STEREOCHEIHSTRY.

ALL substances exhibiting optical activity in solution which have hitherto been prepared are known t o contain one or more asymmetric atoms and i t is customary t o attribute the optical activity to the pre- sence in the molecule of the asymmetric atom. It has, however, gradually become realised that the optical activity is a direct result of the enantiomorphous configuration of the molecule and that the latter is determined by the presence of the asymmetric atom ; it is possible to write numerous constitutional formulae in which asymmetry is not associated with any component atom but which, interpreted in accordance with the tetrahedrsl configuration of methane, actually represent enantiomorphous molecular configurations. Thus, in the acid of the following constitution,

i t must be supposed that the bonds in the hexaniethylene ring all lie in one plane, that of the paper, and that the bonds attaching the groups H and CO,H t o that ethylenic carbon atom not in the ring also lie in the same plane. The bonds holding the H and CH, groups to the carbon atom in the para-position to the ethylene group must, however, lie in a plane at right angles to the first and therefore perpendicular to the paper and consequently the configuration represented must be an enantiomorphous one. No case of this kind mas known until the present year, when W. Marckmald and R. Meth prepared an acid to which they assign the above constitution and resolved it into its optically active components by crystallisation with cinchonine ; they thus obtained the dl-4-methylcyclohexylidene-1-acetic acid with a specitic rotatory power of [a],, + 1 6 O . 1 Subsequent to this, W. 11. Perkin, jun., and W. J. Pope2 state that they have prepared an acid to which they assign the above constitution and have been for some time endeavouring to resolve it ; their acid is different from that of Marckwald and Meth, and for the latter they suggest the following constitution :

Bw., 1906, 39, 1171 and 6404. Proc., 1906, 22, 107.

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186 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.

Marckwald and Meth quote reasons 1 supporting the constitution which they originally assigned to their acid, and conclude that the acid of Perkin and Pope is the one which contains the double bond in the closed ring. I n the event of Marckwald and Meth's view proving correct, their results must be regarded as marking a distinct advance in stereochemistry, in that they furnish the first case of a substance possessing optical activity in consequence of enantiomorphous molecular configuration not due to the presence of an asymmetric atom.

E. Erlenmeyer has continued his previous work on the stereoisomeric cinnamic acids, C,H,*CH:CH*CO,H, and finds 3 that from alcoholic solu- tion three different brucine salts of synthetic cinnamic acid can be separated ; these melt at 1 3 5 O , 11 3O, and 107" respectively. Cinnamic acid from storax is less soluble in alcohol than the former and gives only the brucine salt melting at 135' ; this salt is practically inactive whilst the others are strongly laevorotatory in alcoholic solution. Erlenmeyer therefore suggests that cinnamic acid from storax is only one of the com- ponents of synthetic cinnamic acid, and supports this contention by quoting results obtained by crystallising cinnamic acid from the two sources with d- and Z-isodiphenyloxyethylamine. The further investi- gation of these substances and their crystallographic examination has led Erlenmeyer and Barkow 4 to conclude that the following six iso- meric cinnamic acids must be regarded as distinct substances : (1) Erlenmeyer, sen.'s, isocinnamic acid, m. p. 37-38' ; (2) allocinnamic acid, m. p. 68"; (3) Liebermann's isocinnamic acid, m. p. 5 9 O ; (4) anorthic cinnamic acid, m. p. 80' ; (5) a-cinnamic acid, m. p. 134-135' ; (6) p-cinnamic acid, m. p. 132-1 33'. The isocinnamic acid contained in the most soluble of the brucine salts, which differs slightly in crystal- line form from Liebermann's acid, and the synthetic acid apparently Con- stitute two more isomerides. Erlenmeyer's conclusions have been criticised very adversely by W. Marckwald and R. Meth; these authors show that the salt melting at 11 3' contains alcohol of crystal- lisation and that the salt melting at 135" contains two molecules of cinnamic acid to each one of brucine. They also point out that on dis- solving equivalent quantities of synthetic and natural cinnamic acid and brucine in alcohol, the solutions have the same rotatory power. They therefore conclude that the experimental evidence does not justify the conclusions of Erlenmeyer.

The view that mineral oil originates from the bacterial decompos- tion of proteins is put forward by C. Neuberg and supported by the

1 Ber., 1906, 39, 2035. 3 Ber., 1906, 39, 285. 5 Ibid., 1177, 1966, and 2598.

2 A m . Report, 1905, 168. 4 r b i d . , m o .

Biochem. Zeit., 1906, 1, 368.

