高等学校化学学报

高等学校化学学报 ›› 1993, Vol. 14 ›› Issue (3): 402.

• 研究论文 • 上一篇    下一篇

Meso-2,3-二氰基-2,3-二苯基丁二酸二乙酯熔融相热异构化反应动力学及中间体EPR测定

齐陈泽, 贾志胜, 杨第伦   

  1. 兰州大学化学系, 兰州 730000
  • 收稿日期:1992-07-28 修回日期:1992-11-14 出版日期:1993-03-24 发布日期:1993-03-24
  • 通讯作者: 杨第伦
  • 基金资助:

    国家自然科学基金

Kinetics of Thermal Isomerization of meso-Diethyl 2,3-Dicyano-2,3-Diphenyl Succinate and the EPR Spectra of the Intermediate in Melten State

QI Chen-Ze, JIA Zhi-Sheng, YANG Di-Lun   

  1. Department of Chemistry, Lanzhou University, Lanzhou, 730000
  • Received:1992-07-28 Revised:1992-11-14 Online:1993-03-24 Published:1993-03-24

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被引次数

1

摘要： 测定了2,3-二氰基-2,β-二苯基丁二酸二乙酯meso-异构体熔融相的热异构化反应动力学及苯环对位为X(X=OCH3,CH3,H,Cl,NO2)的相应二乙酯反应中间体自由基的EPR谱,自由基的结构由计算机模拟确定.结果表明,在实验温度范围内,平衡常数随温度的升高而降低.热力学数据为:ΔHdl-meao= - 18.02 kJ/mol, ΔSdl-meao= - 26.51 J/mol·K, ΔH≠ = 151.78 kJ/mol, ΔS≠ = 71.64 J/mol·K.反应机理是内消旋体的中心碳-碳键发生均裂,生成α-氰基-α-乙氧甲酰基-P-X取代苄基自由基,再重新结合时发生异构化,生成dl-异构体.

关键词: meso-2, 3-二氰基-2, 3-二苯基丁二酸二乙酯, 熔融态, 热异构化, 动力学, EPR

Abstract: The kinetics were studied for the thermal isomerization of meso-diethyl 2,3-dicyano-2,3-di (p-Xsubstituted phenyl) succinates (X = H) in melten state and the EPRspectra of the intermediates (X = OCH3, CH3, H, Cl, NO2) were observed.The central carbon-carbon bond of the five isomers was homolysed to give ethyl α-cyano-α-ethoxycarbonyl-p-substituted benzyl radicals.The structures of the intermediates were determined by compute simulation.The kinetic results indicate that the equilibrium constant Kreduced as the rise of the reaction temperature.The active parameters were found to be ΔHdl-meao= - 18.02 kJ/mol, ΔSdl-meao= - 26.51 J/mol·K, ΔH≠ = 151.78 kJ/mol, ΔS≠ = 71.64 J/mol·K.dl-Isomer is more stable than the corresponding meso-iscmer.

Key words: Meso-diethyl 2, 3-dicyano-2, 3-di(p-X substituted phenyl) succinate, Melten state, Thermal isomeriztion, Kinetics, EPR

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