C21H15O12Dy·4H2O; � ��2� Water; H2O; �7732-18-5�



Solubility of dysprosium 2,3-dihydroxybenzoate in water



293 5.8


Methods/Apparatus/Procedure:The solubility of dysprosium 2,3-dihydroxybenzoate in water at 293 Kunder isothermal condition was determined by a Specord M-40spectrophotometer, using arsenazo III.

Source and Purity of Materials:The complex of Dy�III� with 2,3-dihydroxybenzoic acid was obtained bythe same method as for cerium 2,3-dihydroxybenzoate using Dy�III�carbonate �the formula of the complex: �Dy�C6H3�OH�2COO�3� ·4H2O�.




Components: Original Measurements:�1� Erbium2,3-dihydroxybenzoatetetrahydrate; C21H15O12Er·4H2O;� ��2� Water; H2O; �7732-18-5�



Solubility of erbium 2,3-dihydroxybenzoate in water



293 4.0


Methods/Apparatus/Procedure:The solubility of erbium 2,3-dihydroxybenzoate in water at 293 K underisothermal condition was determined by a Specord M-40spectrophotometer, using arsenazo III.

Source and Purity of Materials:The complex of Er�III� with 2,3-dihydroxybenzoic acid was obtained bythe same method as for cerium 2,3-dihydroxybenzoate using Er�III�carbonate �the formula of the complex: �Er�C6H3�OH�2COO�3� ·4H2O�.


Components: Original Measurements:�1� Europium2,3-dihydroxybenzoate;C21H15O12Eu; � ��2� Water; H2O; �7732-18-5�



Solubility of europium 2,3-dihydroxybenzoate in water



293 10.3


Methods/Apparatus/Procedure:The solubility of europium 2,3-dihydroxybenzoate in water at 293 Kunder isothermal condition was determined by a Specord M-40spectrophotometer, using arsenazo III.

Source and Purity of Materials:The complex of Eu�III� with 2,3-dihydroxybenzoic acid was obtained bythe same method as for cerium 2,3-dihydroxybenzoate using Eu�III�carbonate �the formula of the complex: Eu�C6H3�OH�2COO�3�.




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Components: Original Measurements:�1� Gadolinium2,3-dihydroxybenzoate;C21H15O12Gd; � ��2� Water; H2O; �7732-18-5�



Solubility of gadolinium 2,3-dihydroxybenzoate in water



293 9.7


Methods/Apparatus/Procedure:The solubility of gadolinium 2,3-dihydroxybenzoate in water at 293 Kunder isothermal condition was determined by a Specord M-40spectrophotometer, using arsenazo III.

Source and Purity of Materials:The complex of Gd�III� with 2,3-dihydroxybenzoic acid was obtained bythe same method as for cerium 2,3-dihydroxybenzoate using Gd�III�carbonate �the formula of the complex: Gd�C6H3�OH�2COO�3�.


Components: Original Measurements:�1� Holmium2,3-dihydroxybenzoatetetrahydrate;C21H15O12Ho·4H2O; � ��2� Water; H2O; �7732-18-5�



Solubility of holmium 2,3-dihydroxybenzoate in water



293 4.7


Methods/Apparatus/Procedure:The solubility of holmium 2,3-dihydroxybenzoate in water at 293 K underisothermal condition was determined by a Specord M-40spectrophotometer, using arsenazo III.

Source and Purity of Materials:The complex of Ho�III� with 2,3-dihydroxybenzoic acid was obtained bythe same method as for cerium 2,3-dihydroxybenzoate using Ho�III�carbonate �the formula of the complex: �Ho�C6H3�OH�2COO�3� ·4H2O�.



Components: Original Measurements:�1� Neodymium2,3-dihydroxybenzoate;C21H15O12Nd; � ��2� Water; H2O; �7732-18-5�



Solubility of neodymium 2,3-dihydroxybenzoate in water



293 2.8


Methods/Apparatus/Procedure:The solubility of neodymium 2,3-dihydroxybenzoate in water at 293 Kunder isothermal condition was determined by a Specord M-40spectrophotometer, using arsenazo III.

Source and Purity of Materials:The complex of Nd�III� with 2,3-dihydroxybenzoic acid was obtained bythe same method as for cerium 2,3-dihydroxybenzoate using Nd�III�carbonate �the formula of the complex: Nd�C6H3�OH�2COO�3�.


Components: Original Measurements:�1� Lanthanum2,3-dihydroxybenzoate;C21H15O12La; � ��2� Water; H2O; �7732-18-5�



Solubility of lanthanum 2,3-dihydroxybenzoate in water



293 1.0


Methods/Apparatus/Procedure:The solubility of lanthanum 2,3-dihydroxybenzoate in water at 293 Kunder isothermal condition was determined by a Specord M-40spectrophotometer, using arsenazo III.

Source and Purity of Materials:The complex of La�III� with 2,3-dihydroxybenzoic acid was obtained bythe same method as for cerium 2,3-dihydroxybenzoate using La�III�carbonate �the formula of the complex: La�C6H3�OH�2COO�3�.




013101-42 GOTO ET AL.

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Components: Original Measurements:�1� Lutetium2,3-dihydroxybenzoate dihydrate;C21H15O12Lu·2H2O; � ��2� Water; H2O; �7732-18-5�



Solubility of lutetium 2,3-dihydroxybenzoate in water



293 3.4


Methods/Apparatus/Procedure:The solubility of lutetium 2,3-dihydroxybenzoate in water at 293 K underisothermal condition was determined by a Specord M-40spectrophotometer, using arsenazo III.

Source and Purity of Materials:The complex of Lu�III� with 2,3-dihydroxybenzoic acid was obtained bythe same method as for cerium 2,3-dihydroxybenzoate using Lu�III�carbonate �the formula of the complex: �Lu�C6H3�OH�2COO�3� ·2H2O�.


Components: Original Measurements:�1� Praseodymium2,3-dihydroxybenzoate;C21H15O12Pr; � ��2� Water; H2O; �7732-18-5�



Solubility of praseodymium 2,3-dihydroxybenzoate in water



293 4.9


Methods/Apparatus/Procedure:The solubility of praseodymium 2,3-dihydroxybenzoate in water at 293 Kunder isothermal condition was determined by a Specord M-40spectrophotometer, using arsenazo III.

Source and Purity of Materials:The complex of Pr�III� with 2,3-dihydroxybenzoic acid was obtained bythe same method as for cerium 2,3-dihydroxybenzoate using Pr�III�carbonate �the formula of the complex: Pr�C6H3�OH�2COO�3�.




Components: Original Measurements:�1� Samarium2,3-dihydroxybenzoate;C21H15O12Sm; � ��2� Water; H2O; �7732-18-5�



Solubility of samarium 2,3-dihydroxybenzoate in water



293 4.3


Methods/Apparatus/Procedure:The solubility of samarium 2,3-dihydroxybenzoate in water at 293 Kunder isothermal condition was determined by a Specord M-40spectrophotometer, using arsenazo III.

Source and Purity of Materials:The complex of Sm�III� with 2,3-dihydroxybenzoic acid was obtained bythe same method as for cerium 2,3-dihydroxybenzoate using Sm�III�carbonate �the formula of the complex: Sm�C6H3�OH�2COO�3�.


Components: Original Measurements:�1� Terbium2,3-dihydroxybenzoate;C21H15O12Tb; � ��2� Water; H2O; �7732-18-5�



Solubility of terbium 2,3-dihydroxybenzoate in water



293 7.4


Methods/Apparatus/Procedure:The solubility of terbium 2,3-dihydroxybenzoate in water at 293 K underisothermal condition was determined by a Specord M-40spectrophotometer, using arsenazo III.

Source and Purity of Materials:The complex of Tb�III� with 2,3-dihydroxybenzoic acid was obtained bythe same method as for cerium 2,3-dihydroxybenzoate using Tb�III�carbonate �the formula of the complex: Tb�C6H3�OH�2COO�3�.




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Components: Original Measurements:�1� Thulium2,3-dihydroxybenzoatetetrahydrate;C21H15O12Tm·4H2O; � ��2� Water; H2O; �7732-18-5�



Solubility of thulium 2,3-dihydroxybenzoate in water



293 4.3


Methods/Apparatus/Procedure:The solubility of thulium 2,3-dihydroxybenzoate in water at 293 K underisothermal condition was determined by a Specord M-40spectrophotometer, using arsenazo III.

Source and Purity of Materials:The complex of Tm�III� with 2,3-dihydroxybenzoic acid was obtained bythe same method as for cerium 2,3-dihydroxybenzoate using Tm�III�carbonate �the formula of the complex: �Tm�C6H3�OH�2COO�3�·4H2O�.


Components: Original Measurements:�1� Ytterbium2,3-dihydroxybenzoate dihydrate;C21H15O12Yb·2H2O; � ��2� Water; H2O; �7732-18-5�



Solubility of ytterbium 2,3-dihydroxybenzoate in water



293 3.0


Methods/Apparatus/Procedure:The solubility of ytterbium 2,3-dihydroxybenzoate in water at 293 Kunder isothermal condition was determined by a Specord M-40spectrophotometer, using arsenazo III.

Source and Purity of Materials:The complex of Yb�III� with 2,3-dihydroxybenzoic acid was obtained bythe same method as for cerium 2,3-dihydroxybenzoate using Yb�III�carbonate �the formula of the complex: �Yb�C6H3�OH�2COO�3� ·2H2O�.



Components: Original Measurements:�1� Yttrium2,3-dihydroxybenzoatetetrahydrate; C21H15O12Y·4H2O;� ��2� Water; H2O; �7732-18-5�



Solubility of yttrium 2,3-dihydroxybenzoate in water



293 6.5


Methods/Apparatus/Procedure:The solubility of yttrium 2,3-dihydroxybenzoate in water at 293 K underisothermal condition was determined by a Specord M-40spectrophotometer, using arsenazo III.

Source and Purity of Materials:The complex of Y�III� with 2,3-dihydroxybenzoic acid was obtained bythe same method as for cerium 2,3-dihydroxybenzoate using Y�III�carbonate �the formula of the complex: �Y�C6H3�OH�2COO�3� ·4H2O�.



Components: Original Measurements:�1� Cerium,tris�2,4-dihydroxybenzoato-�O1 ,O1��dihydrate, �OC-6-11�- �cerium2,4-dihydroxybenzoatedihydrate�; C21H15CeO12·2H2O;�146716-20-3��2� Water; H2O; �7732-18-5�

66W. Brzyska and A. Kula,Thermochim. Acta 211, 199�1992�.





293 0.56


Methods/Apparatus/Procedure:The solubility of cerium 2,4-dihydroxybenzoate in water at 293 K wasgravimetrically determined by measuring the concentration of Ce�III� inthe saturated solution by the oxalate method.



013101-44 GOTO ET AL.

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Source and Purity of Materials:Cerium 2,4-hydroxybenzoate was prepared by addition of an equivalentquantity of ammonium 2,4-hydroxybenzoate �pH 5.0� to a hot solutioncontaining cerium nitrate. The precipitates formed were filtered off,washed with methanol, and dried at 303 K to a constant mass. Thequantitative compositions of the prepared complex were determined byelemental analysis. The crystallization water was determined from the TGcurve. The complex was obtained as solid with a molar ratio of metal toorganic ligand of 1:3 and formula �Ce�C6H3�OH�2COO�3� ·2H2O.


Components: Original Measurements:�1� Dysprosium, tris�2,4-dihydroxybenzoato-�O1 ,O1��tetrahydrate, �OC-6-11�-�dysprosium2,4-dihydroxybenzoatetetrahydrate�;C21H15DyO12·4H2O;�146716-26-9��2� Water; H2O; �7732-18-5�






293 3.94


Methods/Apparatus/Procedure:The solubility of dysprosium 2,4-dihydroxybenzoate in water at 293 Kwas gravimetrically determined by measuring the concentration of Dy�III�in the saturated solution by the oxalate method.

Source and Purity of Materials:Dysprosium 2,4-dihydroxybenzoate was prepared by the same method asfor cerium 2,4-dihydroxybenzoate using dysprosium chloride �the formulaof the complex: �Dy�C6H3�OH�2COO�3� ·4H2O�.


Components: Original Measurements:�1� Erbium,tris�2,4-dihydroxybenzoato-�O1 ,O1��tetrahydrate, �OC-6-11�- �erbium2,4-dihydroxybenzoatetetrahydrate�;C21H15ErO12·4H2O;�146716-28-1��2� Water; H2O; �7732-18-5�








293 4.81


Methods/Apparatus/Procedure:The solubility of erbium 2,4-dihydroxybenzoate in water at 293 K wasgravimetrically determined by measuring the concentration of Er�III� inthe saturated solution by the oxalate method.

Source and Purity of Materials:Erbium 2,4-dihydroxybenzoate was prepared by the same method as forcerium 2,4-dihydroxybenzoate using erbium chloride �the formula of thecomplex: �Er�C6H3�OH�2COO�3� ·H2O�.


Components: Original Measurements:�1� Europiumtris�2,4-dihydroxybenzoato-�O1 ,O1��dihydrate, �OC-6-11�- �europium2,4-dihydroxybenzoatedihydrate�; C21H15EuO12·2H2O;�196716-24-7��2� Water; H2O; �7732-18-5�






293 1.16


Methods/Apparatus/Procedure:The solubility of europium 2,4-dihydroxybenzoate in water at 293 K wasgravimetrically determined by measuring the concentration of Eu�III� inthe saturated solution by the oxalate method.

Source and Purity of Materials:Europium 2,4-dihydroxybenzoate was prepared by the same method as forcerium 2,4-dihydroxybenzoate using europium chloride �the formula of thecomplex: �Eu�C6H3�OH�2COO�3� ·2H2O�.




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Components: Original Measurements:�1� Gadolinium,tris�2,4-dihydroxybenzoato-�O1 ,O1��dihydrate, �OC-6-11�-�gadolinium2,4-dihydroxybenzoatedihydrate�; C21H15GdO12·2H2O;� ��2� Water; H2O; �7732-18-5�






293 1.51


Methods/Apparatus/Procedure:The solubility of gadolinium 2,4-dihydroxybenzoate in water at 293 Kwas gravimetrically determined by measuring the concentration of Gd�III�in the saturated solution by the oxalate method.

Source and Purity of Materials:Gadolinium 2,4-dihydroxybenzoate was prepared by the same method asfor cerium 2,4-dihydroxybenzoate using gadolinium chloride �the formulaof the complex: �Gd�C6H3�OH�2COO�3� ·2H2O�.


Components: Original Measurements:�1� Holmium,tris�2,4-dihydroxybenzoato�O1 ,O1�� tetrahydrate,�OC-6-11�- �holmium2,4-dihydroxybenzoatetetrahydrate�;C21H15HoO12·4H2O;�146716-27-0��2� Water; H2O; �7732-18-5�






293 3.85


Methods/Apparatus/Procedure:The solubility of holmium 2,4-dihydroxybenzoate in water at 293 K wasgravimetrically determined by measuring the concentration of Ho�III� inthe saturated solution by the oxalate method.


Source and Purity of Materials:Holmium 2,4-dihydroxybenzoate was prepared by the same method as forcerium 2,4-dihydroxybenzoate using holmium chloride �the formula of thecomplex: �Ho�C6H3�OH�2COO�3� ·4H2O�.


Components: Original Measurements:�1� Neodymium,tris�2,4-dihydroxybenzoato�O1 ,O1�� dihydrate, �OC-6-11�-�neodymium2,4-dihydroxybenzoatedihydrate�; C21H15O12Nd·2H2O;�146716-22-5��2� Water; H2O; �7732-18-5�






293 0.62


Methods/Apparatus/Procedure:The solubility of neodymium 2,4-dihydroxybenzoate in water at 293 Kwas gravimetrically determined by measuring the concentration of Nd�III�in the saturated solution by the oxalate method.

Source and Purity of Materials:Neodymium 2,4-dihydroxybenzoate was prepared by the same method asfor cerium 2,4-dihydroxybenzoate using neodymium chloride �the formulaof the complex: �Er�C6H3�OH�2COO�3� ·4H2O�.


Components: Original Measurements:�1� Lanthanum,tris�2,4-dihydroxybenzoato-�O1 ,O1��dihydrate, �OC-6-11�-�lanthanum2,4-dihydroxybenzoatedihydrate�; C21H15LaO12·2H2O;�146734-35-2��2� Water; H2O; �7732-18-5�






293 0.67



013101-46 GOTO ET AL.

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Methods/Apparatus/Procedure:The solubility of lanthanum 2,4-dihydroxybenzoate in water at 293 K wasgravimetrically determined by measuring the concentration of La�III� inthe saturated solution by the oxalate method.

Source and Purity of Materials:Lanthanum 2,4-dihydroxybenzoate was prepared by the same method asfor cerium 2,4-dihydroxybenzoate using lanthanum chloride �the formulaof the complex: �La�C6H3�OH�2COO�3� ·2H2O�.


Components: Original Measurements:�1� Lutetium,tris�2,4-dihydroxybenzoato-�O1 ,O1��tetrahydrate, �OC-6-11�-�lutetium 2,4-dihydroxybenzoatetetrahydrate�;C21H15O12Lu·4H2O;�146716-31-6��2� Water; H2O; �7732-18-5�






293 16.12


Methods/Apparatus/Procedure:The solubility of lutetium 2,4-dihydroxybenzoate in water at 293 K wasgravimetrically determined by measuring the concentration of Lu�III� inthe saturated solution by the oxalate method.

Source and Purity of Materials:Lutetium 2,4-dihydroxybenzoate was prepared by the same method as forcerium 2,4-dihydroxybenzoate using lutetium chloride �the formula of thecomplex: �Lu�C6H3�OH�2COO�3� ·4H2O�.


Components: Original Measurements:�1� Praseodymium,tris�2,4-dihydroxybenzoato-�O1 ,O1��dihydrate, �OC-6-11�-�praseodymium2,4-dihydroxybenzoatedihydrate�; C21H15O12Pr·2H2O;�146716-21-4��2� Water; H2O; �7732-18-5�








293 0.58


Methods/Apparatus/Procedure:The solubility of praseodymium 2,4-dihydroxybenzoate in water at 293 Kwas gravimetrically determined by measuring the concentration of Pr�III�in the saturated solution by the oxalate method.

Source and Purity of Materials:Praseodymium 2,4-dihydroxybenzoate was prepared by the same methodas for cerium 2,4-dihydroxybenzoate using praseodymium chloride �theformula of the complex: �Pr�C6H3�OH�2COO�3� ·2H2O�.


Components: Original Measurements:�1� Samarium,tris�2,4-dihydroxybenzoato-�O1 ,O1��dihydrate, �OC-6-11�- �samarium2,4-dihydroxybenzoatedihydrate�; C21H15O12Sm·2H2O;�146716-23-6��2� Water; H2O; �7732-18-5�






293 0.82


Methods/Apparatus/Procedure:The solubility of samarium 2,4-dihydroxybenzoate in water at 293 K wasgravimetrically determined by measuring the concentration of Sm�III� inthe saturated solution by the oxalate method.

Source and Purity of Materials:Samarium 2,4-dihydroxybenzoate was prepared by the same method as forcerium 2,4-dihydroxybenzoate using samarium chloride �the formula ofthe complex: �Sm�C6H3�OH�2COO�3� ·2H2O�.




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Components: Original Measurements:�1� Terbium,tris�2,4-dihydroxybenzoato-�O1 ,O1��tetrahydrate, �OC-6-11�- �terbium2,4-dihydroxybenzoatetetrahydrate�;C21H15O12Tb·4H2O;�146734-36-3��2� Water; H2O; �7732-18-5�






293 2.82


Methods/Apparatus/Procedure:The solubility of terbium 2,4-dihydroxybenzoate in water at 293 K wasgravimetrically determined by measuring the concentration of Tb�III� inthe saturated solution by the oxalate method.

Source and Purity of Materials:Terbium 2,4-dihydroxybenzoate was prepared by the same method as forcerium 2,4-dihydroxybenzoate using terbium chloride �the formula of thecomplex: �Tb�C6H3�OH�2COO�3� ·4H2O�.


Components: Original Measurements:�1� Thulium,tris�2,4-dihydroxybenzoato-�O1 ,O1��tetrahydrate, �OC-6-11�- �thulium2,4-dihydroxybenzoatetetrahydrate�;C21H15O12Tm·4H2O;�146716-29-2��2� Water; H2O; �7732-18-5�






293 9.84


Methods/Apparatus/Procedure:The solubility of thulium 2,4-dihydroxybenzoate in water at 293 K wasgravimetrically determined by measuring the concentration of Tm�III� inthe saturated solution by the oxalate method.


Source and Purity of Materials:Thulium 2,4-dihydroxybenzoate was prepared by the same method as forcerium 2,4-dihydroxybenzoate using thulium chloride �the formula of thecomplex: �Tm�C6H3�OH�2COO�3� ·4H2O�.


Components: Original Measurements:�1� Ytterbium,tris�2,4-dihydroxybenzoato-�O1 ,O1��tetrahydrate, �OC-6-11�-�ytterbium 2,4-dihydroxybenzoatetetrahydrate�;C21H15O12Yb·4H2O;�146716-30-5��2� Water; H2O; �7732-18-5�






293 18.17


Methods/Apparatus/Procedure:The solubility of ytterbium 2,4-dihydroxybenzoate in water at 293 K wasgravimetrically determined by measuring the concentration of Yb�III� inthe saturated solution by the oxalate method.

Source and Purity of Materials:Ytterbium 2,4-dihydroxybenzoate was prepared by the same method as forcerium 2,4-dihydroxybenzoate using ytterbium chloride �the formula ofthe complex: �Yb�C6H3�OH�2COO�3� ·4H2O�.


Components: Original Measurements:�1� Yttrium,tris�2,4-dihydroxybenzoato-�O1 ,O1��tetrahydrate, �OC-6-11�- �yttrium2,4-dihydroxybenzoatetetrahydrate�; C21H15O12Y·4H2O;�146716-19-0��2� Water; H2O; �7732-18-5�






293 3.98



013101-48 GOTO ET AL.

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Methods/Apparatus/Procedure:The solubility of yttrium 2,4-dihydroxybenzoate in water at 293 K wasgravimetrically determined by measuring the concentration of Y�III� in thesaturated solution by the oxalate method.

Source and Purity of Materials:Yttrium 2,4-dihydroxybenzoate was prepared by the same method as forcerium 2,4-dihydroxybenzoate using yttrium chloride �the formula of thecomplex: �Y�C6H3�OH�2COO�3� ·4H2O�.



Components: Original Measurements:�1� Cerium,tris�2,5-dihydroxybenzoato- O, O��, �OC-6-11�- �cerium2,5-dihydroxybenzoate�;C21H15O12Ce; �217952-70-0��2� Water; H2O; �7732-18-5�

67W. Brzyska and A. Kula, J.Therm. Anal. Calorim. 53, 161�1998�.





293 0.99


Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Ce�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Cerium 2,5-dihydroxybenzoate was prepared by dissolving freshlyprecipitated cerium hydroxide or carbonate in a solution of2,5-dihydroxybenzoic acid and crystallization at room temperature. Theprecipitate formed was filtered off, washed with water and methanol, anddried at 303 K to a constant mass. The compositions of the preparedcomplex were determined by elemental analysis. The complex wasprepared as a solid with a molar ratio of metal to organic ligand of 1:3and formula Ce�C6H3�OH�2COO�3.




Components: Original Measurements:�1� Dysprosium,tris�2,5-dihydroxybenzoato- O, O��, �OC-6-11�- �dysprosium2,5-dihydroxybenzoate�;C21H15DyO12; �217952-77-7��2� Water; H2O; �7732-18-5�






293 4.07


Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Dy�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Dysprosium 2,5-dihydroxybenzoate was prepared by the same method asfor cerium 2,5-dihydroxybenzoate using Dy�III� hydroxide or carbonate�the formula of the complex: Dy�C6H3�OH�2COO�3�.


Components: Original Measurements:�1� Erbium,tris�2,5-dihydroxybenzoato- O, O��, �OC-6-11�- �erbium2,5-dihydroxybenzoate�;C21H15ErO12; �217952-79-9��2� Water; H2O; �7732-18-5�






293 4.44


Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Er�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Erbium 2,5-dihydroxybenzoate was prepared by the same method as forcerium 2,5-dihydroxybenzoate using erbium hydroxide or carbonate �theformula of the complex: Er�C6H3�OH�2COO�3�.



Downlo


Components: Original Measurements:�1� Europium, tris�2,5-dihydroxybenzoato- O, O��, �OC-6-11�- �europium2,5-dihydroxybenzoate�;C21H15EuO12; �217952-74-4��2� Water; H2O; �7732-18-5�






293 1.87


Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Eu�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Europium 2,5-dihydroxybenzoate was prepared by the same method as forcerium 2,5-dihydroxybenzoate using europium hydroxide or carbonate �theformula of the complex: Eu�C6H3�OH�2COO�3�.


Components: Original Measurements:�1� Gadolinium,tris�2,5-dihydroxybenzoato- O, O��, �OC-6-11�- �gadolinium2,5-dihydroxybenzoate�;C21H15GdO12; �217952-75-5��2� Water; H2O; �7732-18-5�






293 3.36


Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Gd�III�ions was determined gravimetrically using the oxalate method.


Source and Purity of Materials:Gadolinium 2,5-dihydroxybenzoate was prepared by the same method asfor cerium 2,5-dihydroxybenzoate using gadolinium hydroxide orcarbonate �the formula of the complex: Gd�C6H3�OH�2COO�3�.


Components: Original Measurements:�1� Holmium,tris�2,5-dihydroxybenzoato- O, O��, �OC-6-11�- �holmium2,5-dihydroxybenzoate�;C21H15HoO12; �217952-78-8��2� Water; H2O; �7732-18-5�






293 3.23


Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Ho�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Holmium 2,5-dihydroxybenzoate was prepared by the same method as forcerium 2,5-dihydroxybenzoate using holmium hydroxide or carbonate �theformula of the complex: Ho�C6H3�OH�2COO�3�.


Components: Original Measurements:�1� Lanthanum,tris�2,5-dihydroxybenzoato- O, O��, �OC-6-11�- �lanthanum2,5-dihydroxybenzoate�;C21H15O12La; �217952-69-7��2� Water; H2O; �7732-18-5�






293 1.29



013101-50 GOTO ET AL.

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Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of La�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Lanthanum 2,5-dihydroxybenzoate was prepared by the same method asfor cerium 2,5-dihydroxybenzoate using lanthanum hydroxide or carbonate�the formula of the complex: La�C6H3�OH�2COO�3�.


Components: Original Measurements:�1� Lutetium,tris�2,5-dihydroxybenzoato- O, O��, �OC-6-11�- �lutetium2,5-dihydroxybenzoate�;C21H15LuO12; �217952-82-4��2� Water; H2O; �7732-18-5�






293 2.66


Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Lu�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Lutetium 2,5-dihydroxybenzoate was prepared by the same method as forcerium 2,5-dihydroxybenzoate using lutetium hydroxide or carbonate �theformula of the complex: Lu�C6H3�OH�2COO�3�.


Components: Original Measurements:�1� Neodymium,tris�2,5-dihydroxybenzoato- O, O��, �OC-6-11�- �neodymium2,5-dihydroxybenzoate�;C21H15O12Nd; �217952-72-2��2� Water; H2O; �7732-18-5�








293 2.44


Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Nd�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Neodymium 2,5-dihydroxybenzoate was prepared by the same method asfor cerium 2,5-dihydroxybenzoate using neodymium hydroxide orcarbonate �the formula of the complex: Nd�C6H3�OH�2COO�3�.


Components: Original Measurements:�1� Praseodymium,tris�2,5-dihydroxybenzoato- O, O��, �OC-6-11�-�praseodymium2,5-dihydroxybenzoate�;C21H15O12Pr; �217952-71-1��2� Water; H2O; �7732-18-5�


Variables: Prepared By:T /K=293 H. Miyamoto




293 1.53


Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Pr�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Praseodymium 2,5-dihydroxybenzoate was prepared by the same methodas for cerium 2,5-dihydroxybenzoate using praseodymium hydroxide orcarbonate �the formula of the complex: Pr�C6H3�OH�2COO�3�.




Downlo

Components: Original Measurements:�1� Samarium,tris�2,5-dihydroxybenzoato- O, O��, �OC-6-11�- �samarium2,5-dihydroxybenzoate�;C21H15O12Sm; �217952-73-3��2� Water; H2O; �7732-18-5�






293 3.90


Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Sm�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Samarium 2,5-dihydroxybenzoate was prepared by the same method as forcerium 2,5-dihydroxybenzoate using samarium hydroxide or carbonate�the formula of the complex: Sm�C6H3�OH�2COO�3�.


Components: Original Measurements:�1� Terbium,tris�2,5-dihydroxybenzoato- O, O��, �OC-6-11�- �terbium2,5-dihydroxybenzoate�;C21H15O12Tb; �217952-76-6��2� Water; H2O; �7732-18-5�






293 3.91


Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Tb�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Terbium 2,5-dihydroxybenzoate was prepared by the same method as forcerium 2,5-dihydroxybenzoate using terbium hydroxide or carbonate �theformula of the complex: Tb�C6H3�OH�2COO�3�.