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STEREOCHEMISTRY. 187

similarities between the optically active acids of petroleum and those obtained by the putrefaction of cheese, gelatin, &c. Vegetable lipase was found to liberate d-dibromostearic acid and a dextrorotatory glyceride from dI-dibromostearic triglyceride, showing tha t unorganised ferments are capable of producing optically active substances from in- active fats.

E. Fischerl has contributed in the connected form of a lecture a valuable digest of his chemical investigation of the amino-acids, polypeptides, and proteins, in which the stereochemical relations of these substances are fully considered.

a-Bromoisohexoic acid has been resolved into its optically active components by E. Fischer and H. Carlj2 the method employed being the crystallisation of the mixed brucine salts ; the lavorotatory acid yields d-leucine ( [ u ] ~ - 14-20') with ammonia. a-Bromo-/I-phenylpropionic acid, C6H5*CH2*CHBr* CO,H, has also been resolved by crystallisation with brucine and quinine ; the kevorotatory acid gives d-phenyl- alanine, C,H,*CH,*CH(NH,)*CO,H, ([.ID + 31 T8') with ammonia. Fischer also describes convenient methods for preparing d- and E-leucines, and for converting these amino-acids into derivatives of d-a-bromoisohexoic acid. H e has resolved synthetic a-aminoiso- valeric acid into its optically active components by crystallising it formy1 derivative with brucine ; the compound of the I-acid crystal- lises as the less soluble product. Fischer gives the name valine to the acid and identifies d-valine with the active aminovaleric acid, (cH,),CH*CH(NH, j*CO,H, separated from lupins, horn, and casein ; d-valine has a bitter taste, whilst the I-isomeride, which has not yet been found in nature, possesses a pronounced sweet flavour. This distinction between the taste of two enantiomorphously related iso- merides is similar to that observed in the case of the leucines and asparagines.

E. Fischer and W. A. Jacobs have resolved externally compensated p-nitrobenzoyl-dl-serine, OH*CH2*CH(C0,H)*NH*CO*C,H4*N0,, by crystallisation with quinine ; the salt of the d-acid separates first and the E-acid remaining in the mother liquors is conveniently purified by crystallisation with brucine. The d-and I-serine,

OH*CH,*CH(NH,)-CO,H, prepared by hydrolysing the nitrobenzoyl derivatives, differ in taste, the former being thesweeter; the I-serine is identical with the serine isolated from silk. isoserine, NH,* CH,*CH(OH)*CO,H, and diamino- propionic acid have been also resolved by crystallising their benzoyl derivatives with optically active bases.

C. Neuberg and E. Ascher resolve up-diaminopropionic acid, Ber., 1906, 39, 530. Ibid. , 3996. Ibid. , 2893. Bid., 2320. Ibid., 2943. Biochem. Zeit., 1906, 1, 380.

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188 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.

NH,*CH,*CH(NH,)*CO,H, by crystallisation with d-camphorsul- phonic acid ; the salt of a d-rotatory acid is thus first separated but, as it is donvertible into Z-glyceric acid by the action of nitrous acid, it must be termed Z-ap-diaminopropionic acid.

An improvement of Warburg and Fischer’s method 1 of resolving a-bromopropionic acid, CH,*CHBr *CO,H, has been dsvised by L. Ramberg;, the dZ-acid is frozen out from the acid which has been partially resolved by cry stallisation with cinchonine.

dl-Aminobenzylidene-/3-naphthol has been resolved by M. Betti 3 by crystallisation with d-tartaric acid ; the salt, dBdA, separates in alniost theoretical yield as the more sparingly soluble salt,

J. C. Irvine4 contributes a simple method for the separation of i-lactic acid from the dZ-acid by cry stallisation with morphine ; mor- phine Z-lactate crystallises readily from the mixed solution, and from the mother liquor the d-isomeride can be conveniently separated as the zinc salt.

use Z-menthylcarbamide for the purpose OF resolving externally compensated hydroxy-compounds into their optically active components; the method can be applied either by directly combining the carbimide and the hydroxy .com- pound, or by first converting the latter into a chlorocarbonic ester and then condensing with Z-menthylamine. On applying the method to dZ-~-phenyl-u’-4-hydro~yphenylethane, p-HO*C,H;CHMePh, d-a- phenyl-a’-4-hydroxyphenylethane Z-menthylcarbamate,

C,,H,,NH*CO,.C,H,.CHMePh, is obtained as the less soluble product and, on hydrolysis with soda, yields the optically active hy droxy-compound.

