物理化学学报 >> 1989, Vol. 5 >> Issue (04): 398-402.doi: 10.3866/PKU.WHXB19890405

研究论文 上一篇    下一篇

第四级铵氢氧化物Hofmann消除反应的构象分析及反应机理

徐筱杰; 姚振贵; 叶秀林; 唐有祺; 傅亨; 钱民协   

  1. 北京大学化学系; 中科院化学研究所
  • 收稿日期:1986-06-09 修回日期:1989-01-26 发布日期:1989-08-15
  • 通讯作者:

THE CONFORMATIONAL ANALYSIS AND REACTION MECHANISM FOR HOFMANN ELIMINATION OF QUATERNARY AMMONIUM HYDROXIDES

Xu Xiaojie*; Yao Zhengui; Ye Xiulin; Tang Youqi; Fu Heng; Qian Minxie   

  1. Department of Chemistry; Peking University; Institute of Chemist（?）y; Academia Sinica
  • Received:1986-06-09 Revised:1989-01-26 Published:1989-08-15
  • Contact:

PDF

2681

赞

摘要： 本文用DPCILO, CNDO程序分别计算了一些第四级铵离子不同构象的能量及电荷密度, 探讨Hofmann消除反应的机理, 结果表明构象规则能较好地说明Hofmann消除反应的机理, 只是“直链型”烷基的消除反应应按顺式E_2机理进行。

Abstract: It is known that there are many examples of the thermal elimination of quaternary ammonium hydroxides which do not follow the Hofmann rule. Ye Xiulin et al. proposed the “conformation rule” for the elimination of quaternary ammonium hydroxides, and then, eight quaternary ammonium hydroxides were synthesised and subjected to the elimination. The results show that the conformational rule is superior and acceptable.DPCILO and CNDO/2 methods were used to calculate the conformational energy of some quaternary ammonium cations with different conformations andthe distribution of charge for studying the mechanism of Hofmann eliminaion reaction. The results show that the conformational rule, based on the conformational energy, can be used to explain the Hofmann elimination reaction well, but the elimination of straight chain alkyl groups other than the ethylic groups should follow cis-E_2 elimination mechanism instead of trans-E_2 one proposed by Ye Xiulin.