Components: Original Measurements:�1� Thulium,tris�2,5-dihydroxybenzoato- O, O��, �OC-6-11�- �thulium2,5-dihydroxybenzoate�;C21H15O12Tm; �217952-80-2��2� Water; H2O; �7732-18-5�






293 3.72


Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Tm�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Thulium 2,5-dihydroxybenzoate was prepared by the same method as forcerium 2,5-dihydroxybenzoate using thulium hydroxide or carbonate �theformula of the complex: Tm�C6H3�OH�2COO�3�.


Components: Original Measurements:�1� Ytterbium,tris�2,5-dihydroxybenzoato- O, O��, �OC-6-11�- �ytterbium2,5-dihydroxybenzoate�;C21H15O12Yb; �217952-81-3��2� Water; H2O; �7732-18-5�






293 4.26



013101-52 GOTO ET AL.

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Source and Purity of Materials:Ytterbium 2,5-dihydroxybenzoate was prepared by the same method as forcerium 2,5-dihydroxybenzoate using ytterbium hydroxide or carbonate �theformula of the complex: Yb�C6H3�OH�2COO�3�.

Estimated Errors:Nothing specified

Components: Original Measurements:�1� Yttrium,tris�2,5-dihydroxybenzoato- O, O��, �OC-6-11�- �yttrium2,5-dihydroxybenzoate�;C21H15O12Y; �217952-68-6��2� Water; H2O; �7732-18-5�






293 3.19


Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Y�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Yttrium 2,5-dihydroxybenzoate was prepared by the same method as forcerium 2,5-diydroxybenzoate using yttrium hydroxide or carbonate �theformula of the complex: Y�C6H3�OH�2COO�3�.



Components: Original Measurements:�1� Dysprosium2,6-dihydroxybenzoatehexahydrate;C21H15O12Dy·6H2O; � ��2� Water; H2O; �7732-18-5�

68W. Brzyska, A. Kula, Z.Rzaczynska, and J. Jaroniec,Polish J. Chem. 72, 2524 �1998�.







293 1.54

aThe compiler assumed from Ref. 67.


Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Dy�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Dysprosium 2,6-dihydroxybenzoate was prepared by adding the equivalentamounts of 0.2M ammonium 2,6-dihydroxybenzoate �pH 4.4–5.0� to a hotsolution of DyCl3 and crystallization at room temperature as described inRef. 67.The compositions of the prepared complex were determined by elementalanalysis. The complex was prepared as a crystalline solid with a molarratio of metal to organic ligand of 1:3 and formula�Dy�C6H3�OH�2COO�3� ·6H2O.


Components: Original Measurements:�1� Erbium2,6-dihydroxybenzoatehexahydrate; C21H15O12Er·6H2O;� ��2� Water; H2O; �7732-18-5�






293 1.61



Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Er�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Erbium 2,6-dihydroxybenzoate was prepared by the same method as fordysprosium 2,6-dihydroxybenzoate using ErCl3 �the formula of thecomplex: �Er�C6H3�OH�2COO�3� ·6H2O�.




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Components: Original Measurements:�1� Gadolinium2,6-dihydroxybenzoatehexahydrate;C21H15O12Gd·6H2O; � ��2� Water; H2O; �7732-18-5�






293 1.98



Method/Apparatus/ProcedureIsothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Gd�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Gadolinium 2,6-dihydroxybenzoate was prepared by the same method asfor dysprosium 2,6-dihydroxybenzoate using GdCl3 �the formula of thecomplex: �Gd�C6H3�OH�2COO�3� ·6H2O�.


Components: Original Measurements:�1� Holmium2,6-dihydroxybenzoatehexahydrate;C21H15O12Ho·6H2O; � ��2� Water; H2O; �7732-18-5�






293 1.21



Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Ho�III�ions was determined gravimetrically using the oxalate method.


Source and Purity of Materials:Holmium 2,6-dihydroxybenzoate was prepared by the same method as fordysprosium 2,6-dihydroxybenzoate using HoCl3 �the formula of thecomplex: �Ho�C6H3�OH�2COO�3� ·6H2O�.


Components: Original Measurements:�1� Lutetium2,6-dihydroxybenzoatehexahydrate;C21H15O12Lu·6H2O; � ��2� Water; H2O; �7732-18-5�






293 1.20



Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Lu�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Lutetium 2,6-dihydroxybenzoate was prepared by the same method as fordysprosium 2,6-dihydroxybenzoate using LuCl3 �the formula of thecomplex: �Lu�C6H3�OH�2COO�3� ·6H2O�.


Components: Original Measurements:�1� Terbium2,6-dihydroxybenzoatehexahydrate;C21H15O12Tb·6H2O; � ��2� Water; H2O; �7732-18-5�






293 1.89




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Source and Purity of Materials:Terbium 2,6-dihydroxybenzoate was prepared by the same method as fordysprosium 2,6-dihydroxybenzoate using TbCl3 �the formula of thecomplex: �Tb�C6H3�OH�2COO�3� ·6H2O�.


Components: Original Measurements:�1� Thulium2,6-dihydroxybenzoatehexahydrate;C21H15O12Tm·6H2O; � ��2� Water; H2O; �7732-18-5�






293 1.48



Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Tm�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Thulium 2,6-dihydroxybenzoate was prepared by the same method as fordysprosium 2,6-dihydroxybenzoate using TmCl3 �the formula of thecomplex: �Tm�C6H3�OH�2COO�3� ·6H2O�.


Components: Original Measurements:�1� Ytterbium,2,6-dihydroxybenzoatehexahydrate;C21H15O12Yb·6H2O; � ��2� Water; H2O; �7732-18-5�








293 1.39



Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Yb�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Ytterbium 2,6-dihydroxybenzoate was prepared by the same method as fordysprosium 2,6-dihydroxybenzoate using YbCl3 �the formula of thecomplex: Yb�C6H3�OH�2COO�3 ·6H2O�.


Components: Original Measurements:�1� Yttrium2,6-dihydroxybenzoatehexahydrate; C21H15O12Y·6H2O;� ��2� Water; H2O; �7732-18-5�






293 1.91



Method/Apparatus/Procedure:Isothermal method was used. After equilibrium had been established,samples of 2 and 5 cm3 were withdrawn and the concentration of Y�III�ions was determined gravimetrically using the oxalate method.

Source and Purity of Materials:Yttrium 2,6-dihydroxybenzoate was prepared by the same method as fordysprosium 2,6-dihydroxybenzoate using YCl3 �the formula of thecomplex: �Y�C6H3�OH�2COO�3� ·6H2O�.




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Components: Original Measurements:�1� Ceriumtris�3,4-dihydroxybenzoato- O1,O1�� trihydrate, �OC-6-11�-�cerium 3,4-dihydroxybenzoatetrihydrate�; C21H15CeO12·3H2O;�158477-56-6��2� Water; H2O; �7732-18-5�






293 9.47


Methods/Apparatus/Procedure:The solubility of cerium 3,4-dihydroxybenzoate in water was determinedat 293 K. Samples of 1, 2, 5, and 10 cm3 were removed and theconcentration of Ce�III� ions was determined spectrophotometrically usingarsenazo III.

Source and Purity of Materials:Cerium 3,4-dihydroxybenzoate was prepared by addition of an equivalentquantity of ammonium 3,4-dihydroxybenzoate �pH 4.4–4.5� to a solutionof cerium chloride at room temperature. The precipitate formed wasfiltered, washed with ethanol, and dried at 303 K to a constant mass. Thequantitative compositions of the prepared complex were determined byelemental analysis. The water content of crystallization was determinedfrom the TG curve and by isothermal heating of the complex at specifiedtemperatures. The complex was obtained as a solid with a molar ratio ofmetal to organic ligand of 1:3 and formula �Ce�C6H3�OH�2COO�3� ·3H2O.


Components: Original Measurements:�1� Dysprosium,tris�3,4-dihydroxybenzoato-O1,O1�� dihydrate, �OC-6-11�-�dysprosium3,4-dihydroxybenzoatedihydrate�; C21H15DyO12·2H2O;�158477-53-3��2� Water; H2O; �7732-18-5�






293 5.81



Methods/Apparatus/Procedure:The solubility of dysprosium 3,4-dihydroxybenzoate in water wasdetermined at 293 K. Samples of 1, 2, 5, and 10 cm3 were removed andthe concentration of Dy�III� ions was determined spectrophotometricallyusing arsenazo III.



Components: Original Measurements:�1� Erbium,tris�3,4-dihydroxybenzoato-O1,O1�� trihydrate, �OC-6-11�-�erbium 3,4-dihydroxybenzoatetrihydrate�; C21H15ErO12·3H2O;�158477-60-2��2� Water; H2O; �7732-18-5�






293 8.61


Methods/Apparatus/Procedure:The solubility of erbium 3,4-dihydroxybenzoate in water was determinedat 293 K. Samples of 1, 2, 5, and 10 cm3 were removed and theconcentration of Er�III� ions was determined spectrophotometrically usingarsenazo III.

Source and Purity of Materials:Erbium 3,4-dihydroxybenzoate was prepared by the same method as forcerium 3,4-dihydroxybenzoate using erbium chloride �the formula of thecomplex: �Er�C6H3�OH�2COO�3� ·3H2O�.


Components: Original Measurements:�1� Europium,tris�3,4-dihydroxybenzoato-O1,O1�� dihydrate, �OC-6-11�-�europium 3,4-dihydroxybenzoatedihydrate�; C21H15EuO12·2H2O;�158477-50-0��2� Water; H2O; �7732-18-5�





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293 5.31


Methods/Apparatus/Procedure:The solubility of europium 3,4-dihydroxybenzoate in water wasdetermined at 293 K. Samples of 1, 2, 5, and 10 cm3 were removed andthe concentration of Eu�III� ions was determined spectrophotometricallyusing arsenazo III.



Components: Original Measurements:�1� Gadolinium,tris�3,4-dihydroxybenzoato-O1 ,O1��dihydrate, �OC-6-11�-�gadolinium3,4-dihydroxybenzoatedihydrate�; C21H15GdO12·2H2O;�158477-51-1��2� Water; H2O; �7732-18-5�






293 1.99


Methods/Apparatus/Procedure:The solubility of gadolinium 3,4-dihydroxybenzoate in water wasdetermined at 293 K. Samples of 1, 2, 5, and 10 cm3 were removed andthe concentration of Gd�III� ions was determined spectrophotometricallyusing arsenazo III.





Components: Original Measurements:�1� Holmium,tris�3,4-dihydroxybenzoato-O1 ,O1��trihydrate, �OC-6-11�- �holmium3,4-dihydroxybenzoatetrihydrate�; C21H15HoO12·3H2O;�158477-59-9��2� Water; H2O; �7732-18-5�






293 7.36


Methods/Apparatus/Procedure:The solubility of holmium 3,4-dihydroxybenzoate in water was determinedat 293 K. Samples of 1, 2, 5, and 10 cm3 were removed and theconcentration of Ho�III� ions was determined spectrophotometrically usingarsenazo III.



Components: Original Measurements:�1� Lanthanum,tris�3,4-dihydroxybenzoato-O1 ,O1��trihydrate, �OC-6-11�-�lanthanum3,4-dihydroxybenzoatetrihydrate�; C21H15LaO12·3H2O;�158477-55-5��2� Water; H2O; �7732-18-5�






293 19.81


Methods/Apparatus/Procedure:The solubility of lanthanum 3,4-dihydroxybenzoate in water wasdetermined at 293 K. Samples of 1, 2, 5, and 10 cm3 were removed andthe concentration of La�III� ions was determined spectrophotometricallyusing arsenazo III.



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Components: Original Measurements:�1� Lutetium,tris�3,4-dihydroxybenzoato-O1 ,O1��dihydrate, �OC-6-11�- �lutetium3,4-dihydroxybenzoatedihydrate�; C21H15LuO12·2H2O;�158477-54-4��2� Water; H2O; �7732-18-5�






293 0.84


Methods/Apparatus/Procedure:The solubility of lutetium 3,4-dihydroxybenzoate in water was determinedat 293 K. Samples of 1, 2, 5, and 10 cm3 were removed and theconcentration of Lu�III� ions was determined spectrophotometrically usingarsenazo III.



Components: Original Measurements:�1� Neodymium,tris�3,4-dihydroxybenzoato-O1 ,O1��trihydrate, �OC-6-11�-�neodymium3,4-dihydroxybenzoatetrihydrate�; C21H15NdO12·3H2O;�158477-58-8��2� Water; H2O; �7732-18-5�






293 38.29



Methods/Apparatus/Procedure:The solubility of neodymium 3,4-dihydroxybenzoate in water wasdetermined at 293 K. Samples of 1, 2, 5, and 10 cm3 were removed andthe concentration of Nd�III� ions was determined spectrophotometricallyusing arsenazo III.

Source and Purity of Materials:Neodymium 3,4-dihydroxybenzoate was prepared by the same method asfor cerium 3,4-dihydroxybenzoate using neodymium chloride �the formulaof the complex: �Nd�C6H3�OH�2COO�3� ·3H2O�.


Components: Original Measurements:�1� Praseodymium,tris�3,4-dihydroxybenzoato-O1 ,O1��trihydrate, �OC-6-11�-�praseodymium3,4-dihydroxybenzoatetrihydrate�; C21H15O12Pr·3H2O;�158477-57-7��2� Water; H2O; �7732-18-5�






293 18.65


Methods/Apparatus/Procedure:The solubility of praseodymium 3,4-dihydroxybenzoate in water wasdetermined at 293 K. Samples of 1, 2, 5, and 10 cm3 were removed andthe concentration of Pr�III� ions was determined spectrophotometricallyusing arsenazo III.





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Components: Original Measurements:�1� Samarium,tris�3,4-dihydroxybenzoato-O1 ,O1��dihydrate, �OC-6-11�- �samarium3,4-dihydroxybenzoatedihydrate�; C21H15O12Sm·2H2O;�158477-49-7��2� Water; H2O; �7732-18-5�






293 0.74


Methods/Apparatus/Procedure:The solubility of samarium 3,4-dihydroxybenzoate in water wasdetermined at 293 K. Samples of 1, 2, 5, and 10 cm3 were removed andthe concentration of Sm�III� ions was determined spectrophotometricallyusing arsenazo III.



Components: Original Measurements:�1� Terbium,tris�3,4-dihydroxybenzoato-O1 ,O1��dihydrate, �OC-6-11�- �terbium3,4-dihydroxybenzoatedihydrate�; C21H15O12Tb·2H2O;�158477-52-2��2� Water; H2O; �7732-18-5�






293 1.75


Methods/Apparatus/Procedure:The solubility of terbium 3,4-dihydroxybenzoate in water was determinedat 293 K. Samples of 1, 2, 5, and 10 cm3 were removed and theconcentration of Tb�III� ions was determined spectrophotometrically usingarsenazo III.





Components: Original Measurements:�1� Thulium,tris�3,4-dihydroxybenzoato-O1 ,O1��trihydrate, �OC-6-11�- �thulium3,4-dihydroxybenzoatetrihydrate�; C21H15O12Tm·3H2O;�158477-61-3��2� Water; H2O; �7732-18-5�






293 9.28


Methods/Apparatus/Procedure:The solubility of thulium 3,4-dihydroxybenzoate in water was determinedat 293 K. Samples of 1, 2, 5, and 10 cm3 were removed and theconcentration of Tm�III� ions was determined spectrophotometrically usingarsenazo III.



Components: Original Measurements:�1� Ytterbium,tris�3,4-dihydroxybenzoato-O1 ,O1��trihydrate, �OC-6-11�- �ytterbium3,4-dihydroxybenzoatetrihydrate�; C21H15O12Yb·3H2O;�158477-62-4��2� Water; H2O; �7732-18-5�






293 4.89



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Methods/Apparatus/Procedure:The solubility of ytterbium 3,4-dihydroxybenzoate in water wasdetermined at 293 K. Samples of 1, 2, 5, and 10 cm3 were removed andthe concentration of Yb�III� ions was determined spectrophotometricallyusing arsenazo III.



Components: Original Measurements:�1� Yttrium,tris�3,4-dihydroxybenzoato-O1 ,O1��dihydrate, �OC-6-11�- �yttrium3,4-dihydroxybenzoatedihydrate�; C21H15O12Y·2H2O;�158477-48-6��2� Water; H2O; �7732-18-5�






293 3.41


Methods/Apparatus/Procedure:The solubility of yttrium 3,4-dihydroxybenzoate in water was determinedat 293 K. Samples of 1, 2, 5, and 10 cm3 were removed and theconcentration of Y�III� ions was determined spectrophotometrically usingarsenazo III.




Components: Original Measurements:�1� Cerium3,5-dihydroxybenzoatetetrahydrate; C21H15O12Ce·4H2O;� ��2� Water; H2O; �7732-18-5�







293 11.27


Methods/Apparatus/Procedure:The solubility of cerium 3,5-dihydroxybenzoate in water was determinedat 293 K. Saturated solutions were prepared under isothermal condition.After equilibrium had been established, samples of 1, 2, and 5 cm3 wereremoved and the concentration of Ce�III� ions was determinedgravimetrically using the oxalate method.

Source and Purity of Materials:Cerium 3,5-dihydroxybenzoate was freshly prepared from cerium�III�carbonate in a solution of 3,5-hydroxybenzoic acid at room temperature,followed by crystallization. The precipitates formed were filtered, washedwith water, and dried at 303 K to a constant mass. The quantitativecompositions of the prepared 3,5-hydroxybenzoate were determined byelemental analysis. The water content of crystallization was determinedfrom the TG curve and by isothermal heating of the complex at aspecified temperature. The complex was prepared as a solid with a molarratio of metal to organic ligand of 1:3 and formula�Ce�C6H3�OH�2COO�3� ·4H2O.


Components: Original Measurements:�1� Dysprosium3,5-dihydroxybenzoateheptahydrate;C21H15O12Dy·7H2O; � ��2� Water; H2O; �7732-18-5�






293 6.64


Methods/Apparatus/Procedure:The solubility of dysprosium 3,5-dihydroxybenzoate in water wasdetermined at 293 K. Saturated solutions were prepared under isothermalcondition. After equilibrium had been established, samples of 1, 2, and5 cm3 were removed and the concentration of Dy�III� ions was determinedgravimetrically using the oxalate method.





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Components: Original Measurements:�1� Erbium3,5-dihydroxybenzoateheptahydrate;C21H15O12Er·7H2O; � ��2� Water; H2O; �7732-18-5�






293 7.68


Methods/Apparatus/Procedure:The solubility of erbium 3,5-dihydroxybenzoate in water was determinedat 293 K. Saturated solutions were prepared under isothermal condition.After equilibrium had been established, samples of 1, 2, and 5 cm3 wereremoved and the concentration of Er�III� ions was determinedgravimetrically using the oxalate method.

Source and Purity of Materials:Erbium 3,5-dihydroxybenzoate was prepared by the same method as forcerium 3,5-dihydroxybenzoate using erbium chloride �the formula of thecomplex: �Er�C6H3�OH�2COO�3� ·7H2O�.


Components: Original Measurements:�1� Europium3,5-dihydroxybenzoateheptahydrate;C21H15O12Eu·7H2O; � ��2� Water; H2O; �7732-18-5�






293 9.54




Methods/Apparatus/Procedure:The solubility of europium 3,5-dihydroxybenzoate in water wasdetermined at 293 K. Saturated solutions were prepared under isothermalcondition. After equilibrium had been established, samples of 1, 2, and5 cm3 were removed and the concentration of Eu�III� ions was determinedgravimetrically using the oxalate method.



Components: Original Measurements:�1� Gadolinium3,5-dihydroxybenzoateheptahydrate;C21H15O12Gd·7H2O; � ��2� Water; H2O; �7732-18-5�






293 7.83


Methods/Apparatus/Procedure:The solubility of gadolinium 3,5-dihydroxybenzoate in water wasdetermined at 293 K. Saturated solutions were prepared under isothermalcondition. After equilibrium had been established, samples of 1, 2, and5 cm3 were removed and the concentration of Gd�III� ions was determinedgravimetrically using the oxalate method.



Components: Original Measurements:�1� Holmium3,5-dihydroxybenzoateheptahydrate;C21H15O12Ho·7H2O; � ��2� Water; H2O; �7732-18-5�





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293 6.24


Methods/Apparatus/Procedure:The solubility of holmium 3,5-dihydroxybenzoate in water was determinedat 293 K. Saturated solutions were prepared under isothermal condition.After equilibrium had been established, samples of 1, 2, and 5 cm3 wereremoved and the concentration of Ho�III� ions was determinedgravimetrically using the oxalate method.



Components: Original Measurements:�1� Neodymium3,5-dihydroxybenzoateheptahydrate;C21H15O12Nd·7H2O; � ��2� Water; H2O; �7732-18-5�






293 25.14


Methods/Apparatus/Procedure:The solubility of neodymium 3,5-dihydroxybenzoate in water wasdetermined at 293 K. Saturated solutions were prepared under isothermalcondition. After equilibrium had been established, samples of 1, 2, and5 cm3 were removed and the concentration of Nd�III� ions was determinedgravimetrically using the oxalate method.

Source and Purity of Materials:Neodymium 3,5-dihydroxybenzoate was prepared by the same method asfor cerium 3,5-dihydroxybenzoate using neodymium chloride �the formulaof the complex: �Nd�C6H3�OH�2COO�3� ·7H2O�.



Components: Original Measurements:�1� Lanthanum3,5-dihydroxybenzoatetetrahydrate; C21H15O12La·4H2O;� ��2� Water; H2O; �7732-18-5�






293 10.80


Methods/Apparatus/Procedure:The solubility of lanthanum 3,5-dihydroxybenzoate in water wasdetermined at 293 K. Saturated solutions were prepared under isothermalcondition. After equilibrium had been established, samples of 1, 2, and5 cm3 were removed and the concentration of La�III� ions was determinedgravimetrically using the oxalate method.



Components: Original Measurements:�1� Lutetium3,5-dihydroxybenzoateheptahydrate;C21H15O12Lu·7H2O; � ��2� Water; H2O; �7732-18-5�






293 11.30


Methods/Apparatus/Procedure:The solubility of lutetium 3,5-dihydroxybenzoate in water was determinedat 293 K. Saturated solutions were prepared under isothermal condition.After equilibrium had been established, samples of 1, 2, and 5 cm3 wereremoved and the concentration of Lu�III� ions was determinedgravimetrically using the oxalate method.



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Components: Original Measurements:�1� Praseodymium3,5-dihydroxybenzoatetetrahydrate; C21H15O12Pr·4H2O;� ��2� Water; H2O; �7732-18-5�






293 7.87


Methods/Apparatus/Procedure:The solubility of praseodymium 3,5-dihydroxybenzoate in water wasdetermined at 293 K. Saturated solutions were prepared under isothermalcondition. After equilibrium had been established, samples of 1, 2, and5 cm3 were removed and the concentration of Pr�III� ions was determinedgravimetrically using the oxalate method.



Components: Original Measurements:�1� Samarium3,5-dihydroxybenzoateheptahydrate;C21H15O12Sm·7H2O; � ��2� Water; H2O; �7732-18-5�






293 11.47




Methods/Apparatus/Procedure:The solubility of samarium 3,5-dihydroxybenzoate in water wasdetermined at 293 K. Saturated solutions were prepared under isothermalcondition. After equilibrium had been established, samples of 1, 2, and5 cm3 were removed and the concentration of Sm�III� ions wasdetermined gravimetrically using the oxalate method.



Components: Original Measurements:�1� Terbium3,5-dihydroxybenzoateheptahydrate;C21H15O12Tb·7H2O; � ��2� Water; H2O; �7732-18-5�






293 6.26


Methods/Apparatus/Procedure:The solubility of terbium 3,5-dihydroxybenzoate in water was determinedat 293 K. Saturated solutions were prepared under isothermal condition.After equilibrium had been established, samples of 1, 2, and 5 cm3 wereremoved and the concentration of Tb�III� ions was determinedgravimetrically using the oxalate method.



Components: Original Measurements:�1� Thulium3,5-dihydroxybenzoateheptahydrate;C21H15O12Tm·7H2O; � ��2� Water; H2O; �7732-18-5�





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293 8.58


Methods/Apparatus/Procedure:The solubility of thulium 3,5-dihydroxybenzoate in water was determinedat 293 K. Saturated solutions were prepared under isothermal condition.After equilibrium had been established, samples of 1, 2, and 5 cm3 wereremoved and the concentration of Tm�III� ions was determinedgravimetrically using the oxalate method.



Components: Original Measurements:�1� Ytterbium3,5-dihydroxybenzoateheptahydrate;C21H15O12Yb·7H2O; � ��2� Water; H2O; �7732-18-5�






293 11.12


Methods/Apparatus/Procedure:The solubility of ytterbium 3,5-dihydroxybenzoate in water wasdetermined at 293 K. Saturated solutions were prepared under isothermalcondition. After equilibrium had been established, samples of 1, 2, and5 cm3 were removed and the concentration of Yb�III� ions was determinedgravimetrically using the oxalate method.




Components: Original Measurements:�1� Yttrium3,5-dihydroxybenzoateheptahydrate; C21H15O12Y·7H2O;� ��2� Water; H2O; �7732-18-5�






293 10.89


Methods/Apparatus/Procedure:The solubility of yttrium 3,5-dihydroxybenzoate in water was determinedat 293 K. Saturated solutions were prepared under isothermal condition.After equilibrium had been established, samples of 1, 2, and 5 cm3 wereremoved and the concentration of Y�III� ions was determinedgravimetrically using the oxalate method.



3. Hydroxybenzoic Acids, Parabens, andHydroxybenzoic Acid Salts in Ternary

Aqueous Systems

3.1. Hydroxybenzoic acid–water–organiccompound systems

3.1.1. Salicylic acid

3.1.1.1. Halides

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �59-72-7��2� Water; H2O; �7732-18-5��3� Trichloromethane�chloroform�; CHCl3; �67-66-3�

71E. Cohen and W. D. J. vanDobbenburgh, Z. Phys. Chem.118, 37 �1925�.

Variables: Prepared by:Compositiont / °C=30.5

E. Königsberger and L.-C.Königsberger



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Solubility of salicylic acid in water–chloroform mixtures

TemperatureConcentrationof chloroform Solubility

t / °CShakingtime/h 105w2 100w1

a 100w1b

100w1c

�compiler�

30.5 3 0 1.55 1.56 1.565 0 1.56 1.55 1.563 35.4 1.64 1.63 1.643 60.8 1.69 1.68 1.693 108.1 1.72 1.71 1.723 saturated 1.73 1.72 1.73

aAn undersaturation method was used to determine the solubility.bA supersaturation method was used to determine the solubility.cThe mean value was calculated from the w1

a and w1b values.


Methods/Apparatus/Procedure:In parallel experiments, dry chloroform and chloroform containing aknown amount of water were added to dry salicylic acid contained in twocarefully dried, weighed bottles. These were shaken in an Ostwaldthermostat for 5–6 h at 30.5 °C. After settling of the solid phase, twosamples of the supernatant solution were taken using a glass tubecontaining some cotton wool. The samples were weighed, the chloroformwas evaporated by a dry air stream and the dry residues were weighedagain.

Source and Purity of Materials:Salicylic acid �Kahlbaum� was recrystallized from dry ether, ground, andkept in a desiccator over P4O10. Water was distilled from a tin-coatedapparatus. Chloroform was kept with P4O10 for several days, then distilledslowly.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Water; H2O; �7732-18-5��3� Tetrachloromethane �carbontetrachloride�; CCl4; �56-23-5�

71E. Cohen and W. D. J. vanDobbenburgh, Z. Phys. Chem.118, 37 �1925�.





Solubility of salicylic acid in water–carbon tetrachloride mixtures

TemperatureConcentration

of CCl4 Solubility


a 100w1b

100w1c

�compiler�

30.5 3 0 0.36 0.35 0.365 0 0.35 0.35 0.353 8.7 0.35 0.36 0.363 22.7 0.36 0.36 0.363 65.9 0.36 0.37 0.373 saturated 0.36 0.36 0.36


a and w1b values.


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 71 for thesalicylic acid–chloroform–water system.

Source and Purity of Materials:Salicylic acid �Kahlbaum� was recrystallized from dry ether, ground, andkept in a desiccator over P4O10. Water was distilled from a tin-coatedapparatus. Sulfur-free CCl4 was kept with P4O10 for several days, thendistilled slowly.


3.1.1.2. Alcohols

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�

23Fr. Hoffmann and K. Langbeck,Z. Phys. Chem. 51, 385 �1905�.

