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化学学报
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化学学报 ›› 1993, Vol. 51 ›› Issue (1): 66-72. 上一篇    下一篇

研究论文

α-氰基-P-X苯基乙酸乙酯的[Cu^2+(OH^-)TMEDA]2Cl2-催化氧化偶联反应机理

杨第伦;齐陈泽;卢晓兰;刘有成   

  1. 兰州大学化学系;兰州大学应用有机化学国家重点实验室
  • 发布日期:1993-01-15

Investigation on the mechanism of oxidative coupling reactions of ethyl α- Cyano-P-X substituted phenyl acetates by use of catalyst [Cu^2+(OH^-)TMEDA]2Cl2^-

YANG DILUN;QI CHENZE;LU XIAOLAN;LIU YOUCHENG   

  • Published:1993-01-15

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561

被引次数

2

在[Cu^2+(OH^-)TMEDA]2Cl2^-催化下(TMEDA为N, N, N', N;-四甲基乙二胺),α-氰基-P-X苯基乙酸乙酯(X=OCH3, CH3, Cl, H和NO2)经氧化偶联反应, 获得高产率的二聚体。产物中meso异构体的含量均大于dl异构体的含量。IR, 1H NMR和EPR对反应过程进行研究, 结果表明, 反应机理为底物以CN取代催化剂中的OH^-, 生成反应中间体配合物, OH-夺取底物的α-H, 产生相应的碳负离子, 碳负离子向Cu^2+单电子转移生成自由基, 自由基偶合而生成产物。氧将Cu^+氧化为Cu^2+, 使反应继续进行。

关键词: 反应机理, 红外分光光度法, 苯 P, 乙酸乙酯, 铜络合物, 质子磁共振谱法, 氰基, 乙二胺, 单电子转移反应, 偶合反应

The oxidative coupling reactions of ethyl α-cyano-P-X substituted phenyl acetates (X=OCH3, CH3, H, CL, NO2) with Cu^2+-TMEDA-O2 system give meso-and dl-diethyl 2, 3-dicyano-2, 3-di (p-X substituted phenyl )succinates. on the basis of the stereochemistry and IR , 1H NMR and EPR determination of the reactive interme-diates of the oxidative coupling reactions, the mechanism was suggested. two OH^- of the catalyst [Cu^2+(OH^-)TMEDA]2Cl2^- are substituted by CN of substrates ad give the reactive intermediates [Cu^2+(S-CN)TMEDA]2Cl2(OH^-)2.OH^- extracts α -proton of the substrate and gives the orresponding carbanion .an electron transfers from carbanion to Cu^2+. the coupling of the formated radicals produces diethyl ester dimers. it carries the reactions through that Cu^+ is oxidated to Cu^2+ by oxygen.

Key words: REACTION MECHANISM, INFRARED SPECTROPHOTOMETRY, BENZENE P, ETHYL ACETATE, COPPER COMPLEX, PROTON MAGNETIC RESONANCE SPECTROMETRY, CYANO GROUP, ETHANEDIAMINE, SINGLE ELECTRON TRANSFER REACTION, COUPLING REACTION

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