chapter 10 organometallic compounds
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Chapter 10 Organometallic compounds. 10.1 Introduction 10.2 Preparation of organolithium and organomagnesium compounds 10.3 Carbanions as Br ø sted bases 10.4 Applications of organometallic comp. in organic synthesis - PowerPoint PPT PresentationTRANSCRIPT
Chapter 10 Organometallic compounds
10.1 Introduction10.2 Preparation of organolithium and organomagnesium compounds10.3 Carbanions as Brøsted bases10.4 Applications of organometallic comp. in organic synthesis10.4.1 Synthesis of alcohols using Grignard reagents10.4.2 Retrosynthetic analysis10.4.3 Alkane synthesis by using organocopper reagents10.4.4 Ziegle-Natta Catalysis of alkene polymerization
What' s Organometallic Compounds?C M A carbon-metal bond
Na OEt
Sodium acetylide Sodium ethoxide
The natures of C-M bondsThe natures of C-M bondsThe electronegativity of
the metalThe electronegativity of
the metalDepend on
C MM C M ¦Ä ¦Ä
C M
M= Na+or K+ M=Mg, Li M=Pb, Sn, Hg, Tl
Ionic bond Covalent bond
Carbanions(负碳离子 )
Carbanions(负碳离子 )
H C C Na
10.2 Preparation of Organolithium and Organomagnesium compounds
R X + Mether
R M + M XAlkyl halide
TetrahydrofuranTHF
(四氢呋喃 )
Solvents:EtherHydrocarbon:Pentane, Hexane Anhydrous!
CH3CH2CH2CH2Br + 2LiEt2O
-10¡æCH3CH2CH2CH2Li + LiBr
Butyl bromideButyllithium(80% -90%)
OH3CH2C CH2CH3
Diethyl etherEt2O
O
Br + Mg Et2O35¡æ
MgBr
Grignard reagents: Alkylmagnesium Halides
Phenyl bromide
Characteristics of the reactions:1. Alkyl groups: 1°, 2 °, 3 ° alkyl, cycloalkyl alkenyl, aryl2. Reactivity:
4. Exothermic3. Without substitutes: OH, C
O
, C N Etc.
V. Grignard andP. Sabatier1912 Nobel Prize
V. Grignard andP. Sabatier1912 Nobel Prize
Alkyl > Alkenyl or ArylRI > RBr > RCl > RF
PhenylmagnesiumBromide (95%)
P223,7.4Ch.P185(3)
P223,7.4Ch.P185(3)
Grignard found that, in the presenceof ether, magnesium reacts with alkyl and aryl halides at room temperature to form organo-magnesium compounds. These solutions,called "Grignard reagents" react with most functional groups in a synthetically useful way. For this discovery, tremendously useful in laboratory and industrial synthesis, he was awarded the 1912 Nobel Prize in Chemistry(shared with Paul Sabatier,discoverer of catalytichydrogenation).
François Auguste Victor Grignard
1871-1935
http://www.nobel.se/chemistry/laureates/1912/grignard-bio.html
Acidity of hydrocarbon:
C H H + C
(CH3)3C HPka 71 62 60 45
>CH3CH2 H > CH3 H > CH2 CH H >
H > H2N H > HC C H> CH3CH2O H> HO H
Pka 43 36 26 16 15.7
(CH3)3C HPka 71 62 60 45
>CH3CH2 H > CH3 H > CH2 CH H >
H > H2N H > HC C H> CH3CH2O H> HO H
Pka 43 36 26 16 15.7
Conjugate acid Conjugate base
The stronger the acid is, the weaker the conjugate base is.The stronger the acid is, the weaker the conjugate base is.