have resolved tetrahydro-l-naphthoic

R. H. Pickard and W. 0. Littlebury

R. H. Pickard and J. Yates

acid, CGKI<CH(CO,H) CH2-CH2>CH2, ([MID 2 1 *lo), and tetrahydro-2-naphthoic

([MI,, 90.5’) into their optically active CH,*YH, CH,*CH*CO,H’ acid, C,H,<

components by crystallisation with Z-menthylamine ; in each case the salt ZBZA separates as the least soluble component. The molecular rotatory powers of the acid ions, stated in brackets above, are much smaller than tha t of the A2 (Or ’)-dihydro-l -naphthoic acid,

CH(CO,H)-EH ,CH(C02H) CH, Or C,H, \CH----bH --- 9 C,H,<(TH --- CH

namely, [MI, 374*5”, found by Pickard and Neville.’ R. H. Pickard and W. 0. LittleburyS have resolved ac-tetrahydro-

Ann. Report, 1905, 174. 3 Gazzetla, 1906, 36, ii, 392.

Ibicl., 467. 7 .7bid., 1905, 87, 1766.

Annnlen, 1906, 349, 324. Tmns., 1906, 89, 935.

Ibid. , 1906, 89, 1252. l j &d., 1101.

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STEREOCHEMISTRY 189

by their method which involves con- CH,*F]H, CH,*CH*OH' 2-naphthol, C6H4<

densation with I-menthylcarbamide and cry stallisation of the resulting mixture of the products ZBdA and ZRZA p in the present case the former compound proves to be the less soluble and is readily hydrolysed, yielding the d-ac-tetrahydro-2-naphthol. This substance does not readily undergo optical inversion, and therefore contrasts in behaviour with the corresponding amine which Pope and Harvey1 found to be very easily inverted.

A' "-Dihydrophthalic acid was resolved into its active components by Proost by crystallisation with strychnine, and A. Neville has now resolved the isomeric trans-A' : 5 - ~ ~ r n p ~ ~ n d ,

CH /\

HY YH*CO,G, H C CH*CO,H

LI

\/ C H

by crystallisation of its acid strychnine salt. The salt of the I-base with the I-acid separates from the solution as the least soluble component. The cold aqueous solution of the Z-A-3:5-dihydrophthalic acid does not undergo optical inversion in the cold, b u t at 97" the inversion of the sodium salt proceeds as a unimolecular reaction ; the transformation occurs, also as a unimolecular reaction, much more rapidly in presence of excess of soda. From the solution remaining after the transformation the optically inactive A2 ' 6-dihydrophthalic acid has been isolated, the change proceeding thus :

CK C'H /\ /\

\/ \/ H$J $JH-CO,H NaHO H2V Y-CO,H H C CH*CO,H -+- H,C C*CO,H

C H UH A. Neville has also resolved the 2 : 3-dibydro-3-methylindene-2-carb-

oxyiic acid, C6~~,<~,HM"SCH*C0,H, into its optically active com- 1

ponents by crystallisation with I-menthylamine ; the salt ZBdA is the most sparingly soluble, and from this the pure d-acid is obtained. Although the acid contains two asymmetric carbon atoms only one d- and Z-acid were isolated.

F. W. Kay and W. H. Perkin, j ~ n . , ~ have resolved synthetic dl- 1 -methyl-A3-cyclohexene-4-carboxylic acid,

Trans., 1901, 79, 83. I! Ber., 1894, 27, 3185. Tm?ts., 1906, 89, 1744. 4 lbid., 383. 6 B i d . , 839.

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190 ANNUAT, REPORTS ON THE PROGRESS O F CHEMISTRY.

by crystallisation with brucine and strychnine ; with the first base the salt ZBZA is obtained as the less soluble, whilst with strychnine the salt ZBdA crystallises first. Prom these acids, by the aid of the Grignard reaction, the authors have succeeded in obtaining for the first time synthetic optically active terpenes and their derivatives.

E. Erlenmeyer 5 has resolved dZ-a-brorno-p-phenyl-@-lactic acid, C6H5*CH(OH)*CHBr*C0,H, into its optically components by crystal- lisation with cinchonine and strychnine ; the corresponding chloro- derivative has been resolved by means of strychnine and the iodo- derivative with the aid of cinchonine. E. Erlenmeyer and C. Barkow have prepared a dZ-P-amino-P-phenyl-a-lactic acid,

C,H,*CH(NH,)*CH(OH)*CO,H, isomeric with that already known, by the action of ammonia on sodium phenyl-lactate ; the lzvo-acid is prepared from sodium phenyl-lactate.

CH,*CH,-CH,*CH,*CH(NH,) *CO,H, is excreted in the urine after administering externally Compensated leucine to rabbits; leucine is in general not excreted in the urine of dogs, although in one case the administration of the inactive amino-acid resulted in a small quantity of d-leucine being found in the urine.

