物理化学学报 >> 1994, Vol. 10 >> Issue (08): 680-685.doi: 10.3866/PKU.WHXB19940803

研究论文 上一篇    下一篇

氟、胺取代基对乙烯和甲醛环加成的影响

陈丽涛, 陈光巨, 傅孝愿   

  1. 北京师范大学化学系,北京 100875
  • 收稿日期:1993-04-09 修回日期:1993-06-08 发布日期:1994-08-15
  • 通讯作者: 傅孝愿

The Influence of Fluorine or/and Amine Substituents on the Cycloaddition Reaction of Ethylene and Formaldehyde

Chen Li-Tao, Chen Guang-Ju, Fu Xiao-Yuan   

  1. Chemistry Department, Beijing Normal University, Beijing 100875
  • Received:1993-04-09 Revised:1993-06-08 Published:1994-08-15
  • Contact: Fu Xiao-Yuan

摘要:

采用较新的半经验分子轨道方法AM1研究了氟、胺取代基对乙烯和甲醛环加成反应的影响.对三个环加成反应(C_2H_4+COF_2,H_2NHC=CHNH_2+H_2CO以及H_2NHC=CHNH_2+COF_2)的研究结果表明:1) 各反应均是经历双自由基中间体的两步过程,而第一步是速度控制步骤;2) 三个反应的活化位垒依次降低;3) 胺取代基比氟取代基对活化势垒的降低作用更为显著。

关键词: 双自由基, 分步反应, 氟基, 胺基, 环加成

Abstract:

The influence of fluorine or/and aAnne substituents to the mechainsm of cycloaddition reaction of ethylene and formaldehyde has been studied by using senilemPirical molecular orbital theory UAM1 presented by M.J.S. Dewar et al in 1985, and performed with GAUSSIAN 86 program. Three chendcal reactions (C_2H_4+COF_2, H_2NHC=CHNH_2+H_2CO and H_2NHC=CHNH_2 +COF_2) have been studied in detail. Thevarious critical points of all the reactions studied have been fully optimized with Berny gradients and transtiton structures have been confirmed by frequency analysis. From the results we concluded that: 1) All the reaction pathways studied in this work are found to proceed via a two-step approach characterized by diradical gauche intermediates and the rate determining step is the first step for all the three reactions. 2) The fluoride or/and amine substituents can all reduce the potential energy barrier of the cycloadditon reaction of ethylene and formaldehyde, and amine is more favourable than fluoride.

Key words: Diradical, Stepwise, Cycloaddition, Fluorine substituents, Amine substituents