Variables: Prepared by:Concentration of ethanolt / °C=24.89 and 34.82




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Solubility of salicylic acid in water–ethanol mixtures


of ethanol SolubilityaSolubilitychange

t / °C 102x2 m2 /mol kg−1 104x1

102m1 /mol kg−1

�compiler� %b

24.89 0 0 2.8851c 1.602c 100.000.037 04 0.020 57 2.8931 1.607 100.270.044 88 0.024 92 2.8966 1.609 100.400.072 87 0.040 48 2.9083 1.616 100.800.099 99 0.055 56 2.9150 1.620 101.040.146 90 0.081 66 2.9343 1.632 101.700.313 79 0.174 74 2.9901 1.666 103.640.459 57 0.256 30 3.0396 1.696 105.350.677 90 0.378 89 3.1064 1.737 107.671.399 50 0.787 97 3.3549 1.889 116.281.888 5 1.068 6 3.5279 1.997 122.282.197 5 1.247 4 3.6509 2.073 126.542.865 3 1.637 7 3.9253 2.244 136.05

34.82 0 0 4.1844c 2.324c 100.000.044 67 0.024 80 4.2044 2.336 100.480.050 46 0.028 02 4.2062 2.337 100.520.059 66 0.033 15 4.2093 2.339 100.590.101 55 0.056 43 4.2348 2.354 101.210.203 85 0.113 40 4.2982 2.392 102.720.430 18 0.239 87 4.4341 2.473 105.970.867 9 0.486 10 4.6993 2.633 112.311.332 5 0.762 11 4.9886 2.808c 119.221.752 8 0.990 60 5.2816 2.986 126.22

aThe molality solubility of salicylic acid was calculated from the equation

m1= �x1 /M3� / �1−x1−x2� by the compilers.bwith respect to pure water.cInconsistency in original data �the difference between m1= �55.511x1� / �1−x1−x2� and m1= �55.511x1� is larger than 0.5%�.


Methods/Apparatus/Procedure:Suspensions were shaken in carefully cleaned �steamed� glass bottles withrubber stoppers placed in an Ostwald thermostat �times not specified�.After the solid phase had settled, filtration at equilibrium temperature wasperformed by pressing the solution through a glass tube filled with glasswool. The filtrate, the first 20 cm3 of which was discarded, was weighedand titrated with Ba�OH�2 solution using phenolphthalein as indicator.Care was taken to avoid contamination of Ba�OH�2 with atmosphericCO2.

Source and Purity of Materials:Salicylic acid �Kahlbaum� was recrystallized repeatedly from water andthen from ethanol, m.p. 156 °C. Ethanol �Kahlbaum� 99.8%.




24A. Seidell, Trans. Am.Electrochem. Soc. 13, 319�1908�.

Variables: Prepared by:Concentration of ethanolt / °C=25

A. Goto and H. Miyamoto



of ethanolSp. Gr. ofsatd. soln. Solubility

t / °C 100w2

x2

�compiler� d 100w1

m1 /mol kg−1

�compiler�

25 0.00 0.00 1.001 0.22 0.0168.90 3.68 0.986 0.336 0.0244

32.00 15.54 0.957 2.68 0.19951.00 28.93 0.945 12.82 1.06570.2 47.95 0.941 24.01 2.28888.0 74.14 0.932 31.03 3.25796.30 91.05 0.923 32.45 3.47899.80 99.49 0.919 33.20 3.598


Methods/Apparatus/Procedure:The saturation of the solutions was accomplished by moderate agitation ofthe mixtures of solute and solvent enclosed in tubes immersed in aconstant-temperature water bath maintained at 25 °C. The attainment ofequilibrium was ensured by analyzing solutions which had been agitatedfor different lengths of time. The equilibrium had been reached for 3 days.The analyses were made by titrating aliquot portions of the portions of thesolutions with standard alkali phenolphthalein as indicator.

Source and Purity of Materials:Salicylic acid was pure white crystals with melting point of 156 °C. Bytitration with standard alkali solution, it corresponded to 100% purity.



20R. Wright, J. Chem. Soc. 1927,1334.

Variables: Prepared by:Concentration of ethanolt / °C=20 and 30




013101-66 GOTO ET AL.

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Temperature

Solvent

Solubility



�compiler�

20 Water 0.21 0.210.23 0.23

Av. 0.22 0.22 0.01650% Ethanol 11.8 10.6

11.8 10.6Av. 11.8 10.6 0.854

Ethanol 51.0 33.852.0 34.2

Av. 51.5 34.0 3.7330 Water 0.30 0.30

0.32 0.32Av. 0.31 0.31 0.022

50% Ethanol 17.9 15.218.0 15.3

Av. 18.0 15.2 1.30Ethanol 57.0 53.9

57.5 54.4Av. 57.3 54.2 4.15

aIn original paper, the solubility was given as grams of solute per 100 g ofsolvent.




Methods/Apparatus/Procedure:The saturated solutions were prepared in stoppered tubes in a thermostat,the weighed portions were taken, and the amount of solute was estimatedeither by titration or by evaporation to dryness.


Estimated Errors:Solubility: precision �0.0–4.5Temperature: nothing specified.


31J.O. Halford, J. Am. Chem.Soc. 55, 2272 �1933�.




TemperatureConcentration of

ethanol Solubility

t / °C 100w2

100x2

�compiler�Specificgravity

Undersaturationc1 /mol dm−3

Supersaturationc1 /mol dm−3

Averagec1 /mol dm−3

�compiler�

25 0 0 1.011 0.0153 0.0153 0.015318.8 6.85 0.982 0.0388 0.0389 0.038937.5 19.0 0.950 0.332 0.329 0.33156.2 33.5 0.949 1.070 1.063 1.06775.0 54.0 0.949 1.806 1.802 1.80493.8 85.5 0.922 2.194 2.192 2.193


Methods/Apparatus/Procedure:The saturated solutions were obtained by shaking an excess of the acidwith the solvent for 24 h in a thermostat at 25 °C. The salicylic acidmeasurements were run in pairs, the second solution being supersaturatedby heating before immersion in the oil bath. Both the undersaturation andthe supersaturation methods were performed to approach equilibrium. Thetitration of the acid with sodium hydroxide standardized against benzoicacid was carried out electrometrically with the quinhydrone electrode.

Source and Purity of Materials:No information is given.



72I.L. Krupatkin, Sbornik Stateipo Obshchei. Khim., Akad. NaukS.S.S.R. I, 151 �1953�.

Variables: Prepared by:Composition and temperature A. Goto and H. Miyamoto



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Sectionnumber

TemperatureComposition of

saturated solutions

Demixingtemperature

t / °C

Crystallizationtemperature

t / °CSalicylic acid

100w1

Ethanol100w2

�compiler�

Water100w3

�compiler�

1Ethanol 5%Water 95%

— 128.5 88.97 0.55 10.48— 116.0 79.68 1.02 19.30— 108.0 68.76 1.56 29.68

71.0 — 62.62 1.87 35.5174.0 103.0 60.00 2.00 38.0081.0 101.0 50.00 2.50 47.5082.5 99.0 40.00 3.00 57.0082.0 99.0 29.06 3.55 67.3978.5 — 17.67 4.12 78.2172.0 — 9.88 4.51 85.6165.0 — 7.01 4.65 88.34


— 107.0 68.82 3.12 28.0668.0 — 61.44 3.86 34.7073.0 101.5 56.98 4.30 38.7276.0 97.0 47.26 5.27 47.4775.0 95.0 34.65 6.535 58.815

73.0 93.0 28.31 7.17 64.5267.0 — 14.46 8.55 76.9962.5 84.0 10.00 9.00 81.0056.0 — 9.00 9.10 81.90— 78.03 4.99 9.50 85.51


— 128.5 89.64 1.55 8.81— 114.5 79.64 3.05 17.31

64.0 — 61.14 5.83 33.0365.0 99.5 60.00 6.00 34.0071.0 — 54.45 6.83 38.7271.0 96.0 49.57 7.56 42.8770.0 — 40.00 9.00 51.0065.0 — 29.65 10.55 59.8059.0 — 19.95 12.01 68..0455.0 — 15.87 12.62 71.51


— 131.0 90.84 2.29 6.87— 103.0 69.37 7.66 22.97

61.0 — 54.71 11.32 33.9761.0 — 53.46 11.635 34.905

61.0 83.0 48.63 12.84 38.5359.0 — 40.00 15.00 45.0052.0 — 29.70 17.575 52.725

39.0 — 19.34 20.165 60.495


130.0 89.50 4.20 6.30111.0 77.75 8.90 13.3599.0 68.89 12.44 18.6788.0 59.44 16.22 24.3480.0 49.75 20.10 30.1575.0 40.45 23.82 35.7367.0 31.30 27.48 41.2258.0 21.41 31.44 47.1540.0 9.85 36.06 54.09


135.0 90.11 5.93 3.96117.0 80.02 11.99 7.9999.0 69.91 18.05 12.0481.0 60.13 23.92 15.9567.0 50.00 30.00 20.0054.0 39.92 36.05 24.03



Sectionnumber

TemperatureComposition of

saturated solutions

Demixingtemperature

t / °C


t / °CSalicylic acid

100w1

Ethanol100w2

�compiler�

Water100w3

�compiler�


137.0 90.00 8.00 2.00119.0 80.06 15.95 3.99101.0 70.10 26.92 5.98

83.0 59.94 32.05 8.0164.0 50.14 39.89 9.9743.0 39.89 48.09 12.02


Methods/Apparatus/Procedure:The experiment was performed by the polythermic method.

Source and Purity of Materials:Chemically pure grade salicylic acid with b.p. 155 °C was used. Ethanolwas distilled twice. The boiling point of the ethanol was 78 °C. Waterwas distilled twice.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C6H7O3; �69-72-7��2� 1-Propanol �n-propylalcohol�; C3H8O; �71-23-8��3� Water; H2O; �7732-18-5�

40A.N. Paruta, B.J. Sciarrone, andN.G. Lordi, J. Pharm. Sci. 53,1349 �1964�.

Variables: Prepared by:t / °C=30.6 A. Goto and R. Goto

Solubility of salicylic acid in water–1-propanol mixtures

Temperature Solubilityb

t / °CDielectricconstanta

�1 /g dm−3

�compiler�c1 /mol dm−3

�compiler�

30.6 22.3 320 2.32

aThe dielectric constant of the binary mixtures at the maximum solubility ofsalicylic acid.bIn the original paper, the solubility was given as mg/ml of solution. The �1

value was calculated by the compiler.


Methods/Apparatus/Procedure:The solubility of salicylic acid was determined in aqueous solventmixtures using 15 ml screw-capped vials fitted with Teflon liners. Thevials were attached to a rotating wheel in a water bath maintained at30.6 °C. Equilibration for 24 h was sufficient. Samples were withdrawnfrom the reaction vials using a pipet fitted with a glass wool filtering plug.The solubility of salicylic acid was determined by base titration usingfreshly prepared 0.1 mol dm−3 NaOH as titrant and phenolphthalein as anindicator. The dielectric constants of all solvent systems were measured bya resonance method at 25 °C.



013101-68 GOTO ET AL.

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Source and Purity of Materials:The solvents were purified by the method described by A. Weissberger etal., Organic Solvents, 2nd ed. �Interscience, New York, 1955�, Chaps. 4and 5.

Estimated Errors:Solubility: nothing specified.Temperature: precision �0.2 °C �solubility� and �1.0 °C �dielectricconstant�.

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� 2-Propanol �isopropanol;isopropyl alcohol�; C3H8O;�67-63-0��3� Water; H2O; �7732-18-5�

34N.A. Hall, Am. J. Pharm. 132,406 �1960�.

Variables: Prepared by:Concentration of 2-propanolt / °C=25

A. Goto and R. Goto

Solubility of salicylic acid in water–2-propanol mixtures

Temperature Concentration of 2-propanol Solubilitya

t / °C w2

x2

�compiler��1 /g dm−3


�compiler�

25 0 0 2.24 0.016210 3.2 3.73 0.027020 7.0 10.99 0.079630 11 46.4 0.33640 17 99.9 0.72350 23 157.7 1.14260 31 207.4 1.50270 41 257.3 1.86380 55 293.7 2.12690 73 314 2.273

aIn the original data, the solubility was given as grams per 100 ml of solu-

tion.


Methods/Apparatus/Procedure:A triplicate series of test tubes containing known concentration of aqueous2-propanol solution was prepared, and to each tube, an excess ofpowdered salicylic acid was added. The tubes were closed with previouslywashed rubber stoppers, shaken vigorously for three minutes, and setaside for 3 weeks at room temperature �approximately 29 °C�. During thewaiting period, the samples were shaken at least once daily with care toassure the dispersion of the compacted mass of salicylic acid at thebottom of the tube. The samples were placed in a thermostaticallycontrolled water bath at 25 °C for another 2 weeks during which timedaily shaking was continued. Evidence of attainment of saturatedequilibrium was shown when the assay of the sample containing 50%2-propanol was the same on two subsequent days. The solutions wereassayed for salicylic acid after removal of a sample with a pipe protectedagainst withdrawal of undissolved crystals by glass wool. All solutionswere titrated with standard sodium hydroxide solution. In addition, thosecontaining distilled water alone and 10% isopropanol were analyzedcolorimetrically. The average of triplicate determination was obtained.



Source and Purity of Materials:Chemical 2-propanol �British Drug Houses� was treated with calciumoxide and fractionally distilled under anhydrous conditions. Mixtures ofpurified 2-propanol and distilled water were prepared by weight. Salicylicacid was recrystallized twice from 70% ethanol and dried in a vacuumoven at 60 °C.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� 1-Propanol, 2-methyl�isobutanol; isobutyl alcohol�;C4H10O; �78-83-1��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of isobutyl alcoholt / °C=24.89 and 34.82


Solubility of salicylic acid in water–isobutyl alcohol mixtures


of isobutyl alcohol SolubilityaSolubilitychange

t / °C 102x2 m2 /mol kg−1 104x1

102m1 /mol kg−1

�compiler� %b

24.89 0 0 2.8851 1.602 100.000.036 02 0.020 00 2.9090 1.616 100.830.044 58 0.024 76 2.9159 1.620 101.090.059 30 0.032 94 2.9334 1.630 101.670.091 19 0.050 62 2.9547 1.642 102.410.180 23 0.100 23 3.0330 1.687 105.130.453 84 0.253 09 3.2648 1.821 113.160.926 00 0.318 89 3.7179 2.084 128.66

34.82 0 0 4.1844 2.324 100.000.036 01 0.020 00 4.2295 2.350 101.080.045 14 0.025 07 4.2379 2.355 101.280.059 29 0.032 94 4.2634 2.369 101.890.090 30 0.050 18 4.2983 2.389 102.720.180 91 0.100 62 4.4347 2.467 105.890.465 66 0.259 76 4.8391 2.700 115.650.933 08 0.523 02 5.6236 3.153 134.40

aThe molality solubility of salicylic acid was calculated from the equation,

m1= �x1 /M3� / �1−x1−x2�.bWith respect to pure water.


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 23 for thesalicylic acid–ethanol–water system.

Source and Purity of Materials:Salicylic acid �Kahlbaum� was recrystallized repeatedly from water andthen from ethanol, m.p. 156 °C. Isobutyl alcohol was double distilled at106–107 °C.


3

ic


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Estimated Errors:Solubility: nothing specified,Temperature: precision �0.03 K.

3.1.1.3. Ketones and acids

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C6H7O3; �69-72-7��2� 2-Propanone �acetone�;C3H6O; �67-64-1��3� Water; H2O; �7732-18-5�



Solubility of salicylic acid in water–acetone mixture

Temperature

Solvent system Dielectric constanta

Solubilityb

t / °C�1 /g dm−3

�compiler�c1 /mol dm−

�compiler�

30.6 Water 78.5 3 0.022Water-acetone 25.0 387 2.78

aThe dielectric constant of the binary mixtures at the maximum solubility of

salicylic acid.bIn the original paper, the solubility was given as mg/ml of solution. The �1



Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 40 for thesalicylic acid–1-propanol–water system in Sec. 3.1.1.2.

Source and Purity of Materials:The solvent was purified by the method described by A. Weissberger etal., Organic Solvents, 2nd ed. �Interscience, New York, 1955�, Chaps. 4and 5.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Formic acid; CH2O2;�64-18-6��3� Water; H2O; �7732-28-5�

27J. Kendall, Proc. R. Soc.London Ser. A 85, 200 �1911�.

Variables: Prepared by:Concentration of formic acidt / °C=25



Solubility of salicylic acid in water–formic acid mixtures

TemperatureConcentrationof formic acida Solubilityb, c �Av.d =0.016 32 mol dm−3�

t / °C %Original

data �1 /g dm−3

102c1 /mol dm−3

Gravimetric Volumetr

25 0 0.0563 2.252 1.631 1.6340.24 — — — 1.5310.46 — — — 1.4740.625 0.0512 2.048 1.484 —1.25 0.0515 2.060 1.496 —2.5 0.0530 2.120 1.536 —5 0.0592 2.368 1.716 —

10 0.0725 2.900 2.101 —

aNo specific information on mass or volume percent was stated in the origi-

nal paper.bIn the original paper, the solubility was given as grams per 25 cm3 of the

saturated solution.cThe concentration of the acid was given as “Normality” units.dThe average in pure water was calculated from c1 �Calc. by using �1�, c1

�Gravimetric�, and c1 �Volumetric� by the compiler.


Methods/Apparatus/Procedure:Salicylic acid crystals were placed in a glass-stoppered bottle with solvent.The bottles were rotated in a thermostat for several days. A measuredquantity was removed by a pipet fitted with a filter-cover to prevent theentrance of any crystals. The solution was evaporated to dryness and thenthe product was weighed. In the dilute solution, the acid concentrationwas determined by titration with barium hydroxide solution usingphenolphthalein as an indicator.

Source and Purity of Materials:Salicylic acid was recrystallized from freshly distilled water. Formic acidwas purified by distilling.

Estimated Errors:Solubility: precision �0.2%–0.4%.Temperature: precision �0.1 °C.

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Acetic acid; C2H4O2;�64-19-7��3� Water; H2O; �7732-28-5�


Variables: Prepared by:Concentration of acetic acidt / °C=25




c

013101-70 GOTO ET AL.

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Solubility of salicylic acid in water–acetic acid mixtures

TemperatureConcentrationof acetic acida Solubilityb,c �Av.d=0.016 32 mol dm−3�

t / °C %Original

data �1 /g dm−3

102c1 /mol dm−3

Gravimetric Volumetri

25 0 0.0563 2.252 1.631 1.6340.625 0.0584 2.336 1.691 —1.25 0.0602 2.408 1.745 —2.5 0.0636 2.544 1.846 —5 0.0710 2.840 2.059 —

aNo specific information on mass or volume percent was stated in the origi-nal paper.bIn the original paper, the solubility was given as grams per 25 cm3 of thesaturated solution.cThe concentration of the acid was given as “Normality” units.dThe average in pure water was calculated from c1 �Calc. by using �1�, c1

�Gravimetric�, and c �Volumetric� by the compiler.


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 27 for thesalicylic acid–formic acid–water system.

Source and Purity of Materials:Salicylic acid was recrystallized from freshly distilled water. Formic acidwas purified by distilling.

Estimated Errors:Solubility: precision �0.2%–0.4%.Temperature: precision �0.1 °C.

3.1.1.4. Organic salts

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Formic acid, sodium salt�sodium formate�; CHO2Na;�141-53-7��3� Water H2O; �7732-18-5�

37J.C. Philip, J. Chem. Soc.Trans. 87, 987 �1905�.

Variables: Prepared by:Concentration of sodium formatet / °C=26.4

A. Goto, R. Goto, and H.Miyamoto

Solubility of salicylic acid in water–sodium formate mixtures

Temperature Concentration of sodium formate Solubility

t / °C c2 /mol dm−3 c1 /mol dm−3

26.4 0.0000 0.01710.0122 0.02510.0244 0.03390.0610 0.0535




Methods/Apparatus/Procedure:The water or aqueous sodium carboxylate solution was put into a smallflask and excess of salicylic acid was added. The flask was corked andplaced into a thermostat. The supersaturation method was used. The flaskswere shaken at a higher temperature, so that on cooling to 26.4 °C in thethermostat, the acid was crystallized out in a state of fine division.Equilibrium was reached in about 3 h. Portions of the saturated solutionwere withdrawn by a pipet through a plug of cotton wool and introducedinto Jena flasks. The concentration of each solution was determined bytitration with sodium hydroxide solution using phenolphthalein as anindicator.

Source and Purity of Materials:Salicylic acid and sodium salts used as a solvent were obtained fromKahlbaum. The purity of salicylic acid was characterized by the solubilityof 0.0171 mol dm−3 at 26.4 °C and the value was identical to that givenin Ref. 23.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Formic acid, sodium salt�sodium formate�; CHO2Na;�141-53-7��3� Water; H2O; �7732-18-5�

26J.C. Philip and F.B. Garner, J.Chem. Soc. Trans. 95, 1466�1909�.

Variables: Prepared by:Concentration of sodium formatet / °C=26.4




t / °C 102c2 /mol dm−3 102c1 /mol dm−3

26.4 0.00 1.641.19 2.462.40 3.205.97 5.15

11.97 7.56


Methods/Apparatus/Procedure:The solubility determination was carried out at 25 °C, and the procedurewas identical to that described in Ref. 37.

Source and Purity of Materials:The detail is given in the compilation of Ref. 37 for the salicylic acid–formic acid sodium salt–water system.




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Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Formic acid, sodium salt�sodium formate�; CHO2Na;�141-53-7��3� Water; H2O; �7732-18-5�

18S.S. Doosaj and W.V. Bhagwat,J. Indian Chem. Soc. 10, 225�1933�;19W.V. Bhagwat and S.S. Doosaj,J. Indian Chem. Soc. 10, 477�1933�.

Variables: Prepared by:Concentration of sodium formatet / °C=30




of sodium formate Solubilitya

t / °C �2 /g dm−3c2 /mol dm−3

�compiler� �1 /g dm−3102c1 /mol dm−3

�compiler�

30 0.0000 0.000 0 2.743 0.019 864.6456 0.068 31 8.624 0.062 446.8578 0.100 84 10.35 0.074 939.0009 0.132 35 12.08 0.087 46

13.0922 0.192 51 15.15 0.109 724.0024 0.352 94 21.04 0.152 333.2340 0.488 68 26.36 0.190 836.0035 0.529 41 27.07 0.196 048.0047 0.705 87 32.02 0.231 872.0071 1.058 81 39.87 0.288 7

144.0142 2.117 62 63.66 0.460 9

aIn the original data, the values �1 and �2 were given as grams per liter of

solution.


Methods/Apparatus/Procedure:No information was given.



Components: Original Measurements:�1� Benzoic acid 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Sodium methanoate �sodiumformate�; CHO2Na; �141-53-7��3� Water; H2O; �7732-18-5�

30E. Larsson, Z. Phys. Chem.127, 233 �1927�.

Variables: Prepared by:Concentration of sodium formatet / °C=25





t / °C c2 /mol dm−3 102c1 /mol dm−3

25 0 1.6010.0500 4.590.1000 6.76


Methods/Apparatus/Procedure:Laboratory-glass flasks were filled with salt solutions and an excess ofsolid acid. The mixtures were kept in a thermostat and vigorously shakenby hand from time to time. Every 24 h, a known, filtered amount ofsolution was titrated with approximately 0.025 mol dm−3 Ba�OH�2 withphenolphthalein as indicator. Each solubility value is the average of atleast two independent determinations which deviated from each other by�1%.

Source and Purity of Materials:Salicylic acid was from Kahlbaum.

Estimated Errors:Solubility: precision �1%.Temperature: precision �0.1 K.

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Formic acid, potassium salt�potassium formate�; CHO2K;�590-29-4��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of potassiumformatet / °C=25


Solubility of salicylic acid in water–potassium formate mixtures

Temperature Concentration of potassium formate Solubility


25 0 1.641.22 2.453.05 3.576.10 5.16


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 26 for thesalicylic acid–sodium formate–water system.

Source and Purity of Materials:The detail is given in the compilation of Ref. 26 for the salicylic acid–sodium formate–water system.

Estimated Errors:Solubility: nothing specified.



013101-72 GOTO ET AL.

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Temperature: precision �0.1 °C.

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Acetic acid, sodium salt�sodium acetate�; C2H3O2Na;�127-09-3��3� Water; H2O; �7732-18-5�

37J.C. Philip, J. Chem. Soc.Trans. 87, 987 �1905�.

Variables: Prepared by:Concentration of sodium acetatet / °C=26.4


Solubility of salicylic acid in water–sodium acetate mixtures

Temperature Concentration of sodium acetate Solubility


26.4 0.0100 0.02470.0201 0.03380.0502 0.0613







Variables: Prepared by:Concentration of sodium acetatet / °C=25




t / °C 102c2 /mol dm−3 102c1 /mol dm−3

25 1.23 2.613.06 4.296.13 6.92

12.28 12.17













of sodium acetate Solubilitya

t / °C �2 /g dm−3c2 /mol dm−3


�compiler�

30 0.0000 0.000 0 2.743 0.019 862.3547 0.028 704 4.828 0.034 953.5322 0.043 508 6.026 0.043 637.0643 0.086 114 9.122 0.066 04

10.4281 0.127 119 11.73 0.084 9219.9087 0.242 687 13.99 0.112 436.4989 0.444 922 31.06 0.224 943.7986 0.533 905 36.22 0.262 272.9977 0.889 843 57.25 0.414 3

109.4966 1.334 764 77.43 0.560 6218.9932 2.669 529 147.20 1.066


solution.




Estimated ErrorsNothing specified.



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Components:�1� Benzoic acid 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Acetic acid, sodium salt�sodium acetate�; C2H3O2Na;�127-09-3��3� Water; H2O; �7732-18-5�

Original Measurements:30E. Larsson, Z. Phys. Chem.127, 233 �1927�.






25 0 1.6010.0500 6.000.1000 10.20





Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Propionic acid, sodium salt�sodium propionate�; C3H5O2Na;�137-40-6��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of sodiumpropionatet / °C=27.8



Solubility of salicylic acid in water–sodium propionate mixtures


sodium propionate Solubilitya

t / °C �2 /g dm−3102c2 /mol dm−3


�compiler�

27.8 0.000 0.000 2.479 1.7952.000 2.082 4.957 3.5897.810 8.130 12.795 9.2649.549 9.940 14.954 10.827

17.167 17.890 24.391 17.65928.638 29.830 37.506 27.15542.982 44.740 52.461 37.89285.963 89.480 101.24 73.301

aBoth �1 and �2 values were given by H. Stephen and T. Stephen, Solubili-

ties of Inorganic and Organic Compounds �Pergamon, Oxford, 1979�, Vol.

2, Pt. 1, p. 205. In the original paper, both c1 and c2 values were given as

“Normality” units.





Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Butanoic acid, sodium salt�sodium butylate�; C4H7O2Na;�156-54-7��3� Water H2O; �7732-18-5�


Variables: Prepared by:Concentration of sodium butylatet / °C=25


Solubility of salicylic acid in water–sodium butylate mixtures

Temperature Concentration of sodium butylate Solubility

t / °C 102c2 /mol dm−3 102c1 /mol dm−3

25 1.03 2.502.06 3.485.13 6.43



013101-74 GOTO ET AL.

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Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� 1,2,3-Propane tricarboxylicacid, 2-hydroxy-, trisodium salt,dihydrate; �sodium citrate�;C6H5O7Na3 ·2H2O; �6132-04-3��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of sodium citratet / °C=30


Solubility of salicylic acid in water–sodium citrate mixtures

Temperature Concentration of sodium citrate Solubilitya

t / °C �2 /g dm−3c2 /mol dm−3


�compiler�

30 0.0000 0.000 0 2.743 0.019 865.3701 0.018 26 7.875 0.057 017.924 0.026 94 10.25 0.074 28

15.1313 0.051 45 15.92 0.115 357.7459 0.094 34 24.94 0.180 633.2951 0.113 21 29.73 0.215 255.4918 0.188 68 43.17 0.312 583.2377 0.283 02 57.15 0.413 8

110.9836 0.377 37 71.91 0.520 6166.4754 0.566 05 90.78 0.675 2


solution.







Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� 1,4-Butanedioic acid,disodium salt �disodiumsuccinate�; C4H4O4Na2;�150-90-3��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of disodiumsuccinatet / °C=25


Solubility of salicylic acid in water–disodium succinate mixtures

Temperature Concentration of disodium succinate Solubility

t / °C 102c2 /mol dm−3 102c1 /mol dm−3

25 0.73 2.151.81 3.143.61 4.757.25 7.84





Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Acetic acid, monochloro-,sodium salt �sodiumchloroacetate�; C2H2ClO2Na;�3926-62-3��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of sodiumchloroacetate.t / °C=25




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Solubility of salicylic acid in water–sodium chloroacetate mixtures

Temperature Concentration of sodium chloroacetate Solubility

t / °C 102c2 /mol dm−3 102c1 /mol dm−3

25 0.00 1.641.18 2.052.94 2.595.87 3.36

11.76 4.47





Components: Original Measurements:�1� Benzoic acid 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Sodium chloroethanoate;�sodium chloroacetate�;C2H2ClO2Na; �3926-62-3��3� Water; H2O; �7732-18-5�

30E. Larsson, Z. Phys. Chem.127, 233 �1927�.