On administering externally compensated alanine to dogs, A. Schittenhelm and A. Katzenstein find the amino-acid is conveniently separated by aid of its a-naphthalene- sulphonic derivative.

0. Warburg 4 shows that pancreatin hydrolyses leucine ethyl ester asymmetrically, Z-leucine, CH,*CH;CH2*CH,*CH(NH2)*C0,H, being produced.

finds that by the action of yeast on a solution of sucrose and externally compensated alanine, leucine, or a-nminoisoraleric acid, both components of the amino-acid are attacked, but, in general, at very different rates ; Z-alanine, d-leucine, or I-a-aminoisovaleric acid can be readily separated from the product in a 65 to 75 per cent. yield,

According to E. Reiss,o d-alanine is more readily utilised in the animal organism than is i ts enantiomorphously related isomeride.

P. Mayer7 finds that cl-lecithin is converted into dl-lecithin by heating to 100° with methyl alcohol, and that steapsin attacks

E. Abderhalden and F. Samuely found that d-leucine,

that only Z-alanine is excreted

%. Ehrlidh

Bcr., 1906, 39, 788. 2 Zeit. physiol. Chenz., 1906, 47, 3-16. :? %&. m p . Pcd7i. 777iw.) 2, 5 G O .

Zeit. phylsiol. Chem., 1906, 48, 208. f, Biochem. Zeit., 1906,1, 8 ; Zeit. Yer. deut. Zuckwind., 1906, No. 608, 840. 6 Beitr. chem. Physiol. Path., 1906, 8, 332. 7 Bioc7~.em. Zeit., 1906, 1, 39.

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STEREOCITERSISl'RY 191

dZ-lecithin, leaving Z-lecithin in the solution. 0. Riesser shows that d-arginine is converted into a mixture of dl-arginine and dl-ornithine by heating with diluted sulphuric acid at 160-180°.

A number of optsically active alkyl derivatives of benzene have been prepared by A. Klages and R. Sautter.2 The fact that these hydro- carbons are formed without optical inversion from their sulphonic acids has led Klages 3 to attempt the resolution of sec.-butylbenzene, CHMeEtPh, by crystallising the sulphonic acid of the externally compensated hydrocarbon with quinine, cinchonidine, and strychnine ; the attempts were not successful.

Pschorr, Roth, and Tannhauser* show that the optically active a- and p-methylmorphimethines and a-etlhylthiocodide crystallise in the sphenoidally hemihedral subdivision of the orthorhombic system and afford examples of the recently discovered occurrence of optical activity 5 in the crystalline state of biaxial substances.

I n view of the optical activity and other properties of tannin, J. Dekker 6 assigns to it the following constitution which indicates the presence of an asymmetric carbon atom in the molecule,

?(OH): CH-E- GO*? gH*C(OH): ?*OH C(OH):C(OH)*C--C(OH)*C--CH==C*OH'

Haller and March7 have prepared, and determined the specific rotatory powers of, hexahydrobenzyl-, hexahydrobenzylidene-, oen- anthyl-, and oenanthylidene-camphors ; the results confirm the pre- vious conclusion that the specific rotatory power of the unsaturated derivative is higher than that of the corresponding saturated com- pound.

The statement is made by E. Jungfleisch and M, GodchotS that during the preparation of d- or Z-lactide by heating the correspond- ing lactic acid, they observe that Z-lactic acid or Z-lactide is much more rapidly optically inverted by heat than the corresponding d-isomeride.

I n continuation of previous work, J. B. Cohen and I. H. Zortmann have prepared, and determined the rotation constants of, the 2-menthyl esters of the isomeric dibromobenzoic acids,O and J. B. Cohen and H. P. Armes have prepared and examined the Z-menthyl esters of the isomeric chloronitrobenzoic lo and dinitrobenzoic

R. H. Pickard and J. Yates12 have examined as a time reaction the conversion of the sodium or methyl salts of cZ-Az-dihydro-l-

acids.

Zeit. pJn~s/sioZ. Chcm., 1906, 49, 210. Bey. , 1906, 39, 1938 ; compare Ann. f i e p o d , 1905, 178.

L'er., 1906, 39, 2497 and 3754. :! Ber., 1906, 39, 2131.

8 Ibid., 637.

16icl.) 19. Pocklington, Phil. Mag., 1900, 6, 2.

T ~ c m s . , 1906, 89, 47. 7 Compt. rei~cl., 1906,142, 316.

lo Jhid.* 454. Ibid., 1479. 12 Ibid., 1484.

