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Chapter 10 Organometallic compounds

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

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Chapter 10 Organometallic compounds

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  1. Chapter 10 Organometallic compounds 10.1 Introduction 10.2 Preparation of organolithium and organomagnesium compounds 10.3 Carbanions as Brøsted bases 10.4 Applications of organometallic comp. in organic synthesis 10.4.1 Synthesis of alcohols using Grignard reagents 10.4.2 Retrosynthetic analysis 10.4.3 Alkane synthesis by using organocopper reagents 10.4.4 Ziegle-Natta Catalysis of alkene polymerization

  2. Depend on Covalent bond Ionic bond M= Na+or K+ M=Mg, Li M=Pb, Sn, Hg, Tl What' s Organometallic Compounds? A carbon-metal bond Carbanions (负碳离子) Sodium acetylide Sodium ethoxide The natures of C－M bonds The electronegativity of the metal

  3. Solvents: Ether Hydrocarbon: Pentane, Hexane 10.2 Preparation of Organolithium and Organomagnesium compounds Alkyl halide Diethyl ether Et2O Tetrahydrofuran THF (四氢呋喃) Anhydrous! Butyllithium (80% -90%) Butyl bromide

  4. Grignard reagents: Alkylmagnesium Halides V. Grignard and P. Sabatier 1912 Nobel Prize Phenylmagnesium Bromide (95%) Phenyl bromide • Characteristics of the reactions: • Alkyl groups: 1°, 2 °, 3 ° alkyl, • cycloalkyl alkenyl, aryl 2. Reactivity: P223,7.4 Ch.P185(3) Alkyl > Alkenyl or Aryl RI > RBr > RCl > RF 3. Without substitutes: 4. Exothermic

  5. Grignard found that, in the presence of 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 catalytic hydrogenation). François Auguste Victor Grignard 1871-1935 http://www.nobel.se/chemistry/laureates/1912/grignard-bio.html

  6. Conjugate acid Conjugate base 10.3Carbanions as Brøsted bases: Acidity of hydrocarbon: The stronger the acid is, the weaker the conjugate base is.

  7. To different kinds of carbanions: 1) 3 ° > > 2° > > CH3 1° 2) sp3 > sp2 > sp To different element: basicity of anions decrease from left to right in the same period The basicity decreases in order Basicity of anions: Carey(4th): 547

  8. tert-Butyllithium tert-Butane Ethoxymagnesium bromide Phenylmagnesiun bromide Organolithium compounds and Grignard reagents as base: Ch. P186 R－M reacts with much weaker acid than H2O

  9. P296, 9.10 10.4.1 Synthesis of alcohols using Grignard reagents Reactions with carbonyl compounds: • Grignard reagents react with • Formaldehyde(甲醛 ) — Primary alcohols: B. Grignard reagents react with higher aldehydes— secondary alcohols:

  10. C. Grignard reagents react with ketones — Tertiary alcohols: Example: Synthesis of Acetylenic alcohols (炔基醇):

  11. E. J. Corey (1990 Nobel Prize) Problem: suggest two ways To prepare 前体 目标分子 10.4.2 Retrosynthetic analysis(逆合成分析) Target Molecule Precursors n-BuMgX + CH3COCH3 n-BuBr + Mg

  12. 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. His research associates (graduate students and postdoctoral fellows) number over 500 and populate the academic and industrial laboratories of Europe, Asia and the Americas. Elias James Corey 1928- 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",

  13. Alkyllithium Cu (I) halides Lithium dialkylcuprate Lithium halide CuX RLi RLi RCu R2Cu- Li + 10.4.3 Alkanes synthesis by using organocopper reagents Ch.P185 (3) Preparation of lithium dialkylcuprate reagents: Coupling reactions of Organocoppers with Alkylhalides

  14. Lithium dibutylcuprate Iodobenzene Butylbenzene (75%) Characteristics of the reaction: • 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.

  15. 12.44 Ziegle-Natta Catalysis of Alkene Polymerization Carey:P567 14.15 Ziegle catalyst: TiCl4-Et2AlCl Ethylene Ethylene oligomers • Characteristics of the products: • Ethylene oligomers with 6-18 carbons • High-density Isotactic polypropylene 等规 (立构) 的聚丙烯 G. Natta’s contributions:

  16. Coordination polymerization 配位络合聚合 Polypropylene industry was started K. Ziegle and G. Natta shared the 1963 Nobel Prize in Chemistry

  17. Problems: Carey(4th)P573 14.28 (b) 14.29 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) 14.23 14.25 14.26*（选作） 14.27

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