Variables: Prepared by:Concentration of sodiumchloroacetatet / °C=25



TemperatureConcentration of sodium

chloroacetate Solubility


25 0 1.6010.0500 3.000.1000 3.86






Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Acetic acid, monochloro-,sodium salt �chloroacetic acid,sodium salt; sodiumchloroacetate�; C2H2ClO2Na;�3926-62-3��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of sodiumchloroacetatet / °C=25 and 28.2




sodium chloroacetatea Solubilitya

t / °C �2 /g dm−3102c2 /mol dm−3


�compiler�

25 0.0 0.000 2.581 1.8961.538 1.320 3.478 2.5182.994 2.570 3.930 2.8454.413 3.788 4.471 3.2375.735 4.923 4.787 3.4667.013 6.020 5.193 3.7609.399 8.068 5.782 4.186

12.605 10.830 6.369 4.61117.207 14.770 7.384 5.34631.548 27.080 10.055 7.29063.096 54.160 13.550 9.810

28.2 0.00 0.000 2.461 1.7821.538 1.320 3.251 2.3544.413 3.788 4.290 3.106

10.508 9.020 5.780 4.18522.018 18.050 7.836 5.67363.096 54.160 10.637 7.701

aBoth �1 and �2 values were described by H. Stephen and T. Stephen,

Solubilities of Inorganic and Organic Compounds �Pergamon, Oxford,

1979�, Vol. 2, Pt. 1, p. 194. In the original paper, both c1 and c2 values were

given as “Normality” units.







013101-76 GOTO ET AL.

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Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Acetic acid, trichloro-,sodium salt �trichloroacetic acid,sodium salt; sodiumtrichloroacetate�; C2Cl3O2Na;�650-51-1��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of sodiumtrichloroacetatet / °C=30.5


Solubility of salicylic acid in water–sodium trichloroacetate mixtures


sodium trichloroacetatea Solubilitya

t / °C �2 /g dm−3102c2 /mol dm−3


�compiler�

30.5 0.000 0.000 2.935 2.1250.908 0.490b 3.025 2.1903.326 1.794 3.094 2.2409.978 5.382 3.345 2.422

aBoth �1 and �2 values were described by H. Stephen and T. Stephen,

Solubilities of Inorganic and Organic Compounds �Pergamon, Oxford,

1979�, Vol. 2, Pt. 1. In the original paper, both c1 and c2 values were given

by “Normality” units.bThe value “0.4900” in the original paper should be “0.004 90”.





Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Benzoic acid, sodium salt�sodium benzoate�; C7H5O2Na;�532-32-1��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of sodiumbenzoatet / °C=25




Solubility of salicylic acid in water–sodium benzoate mixtures

TemperatureConcentration ofsodium benzoate Solubilitya

t / °C w2 /g dm−3c2 /mol dm−3

�compiler� w1 /g dm−3102c1 /mol dm−3

�compiler�

25 0.0 0.0 1.667 0.012 071.7306 0.012 009 2.427 0.017 573.4612 0.024 019 3.393 0.024 576.9224 0.048 037 3.829 0.027 72

17.3061 0.120 093 4.171 0.030 2034.6121 0.240 186 4.189 0.030 3357.6869 0.400 311 4.436 0.032 1286.5303 0.600 466 4.285 0.031 02

115.3737 0.800 621 4.513 0.032 67173.0606 1.200 931 5.460 0.039 53

aIn the original data, the values �1 and �2 were given as g/l of solution.





Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Sodium benzoate; C7H5O2Na;�532-32-1��3� Water; H2O; �7732-18-5�

33P.A. Ongley, J. Chem. Soc.1954, 3634.


Miyamoto

Solubility of salicylic acid in water–sodium benzoate mixtures

TemperatureConcentration of sodium

benzoate Solubility

t / °C c2 /mol dm−3 pSa 102c1 /mol dm−3 �compiler�

25 0 1.793 1.6111 1.413 3.864

apS is the negative logarithm of the concentration in the saturated solutions

in moles per liter.



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Methods/Apparatus/Procedure:Solubilities were measured by rotating tubes of solvent and solute for atleast 8 h at 25 °C. Preliminary experiments showed that saturation wasreached in 2 h. The solutions were concentrated, if necessary, and weretitrated with standard alkali solution, bromothymol blue-neutral red beingused as mixed indicator.

Source and Purity of Materials:The acid was either of AnalaR standard or recrystallized before use. Noinformation of the purity of sodium salts was reported.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Sodium 2-hydroxybenzoate�sodium salicylate�; C7H5O3Na;�54-21-7��3� Water; H2O; �7732-18-5�

22C. Hoitsema, Z. Phys. Chem.27, 312 �1898�



Solubility of salicylic acid in water–sodium salicylate mixtures at 20.1 °C

Densitya Composition of saturated solutions

Solid phaseb� /g cm−3 c1 /mol dm−3 c2 /mol dm−3 c3 /mol dm−3

1.002 0.0132 0 55.6 A1.003* 0.0117 0.006 55.5 A1.003* 0.0112 0.175 55.5 A1.007* 0.0116 0.068 55.2 A1.009* 0.0124 0.113 54.8 A1.011* 0.0130 0.148 54.8 A1.013* 0.0135 0.175 54.6 A1.016* 0.0143 0.226 54.3 A1.018* 0.0148 0.257 54.2 A1.023 0.018 0.335 53.8 A1.024* 0.0164 0.344 53.7 A1.028* 0.0177 0.406 53.4 A1.029* 0.186 0.422 53.25 A1.034* 0.0203 0.500 52.9 A1.047* 0.0242 0.682 51.9 A1.050 0.024 0.72 51.9 A1.062 0.0312 0.94 50.4 A1.098* 0.0529 1.49 47.3 A1.112 0.062 1.70 46.3 A1.117* 0.0700 1.78 45.3 A1.137 0.095 2.11 43.7 A+B1.144 0.091 2.19 43.4 B1.148* 0.090 2.27 42.9 B1.155 0.087 2.40 42.3 B1.190 0.088 2.95 40.8 B1.215 0.086 3.41 36.7 B1.226 0.087 3.55 36.1 B1.239* 0.085 3.80 34.4 B1.263 0.081 4.23 30.0 B+C


Solubility of salicylic acid in water–sodium salicylate mixtures at 20.1 °C

Densitya Composition of saturated solutions

Solid phaseb� /g cm−3 c1 /mol dm−3 c2 /mol dm−3 c3 /mol dm−3

1.259 0.083 4.20 32.0 B+C1.259* 0.048 4.18 32.4 C1.259 0.040 4.18 32.5 C1.258* 0.021 4.12 32.6 C1.257 0 4.18 32.7 C1.257 0 4.15 32.4 C

a The asterisks refer to values interpolated between measured densities.bA=salicylic acid; B=salicylic acid+sodium salicylate; C=sodium salicy-late.


Methods/Apparatus/Procedure:Suspensions were shaken �time not specified� and phases were separatedeither by gravity or by filtration at saturation temperature. The solidphases were identified by optical microscopy. The clear saturated solutionswere weighed �occasionally densities were measured with a smallpycnometer� and their acid contents were determined volumetrically withKOH solution and a trace of phenolphthalein as indicator. Water of theresulting solutions was evaporated in a platinum dish and the dry residuewas weighed.

Source and Purity of Materials:“Chemically pure” salicylic acid and sodium salicylate �source not given�were recrystallized.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Benzoic acid, 4-amino,sodium salt �sodiumaminobenzoate�; C7H6NO2Na;�555-06-6��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of sodiumaminobenzoatet / °C=28.3 and 29.1


Solubility of salicylic acid in water–sodium aminobenzoate mixtures


sodium aminobenzoatea Solubilitya

t / °C �2 /g dm−3102c2 /mol dm−3


�compiler�

28.3 0.000 0.000 2.461 1.7821.418 0.0891 3.479 2.5181.734 1.090 3.748 2.7142.600 1.634 4.449 3.2215.200 3.268 4.425 3.2047.800 4.902 3.884 2.812

15.600 9.804 3.974 2.877



013101-78 GOTO ET AL.

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Solubility of salicylic acid in water–sodium aminobenzoate mixtures


sodium aminobenzoatea Solubilitya

t / °C �2 /g dm−3102c2 /mol dm−3


�compiler�

29.1 0.000 0.000 2.551 1.8471.734 1.090 3.794 2.7472.600 1.634 4.716 3.4335.200 3.268 4.380 3.1717.800 4.902 3.974 2.877

15.600 9.804 4.065 2.943

a The values �1 and �2 are given by H. Stephen and T. Stephen, Solubilities

of Inorganic and Organic Compounds �Pergamon, Oxford, 1979�, Vol. 2, Pt.

1, p. 235. The “Normality” was used in the original paper.





Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Benzenesulfonic acid, sodiumsalt �sodium benzenesulfonate�;C6H5O3SNa; �515-42-4��3� Water; H2O; �7732-18-56�

35A. Osol and M. Kilpatrick, J.Am. Chem. Soc. 55, 4440�1933�.

Variables: Prepared by:Concentration of sodiumbenzenesulfonatet / °C=25.15


Solubility of salicylic acid in water–sodium benzenesulfonate mixtures

Temperature

Concentration ofsodium

benzenesulfonate Density Solubility

t / °C c2 /mol dm−3 � /g cm−3 102c1 /mol dm−3

25.15 0.00 — 1.5980.10 1.005 1.4470.250 1.015 1.5450.50 1.033 1.7281.00 1.070 2.349




Methods/Apparatus/Procedure:The concentration of salicylic acid was determined by titration of sodiumhydroxide in an atmosphere free from carbon dioxide, using phenol red asindicator �M. Kilpatrick, Jr., and E.F. Chase, J. Am. Chem. Soc. 53, 1732�1931�; E.F. Chase and M. Kilpatrick, Jr., J. Am. Chem. Soc. 53, 2589�1931�; A. Osol and M. Kilpatrick, Jr., J. Am. Chem. Soc. 55, 4430�1933��.

Source and Purity of Materials:Salicylic acid was purified by recrystallization. The melting point was159 °C.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Benzenesulfonic acid,4-methyl, sodium salt �sodiumtoluenesulfonate�; C7H7O3SNa;�657-84-1��3� Water; H2O; �7732-18-56�


Variables: Prepared by:Concentration of sodiumtoluenesulfonatet / °C=25.15


Solubility of salicylic acid in water–sodium toluenesulfonate mixtures

Temperature

Concentration ofsodium

toluenesulfonate Density Solubility


25.15 0.00 — 1.5980.20 1.014 1.6770.50 1.032 2.1911.00 1.066 3.903







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Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� 2-Naphthalene-sulfonic acid,sodium salt �sodium2-naphthalenesulfonate�;C10H7O3SNa; �532-02-5��3� Water; H2O; �7732-18-56�


Variables: Prepared by:Concentration of sodium2-naphthalenesulfonatet / °C=25.15


Solubility of salicylic acid in water–sodium 2-naphthalenesulfonate mix-tures

TemperatureConcentration of sodium2-naphthalenesulfonate Density Solubility


25.15 0.00 — 1.5980.10 1.005 1.5430.2 1.010 1.983





3.1.1.5. Amides

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Acetamide; C2H5ON;�60-35-5��3� Water; H2O; �7732-18-5�

21A.N. Campbell and A.J.R.Campbell, J. Am. Chem. Soc. 62,291 �1940�.

Variables: Prepared by:Concentration of acetamidet / °C=20



Solubility of salicylic acid in water–acetamide mixtures


acetamide SolubilityNature of

equilibrium solidsystemat / °C 100w2

100x2

�compiler� 100w1

100x1

�compiler�

0 — — 0.19 0.025 SA0.4 0.10 0.225 0.029 SA1.6 0.50 0.28 0.037 SA2.0 0.62 0.26 0.034 SA6.2 2.0 0.375 0.051 SA

12.85 4.325 0.53 0.076 SA25.9 9.77 1.30 0.210 SA37.8 16.2 2.71 0.495 SA44.3 20.6 4.13 0.821 SA+Compd.

invariant point48.9 23.9 4.24 0.887 Compd.52.4 26.9 4.19 1.08 Compd.64.5 40.5 7.53 2.02 AC+Compd.

Invariant point79.3 53.9 — — AC

aSA=Salicylic acid; AC=acetamide.


Methods/Apparatus/Procedure:The complete equilibrium diagram for the ternary system salicylicacid–acetamide–water at 20 °C was determined. The salicylic acid wasestimated by titration and the acetamide was estimated by distillation withsodium hydroxide.

Source and Purity of Materials:Salicylic acid was recrystallized from water. Acetamide was distilledseveral times and protected from moist air.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O2; �69-72-7��2� Urea; CH4N2O; �57-13-6��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of ureat / °C=30

A. Goto and R. Goto

Solubility of salicylic acid in water–urea mixtures

Temperature Concentration of urea Solubility

t / °C c2 /mol dm−3 % �obs�a102m1 /mol kg−1

�compiler�

30 0 0.261 2.140.5 0.316 2.601 0.374 3.071.5 0.434 3.572 0.528 4.03

a
The compiler assumed that % should be read as “mass %.”


013101-80 GOTO ET AL.

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Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 39 for the3-hydroxybenzoic acid–water system in Sec. 2.1.1.2. The optical densityof salicylic acid was determined at 232 and 296 nm.

Source and Purity of Materials:Salicylic acid and urea were of the purest reagent grade.


3.1.1.6. Carbohydrates

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� �-D-Glucose �dextrose�;C6H12O6; �492-62-6��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of D-glucoset / °C=24.89 and 34.82


Solubility of salicylic acid in water–D-glucose mixtures

TemperatureConcentrationof D-glucose Solubilitya

Solubilitychange

t / °C 102x2 m2 /mol kg−1 104x1

102m1 /mol kg−1

�compiler� %b

24.89 0 0 2.8851 1.602 100.000.036 13 0.020 06 2.8863 1.603 100.040.045 09 0.025 04 2.8892 1.605 100.140.060 31 0.035 50 2.8915 1.607 100.220.090 45 0.052 53 2.8901 1.606 100.170.181 9 0.101 15 2.8983 1.612 100.430.455 0 0.253 79 2.9232 1.631 101.320.920 0 0.515 48 2.9536 1.655 102.371.367 5 0.769 66 2.9896 1.683 103.621.782 8 1.007 6 3.0149 1.705 104.49

34.82 0 0 4.1844 2.324 100.000.036 11 0.020 05 4.1847 2.325 100.010.045 16 0.025 08 4.1869 2.326 100.060.060 17 0.033 42 4.1845 2.325 100.000.089 70 0.049 84 4.1917 2.330 100.180.178 7 0.099 38 4.2019 2.338 100.420.437 1 0.244 67 4.2152 2.351 100.740.855 6 0.480 51 4.2627 2.388 101.881.239 8 0.696 95 4.3103 2.424 103.011.732 2 0.978 63 4.3601 2.464 104.20

aThe molality solubility was calculated from the equation m1= �x1 /M3� / �1−x1−x2� by the compilers.bWith respect to pure water.




Methods/Apparatus/Procedure:Suspensions were shaken in carefully cleaned �steamed� glass bottles withrubber stoppers placed in an Ostwald thermostat �times not specified�.After the solid phase was settled, filtration at equilibrium temperature wasperformed by pressing the solution through a glass tube filled with glasswool. The filtrate, the first 20 cm3 of which was discarded, was weighedand titrated with Ba�OH�2 solution using phenolphthalein as indicator.Care was taken to avoid contamination of Ba�OH�2 with atmosphericCO2.

Source and Purity of Materials:Salicylic acid �Kahlbaum� was recrystallized repeatedly from water andthen from ethanol, m.p. 156 °C. �-D-Glucose �Kahlbaum� was dried at80–85 °C.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� D-Fructose �levulose�;C6H12O6; �57-48-7��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of D-fructoset / °C=24.89


Solubility of salicylic acid in water–D-fructose mixtures

TemperatureConcentrationof D-fructose Solubilitya

Solubilitychange

t / °C 102x2 m2 /mol kg−1 104x1

102m1 /mol kg−1

�compiler� %b

24.89 0 0 2.8851 1.602 100.000.036 02 0.020 00 2.8883 1.604 100.110.044 84 0.025 00 2.8939 1.608 100.300.059 77 0.033 16 2.8959 1.609 100.380.107 4 0.059 68 2.8954 1.609 100.350.181 1 0.100 67 2.9078 1.618 100.790.450 9 0.251 39 2.9445 1.642 102.06

aThe molality solubility was calculated from the equation m1= �x1 /M3� / �1−x1−x2� by the compilers.bWith respect to pure water.


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 23 for thesalicylic acid–D-glucose–water system.

Source and Purity of Materials:Salicylic acid �Kahlbaum� was recrystallized repeatedly from water andthen from ethanol, m.p. 156 °C. D-Fructose �Kahlbaum� was dried at80–85 °C.



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Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Sucrose �saccharose�;C12H22O11; �57-50-1��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of sucroset / °C=24.89 and 34.82


Solubility of salicylic acid in water–sucrose mixtures


of sucrose SolubilityaSolubility

change

t / °C 102x2 m2 /mol kg−1 104x1

102m1 /mol kg−1

�compiler� %b

24.89 0 0 2.8851 1.602 100.000.036 25 0.020 130 2.9023 1.612 100.590.045 20 0.025 106 2.9047 1.614 100.680.062 70 0.033 476 2.9107 1.617 100.900.091 00 0.050 564 2.9625 1.626 101.430.183 81 0.102 22 2.9637 1.649 102.720.460 60 0.257 12 3.0730 1.714 106.500.916 01 0.513 09 3.2391 1.815 112.271.150 8 0.646 30 3.3264 1.869 115.281.340 4 0.754 18 3.4142 1.922 118.341.940 3 1.098 50 3.6326 2.057 125.90

34.82 0 0 4.1844 2.324 100.00.036 06 0.020 02 4.2060 2.337 100.520.045 10 0.025 05 4.2028 2.335 100.440.060 41 0.033 56 4.2152 2.342 100.740.090 65 0.050 37 4.2383 2.356 101.290.181 24 0.100 80 4.2870 2.385 102.450.455 57 0.254 09 4.4591 2.488 106.570.880 84 0.493 40 4.5967 2.632 112.241.350 1 0.759 87 4.9438 2.783 118.151.942 4 1.099 90 5.2365 2.966 125.14

The average was calculated by the compiler.


aThe molality solubility of salicylic acid was calculated from the equation

m1= �x1 /M3� / �1−x1−x2� by the compilers.bWith respect to pure water.


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 23 for thesalicylic acid–D-glucose–water system.

Source and Purity of Materials:Salicylic acid �Kahlbaum� was recrystallized repeatedly from water andthen from ethanol, m.p. 156 °C. Sucrose was “Feinste Indisch-Raffinade.”

Estimated Errors:Temperature: precision �0.03 K.Solubility: not stated.

3.1.1.7. Aromatic compounds

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid, salicylicacid�; C7H6O3; �59-72-7��2� Water; H2O; �7732-18-5��3� Benzene; C6H6; �71-43-2�

71E. Cohen and W.D.J. vanDobbenburgh, Z. Phys. Chem.118, 37 �1925�.



Solubility of salicylic acid in water–benzene mixtures and in benzene

Temperature Salicylic acid–water–benzene Salicylic acid–benzene

t / °C 105w2

100w1

�first analysis�100w1

�second analysis�100w1

a

�Av.�100w1

�first analysis�100w1

�second analysis�100w1

a

�Av.�

30.50 4 1.015 1.015 1.015 1.003 1.009 1.00614.7 1.049 1.050 1.050 1.003 1.001 1.00237.4 1.094 1.097 1.096 1.007 — �1.007�68.2 1.188 1.193 1.091 1.013 1.014 1.014

104.2 1.308 1.310 1.309 1.015 1.011 1.013147.8 1.347 1.349 1.348 1.011 1.014 1.013217.1 1.353 1.349 1.351 1.011 1.020 1.016313 1.351 1.352 1.352 1.021 1.020 1.021excess 1.354 1.359 1.357

a



1c

ler�

��

013101-82 GOTO ET AL.

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Methods/Apparatus/Procedure:In parallel experiments, dry benzene and benzene containing a knownamount of water were added to dry salicylic acid contained in twocarefully dried, weighed bottles. These were shaken in an Ostwaldthermostat for 5–6 h at 30.50 °C. After settling of the solid phase, twosamples of the supernatant solution were taken using a glass tubecontaining some cotton wool. The samples were weighed, the benzenewas evaporated by a dry air stream, and the dry residues were weighedagain.

Source and Purity of Materials:Salicylic acid �Kahlbaum� was recrystallized from dry ether, ground, andkept in a desiccator over P4O10. Water was distilled from a tin-coatedapparatus. Thiophene-free benzene was kept with P4O10 for several days,then distilled slowly.

Estimated Errors:Temperature: uncertainty �0.02 K.Mass concentration: uncertainty �0.1 mg.

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �59-72-7��2� Water; H2O; �7732-18-5��3� Benzene; C6H6; �71-43-2�

71E. Cohen and W.D.J. vanDobbenburgh, Z. Phys. Chem.118, 37 �1925�.

Variables: Prepared by:Concentration of benzenet / °C=30.50


Solubility of salicylic acid in water–benzene mixtures

Temperature Concentration of benzene Solubility


a 100w1b

100w�compi

30.50 4 0 1.02 1.00 1.014 0 1.01 — �1.013 0 — 1.02 �1.023 66 1.16 1.17 1.174 71 1.19 1.18 1.18


a and w1b values.




Methods/Apparatus/Procedure:Dry organic solvent and solvent containing a known amount of waterwere added to dry salicylic acid contained in carefully dried, weighedbottles. The dry solvent was manipulated in a closed system to avoidcontact with moist air. The bottles were shaken in an Ostwald thermostatat 30.50 °C. After settling of the solid phase, two samples of thesupernatant solution were taken using a glass tube containing some cottonwool. The samples were weighed, the solvent was evaporated by a dry airstream and the dry residues were weighed again. Equilibrium was attainedfrom under- and supersaturation. The latter was obtained by heating thesolution until almost all of the solid phase was dissolved, then thesuspension was shaken at 30.50 °C for 3–5 h.

Source and Purity of Materials:Salicylic acid �Kahlbaum� was recrystallized from dry ether, ground, andkept in a desiccator over P4O10. Water was distilled from a tin-coatedapparatus. Thiophene-free benzene was kept with P4O10 for several days,then distilled slowly.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Benzine �petroleum ether��3� Water; H2O; �7732-18-5�

73I.L. Krupatkin, Zh. Obsh.Khim. 26, 3240 �1956� �J. Gen.Chem. USSR �Engl. Transl.� 26,3609 �1956��.

Variables: Prepared by:Composition A. Goto and H. Miyamoto


e


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Polytherms of salicylic acid–benzine–water system

Section number

Composition of saturated solutionsCrystallizationTemperature Stratification temperature

SalicylicAcid

100w1

Benzine100w2

�compiler�

Water100w3

�compiler� t / °CTwo-phaset / °C

Three-phast / °C

1.Benzine 5%,Water 95%

49.00 2.55 48.45 — 90.0 —

50.00 2.50 47.50 — 100.0 —

2.Benzine 20%,Water 80%

6.00 18.80 75.20 — — 89.07.00 18.60 74.40 — — 96.0

10.00 18.00 72.00 102.00 — 98.020.00 16.00 64.00 101.00 — 102.030.00 14.00 56.00 104.5 — 103.040.00 12.00 48.00 105.0 — 101.045.00 11.00 44.00 — — 99.055.00 9.00 36.00 — — 90.060.00 8.00 32.00 106.0 — 81.069.00 6.20 24.80 — 120.0 —70.00 6.00 24.00 110.0 105.0 —71.00 5.80 23.20 — 78.0 —80.00 4.00 16.00 119.00 — —90.00 2.00 8.00 134.00 — —

100.00 0.00 0.00 155.00 — —3.Benzine 40%Water 60%

7.00 37.20 55.80 — — 92.0010.00 36.00 54.00 103.0 — 100.020.00 32.00 48.00 104.00 — 103.030.00 28.00 42.00 105.0 — 104.040.00 24.00 36.00 106.0 — 100.050.00 20.00 30.00 107.0 — 90.060.00 16.00 24.00 108.0 — —70.00 12.00 18.00 112.0 125.0 —72.00 11.20 16.80 — 102.0 —73.00 10.80 16.20 — 80.0 —80.00 8.00 12.00 121.0 — —90.00 4.00 6.00 147.0 — —

100.00 0.00 0.00 155.0 — —4Benzine 60%Water 40%

6.00 56.40 37.60 — — 85.09.00 54.60 36.40 103.0 — 100.0

18.00 49.20 32.80 104.0 — 102.523.00 46.20 30.80 104.5 — 103.033.00 40.20 26.80 105.0 — 100.037.00 37.80 25.20 105.0 — 98.041.00 35.40 23.60 106.0 — 89.050.00 30.00 20.00 108.0 — 70.060.00 24.00 16.00 110.0 — —69.00 18.60 12.40 — 136.0 —70.00 18.00 12.00 118.0 113.0 —71.00 17.40 11.60 — 91.0 —80.00 12.00 8.00 128.0 — —90.00 6.00 4.00 140.0 — —

100.00 0.00 0.00 155.0 — —5Benzine 80%Water 20%

6.00 75.20 18.80 — — 90.07.30 74.16 18.54 — — 100.09.00 72.80 18.20 107.0 — 103.0

16.00 67.20 16.80 108.0 — 104.022.00 62.40 15.60 — — 100.023.00 61.60 15.40 109.0 — 96.028.00 57.60 14.40 109.5 — 87.0


aded 22 Feb 2011 to 132.163.193.247. Redistribution subject to AIP license or copyright; see http://jpcrd.aip.org/about/rights_and_permissions

ase

013101-84 GOTO ET AL.

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Polytherms of salicylic acid–benzine–water system

Section number

Composition of saturated solutionsCrystallizationTemperature Stratification temperature

SalicylicAcid

100w1

Benzine100w2

�compiler�

Water100w3

�compiler� t / °CTwo-phaset / °C

Three-pht / °C

40.00 48.00 12.00 112.0 — —50.00 40.00 10.00 113.0 — —60.00 32.00 8.00 115.0 — —69.00 24.80 6.20 — 141.0 —70.00 24.00 6.00 123.0 124.0 —71.00 23.20 5.80 — 98.0 —80.00 16.00 4.00 134.0 — —90.00 8.00 2.00 146.0 — —10.00 0.00 0.00 155.0 — —

6Benzine 95%Water 5%

48.00 49.40 2.60 — 80.0 —49.00 48.45 2.55 — 102.0 —50.00 47.50 2.50 — 125.0 —


Methods/Apparatus/Procedure:Equilibrium between three liquid phases was studied by the visualpolythermal method. The ternary system, salicylic acid–water–benzine,was studied by means of polythermal sections drawn through itstemperature-concentration prism. The starting substances were heated insealed glass ampoules in an oil thermostat. The crystallization of themixtures was studied in these ampoules; in this connection needlelikecrystal of salicylic acid was formed at the boundary of two liquid layers.

Source and Purity of Materials:The melting point of C.P. grade salicylic acid used was 155 °C. Thetwice-distilled water and the benzine fraction boiling in the range90–120 °C were used.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Benzoic acid, 2-amino-�o-aminobenzoic acid; anthranilicacid; vitamin L1�; C7H7NO2;�118-92-3��3� Water; H2O; �7732-18-5�

74I.L. Krupatkin, Sbornik Stateipo Obshchei. Khim., Akad. NaukS.S.S.R. 2, 1221 �1953�.




Polytherm for the salicylic acid–aminobenzoic acid–water system

Sectionnumber

Composition ofsaturated solutions Temperature

Water100w3

Aminobenzoicacid 100w2

�compiler�

Salicylicacid

100w1

�compiler�Crystallization

t / °CStratification

t / °C

1.Salicylic acid80%Aminobenzoicacid 20%

0.00 20.00 80.00 141.0 —10.03 17.99 71.98 116.0 —20.53 15.89 63.58 103.0 —31.69 13.66 54.65 98.0 —36.76 12.65 50.59 97.0 62.039.89 12.02 48.09 96.0 72.041.30 11.74 46.96 96.0 73.050.18 9.96 39.86 96.0 80.062.53 7.49 29.98 95.5 81.070.78 5.84 23.38 95.5 81.079.59 4.08 16.33 95.0 81.089.92 2.02 8.06 94.0 74.594.11 1.18 4.71 90.0 65.095.05 0.99 3.96 87.5 —96.08 0.78 3.14 70.0 —


0.00 40.00 60.00 123.5 —10.13 35.95 53.92 109.0 —23.47 30.61 45.92 99.5 —33.52 26.59 39.89 96.00 65.047.53 20.99 31.48 94.0 76.060.11 15.96 23.95 93.5 78.071.57 11.37 17.06 93.5 78.577.34 9.06 13.60 93.0 77.589.77 4.09 6.14 91.0 69.095.53 1.79 2.68 83.0 —96.04 1.58 2.38 60.0 —



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Polytherm for the salicylic acid–aminobenzoic acid–water system

Sectionnumber


Water100w3

Aminobenzoicacid 100w2

�compiler�

Salicylicacid

100w1

�compiler�Crystallization

t / °CStratification

t / °C


0.00 60.00 40.00 117.0 —9.85 54.09 36.06 105.0 —

19.29 48.43 32.28 100.5 —29.57 42.26 28.17 97.0 —35.09 38.95 25.96 96.5 63.039.97 36.02 24.01 96.0 71.550.85 29.49 19.66 95.5 75.560.38 23.77 15.85 95.0 77.069.84 18.10 12.06 95.0 76.579.72 12.17 8.11 94.0 73.089.86 6.08 4.06 91.5 62.094.98 3.01 2.01 81.0 —97.00 1.80 1.20 66.0 —


0.00 80.00 20.00 133.0 —10.33 71.74 17.93 110.0 —20.60 63.52 15.88 103.0 —28.73 57.02 14.25 100.5 —34.85 52.12 13.03 98.5 64.539.60 48.32 12.08 98.0 70.049.72 40.22 10.06 97.0 76.060.21 31.83 7.96 97.0 76.570.04 23.97 5.99 96.5 76.579.55 16.36 4.09 96.0 74.089.94 8.05 2.01 94.0 63.094.97 4.02 1.01 82.0 —97.31 2.15 0.54 63.0 —


Methods/Apparatus/Procedure:The experiment was performed by the polythermic method in sealed glassampoules in an oil thermostat �V. F. Alekseev, J. Russ. Chem. Soc. 8, 249�1876��.

