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