高等学校化学学报

高等学校化学学报 ›› 1991, Vol. 12 ›› Issue (9): 1212.

• 论文 • 上一篇    下一篇

N-取代乙基吡唑热消除反应的量子化学研究

洪三国, 傅孝愿   

  1. 北京师范大学化学系, 北京, 100875
  • 收稿日期:1990-04-14 出版日期:1991-09-24 发布日期:1991-09-24
  • 通讯作者: 傅孝愿
  • 基金资助:

    国家教委访问学者基金

A Quantum Chemical Study on Thermal Elimination of N-Substituted Ethyl Pyrazole

Hong San-guo, Fu Xiao-yuan   

  1. Department of Chemistry, Beijing Normal University, Beijing, 100875
  • Received:1990-04-14 Online:1991-09-24 Published:1991-09-24

PDF (PC)

摘要： 用MINDO/3方法研究了N-取代乙基吡唑热消除反应H3C3N2CH2CH2X→H4C3N2+H2C=CHX(反应Ⅰ～Ⅲ,对应X=H,CH3,F)的机理,结果表明,甲基的超共轭效应以及F的强吸电子作用和邻基参与使得反应Ⅱ和反应Ⅲ的活化势垒降低,比反应Ⅰ更易进行。

关键词: 热消除反应, 过渡态, 内禀反应坐标(IRC)

Abstract: MINDO/ 3 SCF calculations have been carried out to study the thermal elimination of N-substituted ethyl pyrazole;H3C3N2CH2CH2X→H4C3N2+H2C=CHX (I,X=H;Ⅰ, X=CH3;Ⅲ,X=F)Aconcerted reaction involving a five membered ring transition state(TS) was found. The results obtained show that there is a weak influence on the reactivity by the substituents on ft carbon of the ethyl group. The hyperconjugation of the methyl group, and the strong electronegativity and the weak conjugation of the fluorine atom stabilize the corresponding TSrespectively, the activation barriers of these two reactions are lower than that of the non-substituted reactent.

Key words: Thermal elimination, Transition state, Intrinsic reaction coordinate

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