Source and Purity of Materials:Chemically pure grade salicylic acid with m.p. 155 °C and chemicallypure grade aminobenzoic acid with m.p. 145 °C were used.Twice-distilled water was used.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Phenol; C6H6O; �108-95-2��3� Water; H2O; �7732-18-5�

17C.R. Bailey, J. Chem. Soc.Trans. 126, 1951 �1925�.

Variables: Prepared by:Concentration of phenolt / °C=25.0–68.8



Solubility of salicylic acid in water–phenol mixtures


of phenolSolubility ofsalicylic acid Density

Solidphasea

t / °C 100w2

100x2


100x1

�compiler� 103� /kg m−3

25.0 — — 0.22 0.029 1.0008 S+soln.2.42 0.47 0.28 0.037 1.0032 S+soln.5.05 1.01 0.40 0.055 1.0057 S+soln.7.51 1.54 0.53 0.074 1.0080 S+L1+L2

59.07 25.35 8.77 2.56 1.0640 S+L1+L2

62.66 28.87 8.96 2.81 1.0700 S+soln.83.00 58.00 6.32 3.01 1.0761 S+soln.90.74 76.76 4.60 2.65 1.0785 P+S+soln.93.10 79.01 2.49 1.44 1.0793 P+soln.95.70 80.99 — — 1.0803 P+soln.70.19 31.07 — — 1.0470 L1+L2

8.43 1.73 — — 1.0070 L1+L2

69.28 30.46 0.51 0.15 1.0500 L1+L2

8.35 1.71 0.04 0.0056 1.0072 L1+L2

67.41 29.38 1.81 0.54 1.0529 L1+L2

8.23 1.69 0.13 0.018 1.0074 L1+L2

65.79 28.48 3.12 0.93 1.0544 L1+L2

8.14 1.67 0.21 0.029 1.0075 L1+L2

60.80 26.29 7.56 2.23 1.0610 L1+L2

7.66 1.57 0.46 0.064 1.0078 L1+L2

30.0 — — 0.26 0.034 S+soln.2.6 0.51 0.40 0.053 S+soln.7.5 1.54 0.60 0.084 S+soln.

56.6 23.7 9.8 2.8 S+L1+L2

8.0 1.7 0.64 0.090 S+L1+L2

71.6 40.8 9.8 3.8 S+soln.84.9 64.6 7.1 3.7 S+soln.88.5 72.7 5.9 3.3 S+soln.92.5 83.8 4.7 2.9 P+S+soln.94.5 92.8 4.7 3.1 P+soln.97.2 86.9 — — P+soln.69.3 30.2 — — L1+L2

9.1 1.9 — — L1+L2

44.0 — — 0.46 0.060 S+soln.7.8 1.6 1.2 0.17 S+soln.

47.8 18.5 13.6 3.58 L1+L2+S8.9 1.9 1.4 0.20 L1+L2+S

49.6 20.0 14.4 3.96 S+soln.56.8 26.7 15.4 4.94 S+soln.61.9 32.3 15.3 5.45 S+soln.70.9 44.9 14.3 6.17 S+soln.87.8 76.8 8.2 4.9 S+soln.82.8 65.3 10.1 5.43 S+soln.92.5 94.8 7.5 5.2 S+soln.63.5 25.3 0.72 0.20 L1+L2

10.1 2.11 0.09 0.013 L1+L2

59.0 23.3 4.3 1.2 L1+L2

10.4 2.18 0.44 0.063 L1+L2

52.6 20.4 9.2 2.4 L1+L2

9.7 2.0 1.0 0.14 L1+L2

50.3 19.5 11.3 2.98 L1+L2

9.6 2.0 1.2 0.17 L1+L2

64.2 25.6 — — L1+L2

10.2 2.13 — — L1+L2



013101-86 GOTO ET AL.

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Solubility of salicylic acid in water–phenol mixtures


of phenolSolubility ofsalicylic acid Density

Solidphasea

t / °C 100w2

100x2


100x1

�compiler� 103� /kg m−3

58.0 — — 0.80 0.11 S+soln.7.7 1.6 2.3 0.33 S+soln.

33.2 11.0 17.4 3.91 L1+L2+S12.7 2.83 4.3 0.65 L1+L2+S48.0 22.3 22.9 7.24 S+soln.55.6 29.9 22.4 8.21 S+soln.73.2 53.5 16.8 9.36 S+soln.89.0 92.2 11.0 7.77 S+soln.44.2 14.5 6.8 1.5 L1+L2

14.5 3.22 2.4 0.36 L1+L2

15.3 3.34 — — L1+L2

55.6 19.3 — — L1+L2

�— — 4.0 0.54� L1+L2

�— — 76.0 29.2� L1+L2

61.0 28.1 8.98 20.0 4.36 L1+L2+S13.5 3.07 5.6 0.87 L1+L2+S15.9 3.74 6.6 1.1 L1+L2

28.3 8.12 12.0 2.35 L1+L2

19.3 4.67 6.0 0.99 L1+L2

23.0 5.95 8.5 1.5 L1+L2

19.3 4.62 5.0 0.81 L1+L2

29.0 8.00 8.0 1.5 L1+L2

18.9 4.27 — — L1+L2

52.8 17.6 — — L1+L2

�— — 4.6 0.62� L1+L2

�— — 67.2 21.1� L1+L2

63.0 — — 1.0 0.13 S+soln.11.5 2.55 5.2 0.79 S+soln.14.2 3.32 7.6 1.2 S+soln.25.2 7.32 15.8 3.13 S+L3+L4

14.5 3.43 8.5 1.4 S+L3+L4

34.2 12.0 20.6 4.94 S+soln.87.0 90.8 13.0 9.24 S+soln31.8 8.48 2.9 0.53 Crit.Pt.

�L1+L2�43.0 13.0 1.9 0.39 L1+L2

20.5 4.74 0.8 0.13 L1+L2

23.0 5.41 — — L1+L2

49.3 15.7 — — L1+L2

18.0 4.49 10.0 1.70 Crit.Pt.�L1+L2�

16.0 3.87 9.0 1.5 L3+L4

22.3 6.00 12.5 2.29 L3+L4

�— — 4.6 0.62� L3+L4

�— — 68.6 22.2� L3+L4

68.8 — — 1.3 0.17 S+soln9.6 2.1 6.0 0.90 S+soln

19.0 5.21 17.0 3.17 S+soln38.0 16.1 27.6 7.95 S+soln45.9 23.9 30.1 10.7 S+soln60.0 38.6 25.0 11.0 S+soln84.6 89.0 15.4 11.0 S+soln

aS=soln salicylic acid; P=solid phenol; W=ice; L1= �low acid content�layer rich in phenol; L2=layer rich in water; L3= �low phenol content� layer

rich in acid; L4=layer rich in acid. Metastable results are enclosed in square

brackets.




Methods/Apparatus/Procedure:Both analytical and synthetic methods were used. In the analyticalmethod, the mixtures of salicylic acid, phenol and water, were stirred in athermostat. After equilibrium was established, the solution was sucked offthrough a side tube with filter into a stopper flask and weighed,transferred to a measuring flask. Phenol was estimated by thebromide-bromate method. Salicylic acid was determined with bariumhydroxide using p-nitrophenol as an indicator. In the synthetic method,varying amounts of salicylic acid were added to known mixtures ofphenol and water and the temperatures of sudden thickening weredetermined. The work was carried out in sealed tubes. The temperature ofthe beginning of critical opalescence was also determined.

Source and Purity of Materials:Commercial salicylic acid was recrystallized from water four times.Physiologically pure salicylic acid was also used. The salicylic acid wasdissolved in a hot mixture of phenol and water. The solution obtained wasslowly cooled. After recrystallizing twice, the melting point of the productwas 158.7 °C. When allowance was made for stem distillation, themelting point was increased to 160.4 °C. The phenol crystals werepurchased from British Drug Houses and were distilled twice. The meltingpoint of the product was 40.8 °C.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� 2,4,6-Trinitorophenol �picricacid�; C6H3N3O7; �88-89-1��3� Water; H2O; �7732-18-5�

75I.L. Krupatkin, Zh. Obsh.Khim. 25, 1640 �1955�.


Polytherms for the salicylic acid–picric acid–water system

Sectionnumber


Salicylicacid

100w1

�compiler�

Picric acid100w2

�compiler�Water100w3

Stratificationt / °C

Crystallizationt / °C

1.Salicylic acid93%Picric acid7%

60.45 4.55 35.00 58.055.50 4.18 40.32 68.546.50 3.50 50.00 74.037.2 2.80 60.00 76.527.36 2.06 70.58 77.018.56 1.40 80.04 77.0

8.99 0.68 90.33 74.06.51 0.49 93.00 65.0


51.34 8.36 40.30 65.543.00 7.00 50.00 70.033.94 5.52 60.54 72.025.52 4.16 70.32 72.017.17 2.80 80.03 71.0

8.54 1.39 90.07 65.5



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Polytherms for the salicylic acid–picric acid–water system

Sectionnumber


Salicylicacid

100w1

�compiler�

Picric acid100w2

�compiler�Water100w3

Stratificationt / °C

Crystallizationt / °C


48.6 11.4 40.00 64.0040.50 9.50 50.00 69.0032.39 7.60 60.01 69.0024.30 5.70 70.00 69.0015.85 3.72 80.43 68.00

8.10 1.90 90.00 65.004.Salicylic acid78%Picric acid22%

50.70 14.30 35.00 57.00 —46.53 13.13 40.34 63.00 —38.98 10.99 50.03 69.00 1.0431.20 8.80 60.00 69.00 —23.35 6.58 70.07 69.00 99.015.58 4.39 80.03 65.5 —

7.80 2.2 90.00 60.0 99.05.Salicylic acid75%Picric acid25%

48.75 16.25 35.00 61.044.98 14.99 40.03 68.037.47 12.49 50.04 71.029.77 9.92 60.31 71.024.49 7.50 70.02 70.014.97 4.99 80.04 67.0


45.50 19.50 35.00 66.041.57 17.82 40.61 70.034.95 14.98 50.07 73.527.97 11.99 60.05 73.021.00 9.00 70.00 71.513.34 5.72 80.95 67.0


42.00 28.00 30.00 70.037.80 25.20 37.00 79.036.00 24.00 40.00 80.030.00 20.00 50.00 83.024.00 16.00 60.00 83.0 92.018.00 12.00 70.00 83.0 —12.00 8.00 80.00 75.0 93.0

9.00 6.00 85.00 59.5 93.08.Salicylic acid50%Picric acid50%

37.50 37.50 25.00 76.035.00 35.00 30.00 89.030.00 30.00 40.00 97.025.00 25.00 50.00 98.020.00 20.00 60.00 97.015.00 15.00 70.00 96.010.00 10.00 80.00 85.0

7.50 7.50 85.00 62.0


Methods/Apparatus/Procedure:The experiment was performed by polythermic method in sealed glassampoules in an oil thermostat �V.F. Alekseev, J. Russ. Chem. Soc. 8, 249�1876��.


Source and Purity of Materials:The melting point of chemically pure grade salicylic acid was 155 °C.The melting point of chemically pure grade picric acid which wasrecrystallized from ethanol was 122.5 °C. Water was distilled twice.


3.1.1.8. Heterocyclic compounds

Components: Original Measurements:�1� Benzoic acid 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� 1,4-Diethylenedioxide�1,4-dioxane�; C4H8O2;�123-91-1��3� Water; H2O; �7732-18-5�

76W. Herz and E. Lorenz, Z.Phys. Chem. Abt. A 140, 406�1929�.

Variables: Prepared by:Concentration of dioxanet / °C=25


Solubility of salicylic acid in water–dioxane mixtures


dioxane Solubility

t / °C �2 c1 /mmol dm−3

25 10 0.0330 0.22

35-62 a

70 2.7380 3.06

100 3.05

aTwo phases were formed, the dioxane-rich and water-rich containing 2.29and 0.5 mmol dm−3 salicylic acid, respectively.


Methods/Apparatus/Procedure:Excess amounts of “pure” salicylic acid were shaken in sealed bottleswith dioxane–water mixtures in a thermostat for 8–10 h. Aftersedimentation of the solid phase, the solution was analyzed by titrationwith NaOH.



Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C6H7O3; �69-72-7��2� 1,4-Diethylenedioxide�1,4-dioxane�; C4H8O2;�123-91-1��3� Water; H2O; �7732-18-5�





013101-88 GOTO ET AL.

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Solubility of salicylic acid in water–1,4-dioxane mixture

Temperature

Solvent systemDielectricconstanta

Solubilityb

t / °C�1 /g dm−3


�compiler�

30.6 Water 78.5 3 0.022Water–1,4-dioxane 14.5 250 1.81

aThe dielectric constant of the binary mixture at the maximum solubility of

2-hydroxybenzoic acid.bIn the original paper, the solubility was given as mg/ml of solution. The �1



Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 40 for thesalicylic acid–1-propanol–water system in Sec. 3.1.1.2.

Source and Purity of Materials:The solvents was purified by the method described by A. Weissberger etal., Organic Solvents, 2nd ed. �Interscience, New York, 1955�, Chaps. 4and 5.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy- �o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2�2,3-Dimethyl-1-phenyl-3-pyrazolin-5-one�antipyrine; phenazone�;C11H12N2O; �60-80-0��3� Water; H2O; �7732-18-5�



Polytherms of salicylic acid–antipyrine–water systems

Section number

Composition of saturated solutionsDemixing

temperature

Salicylic acid100w1

�compiler�

Antipyrine100w2

�compiler�Water100w3 t / °C

1.Salicylic acid 20%Antipyrine 80%

12.00 48.00 40.00 98.010.00 40.00 50.00 113.0

8.00 32.00 60.00 125.06.00 24.00 70.00 133.04.00 16.00 80.00 128.02.00 8.00 90.00 118.0


27.00 63.00 10.00 52.023.81 55.55 20.64 99.021.00 49.00 30.00 130.013.50 31.50 55.00 148.0

6.00 14.00 80.00 146.02.97 6.93 90.10 131.01.49 3.49 95.02 106.0




Section number


temperature

Salicylic acid100w1

�compiler�

Antipyrine100w2



39.22 51.98 8.80 98.038.14 50.56 11.30 111.536.18 47.96 15.86 125.032.96 38.76 32.00 156.022.62 29.98 47.40 162.015.02 19.91 65.07 163.0

8.60 11.40 80.00 156.04.27 5.65 90.08 136.02.16 2.87 94.97 115.0


44.75 44.75 10.50 108.039.69 39.69 20.63 145.034.71 34.71 30.59 160.030.00 30.00 40.00 167.017.50 17.50 65.00 166.011.00 11.0 78.00 161.05.00 5.00 90.00 143.02.50 2.50 95.00 118.0


53.92 35.95 10.13 100.050.98 33.99 15.03 127.547.35 31.57 21.08 145.036.00 24.00 40.00 164.024.00 16.00 60.00 166.015.00 10.00 75.00 160.0

5.97 3.98 90.05 143.03.00 2.00 95.00 119.0


63.00 27.00 10.00 79.056.00 24.00 20.00 128.049.00 21.00 30.00 149.042.00 18.00 40.00 156.035.00 15.00 50.00 159.028.00 12.00 60.00 161.021.00 9.00 70.00 160.014.00 6.00 80.00 154.0

7.00 3.00 90.00 140.03.50 1.50 95.00 114.0


63.18 15.80 21.02 107.055.94 13.99 30.07 131.048.00 12.00 40.00 144.038.32 9.58 52.10 145.031.68 7.92 60.40 146.023.44 5.86 70.70 149.515.84 3.96 80.20 148.0

7.93 1.98 90.09 134.08.Salicylic acid 90%Antipyrine 10%

63.00 7.00 30.00 94.058.50 6.50 35.00 107.049.26 5.47 45.27 115.044.83 4.98 50.19 119.035.43 3.94 60.63 124.027.09 3.01 69.90 129.018.00 2.00 80.00 132.0

9.00 1.00 90.00 120.01.17 0.13 98.70 108.0



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Section number


temperature

Salicylic acid100w1

�compiler�

Antipyrine100w2



57.00 3.00 40.00 96.047.50 2.50 50.00 104.038.00 2.00 60.00 108.028.50 1.50 70.00 110.018.63 0.98 80.39 116.0

9.50 0.50 90.00 111.0


Methods/Apparatus/Procedure:The experiment was performed by the polythermic method in sealed glassampoules. The three-component system was studied by polythermicsections through their prisms taken from the edge for water to the planefor the binary system antipyrine–salicylic acid.



Source and Purity of Materials:Pharmaceutical antipyrine and chemically pure grade salicylic acid wereused. Water was twice distilled.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2�4-Dimethylamino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one�4-dimethylaminoantipyrine;aminopyrine; pyramidon�;C13H17N3O; �58-15-1��3� Water; H2O; �7732-18-5�



Polytherms of salicylic acid–aminopyrine–water systems

Sectionnumber

Composition ofsaturated solutions


Stratificationtemperature

Salicylicacid

100w1

Aminopyrine100w2

�compiler�

Water100w3

�compiler� t / °C t / °C

1.Salicylic acid0.4%Aminopyrine99.6%

0.36 89.64 10 77.0 —0.32 79.68 20 71.0 —0.28 69.72 30 70.5 80.00.24 59.76 40 70.0 72.00.20 49.80 50 70.0 70.00.18 44.82 55 70.0 70.00.16 39.84 60 70.0 70.00.12 29.88 70 69.5 41.50.08 19.92 80 68.5 76.00.04 9.96 90 61.0 —


0.7 69.3 30 — 85.00.6 59.4 40 — 77.00.5 49.5 50 — 74.00.4 39.6 60 — 73.00.3 29.7 70 — 74.00.2 19.8 80 — 81.0

3.Salicylic acid5%Aminopyrine95%

3.0 57.0 40 99.0 133.52.5 47.5 50 92.5 157.02.0 38.0 60 89.0 163.01.5 28.5 70 88.0 167.01.0 19.0 80 93.0 161.00.9 17.1 82 100.0 155.0


5.0 45.0 50 120.0 133.04.0 36.0 60 116.0 143.03.0 27.0 70 114.0 144.02.5 22.5 75 114.0 144.02.3 20.7 77 116.0 140.0


18.0 27.0 55 95.0 103.516.0 24.0 60 82.0 107.612.0 18.0 70 66.0 97.0

8.0 12.0 80 — 80.0



013101-90 GOTO ET AL.

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Polytherms of salicylic acid–aminopyrine–water systems

Sectionnumber

Composition ofsaturated solutions


Stratificationtemperature

Salicylicacid

100w1

Aminopyrine100w2

�compiler�

Water100w3

�compiler� t / °C t / °C


32.4 39.6 28 80.0 100.031.5 38.5 30 72.0 110.029.25 35.75 35 55.0 120.027.0 33.0 40 39.0 126.022.5 27.5 50 — 129.518.0 22.0 60 — 129.013.5 16.5 70 — 124.0

9.0 11.0 80 — 108.06.75 8.25 85 — 95.04.5 5.5 90 — 77.0


43.6 36.4 20 — 85.042.0 35.0 23 — 110.038.15 31.85 30 — 128.032.7 27.3 40 — 136.027.25 22.75 50 — 137.521.8 18.2 60 — 137.516.35 13.65 70 — 136.010.9 9.1 80 — 125.0

5.4 4.55 90 — 98.02.7 2.3 95 — 70.0


53.29 29.71 17 — 70.051.36 28.64 20 — 105.544.94 25.06 30 — 130.038.52 21.48 40 — 137.032.10 17.90 50 — 138.528.89 16.11 55 — 138.525.68 14.32 60 — 138.519.26 10.74 70 — 137.012.84 7.16 80 — 128.5

6.42 3.58 90 — 108.03.21 1.79 95 — 89.01.93 1.07 97 — 65.0


64.0 16.0 20 — 80.056.0 14.0 30 — 115.048.0 12.0 40 — 125.040.0 10.0 50 — 126.532.0 8.0 60 — 127.024.0 6.0 70 — 127.016.0 4.0 80 — 123.0

8.0 2.0 90 — 105.04.0 1.0 95 — 80.03.2 0.8 96 — 70.0


67.5 7.5 25 — 69.063.0 7.0 30 — 92.054.0 6.0 40 — 105.045.0 5.0 50 — 110.036.0 4.0 60 — 113.027.0 3.0 70 — 113.018.0 2.0 80 — 112.013.5 1.5 85 — 110.0

9.0 1.0 90 — 101.04.5 0.5 95 — 75.0


aded 22 Feb 2011 to 132.163.193.247. Redistribution subject to AIP license or copyright; see http://jpcrd.aip.org/about/rights_and_permissions

3


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Methods/Apparatus/Procedure:Stratification was studied by the well-known Alekseev polythermalmethod �V.F. Alekseev, J. Russ. Phys.-Chem. Soc. 8, 249 �1876�� in sealedglass ampoules in an oil thermostat.

Source and Purity of Materials:Pharmacopoeia aminopyrine with m.p. 108 °C and c.p. salicylic acid withm.p. 155 °C were used. Water was distilled twice.


3.1.2. 3-Hydroxybenzoic acid

Components: Original Measurements:�1� Benzoic acid, 3-hydroxy-�m-hydroxybenzoic acid�;C7H6O3; �99-06-9��2� Methanoic acid �formic acid�;CH2O2; �64-18-6��3� Water; H2O; �7732-18-5�

79O. Aschan, Chem. Ztg. 37,1117 �1913�.

Variables: Prepared by:t / °C=20.8 E. Königsberger and L.-C.

Königsberger

Solubility of 3-hydroxybenzoic acid in water–formic acid mixture at20.8°C

Concentrationof formic acid Solubility

%a Original datab Original datac �1 /g dm−3 c1 /mol dm−

95 2.37 2.7602 27.602 0.199 84

aNot specified as mass % or volume %.bIn the original paper, the solubility was given as grams per 100 g of 95%

formic acid solution.cIn the original paper, the solubility was given as grams per 100 ml of

solution.


Methods/Apparatus/Procedure:Suspensions of solid phase in 95% formic acid were shaken at ambienttemperature for 5 h. A 5 ml saturated solution was weighed, and thesolvent was evaporated on a water bath or at ambient temperature. Theresidue was dried at 110 °C or higher and weighed.

Source and Purity of Materials:The source of the materials was not stated. Melting points of3-hydroxybenzoic acid before and after recrystallization were 196.7 and198.5 °C, respectively.



3.2. Parabens and hydroxybenzoic acidsalt–water–organic compound systems

3.2.1. Methylparaben

3.2.1.1. Alcohols

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O3;�99-76-3��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�

54R.H. Manzo, A.A. Ahumada,and E. Luna, J. Pharm. Sci. 73,1094 �1984�.


A. Goto and R. Goto

Solubility of methylparaben in water–ethanol mixtures

Temperature Solvent Solubility

t / °CEthanol100�2

Water100�3

Originaldataa

100w1


�compiler�

25 0.0 100.0 2.89 0.289 0.28910.0 90.0 3.81 0.381 0.38120.0 80.0 6.73 0.673 0.67330.0 70.0 20.5 2.05 2.0540.0 60.0 49.3 4.93 4.9350.0 50.0 123 12.3 12.360.0 40.0 196 19.6 19.670.0 30.0 265 26.5 26.5

aIn the original paper, the solubility was given as milligrams of the solute

per gram of solution.


Methods/Apparatus/Procedure:The details of the method for the solubility measurements were describedby R.H. Manzo, J. Pharm. Pharmacol. 34, 486 �1982�. Aspectrophotometric determination of substrate concentration at max wasperformed.

Source and Purity of Materials:4-hydroxybenzoic acid methyl ester was obtained from Aldrich andpurified by recrystallization. The melting point of purified methyl esterwas 131 °C. The source of ethanol was not reported.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester; �methylp-hydroxybenzoate;methylparaben�; C8H8O3;�99-76-3��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�




013101-92 GOTO ET AL.

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Variables: Prepared by:Concentration of ethanolT /K=288, 293, and 298

A. Goto and R. Goto


TemperatureT /K

Concentration ofethanol %a

Solubilityc1 /mol dm−3

288 0 8.31�10−3

95 1.54293 0 9.97�10−3

95 1.90298 0 1.14�10−2

95 28.0


nal paper.



Source and Purity of Materials:The 4-hydroxybenzoic acid methyl ester was the gift of Apin ChemicalsLtd. �Abingdon, Great Britain� and was used as received. The purity wasspecified as 99.5%. Ethanol was of Anala R grade.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O3;�99-76-3��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�

48R.H. Manzo and A.A.Ahumada, J. Pharm. Sci. 79,1109 �1990�.

Variables: Prepared by:Concentration of ethanolt / °C=15–50

A. Goto and R. Goto



ethanol Solubility

t / °C 100�2 103x1

15 0 0.18510 0.26720 0.46530 1.46

25 0 0.28610 0.47620 0.391730 2.92





ethanol Solubility

t / °C 100�2 103x1

40 0 0.68310 0.99520 2.5930 10.00

50 0 0.75510 1.6720 6.3730 17.00


Methods/Apparatus/Procedure:Solvent mixtures were prepared by mixing exactly measured volumes ofabsolute ethanol and water. A suitable amount of solvent was introducedinto a stoppered test tube containing an excess of solute and was kept atleast 24 h in a constant-temperature bath with adequate shaking. Sampleswere taken with a small diameter tube having a piece of sintered glass inits end to avoid contamination with the solid. Pipettes and filter deviceswere previously heated in an oven to reach the same temperature as thatof the experiment. The ester concentration was determinedspectrophotometrically.

Source and Purity of Materials:Methylparaben was obtained from Aldrich and purified byrecrystallization. The melting point was 398.4 K. Ethanol was analyticalgrade obtained from Merck.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O3;�99-76-3��2� 1,2-Propanediol �propyleneglycol�; C3H8O2; �57-55-6��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of propyleneglycolt / °C=27

A. Goto and R. Goto



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Solubility of methylparaben in water–propylene glycol mixtures

TemperatureConcentration ofpropylene glycol Solubility

t / °C �2 −ln x1

100x1

�compiler�

27 0.00 8.10 0.03040.10 7.73 0.04390.20 7.31 0.06690.30 6.73 0.1190.40 6.07 0.2310.50 5.23 0.5350.60 4.39 1.240.70 3.75 2.350.80 3.16 4.240.90 2.70 6.721.00 2.36 9.44



Source and Purity of Materials:The detail is given in the compilation of Ref. 59 for the methylparaben–water system in Sec. 2.2.1.1.

Estimated Errors:Solubility: the variation among triplicate samples was �5%.Temperature: �0.2 °C �the authors reported�.

3.2.1.2. Amides

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Formamide; CH3NO;�75-12-7��3� Water; H2O; �7732-18-5�

80A.R. Giaquinto, R.E.Lindstrom, J. Swarbrick, and A.LoSurdo, J. Solution Chem. 6,687 �1977�.

Variables: Prepared by:t / °C=25 A. Goto and R. Goto

Solubility of methylparaben in water–formamide mixture


t / °CFormamidea

x1

Formamide–water mixtureb

x1

25 3.06�10−4 0.0660

aMole fraction solubility in pure amide solvent.bMole fraction solubility in 0.01 mole fraction amide-in-water cosolventmixture.



Methods/Apparatus/Procedure:Excess methylparaben was equilibrated with pure amide and with theamide–water mixture in 20 ml screw-cap vials. The vials were rotated for24 h in a water bath regulated at 25 °C. After equilibrium was reached, asample solution was withdrawn by a pipet from each vial, weighed, anddiluted with methanol. The concentration of the methylparaben wasdetermined spectrophotometrically. The densities of the saturated solutionswere also measured.

Source and Purity of Materials:Methylparaben USP �Rugh Chemical Co.� was used without furtherpurification. The amide was obtained commercially. The amide wasexposed for 24 h to a molecular sieve to remove water, and then distilledunder reduced pressure in a nitrogen atmosphere. The middle 60%fraction was collected. The purity of the purified amide was found to be99.9% by gas chromatography.

Estimated Errors:Solubility: precision �2.0%.Temperature: precision �0.001 °C.