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192 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.

C(CO,€€):~H in naphthoic acid into the inactive Al-acid, C6HH,<CH2--CH,,

presence of a number of basic hydroxides and bases ; the conversion proceeds as a unimolecular reaction and is easily followed polari- metrica1ly.l The hydroxides of the alkaline earths hasten the transfor- mation of the sodium salt more than the alkali hydroxides, and the latter are rather more active than the tetra-alkylammonium hydroxides ; the relative strengths of the bases in this respect differ somewhat from the relative electric conductivities, and this is attributed to the effect of the base on the electrolytic dissociation of the salt. R. H, Pickard, W. 0. Littlebury, and A. Neville have studied the reactions between I-menthylcarbimide and a number of alcohols as time re- actions; the rotation constants of a number of esters of I-menthyl- carbamic acid have been determined.

Further examples of asymmetric syntheses are given by A. M ~ K e n z i e , ~ who applies Grignard's reaction for this purpose. The action of magnesium propyl, isobutyl, tert.buty1, and a-naphthyl iodides or bromides on I-menthyl benzoylformate and of magnesium methyl, ethyl, iso-butyl, and a-nsphthyl iodides or bromides on I-bornyl benzoylformate leads in each case to an asymmetric synthesis of a subbtituted glycollic acid. I n each case a mixture of the d- and I-sub- stituted glycollic acids resulted on hydrolysis of the product, and in this mixture one component predominated; the excess of one component over the other was greater in the case of the rnenthyl than of the bornyl esters. The asymmetric synthesis of phenymethyl- glycollic acid can be effected both by the action of magnesium methyl iodide on I-menthyl benzoylformate and by that of magnesium phenyl bromide on Lmenthyl pyruvate ; the former method leads to formation of excess of the Z-acid, whilst the latter gives the d-acid in larger quantity. A. McKenzie and H. Wren4 also effect an asymmetric synthesis of I-lactic acid by the reduction of I-bornyl pyruvate and subsequent hydrolysis of the p r ~ d u c t . ~

have shown that on heating either dl- or I-mandelic acid, C,H,*CH( OH)*CO,H, with the equivalent quantity of brucine at 150-160' it becomes converted into d-man- delic acid, that is to say, the mandelic acid subsequently separated shows a slight dextrorotation. Similarly, on heating dl-mandelic acid with strychnine or nicotine under the same conditions, the recovered acid is dextrorotatory. On heating dl-p-methoxymandelic acid with brucine or strychnine, it becomes dextrorotatory, and

W. Marckwald and D. M. Paul

A m . Beport, 1905, 174. ]bid., 365. Jbitl. , 688. Compare Ann. Zeport, 1905, 170. Ber., 1906, 39, 3654.

Tyans., 1906, 89, 93.

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STEREOCHEMISTRY. 193

after heating P-phenyl-lactic acid with brucine the recovered acid is found to be slightly I~vorotatory.

Winther shows 1 that in the catalytic optical inversion of d-tartaric acid, i-tartaric acid is first produced, the reaction being one of the first order and reversible ; the generally accepted view that the dl-tartaric acid produced during the optical inversion of d-tartaric acid is a direct product of the change is thus incorrect. The dFtzLrtaric acid obtained is produced from d-tartaric acid, i-tartaric acid being formed as an intermediate product. The effect of alkalis in accelerating the optical inversion of d-tartaric acid is connected with the presence of hydr- oxylic hydrogen, which becoines replaced by the alkali metal ; thus the substance CO,Na*CH(ONa)*CH(OH)*CO,Na can be separated from strongly alkaline solutions of sodium tartrate and caustic soda. No corresponding compound containing potassium could be isolated and in accordance with this it is observed that caustic potash exercises a slighter catalytic effect on the inversion than soda. H e has also found a that the optical inversion of mandelic acid by caustic alkalis proceeds as a unimolecular reaction.

finds that P-cholestene dibromitle gives [a], - 39.6' immediately after solution in chloroform but that the solution becomes optically inactive in a day and after several days gives the specific rotatory power [a],, + 39.4" ; the change occurs more slowly in benzene solution and the solution on evaporation yields the isomeric a-cholestene di bromide, R. Torrese4 has shown that the hydrolysis of sucrose is not

brought about by glutaconimide derivatives of types (1) and (a), but that those derivatives which contain the group (3)

J. Mauthner

are alone capable of causing the hydrolysis. The presence of the single double linking in (3) is thus essential i f the derivative is t o bring about the hydrolysis of sucrose; further, if one of the carbonyl groups is replaced by the group CPlille,, the power to hydrolyse sucrose is lost.

