N-取代乙基吡唑热消除反应的量子化学研究  

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

作　　者：洪三国[1] 傅孝愿[2] 

机构地区：[1]江西师范大学化学系 [2]北京师范大学化学系,北京100875

出　　处：《高等学校化学学报》1991年第9期1212-1215,共4页Chemical Journal of Chinese Universities

基　　金：国家教委访问学者基金

摘　　要：用MINDO/3方法研究了N-取代乙基吡唑热消除反应H_3C_3N_2CH_2CH_2XH_4C_3N_2+H_2C=CHX(反应Ⅰ～Ⅲ,对应X=H,CH_3,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。MINDO/ 3 SCF calculations have been carried out to study the thermal elimination of N-substituted ethyl pyrazole;A concerted 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 TS respectively, the activation barriers of these two reactions are lower than that of the non-substituted reactent.

关 键 词：吡唑 N-取代乙基 热消除反应 

分 类 号：O626.21[理学—有机化学]