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Formamide, N-methyl�N-methylformamide�; C2H5NO;�123-39-7��3� Water; H2O; �7732-18-5�



Solubility of methylparaben in water–N-methylformamide mixture


t / °CN-methylformamidea

x1

Methylformamide–watermixtureb

x1

25 3.44�10−4 0.262

aMole fraction solubility in pure amide solvent.bMole fraction solubility in 0.01 mole fraction amide-in-water cosolvent

mixture.


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 80 for themethylparaben–formamide–water system.

Source and Purity of Materials:The detail is given in the compilation of Ref. 80 for the methylparaben–formamide–water system.




013101-94 GOTO ET AL.

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Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Formamide, N-ethyl�N-ethylformamide�; C3H7NO;�627-45-2��3� Water; H2O; �7732-18-5�



Solubility of methylparaben in water–N-ethylformamide mixture


t / °CN-ethylformamidea

x1

N-ethylformamide–watermixtureb

x1

25 3.88�10−4 0.281


mixture.





Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Formamide, N-propyl�N-propylformamide�; C4H9NO;�6281-94-3��3� Water; H2O; �7732-18-5�





Solubility of methylparaben in water–N-propylformamide mixture


t / °CN-propylformamidea

x1

N-propylformamide–watermixtureb

x1

25 4.45�10−4 0.274


mixture.





Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Formamide, N ,N-dimethyl�N ,N-dimethylformamide�;C3H7NO; �68-12-2��3� Water; H2O; �7732-18-5�



Solubility of methylparaben in water–N ,N-dimethylformamide mixture


t / °CN ,N-dimethylformamidea

x1

N ,N-dimethylformamide–watermixtureb

x1

25 3.06�10−4 0.0660


mixture.



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Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O3;�99-76-3��2� Formamide, N ,N-dimethyl�N ,N-dimethylformamide�;C3H7NO; �68-12-2��3� Water; H2O; �7732-18-5�

55R.E. Lindstrom, J. Pharm. Sci.68, 1141 �1979�.

Variables: Prepared by:Concentration of amidet / °C=25


Solubility of methylparaben in water–N ,N-dimethylformamide mixtures

Temperature Concentration of N ,N-dimethylformamide Solubility

t / °C �2 x2 103x1

25 0 0 0.2460.0409 0.0100 0.4310.0969 0.0249 0.8300.1799 0.0499 2.040.2513 0.0745 4.570.3150 0.0992 10.390.3686 0.1224 22.070.4137 0.1440 40.710.4534 0.1644 61.070.4869 0.1833 83.60


Methods/Apparatus/Procedure:The data used in the preparation of this paper were reported by A. R.Giaquinto, Ph. D. dissertation, University of Connecticut, Storrs, 1972�No. 73-9827, University Microfilms, Ann Arbor, Mich.� and in Ref. 80.The procedures for obtaining these data entailed �a� preparation of theamide–water solvent systems by careful weighing of two ingredients, �b�equilibrium of excess methylparaben with the cosolvent at 25 °C, and �c�determination of the ester concentration in the resulting solutions using astandard UV spectrophotometric procedure.

Source and Purity of Materials:The information is given in Ref. 80.

Estimated Errors:Information is given in Ref. 80


Comment and/or Additional Data:The mole fraction solubility xf �f=1� of ester by volume

fraction is defined as �S. H. Yalkowsky, S. C. Valvami, andG. L. Amidon, J. Pharm. Sci. 65, 1488 �1976��

log10 xf = log10 xw + ��c, �3�

in which xf is the mole-fraction solubility of the solute atvolume fraction �c of the cosolvent and xw is the mole frac-tion solubility of the solute in water. The term � is defined as�=C��w

0 −�c0��HYSA3� /2.303kT, where �w

0 and �c0 are the

microscopic interfacial tensions between tetradecane �amodel hydrophobic surface� and water and between tetrade-cane and pure cosolvent, respectively. The hydrophobic sur-face area for the solute is �HYSA3� and C is a correction forthe extremely small radius of curvature at the solute mol-ecule surface. Tests using aqueous cosolvent mixtures withglycerin, propylene glycol, ethylene glycol, formamide,methanol, and ethanol over the range from pure water to purecosolvent suggest that Eq. �3� is a reliable representation andthat C has a relatively constant value near 0.5.

The volume fractions �a shown in the tables were calcu-lated according to �a=xava / �xava+xwvw�, where x and v re-fer to mole fractions and partial molar volumes, respectively,of the amide a and water w in the binary mixtures. Thepartial molar volumes employed were those corresponding tothe appropriate amide mole fraction. Measurements equiva-lent to density determinations to 1 ppm were the bases forthese volume data �A. R. Giaquinto, Ph. D. dissertation, Uni-versity of Connecticut, Storrs, 1972 �No. 73-9827, Univer-sity Microfilms, Ann Arbor, MI��.

Other detailed description is shown in the original paper.

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Formamide, N ,N-diethyl�N ,N-diethylformamide�;C5H11NO; �617-84-5��3� Water; H2O; �7732-18-5�



Solubility of methylparaben in water–N ,N-diethylformamide mixture


t / °CN ,N-diethylformamidea

x1

N ,N-diethylformamide–watermixtureb

x1

25 5.51�10−4 0.447

aMole fraction solubility in pure amide solvents.bMole fraction solubility in 0.01 mole fraction amide-in-water cosolventmixture.



013101-96 GOTO ET AL.

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Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Acetamide; C2H5NO;�60-35-5��3� Water; H2O; �7732-18-5�



Solubility of methylparaben in water–acetamide mixture


t / °CAcetamidea

x1

Acetamide–water mixtureb

x1

25 5.51�10−4 0.447


mixture.





Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Acetamide, N-methyl�N-methylacetamide�; C3H7NO;�79-16-3��3� Water; H2O; �7732-18-5�





Solubility of methylparaben in water–N-methylacetamide mixture


t / °CN-methylacetamidea

x1

N-methylacetamide-water mixtureb

x1

25 3.89�10−4 0.332


mixture.





Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Acetamide, N-ethyl�N-ethylacetamide�; C4H9NO;�625-50-3��3� Water; H2O; �7732-18-5�



Solubility of methylparaben in water–N-ethylacetamide mixture


t / °CN-ethylacetamidea

x1

N-ethylacetamide–watermixtureb

x1

25 4.27�10−4 0.328


mixture.





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Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Acetamide, N-propyl�N-propylacetamide�; C4H9NO;�5331-48-6��3� Water; H2O; �7732-18-5�



Solubility of methylparaben in water–N-propylacetamide mixture


t / °CN-propylacetamidea

x1

N-propylacetamide–watermixtureb

x1

25 5.24�10−4 0.315


mixture.





Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Acetamide, N ,N-dimethyl�N ,N-dimethylacetamide�;C4H9NO; �127-19-5��3� Water; H2O; �7732-18-5�

80A.R. Giaquinto, R.E.Lindstrom, J. Swarbrick, and A.LoSurdo, J. Solution Chem. 6,687 �1977�



Solubility of methylparaben in water–N ,N-dimethylacetamide mixture


t / °CN ,N-dimethylacetamidea

x1

N ,N-dimethylacetamide–watermixtureb

x1

25 4.81�10−4 0.453


mixture.





Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Acetamide, N ,N-diethyl�N ,N-diethylacetamide�;C6H13NO; �685-91-6��3� Water; H2O; �7732-18-5�



Solubility of methylparaben in water–N ,N-diethylacetamide mixture


t / °CN ,N-diethylacetamidea

x1

N ,N-diethylacetamide–watermixtureb

x1

25 6.69�10−4 0.474


mixture.



013101-98 GOTO ET AL.

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Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Acetamide, N ,N-di-n-propyl�N ,N-di-n-propylacetamide�;C8H17NO; �1116-24-1��3� Water; H2O; �7732-18-5�



Solubility of methylparaben in water–N ,N-di-n-propylacetamide mixture


t / °CN ,N-di-n-propylacetamidea

x1

N ,N-di-n-propylacetamide–watermixtureb

x1

25 �phase separation� 0.464






Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Propionamide; C3H7NO;�79-05-0��3� Water; H2O; �7732-18-5�





Solubility of methylparaben in water–propionamide mixture


t / °CPropionamidea

x1 Propionamide–water mixture

25 3.62�10−4 not reported






Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Propionamide, N-methyl�N-methylpropionamide�;C4H9NO; �1187-58-2��3� Water; H2O; �7732-18-5�



Solubility of methylparaben in water–N-methylpropionamide mixture


t / °CN-methylpropionamidea

x1

N-methylpropionamide–watermixtureb

x1

25 4.15�10−4 0.211







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Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Propionamide, N-ethyl�N-ethylpropionamide�;C5H11NO; �5129-72-6��3� Water; H2O; �7732-18-5�



Solubility of methylparaben in water–N-ethylpropionamide mixture


t / °CN-ethylpropionamidea

x1

N-ethylpropionamide–watermixtureb

x1

25 4.42�10−4 0.315


mixture.





Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Propionamide, N-propyl�N-propylpropionamide�;C5H13NO; �3217-86-5��3� Water; H2O; �7732-18-5�




Solubility of methylparaben in water–N-ethylpropionamide mixture


t / °CN-ethylpropionamidea

x1

N-ethylpropionamide–watermixtureb

x1

25 5.12�10−4 0.321


mixture.





Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Propionamide, N ,N-dimethyl�N ,N-dimethylpropionamide�;C5H11NO; �758-96-3��3� Water; H2O; �7732-18-5�



Solubility of methylparaben in water–N ,N-dimethylpropionamide mixture


t / °CN ,N-dimethylpropionamidea

x1

N ,N-dimethylpropionamide-water mixtureb

x1

25 5.54�10−4 0.470


mixture.






013101-100 GOTO ET AL.

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Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O5;�99-78-3��2� Propionamide, N ,N-diethyl�N ,N-diethylpropionamide�;C7H15NO; �1114-51-8��3� Water; H2O; �7732-18-5�



Solubility of methylparaben in water–N ,N-diethylpropionamide mixture


t / °CN ,N-diethylpropionamidea

x1

N ,N-diethylpropionamide–watermixtureb

x1

25 �phase separation� 0.468






3.2.1.3. Carbohydrate

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O3;�99-76-3��2� �-D-Glucopyranoside,�-D-fructofuranosy �sucrose;sugar�; C12H22O11; �57-50-1��3� Water; H2O; �7732-18-5�

51A.N. Paruta and B.B. Sheth, J.Pharm. Sci. 55, 1208 �1966�.

Variables: Prepared by:Concentration of sucroset / °C=25

A. Goto and R. Goto



Solubility of methylparaben in water–sucrose mixtures


sucrose Solubilitya

t / °C 100w1

�1 /g dm−3

�compiler�102c1 /mol dm−3

�compiler�

25 0.0 2.26 1.497.5 2.24 1.47

18.5 2.21 1.4531.5 2.15 1.4141.5 2.12 1.3946.0 2.11 1.3963.5 2.02 1.33

aIn the original paper, the solubility was given as mg of ester per ml of

solution.


Methods/Apparatus/Procedure:An aqueous sucrose solution was prepared from commercial granulatedsugar and de-ionized or distilled water. Details of the solubilitydetermination at 25 °C were described by A.N. Paruta, J. Pharm. Sci. 53,1252 �1964�; A.N. Paruta and B.B. Sheth, J. Pharm. Sci. 55, 896 �1966�.Equilibrium was reached in 72 h. All solubility runs were done at leastfour times. After allowing to settle in a water bath for several hours, clearsample solutions were readily obtained. Solubilities were determined by agravimetric procedure.

Source and Purity of Materials:Methylparaben was obtained from the Nepera Chem. Co. The solute wasused without further purification.


3.2.1.4. Polyethylene glycol derivative

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O3;�99-76-3��2� Poly�oxy-1,1,2-ethanediyl�,�-hydro-�-hydroxy-�polyethylene glycol 400; PEG400�; �C2H4O�nH2O;�25322-68-3��3� Water; H2O; �7732-18-5�

58F. Shihab, W. Sheffield, J.Sprowls, and J. Nematollahi, J.Pharm. Sci. 59, 1574 �1970�.

Variables: Prepared by:Concentration of PEG 400t / °C=27

A. Goto and R. Goto



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Solubility of methylparaben in water–PEG 400 mixtures

Temperature Concentration of PEG 400 Solubility

t / °C 100w2 �1 /g dm−3 c1 /mol dm−3

27 0 2.512 0.016520 9.150 0.060140 40.700 0.267560 174.00 1.141080 337.75 2.2199

100 343.75 2.2594


Methods/Apparatus/Procedure:The solubility of methylparaben in PEG–water mixed solvent wasdetermined by adding an excess of solid methylparaben to the mixedsolvent and shaking the mixture in a water bath at 27 °C for 24 h. Theanalysis of the saturated solution was carried out by a UVspectrophotometer �Beckman DB�. For UV analysis, a known volume ofthe sample was diluted further with 50% ethanol using volumetric flasks.The absorbance values were recorded at 256 m�. The standard molarsolution of methylparaben was prepared by weighing accurately aprecalculated quantity of methylparaben in a volumetric flask and thendissolving the solid in 60% PEG–water by gentle shaking.

Source and Purity of Materials:All the compounds were analytical grade. Methylparaben was obtainedfrom Matheson Coleman & Bell. Polyethylene glycol was supplied byCity Chemical Corp. The solvents were prepared by weighed quantities ofpolyethylene glycol 400 and water.

Estimated Errors:

Solubility: nothing specified.Temperature: precision �0.1 °C.

3.2.1.5. Aromatic compound

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O3;�99-76-3��2� Benzoic acid, 4-hydroxy-,1-propyl ester �propylp-hydroxybenzoate;propylparaben�; C10H12O3;�94-13-3��3� Water; H2O; �7732-18-5�

49R. Huttenrauch and I. Keiner,Pharmazie 31, 489 �1976�.

Variables: Prepared by:Concentration of propylparabent / °C=20



Solubility of methylparaben in propylparaben–water mixture


propylparaben Solubility

t / °C %a �1 /g dm−3 c1 /mol dm−3

20 0 1.91 0.01260.04 2.03 0.0134

aThe compiler assumed mass % units.


Methods/Apparatus/Procedure:The supersaturation method was used. Either pure, crystallinemethylparaben, or a mixture of methylparaben and propylparaben wasadded to water. The mixtures were shaken in a thermostat for 3 h at30 °C, and then the solutions were further shaken for 1 h at 20 °C. Theconcentration of the methyl ester was determined by UVspectrophotometry.



Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O3;�99-76-3��2� Benzoic acid, 4-hydroxy-,propyl ester �propylp-hydroxybenzoate;propylparaben�; C10H12O3;�94-13-3��3� Water-d2; D2O; �7789-20-0�

49R. Huttenrauch and I. Keiner,Pharmazie 31, 489 �1976�.

Variables: Prepared by:Concentration of propylparabent / °C=20


Solubility of methylparaben in propylparaben–water-d2 mixture


propylparaben Solubility

t / °C %a �1 /g dm−3 c1 /mol dm−3

20 0 1.74 0.01150.04 1.80 0.0119

athe compiler assumed mass % units.



013101-102 GOTO ET AL.

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Methods/Apparatus/Procedure:The supersaturation method was used. Either pure, crystallinemethylparaben, or a mixture of methylparaben and propylparaben wasadded to water-d2. The mixtures were shaken in a thermostat for 3 h at30 °C, and then the solutions were further shaken for 1 h at 20 °C. Theconcentration of the methyl ester was determined by UVspectrophotometry.



3.2.2. Ethylparaben

3.2.2.1. Alcohols

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,ethyl ester �ethylp-hydroxybenzoate;ethylparaben�; C9H10O3;�120-47-8��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of ethanolT /K=288, 293, and 298

A. Goto and R. Goto

Solubility of ethylparaben in water–ethanol mixtures

TemperatureT /K

Concentration ofethanol, %a


288 0 2.75�10−3

95 1.93293 0 3.37�10−3

95 2.19298 0 4.09�10−3

95 2.87

aNo specific information on mass or volume percent was stated in the origi-nal paper.



Source and Purity of Materials:The methylparaben was the gift of Apin Chemicals Ltd. �Abingdon, GreatBritain� and was used as received. The purity was specified as 99.5%.Ethanol was of Anala R grade.




Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,ethyl ester �ethylp-hydroxybenzoate;ethylparaben�; C9H10O3;�120-47-8��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�

48R.H. Manzo and A.A.Ahumada, J. Pharm. Sci. 79,1109 �1990�.

Variables: Prepared by:Concentration of ethanolt / °C=15–50

A. Goto and R. Goto

Solubility of ethylparaben in water–ethanol mixtures


ethanol Solubility

t / °C 100�2 103x1

15 0 0.021110 0.042320 0.077630 0.346

25 0 0.033210 0.069120 0.16630 0.704

40 0 0.070710 0.15320 0.49330 —

50 0 0.11710 0.27520 1.1230 —


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 48 for themethylparaben–ethanol–water system in Sec. 3.2.1.1.

Source and Purity of Materials:Ethylparaben was obtained from Aldrich and purified by recrystallization.The melting point was 369.2 K. Ethanol was analytical grade obtainedfrom Merck.




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Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,ethyl ester �ethylp-hydroxybenzoic acid;ethylparaben�; C9H10O3;�120-47-8��2� 1,2-Propanediol �propyleneglycol�; C3H8O2; �57-55-6��3� Water; H2O; �7732-18-5�



A. Goto and R. Goto

Solubility of ethylparaben in propylene glycol–water mixtures


t / °C �2 −ln x1

100x1

�compiler�

27 0.00 9.19 0.01020.10 8.83 0.01460.20 8.22 0.02690.30 7.65 0.04760.40 7.02 0.08940.50 6.00 0.2480.60 5.10 0.6100.70 4.28 1.380.80 3.67 2.550.90 3.03 4.831.00 2.55 7.81



Source and Purity of Materials:Ethylparaben of high purity was obtained from Sigma Chemical Companyand used as received from the supplier. The melting point was 116 °C andthe value agreed with that reported in Ref. 46.



Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,ethyl ester �ethylp-hydroxybenzoate;ethylparaben�; C9H10O3;�120-47-8��2� �-D-Glucopyranoside,�-D-fructofuranosy �sucrose;sugar�; C12H22O11; �57-50-1��3� Water; H2O; �7732-18-5�




A. Goto and R. Goto

Solubility of ethylparaben in water–sucrose mixtures


sucrose Solubilitya

t / °C 100w1

�1 /g dm−3


�compiler�

25 0.0 1.06 6.387.5 1.04 6.26

18.5 1.02 6.1431.5 1.01 6.0841.5 1.00 6.0246.0 0.99 5.9663.5 0.95 5.72

aIn the original paper, the solubility was given as milligrams of ester permilliliters of solution.


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 51 for themethylparaben–sucrose–water system in Sec. 3.2.1.3.

Source and Purity of Materials:Ethylparaben was obtained from Heyden Chem. Corp. The solute wasused without further purification.


3.2.2.3. Organic salt

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,ethyl ester �ethylp-hydroxybenzoate;ethylparaben�; C9H10O3;�120-47-8��2� Sulfuric acid monododecylester, sodium salt �sodium laurylsulfate; sodium dodecyl sulfate�;C12H25O4SNa; �151-21-3��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of sodium laurylsulfatet / °C=27

A. Goto

Solubility of ethylparaben in water–sodium lauryl sulfate mixture

Temperature Concentration of sodium lauryl sulfate Solubility

t / °C 103c2 /mol dm−3 103c1 /mol dm−3

27 0 5.440 22.7



013101-104 GOTO ET AL.

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Methods/Apparatus/Procedure:The excess paraben was put in glass-stoppered flasks containing 10 ml ofwater or sodium lauryl sulfate �SLS� solutions. The flasks were thenshaken at 27.0�0.1 °C in an incubator �Taiyo incubator, M-I type� toattain an equilibrium. After a given volume of the supernatant was dilutedadequately with water, the concentration of the paraben in the solutionwas determined by measuring the absorbance at 256 nm �HITACHI 101Spectrophotometer�. A concentration of the paraben was measured bydiluting each fraction to be below 1 mM with respect to SLS, since nointerference by the presence of SLS below 1 mM was observed for thedetermination of the paraben.

Source and Purity of Materials:Ethylparaben was of reagent grade. Sodium lauryl sulfate was purified bythe method of S. Miyamoto, Bull. Chem. Soc. Jpn. 33, 371 �1959�. Waterwas purified by distillation from de-ionized water.


3.2.2.4. Polyethylene glycol derivatives

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,ethyl ester �ethylp-hydroxybenzoate;ethylparaben�; C9H10O3;�120-47-8��2� Poly�oxy-1,1,2-ethanediyl�,�-hydro-�-hydroxy-�polyethylene glycol 400; PEG400�; �C2H4O�nH2O;�71767-64-1��3� Water; H2O; �7732-18-5�



A. Goto and R. Goto

Solubility of ethylparaben in water–PEG 400 mixtures


t / °C 100w2 �1 /g dm−3 c1 /mol dm−3

27 0 1.030 0.006220 4.063 0.024440 18.750 0.112860 141.690 0.852780 362.500 2.0116

100 365.000 2.0255


Methods/Apparatus/Procedure:All procedures were identical to those given in the compilation of Ref. 58for the methylparaben–PEG 400–water system in Sec. 3.2.1.4.



Source and Purity of Materials:All the compounds were analytical grade. Ethylparaben was obtained fromMatheson Coleman & Bell. Polyethylene glycol was supplied by CityChemical Corp. The solvents were prepared by weighed quantities ofpolyethylene glycol 400 and water.


Components: Original Measurements:�1� Benzoic acid, 4-hydrdoxy-,ethyl ester �ethylp-hydroxybenzoate;ethylparaben�; C9H10O3;�120-47-8��2� Poly�oxy-1,2-ethanediyl�,�-hydro-�-hydroxy-�polyethylene glycol 1000; PEG1000�; �C2H4O�nH2O;�25322-68-3��3� Water; H2O; �7732-18-5�


Variables: Prepared By:Concentration of PEG 1000t / °C=20

A. Goto and R. Goto


Temperature Concentration of PEG 1000a Solubility

t / °C %w /v m1 /mmol kg−1

20 10 10.520 35.030 69.3

aIn the original paper, %w /v was given as the concentration units.



Source and Purity of Materials:Ethylparaben �BDH Ltd., Lab. reagent� was recrystallized from distilledwater and dried overnight at 40 °C in a vacuum over phosphorouspentaoxide. PEG of BDH Laboratory Reagent was used as received.

Estimated Errors:Solubility: the standard error was �0.06 mmol kg−1.

Components: Original Measurements:�1� Benzoic acid, 4-hydrdoxy-,ethyl ester �ethylp-hydroxybenzoate;ethylparaben�; C9H10O3;�120-47-8��2�3,6,9,12,15-Pentaoxaheptadecane-1,17-diol�hexaoxyethylene glycol;hexagol�; C12H26O7; �2615-15-8��3� Water; H2O; �7732-18-5�




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Variables: Prepared by:Concentration of hexagolt / °C=20

A. Goto and R. Goto

Solubility of ethylparaben in water–hexagol mixtures

Temperature Concentration of hexagola Solubility


20 10 7.3840 25.5



Methods/Apparatus/Procedure:Saturation solubility of solid ethylparaben was determined as described byP.H. Elworthy and F.J. Lipscomb, J. Pharm. Pharmacol. 20, 790 �1968�.Solubility was determined by a spectrophotometer.

Source and Purity of Materials:The ethylparaben �BDH Ltd., Lab. reagent� was recrystallized fromdistilled water, then dried overnight at 40 °C in a vacuum overphosphorous pentaoxide. Hexagol was prepared by the method of P.H.Elworthy and C.B. Macfarlane, J. Chem. Soc. 1963, 907.


Components: Original Measurements:�1� Benzoic acid, 4-hydrdoxy-,ethyl ester �ethylp-hydroxybenzoate;ethylparaben�; C9H10O3;�120-47-8��2� Polyethylene glycol 1000monocetyl ethers �cetomacrogol1000�;CH3�CH2�mO�CH2OCH2�nCH2OH�m=15 or 17, n=19 to 23�; � ��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of cetomacrogol1000t / °C=20

A. Goto and R. Goto

Solubility of ethylparaben in water–cetomacrogol 1000 mixtures

Temperature Concentration of cetomacrogol 1000a Solubility


20 1 13.95 45.1

10 78.6




Methods/Apparatus/Procedure:Saturation solubilities of solid compound were determined as described byP.H. Elworthy and F.J. Lipscomb, Pharm. Pharmacol. 20, 790 �1968�. Theanalysis was carried out by UV spectroscopy.

Source and Purity of Materials:Ethylparaben �BDH Ltd., Lab. reagent� was recrystallized from distilledwater and dried overnight at 40 °C in a vacuum over phosphorouspentaoxide. Cetomacrogol 1000 B.P.C. �Macarthy’s Ltd.� was used asreceived. The number of oxyethylene units was 21.5 and the molecularweight was taken as 1210.


Components: Original Measurements:�1� Benzoic acid, 4-hydrdoxy-,ethyl ester �ethylp-hydroxybenzoate;ethylparaben�; C9H10O3;�120-47-8��2� Heptaoxyethylene glycolmonohexadecyl ether �C16E7�;CH3�CH2�15O�CH2CH2O�7H; � ��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of C16E7

t / °C=20A. Goto and R. Goto

Solubility of ethylparaben in water–C16E7 mixtures

Temperature Concentration of C16E7a Solubility


20 1 15.92 27.6



Methods/Apparatus/Procedure:Saturation solubility of the solid compound was determined as describedby P.H. Elworthy and F. J. Lipscomb, J. Pharm. Pharmacol. 20, 790�1968�. The analysis was carried out by UV spectroscopy.

Source and Purity of Materials:Ethylparaben �BDH Ltd., Laboratory reagent� was recrystallized fromdistilled water, then dried overnight at 40 °C in a vacuum overphosphorous pentaoxide. Heptaoxyethylene glycol monohexadecyl etherprepared by P.H. Elworthy and C.B. Macfarlane, J. Chem. Soc. 1963, 907,was chromatographed to yield white crystals.




013101-106 GOTO ET AL.

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3.2.3. Propylparaben

3.2.3.1. Alcohols

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,propyl ester; �propylp-hydroxybenzoate;propylparaben�; C10H12O3;�94-13-3��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�

47A.E. Beezer, S. Forster, W-B.Park, and G.J. Rimmer,Thermochim. Acta 178, 59�1991�.

Variables: Prepared by:T /K=288.2, 293.2, and 298.2. A. Goto and R. Goto

Solubility of propylparaben in water–ethanol mixtures

TemperatureT /K



288.2 0 2.05�10−3

95 2.23293.2 0 2.41�10−3

95 2.22298.2 0 2.57�10−3

95 2.31


nal paper.



Source and Purity of Materials:The propylparaben was the gift of Apin Chemicals Ltd. �Abingdon, GreatBritain� and was used as received. The purity was specified as 99.5%.Ethanol was of Anala R grade.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,propyl ester �propylp-hydroxybenzoate;propylparaben�; C10H12O3;�94-13-3��2� 1,2-Propanediol �propyleneglycol�; C3H8O2; �57-55-6��3� Water; H2O; �7732-18-5�



A. Goto and R. Goto



Solubility of propylparaben in water–propylene glycol mixtures


t / °C �2 −ln x1

100x1

�compiler�

27 0.00 10.04 0.004 360.10 9.60 0.006 770.20 9.12 0.010 90.30 8.50 0.020 30.40 7.57 0.051 60.50 6.43 0.1610.60 5.54 0.3930.70 4.56 1.050.80 3.71 2.450.90 2.87 5.671.00 2.45 8.63



Source and Purity of Materials:Propylparaben of high purity was obtained from Sigma Chemical Co. andused as received from the supplier. The melting point was 96 °C and thevalue agreed with that reported in Ref. 46.



Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,propyl ester �propylp-hydroxybenzoate;propylparaben�; C10H12O3;�94-13-3��2� �-D-Glucopyranoside,�-D-fructofuranosy �sucrose;sugar�; C12H22O11; �57-50-1��3� Water; H2O; �7732-18-5�



A. Goto and R. Goto



Downlo

Solubility of propylparaben in water–sucrose mixtures


sucrose Solubilitya

t / °C 100w1

�1 /g dm−3


�compiler�

25 0.0 0.516 2.867.5 0.510 2.83

18.5 0.500 2.7731.5 0.497 2.7641.5 0.493 2.7446.0 0.491 2.7263.5 0.484 2.69

aIn the original paper, the solubility was given as milligrams of ester permilliliter of solution.



Source and Purity of Materials:Propylparaben was obtained from the Nepera Chem. Co. The solute wasused without further purification.


3.2.3.3. Polyethylene glycol derivative

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,propyl ester �propylp-hydroxybenzoate;propylparaben�; C10H12O3;�94-13-3��2� Poly�oxy-1,1,2-ethanediyl�,�-hydro-�-hydroxy-�polyethylene glycol 400; PEG400�; �C2H4O�nH2O;�71767-64-1��3� Water; H2O; �7732-18-5�



A. Goto and R. Goto



t / °C 100w2 �1 /g dm−3 c1 /mol dm−3

27 0 0.400 0.002220 1.825 0.010140 9.000 0.049960 116.000 0.643780 362.500 2.0116

100 365.000 2.0255




Source and Purity of Materials:All the compounds were analytical grade. Propylparaben was obtainedfrom Matheson Coleman & Bell. Polyethylene glycol was supplied byCity Chemical Corp. The solvents were prepared by weighed quantities ofpolyethylene glycol 400 and water.