A convenient method for graphically representing the configurations of sugar-like substances and their derivatives is given by Rosanoff ; he considers that the stereochemical classification of these and related substances would be rendered more consistent by regarding d-gulose

Zeit. phpsilial. Chenz., 1900, 56, 719. Monutsh., 1906, 27, 421.

a ]bid., 465. Atti B. Accad. Xci. Torirzo, 1906, 41, 309.

6 J. Amer. Chern. Soc., 1906, 28, 114. VOL. 111. 0

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194 ANKUAL REPORTS ON THE PROGRESS OF CHEMISTRY.

as belonging to the I-family and not to that of &glucose and by making corresponding changes in the nomenclature of other similarly related compounds. H e also discusses 1 the question of optical superposition and states as a new principle that ‘ I the optical rotatory power of an asymmetric carbon atom depends upon the composition, constitution, and configuration of each of the four groups.”

T. &I. Lowry 2 has applied his solubility method 3 for determining the proportions in which dynamic isomerides are in equilibrium i n solution, t o the halogen derivatives of camphor, which Kipping has shown to undergo reversible isomeric change in presenco of alkalis. H e finds that the solubility of each of these substances which contains the group -CHBr*CO- or -CHCl*CO- is increased by approximately one- tenth by the addition of the alkali, but no such increased solubility is observed with camphor derivatives containing the group -CH,*CO- or -CBr(NO,)*CO-. The extent to which the partial optical inversion occurs is a result of the isodynamic reversal in sign of the asymmetric carbon atom in the group -CHBr*CO- or -CHCl*CO-. T. M. Lowry and E. H. Magson4 have applied similar methods to the study of a large number of sulphonic derivatives of camphor, and have obtained evidence enabling the above conclusions t o be extended.

T. Purdie and C. R. Young5 regard ordinary crystalline rhamnose as the a-form and Fischer’s crystalline anhydrous rhamnose as the @-form of the sugar; they describe an improved method fo r the preparation of the latter form, which involves assisting the change a -+ P t o occur. The P-rhamnose is stable a t high temperatures and the a-€orm a t low temperatures; the former is I-rotatory and the latter strongly d-rotatory in aqueous solution. A number of methyl- rhamnosides have been prepared and classified as of the a- and p-form.

have isolated /3-methylarabinoside cor- responding to Fischer’s a-methylarabinoside from the mother liquors obtained during the preparation of the latter ; both are unaffected by yeast enzymes or by emulsin. Trimetbyl-a-arabinoside is crystalline and was isolated ; the P-isomeride is apparently a liquid and has a lower dextrorotation than the former.

J. C. Irvine and A. Bl. Moodie7 have investigated the addition of alkyl iodides to alkylated sugars and glucosides, and, from the behaviour of tetramethyl-a- and -P-glucosides and tetramethyl glucose towards such substances, conclude that the observed mutarotation takes the following course when the solutions are cooled and then reheated : (1) a decrease in rotatory power owing t o formation of an oxonium derivative ; (2) an increase in rotatory power a t the lower temperature owing to the

T. Purdie and 3%. E. Rose

J. Amer. Clzem. Xoc., 1906, 28, 524, Ibid. , 1904, 85, 1541. Ibid. , 1194. (i Ibid,, 1204, Did., 1578.

Trans., 1906, 89, 1033. Ibid., 1906, 89, 1042.

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STEREOCHE?UZISTKT. 195

uncombined sugar changing in the direction p -+ a ; (3) a rapid rise in rotatory power during reheating owing to the dissociation of the oxonium derivative; and (4) a fall in rotatory power a t the higher temperature due to the change a -+ p in the sugar,

P. Waldenl has determined the rotation constants of a large number of optically active esters and other substances for light of different wave-lengths under a variety of different conditions of solvent, concentration, and temperature. H e concludes that the rotatory dispersion is a highly constitutive property, and is in the main independent of the temperature and solvent ; homologous substances have practically the same rotatory dispersions, but deviations from this rule are found in the lower members of a homologous series. A high rotatory power usually accompanies a high rotatory disper- sion, although this is not always true, the two constants being not generically related. Most solvents have li?hle influence on the rotatory dispersion of a dissolved substance, but some, which differ widely in constitution and optical properties, exert a distinct in- fluence on the rotatory dispersion of the solute. A few solvents, such as chloroform, quinoline, and cinnamaldehyde, sometimes effect a complete change in the rotatory dispersion of the solute; this alteration is to be traced to chemical change leading to the forma- tion of new optically active complexes. Walden replies to Patterson's criticism of his previous conclusion^,^ quoting a large amount of fresh experimental data, and adhering to his former statement that a direct relation is observable between the molecular weight and the rotatory power of an optically active substance in both concentrated and dilute solutions.

