厦门大学化学化工学院：《有机化学》课程教学资源（课件讲稿，双语版）Chapter 8 Alkenes and Alkynes II：（8.9-8.15）Divalent Carbon Compounds：Carbenes

ORGANIC CHEMISTRY Chapter 8 8.9 Divalent Carbon Compounds Carbenes 卡宾 Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 8 8.9 Divalent Carbon Compounds: Carbenes 卡宾

ORGANIC CHEMISTRY Chapter 8 o There is a group of compounds in which carbon forms only two bonds These neutral divalent carbon compounds are called carbenes o Most carbenes are highly unstable compounds that are capable of only fleeting existence Soon after carbenes are formed they usually react with another molecule RC° Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 8 There is a group of compounds in which carbon forms only two bonds. These neutral divalent carbon compounds are called carbenes. Most carbenes are highly unstable compounds that are capable of only fleeting existence. Soon after carbenes are formed they usually react with another molecule. R2C

ORGANIC CHEMISTRY Chapter 8 8.9a Structure and Reactions of methylene h CHOC=O CH2 CO CH CH, t n2 RI (4 R R 单线态三线态 Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 8 8.9A Structure and Reactions of Methylene CH2 C O





















CH2 + CO







































CH2 N+ N−














































hv hv










CH2 + N 2

C R R R C R 单线态 三线态

ORGANIC CHEMISTRY Chapter 8 H C-C. + CH 2 C-C CH CH CH (A-2-Butene Methylene CH cis-1, 2-Dimethylcyclopropane Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 8 H C CH3 C H CH3 H C CH3 C HCH3 CH2 H C CH3 C H CH3 CH2 + CH2 Methylene cis-1,2-Dimethylcyclopropane (Z)-2-Butene

ORGANIC CHEMISTRY Chapter 8 8.9B Reactions of other Carbenes Dihalocarbenes(二氯卡宾) OH CHC CCh CCb H Cl C CI CH H t CCl CH2C-C、H H CH C\CH3 H CH3 CH H (CH3)3COK CHCl3 Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 8 8.9B Reactions of Other Carbenes: Dihalocarbenes (二氯卡宾) CHCl3










OH










− CCl2 Cl
























−H+























Cl − CCl2



CH3 C H C H CH3 CCl + 2 CH3 C H C H CH3 C Cl Cl H C CH3 C CH3 H C Cl Cl + + CHCl3 (CH3)3COK Cl Cl

ORGANIC CHEMISTRY Chapter 8 8. 9C Carbenoids The Simmons-Smith Cyclopropane Synthesis CH2I2 Zn( Cu)- ICh,ZnI=: CH A carbenoid Zn(Cu) t ch CH Et,o Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 8 8.9C Carbenoids: The Simmons-Smith Cyclopropane Synthesis CH2I2 + Zn(Cu) ICH2ZnI = CH2 A carbenoid + CH2I2 CH2 Zn(Cu) Et2O H H

ORGANIC CHEMISTRY Chapter 8 8.10 Oxidation of Alkenes: Syn Hydroxylation Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 8 8.10 Oxidation of Alkenes: Syn Hydroxylation

ORGANIC CHEMISTRY Chapter 8 0 OH CC=C\+KMnO cold 111 C-C OH HO A.2-Dic (1)OsO4, pyridine CH3CH=CH CHrCH-CH (2)Na2 SO3/H2O or naSO,/ho HO OH Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 8 C C C C HO OH + KMnO4 cold OH , H2O A 1,2-Diol CH3CH CH2 (1) OsO4, pyridine (2) Na2SO3 / H2O or NaHSO3 / H2O CH3CH CH2 HO OH

ORGANIC CHEMISTRY Chapter 8 8. 10A Mechanism for Syn Hydroxylation of alkenes cold HO H H HO OH M Mn OK OK cis-1, 2-Cyclohexanediol EtO H,O or THF H H HO OH Os cis-1, 2-Cyclohexanediol Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 8 8.10A Mechanism for Syn Hydroxylation of Alkenes Mn O O OK O cold H H Mn O O OK O HO OH H H cis-1,2-Cyclohexanediol H2O Os O O O O H H Os O O H2O HO OH H H cis-1,2-Cyclohexanediol O O or THF Et2O

ORGANIC CHEMISTRY Chapter 8 Anti Hydroxylation OH RCO2H HO C—C C—C C=C H or oH OH oxirane, epoxide 环氧化合物 RCO3 h Peroxycarboxylic acid过氧酸 CH3C-O-OH CF3C-0-OH C-0-0H C-O-OH 33%H2O2 CH2C-OH CH2C-O-OH H Department of Chemistry, Xiamen University

ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 8 Anti Hydroxylation Anti Hydroxylation C C C C O 环氧化合物 oxirane , epoxide RCO3H H2O H or OH C C OH OH RCO3H Peroxycarboxylic acid 过氧酸 CH3C OH O 33% H2O2 CH3C O O OH H+ CH3C O O OH CF3C O O OH C O OH O C O OH Cl O