脱羧和还原 R CH H 酸性 H --Y 衍生物 a-H的取代 被取代
酸性 被取代 脱羧和还原 -H的取代 R CH C O H H O ---Y 衍生物
Alpha Substitution Replacement of a hydrogen on the carbon adjacent to the carbonyl,C=O. Step 1:Deprotonation Step 2:Attack on electrophile E base: enolate ion Copyright 2005 Pearson Prentice Hall,Inc
Alpha Substitution Replacement of a hydrogen on the carbon adjacent to the carbonyl, C=O
2.a Halogenation Iodoform Reaction (碘仿反应) 卤代反应：+X2 RCH2-C-H(R)_ r2 RCHBrC-H(R) H+ 0 Br-BrCHCO2H) H0,70°C H-CH2CCH3 BrCH2CCH3 HBr 44% Bromoacetone
2. Halogenation & Iodoform Reaction （碘仿反应） 卤代反应：+X2 O RCHBrC H(R') Br 2 RCH2 C H(R') O H+
Multiple Halogenations The a-halo ketone produced is more reactive than ketone. Enolate ion stabilized by e-withdrawing halogen. OH R-CH-CH3 I2 R-C-CH 2HI excess 12 OH 0H,H20 Copyright 2005 Pearson Prentice Hall,Inc
Multiple Halogenations ◼The -halo ketone produced is more reactive than ketone. ◼Enolate ion stabilized by e--withdrawing halogen. O H Cl Cl 2 OH , H2O _ O Cl Cl O Cl C Cl l O Cl C Cl l Cl
卤仿（碘仿）反应 CH3 I2/0H- cr t-nay OH 黄↓ 或N0 CH+R')HC-O CH2CHO OHA ICH,CHO OH-/I2 I.CHCHO OH/2 I3CCHO OH-/I2 CHI3+HCOOH 规律：乙醛，甲基酮，乙醇，异丙醇均可 CH3COR(H);CH3COHR(H); ?CH3COOH
卤仿(碘仿)反应 CH3CHO ICH2CHO I2CHCHO I3CCHO CHI3+ HCOOH OH-/I2 OH-/I2 OH-/I2 OH-/I2 规律: 乙醛,甲基酮,乙醇,异丙醇均可 CH3COR(H); CH3COHR(H); ?CH3COOH C H 3 C H (R ') O I 2 /O H - 或 N aIO 黄↓ CI3 C H(R') O OHCHI3 + (R')HC OO