C. Winther contributes a quantity of experimental data from which he concludes tha t a simple relation exists between changes of rotatorypower on the one hand and the specific volume and molecular weiiht on the other. I n the case of certain substances, such as nicotine and amyl itaconate, the results obtained a t different temperatures indicate that the changes in rotatory power are due solely to changes in the molecular volume or molecular solution volume ; the same holds in numerous cases investigated by Frankland and Patterson, in which the rotatory power and molecular volume change proportionally when the temperature is altered. I n other cases, such as those of menthol, ethyl and propyl tartrates, and diethyl dibenzoyltartrate, the changes of rotatory power are functions of the changes in molecular volume and also in molecular weight. If a certain change in rotatory power, A[a], occurs as the result of the quantity, Am,, of single molecules being produced from double

Zeit. pkysiknl. G ' l z m . , 1906, 55, 1. BcT., 1906, 39, 6%. Zeit. physiknl. Chcm., 1906, 55, 257 ; 56, TO,?. 3 Ann. Eepoyt, 1905, 176.

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196 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.

molecules in the liquid by a rise of temperature, T, the change in rotatory power should be represented by

A [ a ] = K-Am, + K',*Av = 1ClaAT/T17, + IC2*Av. This expression applies satisfactorily to the substances last mentioned both in the undissolvecl and dissolved state. The amount of association occurring in the solutions may be determined from a knowledge of the changes in rotatory power ancl in molecular volume, because K* An?, = A[a] - hr2*4v.

Cases like those of nicotine and ethyl tartrate, in which A[.]= E A v , are found in camphor and turpentine in the dissolved state.

Grossmann and Wieneke from an extensive series of rotatory power determinations a t different temperatures and concentrations conclucle that in aqueous solution boric acid and tartaric acid form R monoboryl tartaric acid,CO,H* CR(0H) 'CH(0H) CO; BO, the hydrolytic dissociation of which increases with rise of temperature and decrease of concentration. The sodinm salt of this acid appears to exist in solution arid evidence of the forlaation of a sodium boryl bitartrate is also adduced. Both normal and acid tartrates and malates of pyrirline exist in aqueous solution.

Wi th the aid of the approximately monochromatic light of mave-length 4SS.5pp which passes throngh R pale-blue light filter, H. Grossniann has investigated the optical effect of adding alkaline copper solutions to solutions of c2-glucose, d-fructose, d-mannitol, rl-rhamnose, sucrose, isosaccharin, asparagine, and tartaric and quinic acids. The effect of the alkaline copper solution is in all cases greatly to increase the rotatory power, and in the cases of glucose, fructose, sucrose, ancl 1-hamnose, the sign of the rotation is reversed. The maximum changes in specific rotatory power due to the addition of copper solution are from + 78.0" to - 375" with glucose, - 134.5Oto + 1423' with fructose, +1012" to - 111.3' with sucrose, and +72*Oo t o +1327" with tartaric acid.

T. S. Patterson and J. K s y e 3 have examined Z-menthyl 2-tartrate for purposes of comparison with Z-menthyl d-tartmte.4 Z-Mentbyl &tartrate gives [MI, - 35S.1" a t 15' and - 382.5" a t 103" in the pure state and, together with its diacetyl derivative, has been examined in a number of solvents. It is shown tha t the optical effect of each com- ponent optically active group in the two diacetyl derivatives is roughly traceable in the changes of molecular rotatory power which occur on heating from 0' t o 100' and the results are ciiscussed in connexion with the question of optical superposition,

T. S. Patterson and J. Frew5 have determined the rotatory powers

Tmns., 1906, 89, 1884. Zrit. pJbpiku2. Chcna., 1906, 54, 385. Zeit. Ycr. dczit. Zz~ckeerincl., 1906, No. 610, 1024. Awl. B ~ p o r f , 1905, 176. Ti T m w , 1906, 89, 332.

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STE R E 0 CH El1 I STR Y. 197

of I-menthyl benzenesulphonate and P-naphthalenesulphonate in alcohol, benzene, and nitrobenzene solutions at different temperatures and con- centrations ; the values for the benzenesulphonate are larger than those for the other ester, and in each case the highest values are obtained in alcohol solutions, the lowest in nitrobenzene, and intermediate values in benzene solutions.