3.2.4. Butylparaben

3.2.4.1. Alcohols

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,butyl ester; �n-butylp-hydroxybenzoate;butylparaben�; C11H14O3;�94-26-8��2� Ethanol; C2H3O; �64-17-5��3� Water; H2O; �7732-18-5�


Variables: Prepared by:T /K=288, 293, and 298 A. Goto and R. Goto

Solubility of butylparaben in water–ethanol mixtures

TemperatureT /K



288 0 7.04�10−3

95 3.21293 0 8.35�10−4

95 3.36298 0 1.05�10−4

95 2.31




Source and Purity of Materials:The butylparaben was the gift of Apin Chemicals Ltd. �Abingdon, GreatBritain� and was used as received. The purity was specified as 99.5%.Ethanol was of Anala R grade.




013101-108 GOTO ET AL.

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Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,butyl ester �n-butylp-hydroxybenzoate;butylparaben�; C11H14O3;�94-26-8��2� 1,2-Propanediol �propyleneglycol�; C3H8O2; �57-55-6��3� Water; H2O; �7732-18-5�

59J. Rubino and E.K. Obeng, J.Pharm. Sci. 80, 479 �1991�.


A. Goto and R. Goto

Solubility of butylparaben in water–propylene glycol mixtures


t / °C �2 −ln x1

100x1

�compiler�

27 0.00 10.45 0.002 890.10 9.95 0.004 770.20 9.43 0.008 030.30 8.70 0.016 70.40 7.68 0.046 20.50 6.43 0.1610.60 5.13 0.5920.70 3.59 2.760.80 2.50 8.210.90 1.90 15.01.00 1.76 17.2



Source and Purity of Materials:Butylparaben of high purity was obtained from Eastman Chemical Co.and used as received from the supplier. The melting point was 68 °C andthe value agreed with that reported in Ref. 46.



Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,butyl ester �butylp-hydroxybenzoate;butylparaben�; C11H14O3;�94-26-8��2� �-D-Glucopyranoside,�-D-fructofuranosy �sucrose;sugar�; C12H22O11; �57-50-1��3� Water; H2O; �7732-18-5�





A. Goto and R. Goto

Solubility of butylparaben in water–sucrose mixtures


sucrose Solubilitya

t / °C 100w1

�1 /g dm−3


�compiler�

25 0.0 0.145 7.477.5 0.149 7.67

18.5 0.150 7.7231.5 0.153 7.8841.5 0.150 7.7263.5 0.153 7.88

aIn the original paper, the solubility was given as milligrams of ester permilliliter of solution.



Source and Purity of Materials:Butylparaben was obtained from Eastman Kodak. The solute was usedwithout further purification.


3.2.4.3. Organic salt

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,butyl ester �butyl4-hydroxybenzoate;butylparaben�; C11H14O3;�94-26-8��2� Sulfuric acid monododecylester, sodium salt �sodium laurylsulfate; sodium dodecyl sulfate�;C12H25O4SNa; �151-21-3��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of sodium laurylsulfatet / °C=27

A. Goto

Solubility of butylparaben in water–sodium lauryl sulfate mixture

Temperature Concentration of sodium lauryl sulfate Solubility

t / °C 103c2 /mol dm−3 103c1 /mol dm−3

27 0 1.140 24.3



Downlo


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 5 for theethylparaben–sodium lauryl sulfate–water system in Sec. 3.2.2.3.

Source and Purity of Materials:The detail is given in the compilation of Ref. 5 for the ethylparaben–sodium lauryl sulfate–water system in Sec. 3.2.2.3.


3.2.4.4. Polyethylene glycol derivatives

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,1-butyl ester �n-butylp-hydroxybenzoate;butylparaben�; C11H14O3;�94-26-8��2� Poly�oxy-1,1,2-ethanediyl�,�-hydro-�-hydroxy-�polyethylene glycol 400; PEG400�; �C2H4O�nH2O;�71767-64-1��3� Water; H2O; �7732-18-5�





Solubility of butylparaben in water–PEG 400 mixtures


t / °C 100w2 �1 /g dm−3 c1 /mol dm−3

27 0 0.240 0.001220 1.313 0.006840 7.750 0.039960 207.500 1.0683a

80 610.000 3.1406100 612.000 3.1514

aConcentration of butylparaben at a point just prior to separation into twophases.



Source and Purity of Materials:All the compounds were analytical grade. Butylparaben was obtained fromMatheson Coleman & Bell. Polyethylene glycol 400 was supplied by CityChemical Corp.


Comment and/or Additional Data:

Temperature

Solvent

Concentration in phases Solubility in phases

t / °CT /K

�compiler�

Upper phase Lower phase Upper phase Lower phase

%w /va 100w1 %w /va 100w1 %w /va 100w2 %w /va 100w2

27 303.2 PEG 43.39 42.13 40.53 38.66 1.25 1.21 54.31 51.94Water 58.16 56.66 9.92 9.40

aIn the original paper, these concentration units were used by the author.

Components: Original Measurements:�1� Benzoic acid, 4-hydrdoxy-,1-butyl ester �n-butylp-hydroxybenzoate;butylparaben�; C11H14O3;�94-26-8��2� Poly�oxy-1,2-ethanediyl�,�-hydro-�-hydroxy-�polyethylene glycol 1000; PEG1000�; �C2H4O�nH2O;�25322-68-3��3� Water; H2O; �7732-18-5�



A. Goto and R. Goto

Solubility of butylparaben in water–PEG 1000 mixtures

Temperature Concentration of PEG 1000a Solubility


20 0 1.06510 2.5430 11.040 22.1




013101-110 GOTO ET AL.

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Source and Purity of Materials:Butylparaben �BDH Ltd., Lab. reagent� was recrystallized from aethanol–water mixture and dried overnight at 40 °C in a vacuum overphosphorous pentaoxide. PEG of BDH Laboratory Reagent was used asreceived.


Components: Original Measurements:�1� Benzoic acid, 4-hydrdoxy-,1-butyl ester �n-butylp-hydroxybenzoate;butylparaben�; C11H14O3;�94-26-8��2�3,6,9,12,15-Pentaoxaheptadecane-1,17-diol�hexaoxyethylene glycol;hexagol�; C12H26O7; �2615-15-8��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of hexagolt / °C=20

A. Goto and R. Goto

Solubility of butylparaben in water–hexagol mixtures

Temperature Concentration of hexagola Solubility


20 0 1.06510 1.9640 8.02



Methods/Apparatus/Procedure:Saturation solubilities of the solid compound were determined asdescribed by P.H. Elworthy and F.J. Lipscomb, J. Pharm. Pharmacol. 20,790 �1968�. Solubility was determined by a spectrophotometer.

Source and Purity of Materials:Butylparaben �BDH Ltd., Lab. reagent� was recrystallized from distilledwater and dried overnight at 40 °C in a vacuum over phosphorouspentaoxide. Hexagol was prepared by the method of P.H. Elworthy andC.B. Macfarlane, J. Chem. Soc. 1963, 907.




Components: Original Measurements:�1� Benzoic acid, 4-hydrdoxy-,1-butyl ether �n-butylp-hydroxybenzoate;butylparaben�; C11H14O3;�94-26-8��2� Polyethylene glycol 1000monocetyl ether �cetomacrogol1000�;CH3�CH2�mO�CH2�nCH2OH; �m=15 or 17, n=19 to 23�; � ��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of cetomacrogol1000t / °C=20

A. Goto and R. Goto

Solubility of butylparaben in water–cetomacrogol 1000 mixtures

Temperature Concentration of cetomacrogol 1000a Solubility


20 0 1.0651 1.355 58.3

10 121



Methods/Apparatus/Procedure:Saturation solubilities of the solid compound were determined asdescribed by P.H. Elworthy and F.J. Lipscomb, J. Pharm. Pharmacol. 20,790 �1968�. Solubility was determined by a spectrophotometer.

Source and Purity of Materials:Butylparaben �BDH Ltd. Lab. reagent� was recrystallized from distilledethanol–water and dried overnight at 40 °C in a vacuum overphosphorous pentaoxide. Cetomacrogol 1000 B.P.C. �Macarthy’s Ltd.� wasused as received. The number of oxyethylene units was 21.5 and themolecular weight was taken as 1210.


3.2.5. Alkylparabens

3.2.5.1. Alcohol

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,2-methylpropyl ester; �isobutylp-hydroxybenzoate;isobutylparaben�; C11H14O3;�4247-02-3��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�





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Solubility of isobutylparaben in water–ethanol mixtures

TemperatureT /K



288 95 3.10293 95 3.29298 95 4.32


nal paper.



Source and Purity of Materials:The isobutylparaben was the gift of Apin Chemicals Ltd. �Abingdon,Great Britain� and was used as received. The purity was specified as99.5%. Ethanol was of Anala R grade.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,hexyl ester; �hexylp-hydroxybenzoate;hexylparaben�; C13H18O3;�1083-27-8��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�



Solubility of hexylparaben in water–ethanol mixtures

TemperatureT /K



288 0 3.68�10−4

95 3.16293 0 3.81�10−4

95 3.50298 0 6.19�10−4

95 3.95


nal paper.



Source and Purity of Materials:The hexylparaben was the gift of Apin Chemicals Ltd. �Abingdon, GreatBritain� and was used as received. The purity was specified as 99.5%.Ethanol was of Anala R grade.



Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,heptyl ester; �heptylp-hydroxybenzoate;heptylparaben�; C14H20O3;�1085-12-7��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�



Solubility of heptylparaben in water–ethanol mixtures

TemperatureT /K



288 0 2.01�10−4

95 3.29293 0 2.52�10−4

95 3.79298 0 2.63�10−4

95 4.14


nal paper.



Source and Purity of Materials:The heptylparaben was the gift of Apin Chemicals Ltd. �Abingdon, GreatBritain� and was used as received. The purity was specified as 99.5%.Ethanol was of Anala R grade.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,octyl ester; �octylp-hydroxybenzoate;octylparaben�; C15H22O3;�5153-25-3��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�





013101-112 GOTO ET AL.

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Solubility of octylparaben in water–ethanol mixtures

TemperatureT /K



288 0 1.47�10−4

95 3.00293 0 2.30�10−4

95 3.07298 0 4.65�10−4

95 3.16


nal paper.



Source and Purity of Materials:The octylparaben was the gift of Apin Chemicals Ltd. �Abingdon, GreatBritain� and was used as received. The purity was specified as 99.5%.Ethanol was of Anala R grade.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,decyl ester; �decylp-hydroxybenzoate;decylparaben�; C17H26O3;�69679-30-7��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�



Solubility of decylparaben in water–ethanol mixtures

TemperatureT /K



288 0 3.20�10−5

95 1.66293 0 3.71�10−4

95 1.66298 0 8.80�10−4

95 2.15


nal paper.





Source and Purity of Materials:The decylparaben was the gift of Apin Chemicals Ltd. �Abingdon, GreatBritain� and was used as received. The purity was specified as 99.5%.Ethanol was of Anala R grade.


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,dodecyl ester �dodecylp-hydroxybenzoate;dodecylparaben�; C19H30O3;�2664-60-0��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�



Solubility of dodecylparaben in water–ethanol mixture

TemperatureT /K



288 95 2.30293 95 2.40298 95 2.49




Source and Purity of Materials:The dodecylparaben was the gift of Apin Chemicals Ltd. �Abingdon,Great Britain� and was used as received. The purity was specified as99.5%. Ethanol was of Anala R grade.


3.2.6. Benzylparaben

3.2.6.1. Alcohol

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,phenylmethyl ester; �benzylp-hydroxybenzoate;benzylparaben�; C14H12O3;�94-18-8��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�





Downlo

Solubility of benzylparaben in water–ethanol mixtures

TemperatureT /K



288 95 1.41293 95 1.79298 95 2.39




Source and Purity of Materials:The benzylparaben was the gift of Apin Chemicals Ltd. �Abingdon, GreatBritain� and was used as received. The purity was specified as 99.5%.Ethanol was of Anala R grade.



Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,phenylmethyl ester �benzylp-hydroxybenzoate;benzylparaben�; C14H13O3;�94-18-8��2� �-D-Glucopyranoside,�-D-fructofuranosy �sucrose;sugar�; C12H22O11; �57-50-1��3� Water; H2O; �7732-18-5�



A. Goto and R. Goto

Solubility of benzylparaben in water–sucrose mixtures


sucrose Solubilitya

t / °C 100w1

�1 /g dm−3


�compiler�

25 0.0 0.092 4.037.5 0.116 5.08

18.5 0.131 5.7431.5 0.140 6.1341.5 0.143 6.2746.0 0.149 6.5363.5 0.153 6.70

aIn the original paper, the solubility was given as milligrams of ester permilliliters of solution.




Source and Purity of Materials:Benzylparaben was obtained from Heyden Chem. Co. The solute was usedwithout further purification.


3.2.7. 2-Hydroxybenzoic acid salts

3.2.7.1. Alcohol

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-,sodium salt �sodium salicylate�;C7H5ONa; �54-21-7��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�

25A. Seidell, J. Am. Chem. Soc.31, 1164 �1909�.



Solubility of sodium salicylate in water–ethanol mixtures


of ethanol Solubility

t / °C 100w2

100x2


100x1


�compiler�

25 0 0.00 53.6 11.0 0.72210 4.16 52.1 11.5 0.67920 8.91 50.2 11.4 0.63030 14.4 48.0 11.3 0.57740 20.7 45.5 11.0 0.52150 28.1 42.2 10.6 0.45660 37.0 38.4 9.95 0.38970 47.7 33.0 8.81 0.30780 61.0 25.0 6.82 0.20890 77.9 15.0 4.20 0.110

92.3 82.4 12.0 3.39 0.0852100 100 3.82 1.13 0.0248



013101-114 GOTO ET AL.

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Methods/Apparatus/Procedure:Saturation of the solutions was effected by moderate agitation of themixtures of solute and solvent enclosed in tubes immersed in aconstant-temperature water bath maintained at 25 °C. The attainment ofequilibrium was insured by analyzing solutions shaken for differentlengths of time. The dissolved material was determined usually byevaporation and weighing the residues after carefully drying at roomtemperature in vacuum desiccators.

Source and Purity of Materials:Sodium salicylate was recrystallized and dried.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-,monolithium salt �lithiumsalicylate�; C7H5LiO3; �552-38-5��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�




Solubility of lithium salicylate in water–ethanol mixtures



t / °C 100w2

100x2


100x1


�compiler�

25 0 0.00 56.0 13.7 8.8310 4.16 55.9 14.4 8.8020 8.91 55.4 15.0 8.6230 14.4 54.5 15.5 8.3140 20.7 53.7 16.9 8.0550 28.1 52.5 16.6 7.6760 37.0 51.1 17.1 7.2570 47.7 49.5 17.6 6.8080 61.0 47.5 18.1 6.2890 77.9 45.8 19.0 5.87

92.3 82.4 45.0 18.9 5.68100 100 48.2 22.9 6.46


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 25 for thesodium salicylate–ethanol–water system.

Source and Purity of Materials:The recrystallized lithium salicylate sample contained, when analyzed bythe United States Pharmacopoeia method, 95.5% C6H4OHCOOLi.




Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-,ammonium salt �ammoniumsalicylate�; C7H5O3H4N;�528-94-9��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�




Solubility of ammonium salicylate in water–ethanol mixtures



t / °C 100w2

100x2


100x1


�compiler�

25 0 0.00 50.8 10.7 6.6520 8.91 50.3 11.8 6.5240 20.7 48.3 12.5 6.0250 28.1 46.7 12.76 5.6560 37.0 42.0 12.78 4.6780 61.0 38.0 12.2 3.9585 68.9 35.0 11.5 3.4790 77.9 31.6 10.6 2.98

92.3 82.4 30.0 10.2 2.7695 88.1 27.8 9.59 2.48

100 100 22.3 7.85 1.85



Source and Purity of Materials:The ammonium salicylate sample was practically neutral to litmus paperand contained 98.7% C6H4OHCOONH4 calculated from ammoniadetermination made by the Kjeldahl method.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-,strontium salt �strontiumsalicylate�; C14H10O6Sr;�526-26-1��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�






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Solubility of strontium salicylate in water–ethanol mixtures



t / °C 100w2

100x2


100x1


�compiler�

25 0 0.00 5.04 0.264 0.14710 4.16 4.88 0.271 0.14220 8.91 5.22 0.311 0.15230 14.4 6.20 0.401 0.18340 20.7 7.70 0.546 0.23150 28.1 8.08 0.625 0.24360 37.0 7.15 0.600 0.21370 47.7 5.90 0.541 0.17380 61.0 4.40 0.445 0.12790 77.9 2.56 0.289 0.0726

92.3 82.4 2.02 0.234 0.0570100 100 0.44 0.056 0.0122




Source and Purity of Materials:The strontium salicylate samples were analyzed by the United StatesPharmacopoeia method and contained 99.04% and 99.55%�C6H4OHCOO�2Sr+2H2O, respectively.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-,silver salt �sliver salicylate�;C7H5O3Ag; �528-95-8��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�

31J.O. Halford, J. Am. Chem.Soc. 55, 2272 �1933�.



Solubility of silver salicylate in water–ethanol mixtures



t / °C 100w2

100x2

�compiler�Undersaturation103c1 /mol dm−3

Supersaturation103c1 /mol dm−3

Average103c1 /mol dm−3

�compiler�

25 0 0 4.18 4.18 4.1818.8 6.85 3.86 4.01 3.9437.5 19.0 4.83 4.75 4.7956.2 33.5 4.43 4.40 4.4275.0 54.0 2.60 2.61 2.6193.8 85.5 0.80 0.80 0.80


Methods/Apparatus/Procedure:The saturated solutions were obtained by shaking an excess of silver saltwith the solvent for 24 h in a thermostat at 25 °C. Both theundersaturation and the supersaturation methods were performed toapproach the equilibrium. The concentration in the saturated solution wasdetermined by titration with sodium chloride, standardized against silvernitrate, to an end-point with the silver electrode.

Source and Purity of Materials:Silver salicylate was prepared by precipitation from solution of sodiumsalicylate. The obtained silver salicylate was washed with water, then withalcohol.


Components: Original Measurements:�1� Salicylic acid, basic bismuthsalt �bismuth salicylate, basic;bismuth subsalicylate�;C7H5O4Bi; �14882-18-9��2� Ethanol; C2H6O; �64-17-5��3� Water; H2O; �7732-18-5�






013101-116 GOTO ET AL.

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Solubility of bismuth salicylate in water–ethanol mixtures

Temperature Concentration of ethanol Solubility

t / °C 100w2

100x2


100x1


�compiler�

25 0 0.00 0.01 0.000 50 0.2820 8.91 0.015 0.000 85 0.4140 20.7 0.022 0.001 4 0.6160 37.0 0.036 0.002 8 0.9980 61.0 0.065 0.006 3 1.890 77.9 0.095 0.010 2.692.3 82.4 0.105 0.011 9 2.85

100 100 0.160 0.020 8 4.43



Source and Purity of Materials:No information given was given.


3.3. Hydroxybenzoic acid–water–inorganiccompound systems


3.3.1.1. Inorganic salts

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Lithium chloride; LiCl;�7447-41-8��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of LiClt / °C=25.15


Solubility of salicylic acid in water–LiCl mixtures

Temperature Concentration of LiCl Density Solubility


25.15 0.00 — 1.5980.5 1.010 1.1940.673 1.014 1.1041.198 1.025 0.8822.067 1.047 0.607




Methods/Apparatus/Procedure:The concentration of salicylic acid was determined by titration of sodiumhydroxide in an atmosphere free from carbon dioxide, using phenol red asindicator �M. Kilpatrick, Jr. and E.F. Chase, J. Am. Chem. Soc. 53, 1732�1931�; E.F. Chase and M. Kilpatrick, Jr., J. Am. Chem. Soc. 53, 2589�1931�; A. Osol and M. Kilpatrick, Jr., J. Am. Chem. Soc. 55, 4430�1933��. The temperature was indicated by E.F. Chase and M. Kilpatrick,Jr., J. Am. Chem. Soc. 53, 2589 �1931�.



Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Sodium chloride; NaCl;�7647-14-5��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of NaClt / °C=24.89 and 34.82


Solubility of salicylic acid in water–NaCl mixtures


of NaCl SolubilityaSolubility

change

t / °C 102x2 m2 /mol kg−1 104x1

102m1 /mol kg−1

�compiler� %b

24.89 0 0 2.8851 1.602 100.000.036 06 0.020 025 2.9110 1.617 100.890.045 043 0.025 012 2.9183 1.621 101.150.059 975 0.033 313 2.9324 1.629 101.640.089 968 0.049 988 2.9176 1.622 101.130.179 64 0.099 90 2.9027 1.615 100.610.448 19 0.249 91 2.8149 1.570 97.570.879 72 0.492 66 2.6128 1.464 90.561.302 3 0.732 46 2.4236 1.363 84.001.719 9 0.971 38 2.2487 1.270 77.94

34.82 0 0 4.1844 2.324 100.000.036 08 0.020 041 4.2062 2.337 100.520.045 12 0.025 062 4.2103 2.339 100.630.060 14 0.033 407 4.2169 2.343 100.780.089 88 0.049 942 4.2127 2.342 100.680.179 98 0.100 10 4.1806 2.326 99.910.448 14 0.249 91 4.0196 2.242 96.060.894 34 0.500 98 3.7171 2.083 88.831.337 2 0.752 40 3.4398 1.936 82.201.779 7 1.005 8 3.1596 1.786 75.51

aThe molality solubility was calculated from the equation m1= �x1 /M3� / �1−x1−x2�.bWith respect to pure water.



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Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 23 for thesalicylic acid–ethanol–water system in Sec. 3.1.1.2.

Source and Purity of Materials:Salicylic acid �Kahlbaum� was recrystallized repeatedly from water andthen from ethanol, m.p. 156 °C. Sodium chloride was of the best quality�Kahlbaum� and further purified by precipitation from saturated solutionwith hydrochloric acid.



18S.S. Doosaj and W.V. Bhagwat,J. Indian Chem. Soc. 10, 225�1933�19W.V. Bhagwat and S.S. Doosaj,J. Indian Chem. Soc. 10, 477�1933�.

Variables: Prepared by:Concentration of NaClt / °C=25



Temperature Concentration of NaCl Solubilitya

t / °C �2 /g dm−3c2 /mol dm−3


�compiler�

25 0 0 2.478 1.7941.176 0.020 12 2.229 1.6145.88 0.100 6 2.219 1.607

11.76 0.201 2 2.150 1.55714.70 0.251 5 2.125 1.53819.60 0.335 4 2.075 1.50229.40 0.503 1 2.000 1.44839.20 0.670 7 1.901 1.37658.80 1.006 1.719 1.245

aIn the original data, the values �1 and �2 were given as g/l of solution.








Variables: Prepared by:Concentration of NaClt / °C=25.15



Temperature Concentration of NaCl Density Solubility


25.15 0.00 — 1.5980.2 1.005 1.3260.5 1.018 1.1881.0 1.039 0.9842.0 1.076 0.666


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 35 for thesalicylic acid–LiCl–water system.




33P. A. Ongley, J. Chem. Soc.1954, 3634.


Miyamoto

Solubility of salicylic acid in water–NaCl mixture

Temperature Concentration of NaCl Solubility

t / °C c2 /mol dm−3 pSa102c1 /mol dm−3

�compiler�

25 0 1.793 1.6111 1.991 1.021

apS is the negative logarithm of the concentration in the saturated solutionsin moles/l.


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 33 for thesalicylic acid–sodium benzoate–water system in Sec. 3.1.1.4.

Source and Purity of Materials:The acid was either of AnalaR standard or was recrystallized before use.No information of the purity of sodium salts was reported.




013101-118 GOTO ET AL.

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Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Potassium chloride; KCl;�7447-40-7��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of KClt / °C=24.89 and 34.82


Solubility of salicylic acid in water–KCl mixtures

Temperature Concentration of KCl SolubilityaSolubility

change

t / °C 102x2 m2 /mol kg−1 104x1

102m1 /mol kg−1

�compiler� %b

24.89 0 0 2.8851 1.602 100.000.036 06 0.020 024 2.9216 1.623 101.260.045 06 0.025 027 2.9278 1.626 101.480.060 10 0.033 305 2.9364 1.631 101.780.089 99 0.050 001 2.9364 1.632 101.780.179 8 0.099 987 2.9377 1.634 101.820.447 0 0.249 24 2.8831 1.608 99.700.877 7 0.491 54 2.6321 1.474 95.531.332 2 0.749 49 2.6131 1.471 90.571.776 0 1.003 60 2.4759 1.400 85.82

34.82 0 0 4.1844 2.324 100.000.036 08 0.020 042 4.2206 2.345 100.870.045 12 0.025 061 4.2263 2.348 101.000.060 10 0.033 378 4.2337 2.353 101.180.090 24 0.050 144 4.2325 2.353 101.150.179 95 0.100 05 4.2203 2.348 100.860.450 32 0.251 13 4.1277 2.303 98.650.882 82 0.494 47 3.9268 2.200 93.851.340 7 0.754 44 3.7075 2.087 88.601.777 8 1.004 8 3.5003 1.976 83.65

aThe molality solubility was calculated from the equation m1= �x1 /M3� / �1−x1−x2�.bWith respect to pure water.



Source and Purity of Materials:Salicylic acid �Kahlbaum� was recrystallized repeatedly from water andthen from ethanol. The melting point of salicylic acid was m.p. 156 °C.Potassium chloride was of the best quality �Kahlbaum� and furtherpurified by chlorination, evaporation and recrystallization.

Estimated Errors:Solubility: nothing specified.Temperature: precision �0.03K.



Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Potassium chloride; KCl;�7447-40-7��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of KClt / °C=25.15


Solubility of salicylic acid in water–KCl mixtures

Temperature Concentration of KCl Density Solubility


25.15 0.0 — 1.5980.2 1.008 1.3530.5 1.021 1.2521.0 1.042 1.0961.5 1.064 0.9452.0 1.087 0.833





Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Potassium bromide; KBr;�7758-02-3��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of KBrt / °C=25.15


Solubility of salicylic acid in water–KBr mixtures

Temperature Concentration of KBr Density Solubility


25.15 0.0 1.5980.2 1.014 1.3810.5 1.038 1.3081.0 1.080 1.185



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Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Potassium nitrate; KNO3;�7757-79-1��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of KNO3

t / °C=24.89 and 34.82E. Königsberger and L.-C.Königsberger

Solubility of salicylic acid in water–KNO3 mixtures


of KNO3 SolubilityaSolubility

change

t / °C 102x2 m2 /mol kg−1 104x1

102m1 /mol kg−1

�compiler� %b

24.89 0 0 2.8851 1.602 100.000.036 08 0.020 029 2.9351 1.630 101.730.045 093 0.025 044 2.9433 1.635 102.020.059 847 0.033 241 2.9588 1.644 102.550.089 994 0.050 00 2.9776 1.655 103.200.180 47 0.100 36 3.0103 1.675 104.340.453 45 0.252 86 3.0672 1.711 106.310.901 92 0.502 53 3.1061 1.740 107.661.337 9 0.752 77 3.1198 1.756 108.131.776 6 1.004 0 3.1249 1.767 108.31

34.82 0 0 4.1844 2.324 100.000.036 08 0.020 036 4.2499 2.361 101.570.045 08 0.025 044 4.2548 2.364 101.680.059 84 0.033 241 4.2683 2.372 102.010.089 98 0.050 00 4.2874 2.383 102.460.180 55 0.100 42 4.3334 2.411 103.560.453 40 0.252 86 4.3855 2.447 104.810.899 04 0.503 66 4.4123 2.473 105.451.337 7 0.752 77 4.4007 2.477 105.171.776 4 1.004 0 4.3848 2.479 104.79

aThe molality solubility was calculated from the equation m1= �x1 /M3� / �1−x1−x2�.bwith respect to pure water.




Source and Purity of Materials:Salicylic acid �Kahlbaum� was recrystallized repeatedly from water andthen from ethanol. The melting point of salicylic acid was 156 °C.Potassium nitrate was of the best quality �Kahlbaum� and further purifiedby recrystallization.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Hydrochloric acid; HCl;�7647-01-0��3� Water; H2O; �7732-28-5�


Variables: Prepared by:Concentration of HClt / °C=25




013101-120 GOTO ET AL.

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Solubility of salicylic acid in water–HCl mixtures


HCl Solubilitya �Av.b=0.016 32 mol dm−3�

t / °C c2 /mol dm−3Original

data �1 /g dm−3

102c1 /mol dm−3

Gravimetric Volumetric

25 0.0000 0.0563 2.252 1.631 1.6340.0179 — — — 1.2900.0357 — — — 1.2380.1250 0.0419 1.676 1.214 —0.2500 0.0412 1.648 1.194 —0.5000 0.0387 1.548 1.123 —

aIn the original paper, the concentrations of HCl and salicylic acid were given as “Normality” units. In the original paper, the solubility was given as gramsper 25 cm3 of the saturated solution. �1=m1 /V, where m1 is mass of 2-hydroxybenzoic acid and V is volume of the solution. The mass concentrations in thetable were calculated by the compiler.b
The average in pure water was calculated by the compiler from c1 �calc. by using �1�, c1 �gravimetric�, and c1 �volumetric�.

Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 27 for thesalicylic acid–formic acid–water system in Sec. 3.1.1.3.

Source and Purity of Materials:Salicylic acid was recrystallized from freshly distilled water.

Estimated Errors:Solubility: precision 0.2%–0.4%.Temperature: precision �0.1 °C.


28J. Knox and M.B. Richards, J.Chem. Soc. 115, 508 �1919�.




Temperature Concentration of HCla Solubility


25 0.000 1.6131.459 0.9823.057 0.8224.374 0.7156.164 0.6547.311 0.6667.311 0.7108.730 0.794

10.20 0.856

aIn the original paper, the concentration of the acids was expressed in

equivalent normality.




Methods/Apparatus/Procedure:The solubilities were determined at 25 °C, excess of the solid beingshaken with solutions of hydrochloric acid of varying concentration in athermostat for several days. After saturation, the clear solution wasanalyzed both for dissolved and solvent acid. Solvent acid �hydrochloricacid� was determined gravimetrically, dissolved acids �salicylic acid� bydirect weighing after evaporation in a vacuum over soda lime. The authorstated that this method was used for most of the sparingly soluble acid inhydrochloric acid.




29J. Kendall and J.C. Andrews, J.Am. Chem. Soc. 43, 1545�1921�.




Temperature Concentration of HCla Solubilityt / °C c2 /mol dm−3 102c1 /mol dm−3

25 0.0 1.620.500 1.121.180 1.011.848 0.9122.498 0.8343.308 0.7774.410 0.7327.172 0.6959.522 0.721

11.73 0.768

a
The author used “normality units”.


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Methods/Apparatus/Procedure:Standardized hydrochloric acid solutions were rotated with excess ofpowdered solute in a thermostat until saturation was reached. Samples ofthe clear solutions were pipetted out into tared porcelain crucibles andwere allowed to reach constant weight in a desiccator at roomtemperature.

Source and Purity of Materials:Salicylic acid was purified by recrystallization from water.



81H. Tomida, T. Yotsuyanagi, andK. Ikeda, Chem. Pharm. Bull. 26,2824 �1978�.


A. Goto and R. Goto

Solubility of salicylic acid in water–HCl mixture

Temperature Concentration of HCl Solubilityt / °C c2 /mol dm−3 102c1 /mol dm−3

25 1.0 1.08


Methods/Apparatus/Procedure:An excess of salicylic acid was added to 10 ml volumes of aqueoushydrochloric acid solution. The solution was shaken for 2 days at aconstant temperature. After equilibration, sample solutions were pipettedthrough cotton filters. The samples were diluted with pH 7.0 phosphatebuffer and assayed spectrophotometrically.

Source and Purity of Materials:Salicylic acid was recrystallized from a water–ethanol mixture.

Estimated Errors:Solubility: nothing specified.Temperature: precision �1 °C.

Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Nitric acid; HNO3;�7697-37-2��3� Water; H2O; �7732-18-5�

29J. Kendall and J.C. Andrews, J.Am. Chem. Soc. 43, 1545�1921�.

Variables: Prepared by:Concentration of HNO3

t / °C=25A. Goto, R. Goto, and H.Miyamoto


Solubility of salicylic acid in water–HNO3 mixtures

Temperature Concentration of HNO3a Solubility


25 0.0 1.620.0109 1.490.0420 1.400.0807 1.390.2409 1.410.5514 1.501.019 1.84

aThe author used “normality unit”.


Methods/Apparatus/Procedure:Standardized nitric acid solutions were rotated with an excess ofpowdered solute in a thermostat until saturation was reached. Samples ofthe clear solutions were pipetted out into tared porcelain crucibles andwere allowed to reach constant weight in a desiccator at roomtemperature.

Source and Purity of Materials:Salicylic acid was purified by recrystallization from water.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Sodium perchlorate; NaClO4;�7601-89-9��3� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of NaClO4

t / °C=25.15A. Goto, R. Goto, and H.Miyamoto

Solubility of salicylic acid in water–NaClO4 mixtures


NaClO4 Density Solubilityt / °C c2 /mol dm−3 � /g cm−3 102c1 /mol dm−3

25.15 0.00 1.5980.472 1.034 1.4000.500 1.038 1.3961.000 1.076 1.3381.103 1.082 1.3321.863 1.141 1.215






013101-122 GOTO ET AL.

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Components: Original Measurements:�1� Benzoic acid, 3-hydroxy-�m-hydroxybenzoic acid�;C7H6O3; �99-06-9��2� Sodium chloride; NaCl;�7647-14-5��3� Water; H2O; �7732-18-5�

33P. A. Ongley, J. Chem. Soc.1954, 3634.


Miyamoto

Solubility of 3-hydroxybenzoic acid in water–NaCl mixture



�compiler�

25 0 1.275 5.3091 1.422 3.784

apS is the negative logarithm of the concentration in the saturated solutions

in moles/l.



Source and Purity of Materials:The acid was either of AnalaR standard or was recrystallized before use.No information on the purity of organic solvents was reported.


Components: Original Measurements:�1� Benzoic acid, 3-hydroxy-�m-hydroxybenzoic acid�;C7H6O3; �99-06-9��2� Potassium chloride, KCl;�7447-40-7��3� Water; H2O; �7732-18-5�






Solubility of 3-hydroxybenzoic acid in water–KCl mixtures

Temperature Concentration of KCl Density Solubilityt / °C c2 /mol dm−3 � /g cm−3 102c1 /mol dm−3

25.15 0.0 — 7.060.2 1.010 6.570.5 1.024 6.061.0 1.044 5.291.5 1.067 4.702.0 1.088 3.99


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 35 for thesalicylic acid–LiCl–water system in Sec. 3.3.1.1.

Source and Purity of Materials:3-Hydroxybenzoic acid was purified by recrystallization. The meltingpoint was 201 °C.



Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-�p-hydroxybenzoic acid�;C7H6O3; �99-96-7��2� Sodium chloride; NaCl;�7647-14-5��3� Water; H2O; �7732-18-5�

33P.A. Ongley, J. Chem. Soc.1954, 3634.


Miyamoto

Solubility of 4-hydroxybenzoic acid in water–NaCl mixture



�compiler�

25 0 1.370 4.2061 1.530 2.951

apS is the negative logarithm of the concentration in the saturated solutionsin moles/l.



Source and Purity of Materials:The acid was either of AnalaR standard or was recrystallized before use.No information of the purity of organic solvents was reported.

Estimated Errors:Nothing specified



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Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-�p-hydroxybenzoic acid�;C7H6O3; �99-96-7��2� Potassium chloride; KCl;�7447-40-7��3� Water; H2O; �7732-18-56�




Solubility of 4-hydroxybenzoic acid in water–KCl mixtures

Temperature Concentration of KCl Density Solubilityt / °C c2 /mol dm−3 � /g cm−3 102c1 /mol dm−3

25.15 0.0 — 4.510.2 1.009 4.300.5 1.023 3.990.7 1.030 3.811.0 1.043 3.541.5 1.066 3.232.0 1.088 2.892.5 1.109 2.56


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 35 for thesalicylic acid–LiCl–water system in Sec. 3.3.1.1.

Source and Purity of Materials:4-Hydroxybenzoic acid was purified by recrystallization. The meltingpoint was 214 °C.


4. Hydroxybenzoic Acids and Parabensin Multicomponent Aqueous Systems

4.1. Hydroxybenzoic acid–water–organiccompound–inorganic compound systems


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-�p-hydroxybenzoic acid�;C7H6O3; �99-96-7��2� Hydrochloric acid; HCl;�7647-01-0��3� 1,4-Dioxane; C4H8O3;�123-91-1��4� Water; H2O; �7732-18-5�

43P.L. Wu and A. Martin, J.Pharm. Sci. 72, 587 �1983�82A. Martin, P.L. Wu, Z. Liron,and S. Cohen, J. Pharm. Sci. 74,638 �1985�.

Variables: Prepared by:Concentration of dioxanet / °C=25

A. Goto and R. Goto


Solubility of 4-hydroxybenzoic acid in water–HCl–dioxane mixtures

TemperatureVolume fraction of

dioxane Solubilityt / °C �3 x1 c1 /mol dm−3

25 0.0 0.000 60 0.03350.20 0.007 2 0.3300.45 0.030 2 1.060.50 0.047 8 1.450.55 0.058 5 1.640.60 0.071 0 1.830.65 0.082 0 1.950.70 0.093 9 2.050.80 0.115 2.100.85 0.121 2.020.90 0.127 1.890.95 0.122 1.621.00 0.084 4 0.968


Methods/Apparatus/Procedure:The solubility of the acid was determined in dioxane–HCl–water systems.The pH 2 hydrochloric aqueous solution was used alone or mixed withdioxane. A suitable amount of dioxane, water or mixture was introducedinto screw-capped vials containing an excess amount of solute. Afterbeing sealed with several turns of electrical tape, the vials weresubmerged in water at 25 °C and shaken at 100 cpm for 24 h in aconstant-temperature bath. After equilibrium had been attained, thesaturated solutions were transferred to a syringe and filtered by a filter ofpore size �1 �m. The solutions were assayed using a spectrophotometer.The solubility of the solute was determined at least six times.

Source and Purity of Materials:4-Hydroxybenzoic acid �Matheson Coleman Bell, Norwood, OH� wasrecrystallized from aqueous ethanol and dried at 105 °C overnight.A pure grade of dioxane �Mallinckrodt Chem. Works, St. Louis, MO� wasused as received.

Estimated Errors:Solubility: The experimental variation in solubility was �3% in replicatesamples.Temperature: precision �0.1 °C.

4.2. Hydroxybenzoic acid–water–inorganiccompound „1…–inorganic compound „2… systems


Components: Original Measurements:�1� Benzoic acid, 3-hydroxy-�o-hydroxybenzoic acid�;C7H6O3; �99-06-9��2� Hydrochloric acid; HCl;�7647-01-0��3� Potassium chloride; KCl;�7447-40-7��4� Water; H2O; �7732-18-5�





n

013101-124 GOTO ET AL.

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Solubility of 3-hydroxybenzoic acid in water–HCl–KCl mixture. Thebuffer solution at pH=1.0 was used as a solvent.

Temperature Solubilityt / °C 102c1 /mol dm−3

25 5.71


Methods/Apparatus/Procedure:An excess of 3-hydroxybenzoic acid was added to 10 ml volumes of pH1.0 HCl–KCl buffer solution. The solution was shaken for 2 days at aconstant temperature. After equilibration, sample solutions were pipettedthrough cotton filters. The samples were diluted with pH 7.0 phosphatebuffer and assayed spectrophotometrically.

Source and Purity of Materials:3-Hydroxybenzoic acid was recrystallized from a water–ethanol mixture.

Estimated Errors:Solubility: nothing specified.Temperature: precision �1 °C


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-�p-hydroxybenzoic acid�;C7H6O3; �99-96-7��2� Hydrochloric acid; HCl;�7647-01-0��3� Potassium chloride; KCl;�7447-40-7��4� Water; H2O; �7732-18-5�



Solubility of 4-hydroxybenzoic acid in water–HCl–KCl mixture. Thebuffer solution at pH 1.0 was used as a solvent.

Temperature Solubilityt / °C 102c1 /mol dm−3

25 4.17







4.3. Hydroxybenzoic acid andparaben–water–urea–inorganic compound systems


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C6H7O3; �69-72-7��2� Urea; CH4N2O; �57-13-6��3� Hydrochloric acid; HCl;�7647-01-0��4� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of ureat / °C=25.5, 37.0 and 45.0

A. Goto and R. Goto

Solubility of salicylic acid in water–HCl–urea mixtures


of urea SolubilitySalicylic acid concentratio

as complexa

t / °C 101c2 /mol dm−3 102c1 /mol dm−3 102ccomplex /mol dm−3

25.5 0.0 1.491 —10.0 1.882 0.39120.0 2.222 0.73130.0 3.041 1.55032.5 3.065 1.57435.0 3.135 1.64437.5 2.693 1.20240.0 2.606 1.11542.5 2.932 1.44145.0 2.447 0.95650.0 2.534 1.04360.0 2.461 0.970

37.0 0.0 1.810 —10.0 2.389 0.57920.0 3.041 1.23122.5 3.387 1.57725.0 3.651 1.84127.5 4.235 2.42530.0 4.402 2.59232.5 4.651 2.84137.5 4.792 2.98240.0 4.832 3.02250.0 4.651 2.84160.0 4.199 2.389

45.0 0.0 2.751 —10.0 3.837 1.08620.0 4.561 1.81030.0 6.009 3.25840.0 7.511 4.72650.0 7.456 4.70560.0 7.420 4.669

aSalicylic acid–urea complex is formed by the interaction of urea with sali-

cylic acid.



Downlo


Methods/Apparatus/Procedure:Definite quantities of salicylic acid �2 g at 25.5 and 37.0 °C, 2 and 2.5 gat 45.0 °C� and 50 ml portions of each solution �1–6 mol dm−3 ureasolution adjusted to 0.1 mol dm−3 �H+� with HCl� were placed in 100 mlvolumetric flasks. The flasks were stoppered and the mixtures shaken in athermostat for 12 h at 25.5, 37.0, and 45.0 °C. 1 ml volumetric pipettesequipped with twine were used. Aliquot quantities were removed from thedissolution fluids, diluted to the proper concentration, and assayedspectrophotometrically for the amount of acid at 236 m�. All samples andcontrols were run in triplicate.

Source and Purity of Materials:Salicylic acid was of Baker analyzed reagent. Melting point of the acidwas 159 °C.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Urea; CH4N2O; �57-13-6��3� Hydrochloric acid; HCl;�7647-01-0��4� Water; H2O; �7732-18-5�

83S. Feldman and M. Gibaldi, J.Pharm. Sci. 56, 370 �1967�.

Variables: Prepared by:Concentration of ureat / °C=30, 37 and 45

A. Goto and R. Goto

Solubility of salicylic acid in water–HCl–urea mixtures


ureaConcentration of

HCl Solubilitya

t / °C c2 /mol dm−3 c3 /mol dm−3�1 /g dm−3


�compiler�

30 0.0 0.1 1.97 1.430.5 0.1 2.27 1.641.0 0.1 2.61 1.891.5 0.1 2.86 2.072.0 0.1 3.32 2.402.5 0.1 3.68 2.663.0 0.1 4.03 2.92

37 0.0 0.1 2.62 1.900.5 0.1 3.05 1.211.0 0.1 3.60 2.611.5 0.1 3.96 2.872.0 0.1 4.46 3.232.5 0.1 4.94 3.583.0 0.1 5.57 4.03

45 0 0.1 3.40 2.460.5 0.1 3.87 2.801.0 0.1 4.51 3.271.5 0.1 5.03 3.642.0 0.1 5.74 4.152.5 0.1 6.35 4.603.0 0.1 6.92 5.01


aIn the original paper, the solubility was given as milligrams of solute per

milliliter of solution.


Methods/Apparatus/Procedure:The solubility study was carried out according to Altewin’s method.36

Solutions of urea ranging from 0 to 3 mol dm−3 were prepared in 25 mmscrew-cap culture tubes, by adding an appropriate amount of 3 mol dm−3

urea solution and sufficient 0.1 mol dm−3 HCl to bring the total volume to10 ml. 0.6 g of salicylic acid was added to the tubes. The sample wasequilibrated in a water bath shaker at temperatures of 30 and 45 °C andin a Gyrotory incubator shaker model G-25 at 37 °C for periods of notless than 12 or more than 18 h. After allowing to settle, the liquid wasfiltered through a Millipore filter �0.45 �m pore size�. 1 ml of sample waswithdrawn from the filtrate and was diluted to 10 ml with 0.1 mol dm−3

HCl acidified methanol. All subsequent dilutions were made with acidifiedmethanol �1:10�. The salicylic acid concentration was determinedspectrophotometrically.

Methods/Apparatus/Procedure:Salicylic acid �m.p. 159 °C� and urea �m.p. 132 °C� were of Fishercertified reagent grade.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Urea, methyl- �methylurea�;C2H6N2O; �598-50-5��3� Hydrochloric acid; HCl;�7647-01-0��4� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of methylureat / °C=30, 37, and 45

A. Goto and R. Goto

Solubility of salicylic acid in water–HCl–methylurea mixtures


methylureaConcentration

of HCl Solubilitya

t / °C c2 /mol mol−3 c3 /mol dm−3�1 /g dm−3


�compiler�

30 0.0 0.1 1.97 1.430.5 0.1 2.52 1.821.0 0.1 3.14 2.271.5 0.1 4.03 2.922.0 0.1 5.17 3.742.5 0.1 5.96 4.313.0 0.1 7.42 5.37

37 0.0 0.1 2.62 1.900.5 0.1 3.35 2.431.0 0.1 4.39 3.181.5 0.1 5.25 3.802.0 0.1 6.64 4.812.5 0.1 8.24 5.973.0 0.1 9.74 7.05



013101-126 GOTO ET AL.

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Solubility of salicylic acid in water–HCl–methylurea mixtures


methylureaConcentration

of HCl Solubilitya

t / °C c2 /mol mol−3 c3 /mol dm−3�1 /g dm−3


�compiler�

45 0 0.1 3.40 2.460.5 0.1 4.46 3.231.0 0.1 5.75 4.161.5 0.1 7.39 5.352.0 0.1 8.92 6.462.5 0.1 11.21 8.1163.0 0.1 13.46 9.745

aIn the original paper, the solubility was given as milligrams of solute permilliliter of solution.


Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 83 for thesalicylic acid–urea–hydrochloric acid–water system.

Source and Purity of Materials:Salicylic acid �m.p. 159 °C� and methylurea �m.p. 101 °C� were obtainedfrom Fisher and Eastman Kodak, respectively. The purity of each reagentwas determined by melting point analysis and spectrometric method.


Components: Original Measurements:�1� Benzoic acid, 2-hydroxy-�o-hydroxybenzoic acid; salicylicacid�; C7H6O3; �69-72-7��2� Urea, 1,3-dimethyl�1,3-dimethylurea�; C3H8N2O;�96-31-1��3� Hydrochloric acid; HCl;�7647-01-0��4� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of1,3-dimethylureat / °C=30

A. Goto and R. Goto

Solubility of salicylic acid in water–HCl–1,3-dimethylurea mixtures

TemperatureConcentration of1,3-dimethylurea

Concentrationof HCl Solubilitya

t / °C c2 /mol dm−3 c3 /mol dm−3�1 /g dm−3


�compiler�

30 0.0 0.1 1.97 1.430.5 0.1 2.97 2.151.0 0.1 4.04 2.921.5 0.1 5.61 4.062.0 0.1 7.33 5.312.5 0.1 9.71 7.033.0 0.1 12.53 9.07

aIn the original paper, the solubility was given as milligrams of solute per
milliliter of solution.



Methods/Apparatus/Procedure:The experimental detail is given in the compilation of Ref. 83 for thesalicylic acid–urea–hydrochloric acid–water system.

Source and Purity of Materials:Salicylic acid �m.p. 159 °C� was of Fisher certified reagent grade.1,3-dimethylurea �m.p. 107 °C� was obtained from Eastman Kodak. Thepurity of each reagent was determined by melting point analysis andspectrophotometric method.



Components: Original Measurements:�1� Benzoic acid, 3-hydroxy-�m-hydroxybenzoic acid;C6H7O3; �99-06-9��2� Urea; CH4N2O; �57-13-6��3� Hydrochloric acid; HCl;�7646-01-0��4� Water; H2O; �7732-18-5�


Variables: Prepared by:Concentration of ureat / °C=25.5, 37.0, and 45.0

A. Goto and R. Goto

Solubility of 3-hydroxybenzoic acid in water–HCl–urea mixtures

Temperature

Originalconcentration

of urea Solubility3-Hydroxybenzoic acid

concentration as complex


25.5 0.0 5.249 —10.0 6.877 1.62815.0 8.064 2.81520.0 8.687 3.43825.0 9.954 4.70530.0 10.316 5.06735.0 12.850 7.60140.0 14.479 9.23045.0 16.108 10.85950 18.714 13.46560 21.718 16.469

37.0 0.0 10.135 —10.0 13.610 3.47520.0 18.099 7.96430.0 22.805 12.67040.0 26.285 16.14550.0 30.193 20.77860.0 32.912 22.777

45.0 0.0 11.801 —10.0 16.434 4.63320.0 22.370 10.56930.0 27.510 15.70940.0 32.578 20.77750.0 38.514 26.71360.0 44.885 33.084



Downlo


Methods/Apparatus/Procedure:The experimental procedure was similar to that for salicylic acid. 3 g of3-hydroxybenzoic acid and 50 ml portions of each solution�1–6 mol dm−3 urea solution adjusted to 0.1 mol dm−3 �H+� with HCl�were placed in 100 ml volumetric flasks. The flasks were stoppered andthe mixtures shaken in a thermostat for 12 h. 1 ml volumetric pipetsequipped with twine were used. Aliquot quantities were removed from thedissolution fluids, diluted to the proper concentration, and assayedspectrophotometrically for the amount of acid at 236 m�. All samples andcontrols were run in triplicate.

Source and Purity of Materials:3-Hydroxybenzoic acid �Eastman Organic Chemicals� was used. The m.p.was 201 °C.



Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-�p-hydroxybenzoic acid�;C6H7O3; �99-96-7��2� Urea; CH4N2O; �57-13-6��3� Hydrochloric acid; HCl;�7647-01-0��4� Water; H2O; �7732-18-55�


Variables: Prepared by:Concentration of ureat / °C=25.5, 37.0, and 45.0

A. Goto and R. Goto






25.5 0.0 3.873 —10.0 6.407 2.53420.0 8.144 4.27130.0 9.448 5.57540.0 10.570 6.69745.0 11.221 7.34850.0 11.942 8.06960.0 12.923 9.050

37.0 0.0 7.457 —10.0 11.583 4.12615.0 13.465 6.00820.0 14.625 7.16725.0 15.203 7.74627.5 18.316 10.85930.0 17.954 10.49732.5 18.764 11.30740.0 18.731 11.27445.0 18.823 11.36650.0 19.692 12.23560.0 21.357 13.900







45.0 0.0 12.814 —10.0 18.135 5.32120.0 22.081 9.26730.0 27.148 14.33440.0 27.438 14.62450.0 27.655 14.84160.0 29.854 17.040


Methods/Apparatus/Procedure:The experimental procedure was similar to that for salicylic acid. 2 g of4-hydroxybenzoic acid and 50 ml portions of each solution�1–6 mol dm−3 urea solution adjusted to 0.1 mol dm−3 �H+� with HCl�were placed in 100 ml volumetric flasks. The flasks were stoppered andthe mixtures shaken in a thermostat for 12 h. 1 ml volumetric pipetsequipped with twine were used. Aliquot quantities were removed from thedissolution fluids, diluted to the proper concentration, and assayedspectrophotometrically for the amount of acid at 254 m�. All samples andcontrols were run in triplicate.

Source and Purity of Materials:4-Hydroxybenzoic acid of Eastman Organic Chemicals was used. Themelting point was 214 °C.



Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O3;�99-76-3��2� Sodium chloride; NaCl;�7647-14-5��3� Urea; CH4N2O; �57-13-6��4� Water; H2O; �7732-18-5�

84C. McDonald and R.E.Lindstrom, J. Pharm. Pharmacol.26, 39 �1974�.

Variables: Prepared by:Concentration of urea andsodium chloridet / °C=25




013101-128 GOTO ET AL.

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Solubility of methylparaben in water–NaCl–urea mixtures

Temperature Concentration of NaCl Concentration of urea Solubility

t / °C c2 /kmol m−3 c3 /kmol m−3 c1 /kmol m−3

25 0 0 0.01460 1 0.01970 2 0.02420 3 0.02960 4 0.03540 5 0.0413

25 1 0 0.00931 1 0.01281 2 0.01641 3 0.02081 4 0.02581 5 0.0312

25 2 0 0.00622 1 0.00842 2 0.01142 3 0.01432 4 0.01872 5 0.0227

25 3 0 0.00383 1 0.00543 2 0.00763 3 0.01003 4 0.01293 5 0.0166


Methods/Apparatus/Procedure:Solubilities of methylparaben were determined in water, in 1–5 mol dm−3

sodium chloride solutions, in 1–5 mol dm−3 urea solutions, and in1–5 mol dm−3 sodium chloride solutions containing 1–5 mol dm−3 urea,respectively. Excess methylparaben was equilibrated with the solutions at25 °C for 24 h. Samples were taken, filtered, diluted with water, andconcentrations were determined from ultraviolet absorption plots ofstandard solutions determined at 256.75 nm. The saturated solubility wasreached within 24 h.

Source and Purity of Materials:Sodium chloride Analar �BDH� was used without further purification.Urea �Fisons� was recrystallized from absolute ethanol and dried.Methylparaben was used without further purification.

Estimated Errors:Solubility: the overall experimental error is approximately �2.5%.Temperature: precision �0.1 °C.



4.4. Hydroxybenzoic acid andparaben–water–urea–inorganic compound

„1…–inorganic compound „2… systems


Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-�p-hydroxybenzoic acid�;C7H6O3; �99-96-7��2� Hydrochloric acid; HCl;�7647-01-0��3� Potassium chloride; KCl;�7447-40-7��4� Water; H2O; �7732-18-5�



Solubility of 4-hydroxybenzoic acid in water–HCl–KCl mixturesa


t / °C 102c1 /mol dm−3

25 4.17

aThe buffer solution at pH 1.0 was used as a solvent.






Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,methyl ester �methylp-hydroxybenzoate;methylparaben�; C8H8O3;�99-76-3��2� Phosphate, hydrogen sodiumsalt; Na2HPO3; �7558-59-4��3� Phosphate, dihydrogenmonopotassium salt; KH2PO3;�13977-65-6��4� Water; H2O; �7732-18-5�

52G. Dempsey and P. Molyneux,J. Chem. Soc. Faraday Trans. 88,971 �1992�.




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Solubility of methylparaben in water–Na2HPO3–KH2PO3 mixture


t / °C 103c1 /mol dm−3

25 16.0

aThe species of the solute was the monoanion �94%� at pH 6.


Methods/Apparatus/Procedure:The solubilities of the cosolute in pH 6.0 Sorenson phosphate buffer inthe presence of urea were determined using the piston-filter tube method,which enable the dissolution, equilibration, and filtration to be carried outin the same closed system. The tubes were equilibrated by shaking for24 h at 25.0°C. A sample of the supernatant was diluted 100-fold andassayed by UV spectrophotometry.

Source and Purity of Materials:The urea was BDH Laboratory grade. The methylparaben was BDHLaboratory grade and recrystallized once from water.


4.4.3. Ethylparaben

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,ethyl ester �ethylp-hydroxybenzoate;ethylparaben�; C9H10O3;�120-47-8��2� Phosphate, hydrogen sodiumsalt; Na2HPO3; �7558-79-4��3� Phosphate, dihydrogenmonopotassium salt; KH2PO3;�13977-65-6��4� Water; H2O; �7732-18-5�



Solubility of ethylparaben in water–Na2HPO3–KH2PO3 mixture


t / °C 103c1 /mol dm−3

25 5.30



Methods/Apparatus/Procedure:The solubility was determined by the same method as described in thecompilation of Ref. 52 for the methylparaben–phosphate hydrogen sodiumsalt–phosphate dihydrogen potassium salt system in Sec. 4.4.2.

Source and Purity of Materials:The urea was BDH Laboratory grade. The ethylparaben was BDHLaboratory grade and recrystallized once from water.



4.4.4. Propylparaben

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,propyl ester �propylp-hydroxybenzoate;propylparaben�; C10H12O3;�94-13-3��2� Phosphate, hydrogen sodiumsalt; Na2HPO3; �7558-79-4��3� Phosphate, dihydrogenmonopotassium salt; KH2PO3;�13977-65-6��4� Water; H2O; �7732-18-5�



Solubility of propylparaben in water–Na2HPO3–KH2PO3 mixture


t / °C 103c1 /mol dm−3

25 1.99




Source and Purity of Materials:The urea was BDH Laboratory grade. The propylparaben was BDHLaboratory grade and recrystallized once from water.


4.4.5. Butylparaben

Components: Original Measurements:�1� Benzoic acid, 4-hydroxy-,butyl ester �butylp-hydroxybenzoate;butylparaben�; C11H14O3;�94-26-8��2� Phosphate, hydrogen sodiumsalt; Na2HPO3; �7558-79-4��3� Phosphate, dihydrogenmonopotassium salt; KH2PO3;�13977-65-6��4� Water; H2O; �7732-18-5�



Miyamoto



013101-130 GOTO ET AL.

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Solubility of butylparaben in water–Na2HPO3–KH2PO3 mixture


t / °C 103c1 /mol dm−3

25 1.13




Source and Purity of Materials:The urea was BDH Laboratory grade. The butylparaben was BDHLaboratory grade and recrystallized once from water.


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