α-活泼氢的反应.pdf
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1、Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity 9.3.4 -活泼氢的反应 1. 烯醇化和烯醇负离子 -氢的酸性 RCH H Y RCHY + H+ Y 吸电子基团 Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity CH3CH3CH2CHCH3(C6H5)2CH2CH3CN CH3SO2CH3 C6H5COCH3 CH3NO2 pKa H H 50 40 32.3 31.3 29 24.7 16.6 17.21 酮
2、式和烯醇式酮式和烯醇式 互变异构互变异构 CH3CCH3 O CH3CCH2 OH H+ or OH Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity 烯醇式含量烯醇式含量 CH3CCH3 O C2H5OCCH2 O COC2H5 O O CH3CCH2 O COC2H5 O CH3CCH2 O CCH3 O 1.5 X 10-47.7 X 10-3 2.0 X 10-27.3 76.5 Organic Chemistry Organic Chemistry XiamenXiamen University
3、University 烯醇负离子 RCCH2 O RCCH2 O RCCH2 O 碳负离子 烯醇负离子 Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity 烯醇化反应机理 CH3CCH3 O CH3CCH2 OH CH3CCH3 OH CH3CCH3 OH H+ H+ CH3CCH3 O B CH3CCH2 O CH3CCH2 O BH CH3CCH2 OH Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity 不对称酮的
4、烯醇化 CH3CCH2CH3 O CH3CCHCH3 OH CH2CCH2CH3 OH 热力学控制产物 动力学控制产物 Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity 烯醇化的应用: (1) 外消旋化 R HCH3 C R O H+ 或 OH RCH3 ROH H+ 或 OH R CH3H C R O Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity (2) 重氢交换重氢交换 C H C O ODD2O CC O
5、CC OD C D C O Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity 2. 醛酮的-卤化 C H C O H+ 或 OH X2 C X C O + HCl O + Cl2 H2O O Cl + HX Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity 酸催化下的反应机理: CH3CCH3 O H+ CH3CCH3 OH CH3CCH3 OH H+ CH3CCH2 OH BrBr CH3CCH2Br OH H+
6、CH3CCH2Br O Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity 碱催化下的反应机理: CH3CCH3 O OH CH3CCH2 O CH3CCH2 O BrBr CH3CCH2Br O + Br CCH3 O Br2 HOAc CCH2Br O + HBr 69 77% Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity 3. 卤仿反应 CCH3 O R X2 NaOH CO O R+ CHX3 卤仿 Hal
7、oformHaloform reaction CCH3 O CHCH3 OH 具有 结构的 化合物都能发生反应?碘仿反应可用于鉴别? 碘仿CHI3黄色 Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity 反应机理反应机理 CCH3 O R X2 NaOH COH O R + CX3 CCX3 O R OH CCX3 O R OH CO O R+ CHX3 H+ COH O R Organic Chemistry Organic Chemistry XiamenXiamen UniversityUnivers
8、ity C CH3 O (1) X2 , OH (2) H+ C OH O (CH3)3CCCH3 O (1) X2 , OH (2) H+ (CH3)3CCOH O O O (1) Cl2 , KOH (2) H+ CH3 C CH3 CH2CO2H CH2CO2H Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity 4. 羟醛缩合(Aldol condensation) 2 CH3CHOCH3CHCH2CHO OH OH 含有-H的醛(酮)在酸或碱的作用下,缩合生成 -羟基醛(酮) -羟基醛(酮)易脱水
9、形成,不饱和醛(酮): CH3CHCH2CHO OH H2O CH3CHCHCHO Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity 反应机理反应机理: CH3C O HCH2C O HCH2 C O H OH CH3C O H CH3C O H CH2C O H H2O CH3C OH H CH2C O H Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity 酸催化下的反应机理: CH3CCH3 O H+ CH3CC
10、H3 OH CH3CCH3 OH H+ CH3CCH2 OH CH3CCH3 OH CH3CCH3 OH CH3CCH2 OH H+ CH3CCH2 OH C O CH3 CH3 Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity 羟醛缩合反应的类型: (1)自身缩合 2 CH3CH2CH2CHOCH3CH2CH2CHCHCHO OH OH CH2CH3 CH3CH2CH2CCCHO CH2CH3 I2 Organic Chemistry Organic Chemistry XiamenXiamen Uni
11、versityUniversity O 2 HO O EtOH NaOH O 2 PhCH 2CHO EtOH NaOH PhCH 2CH OH CHCHO Ph90% Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity (2) 分子内缩合分子内缩合 CH3C(CH2)3CH2CCH3 OO KOH, H2O CH3 CCH3 O 85% + OH O OH Organic Chemistry Organic Chemistry XiamenXiamen UniversityUniversity O O N
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