10.3 Carbanions as Brøsted bases:
To different kinds of carbanions:3 ° >2° 1°>> > CH3
1)2) sp3 > sp2 > sp
The basicity decreases in order
(CH3)3C > (CH3)2HC > CH3CH2 > H3C
CH2 CH > > HC C>>CH3CH2
C > N > O > X
Basicity of anions:
To different element:basicity of anions decrease from left to right in the same period
Carey(4th):547
Carey(4th):547
R M + R'O H ¦Ä ¦Ä
R H + R'O M
Organolithium compounds and Grignard reagents as base:
Li + H2OLi H + LiOH
MgBr + EtOH H + EtOMgBr
tert-Butyllithium tert-Butane
Phenylmagnesiun bromide
Ethoxymagnesiumbromide
RC C H + R' MgX ¦Ä ¦Ä
RC C MgX + R' H ¦Ä ¦Ä
R-M reacts with much weaker acid than H2O
Ch. P186Ch. P186
10.4.1 Synthesis of alcohols using Grignard reagents
Reactions with carbonyl compounds:A.Grignard reagents react with Formaldehyde( 甲醛 ) — Primary alcohols:
R:MgX¦Ä ¦Ä
+ C OH
HC
H
H
R O MgXH3O
C
H
H
R OHR:MgX¦Ä ¦Ä
+ C OH
HC
H
H
R O MgXH3O
C
H
H
R OH
R:MgX¦Ä ¦Ä
+ C OR'
HC
R'
H
R O MgXH3O
C
R'
H
R OHR:MgX¦Ä ¦Ä
+ C OR'
HC
R'
H
R O MgXH3O
C
R'
H
R OH
B. Grignard reagents react with higher aldehydes— secondary alcohols:
P296,9.10
P296,9.10
Example: PhMgBr + C OH
HEt2O PhCH2OMgBr
H3+O PhCH2OH
Synthesis of Acetylenic alcohols (炔基醇 ):RC CH + CH3CH2 MgBr
Et2ORC C MgBr + CH3CH3
Et2O
RC C MgBr + H C HO
1. Et2O
2. H3ORC CCH2OH
R:MgX¦Ä ¦Ä
+ C OR'
R"C
R'
R O MgXH3O
C
R'
R OH
R" R"
R:MgX¦Ä ¦Ä
+ C OR'
R"C
R'
R O MgXH3O
C
R'
R OH
R" R"
CH2 CHLi + C
O
H1. Et2O2. H3O
+ CHCH
OH
CH2
C. Grignard reagents react with ketones — Tertiary alcohols:
10.4.2 Retrosynthetic analysis ( 逆合成分析 )E. J. Corey
(1990 Nobel Prize)Target Molecule
Precursors
目标分子 前体
CH3CH2CH2CH2 C
CH3
CH3
OH n-BuMgX + CH3COCH3
+CH3CH2CH2CH2MgBr C OCH3
CH3
Et2O
CH3CH2CH2CH2COMgBr
CH3
CH3
H3O C OHCH3CH2CH2CH2
CH3
CH3
n-BuBr + Mg
Problem: suggest two waysTo prepare C6H5C(CH3)2
OH
Elias James Corey1928-
which changed the way organic chemists undertake the synthesis of complex natural products, the synthesis of longifolene, maytansine, the ginkolides, prostaglandins and leukotrienes, the development of new synthetic methods, particularly using chiral catalysts, and the application of computers to synthesis design are among his most notable achievements.Corey has received many honors, including the Wolf Prize (1986), the National Medal of Science (1988), the Japan Prize in Medicinal Science (1989) and the Nobel Prize in Chemistry (1990).Born in Massachusetts, Corey obtained the Ph.D. at M.I.T. (1951), was on the faculty at the University of Illinois (1951-59) where he became full professor at the early age of 27, and since 1959 he has been professor at Harvard. Hisresearch associates (graduate students and postdoctoral fellows) number over 500 and populate the academic and industrial laboratories of Europe, Asia and the Americas.
Professor Corey (to collea-Gues and friends, E.J.) is known for his many spectacular contributions to synthetic organic chemistry. The concept of "retrosynthetic analysis",
Preparation of lithium dialkylcuprate reagents:
2 R Li + CuXEt2O
or THFR2CuLi + LiX
Alkyllithium Cu (I) halides
Lithiumdialkylcuprate
Lithiumhalide
RLi CuX RCu RLi R2Cu- Li +
Coupling reactions of Organocoppers with Alkylhalides
(CH3)2CuLi + CH3(CH2)8CH2IEt2O
0¡æCH3(CH2)8CH2CH3
Undecane (90%)
Ch.P185(3)
Ch.P185(3)
10.4.3 Alkanes synthesis by using organocopper reagents
Characteristics of the reaction:
1. SN2 reaction The order of the reactivity : CH3 > 1°> 2°> 3° I > Br > Cl > F
2. To alkyl halides, R: primary,vinyl and aryl groups. To Lithium dialkylcuprate, R’: primary group or -CH3.
(n-Bu)2CuLi + IEt2O n-Bu
Lithium dibutylcuprate
Iodobenzene Butylbenzene(75%)
12.44 Ziegle-Natta Catalysis of Alkene Polymerization
Ziegle catalyst: TiCl4-Et2AlClnH2C CH2
TiCl4-Et2AlClCH3CH2(CH2CH2)n-2CH CH2
Ethylene Ethylene oligomersCharacteristics of the products:1. Ethylene oligomers with 6-18 carbons2. High-density
G. Natta’s contributions:
H HH3CH3C HH3C HH3C H H3C H H3C
Isotactic polypropylene 等规 ( 立构 ) 的聚丙烯
Carey:P56714.15
Carey:P56714.15
Coordination polymerization配位络合聚合
Polypropylene industry was started
K. Ziegle and G. Natta shared the 1963 Nobel Prize in Chemistry
Problems: Carey(4th)P573 14.15 (b), (d)14.17 (h), (m), (n)14.18 (d), (e)14.19 ((b), (f)14.20 (d), (e)14.21 (a)-(c)14.22 (b), (f), (g)14.2314.2514.26* (选作)14.27
14.28 (b)14.29