I n addition to those previously described,l P. F. Frankland and D. F. Twiss2 have determined the rotatory powers of a number of other derivatives of tartramide; i t is notable tha t the specific rotatory power of d-tartaric diallylamide is less than tha t of the dipropylamide, as this forms an exception t o the general rule tha t the introduction of a double bond increases the specific rotatory power. A similar observation is made by P. E. Frankland and E. Done 3 in a n investigation on the influence of substituents on the optical activity of nialamide; it is there shown t h a t maldi-n-propylamide has a higher specific rotatory power than maldiallglamide.

The autorscemieation of iodides and bromides of optically active quarternary ammonium bases in chloroform solution f i t st observed in the case of phenyl benzylmethylallylammonium compounds and tlle optical stability in aqueous solution of the corresponding salts of the same base in aqueous solution4 have been reinvestigated by Wedekind in connexion with the iodide, bromide, chloride, and fluoride of d-phenylbenzylmethylpropylammonium. As in the firs t - mentioned case, the iodide undergoes autoracemisation in chloro- form solution more rapidly than the bromide; with the fluoride no definite indication of autoracemisation was obtained and the hycir- oxide in chloroform solution becomes slowly optically inverted, although Wedekind hes previously noted tha t another optically active substitutetl ammonium hydroxide is optically stable in aqueous solution.

E. WedekindG finds tha t the optical inversion of phenylbenzyl- methyl-, allyl-, -propyl- and -isobutyl-ammonium iodides proceeds as :t

uoimolecular reaction. The molecular weight of the first compound is normal, so tha t but very slight dissociation can exist in the chloroform solution. H. Goldschmidt tloes not consider it certain tha t Wedekind’s measurements completely establish tha t the optical inversion is due to dissociation into tertiary amine and alkyl iodide ; he contributes R

thermodynamical discussion of the process of optical inversion.s E. Wedekind and E. Friihlich !’ remark that the molecular rotatory

powers previously given by Wedekintl and Jones for the optically

Trans., 1903, 83, 1349. IDicl., 1906, 89, 1855. Ib id . , 1859.

Zcit. Elelctrochesn., 1906, 12, 330. Ibid. , 416 and 516.

.i Trans., 1901, 79, 838. Bcr., 1906, 39, 474.

3 Compare Weclekind, ibicl., 1906, 12, 515. EcT., 1906, 39, 4437.

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198 ANNUAL REPORTS ON THE PROGRESS O F CHEMISTRY.

active ion *NMeEtPh*C,H7 are not such as would be expected from the values obtained for the ions

*NMePrPh*C7H7 and *NMe(isoC,H,)Ph.C~Hp. I n accordance with this it was found that prolonged fractional crystal- lisation of the mixed d- and Z-phenylbenzylmethylethylammonium d-camphorsulphonates led to the separation of a fraction, dEdA, having a much higher rotatory power than in the previous work and from which the value [MI, + 64.4' was obtained for the basic ion. The iodide of the active base undergoes optical inversion rapidly in chloroform but not in alcohol solution.

Wedekind agrees with Jones's view 1 that the so-called P-phenyl- benzylmethylallylammonium iodide is really phenylbenzyldimethyl- ammonium iodide, which is formed in the reaction between phenyl- benzylallylamine and methyl iodide by a replacement of the allyl group by methyl ; he describes several cases of a similar kind in which an allyl or benzyl group is thus displaced by methyl during the formation of a quarternary ammonium iodide. There is therefore at present no known case of stereoisomerism amongst optically inactive asymmetric nitrogen derivatives.2

have determined for purposes of comparison the rotation constants a t cliff erent temperatures and con- centrations of a large number of compounds owing their activity to the presence of a asymmetric nitrogen atom ; the interpretation in the light of Guye's formula of the large quantity of valuable data quoted led to no satisfactory agreement being established between the observed and the calculated values.

A. Ladenburg4 has continued work on the peculiar kind of stereo- chemical isomerism which he believes to occur amongst secondary bases like stilbazoline and coniinem5 Whilst the naturally occurring d-coniine has [u], +15*6", the base obtained by resolving synthetic coniine with a?-tartaric acid gives [aID + 19.2'; the latter Ladenburg regards as d-isoconiine. The only difference observable between t h e properties of the t w o :bases and their derivatives is in the specific rotatory power. d-isoconiine undergoes practically complete conversion into d-coniine OF [.ID + 15.7' on heating at 290-300".

Miss 31. B. Thomas and H. 0. Jones

w. J. POPE.

Awn. Report, 1905, 182. Ber., 1906, 39, 2486.

Ber., 1906, 39, 481. Trans., 1906, 89, 280. A m . Report, 1904, 144.

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