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）第九章 醛和酮 9.3.4 α -活泼氢的反应 LDA Lithium diisopropylamide 二异丙氨基

9.340-活泼氢的反应 烯醇化和烯醇负离子 α-氢的酸性 R一CH-Y R-CH-Y+H H Y 吸电子基团

Organic Chemistry Organic Chemistry Xiamen Xiamen University University 9.3.4 α -活泼氢的反应 1. 烯醇化和烯醇负离子 α -氢的酸性 R C H H Y R C H Y + H + Y 吸电子基团 α

CH3CH3 CH2=CHCH3 (C6H5)2CH2 CH3CN y 50 40 32.3 31.3 CH3SO2 CH3 CAHsCOCH Ch3 nO2 H 29 24.7 16.6 17.21 酮式和烯醇式—一互变异构 OH h or oh CH3-C-CH3 CH3 C=CH2

Organic Chemistry Organic Chemistry Xiamen Xiamen University University CH 3 C H 3 CH 2 CHC H 3 (C 6 H 5 ) 2 C H 2 C H 3CN CH 3SO 2 C H 3 C 6 H 5COC H 3 CH 3NO 2 pK a H H ~ 5 0 40 3 2.3 31.3 2 9 24.7 16.6 1 7.2 1 酮式和烯醇式—— 互变异构 CH 3 C C H 3 O CH 3 C C H 2 OH H+ or OH

目烯醇式含量 CH3C-CH3 C2HsO-C-CH2-C-OC2H5 1.5Ⅹ10 7.7X10 >0 CH2C-CH2-C-oCas 20X102 7.3 CH2C-CHo-C-CH 76.5

Organic Chemistry Organic Chemistry Xiamen Xiamen University University 烯醇式含量 CH 3 C C H 3 O C 2 H 5OCC H 2 O C O C 2 H 5 O O CH 3 C C H 2 O C O C 2 H 5 O CH 3 C C H 2 O C C H 3 O 1.5 X 1 0-4 7.7 X 1 0-3 2.0 X 1 0-2 7.3 76.5

烯醇负离子 fRC-CH2 O R-C—CH RC-CH, 碳负离子 烯醇负离子

Organic Chemistry Organic Chemistry Xiamen Xiamen University University 烯醇负离子 R C C H 2 O R C C H 2 O R C C H 2 O 碳负离子 烯醇负离子

烯醇化反应机理 H +OH OH CH3-C-Ch CH3-C-CH3←-CH3C-CH3 OH ch2-C-CH B 三CH3-C-CH CH3C-CH, + CH3-C-CH OH BH -CH3C-ch 2

Organic Chemistry Organic Chemistry Xiamen Xiamen University University 烯醇化反应机理 CH 3 C C H 3 O CH 3 C C H 2 OH CH 3 C C H 3 O H CH 3 C C H 3 OH H + H + CH 3 C C H 3 O B CH 3 C C H 2 O CH 3 C C H 2 O BH CH 3 C C H 2 OH

不对称酮的烯醇化 CH3C—CHCH OH OH E CH3-C=CHCH3 CHo-C-CHCH 热力学控制产物 动力学控制产物

Organic Chemistry Organic Chemistry Xiamen Xiamen University University 不对称酮的烯醇化 CH 3 C C H 2CH 3 O CH 3 C C H C H 3 OH CH 2 C C H 2CH 3 OH 热力学控制产物 动力学控制产物

烯醇化的应用: (1)外消旋化 R CH R H CH HH+ R H CH C=O或OHR OH OH C=0 R R

Organic Chemistry Organic Chemistry Xiamen Xiamen University University 烯醇化的应用: (1) 外消旋化 R CH 3 H C R' O H + 或 OH R C H 3 R' OH H + 或 OH R H CH 3 C R' O

(2)重氢交换 OD OD D2O -C-C C=C一÷—C=C H C-C

Organic Chemistry Organic Chemistry Xiamen Xiamen University University (2) 重氢交换 C H C O OD D 2 O C C O C C O D C D C O

2.醛酮的Q-卤化 2 C-C C-C—+HX H或OH H2o Cl CI +hcl

Organic Chemistry Organic Chemistry Xiamen Xiamen University University 2. 醛酮的 α -卤化 C H C O H+ 或 OH X 2 C X C O + HCl O + Cl 2 H 2 O O Cl + H X

酸催化下的反应机理: +OH OH H CH3-C-Ch CH3-C-CH3+→CH3C-CH2 BOH +OH Br—Br H CH3c=ch CH3C—CHBr CH3-c-ch, br

Organic Chemistry Organic Chemistry Xiamen Xiamen University University 酸催化下的反应机理: CH 3 C C H 3 O H + CH 3 C C H 3 O H CH 3 C C H 3 O H H + CH 3 C C H 2 O H Br Br CH 3 C C H 2Br O H H + CH 3 C C H 2Br O