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E2机理进行。
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 and the distribution of charge for studying the mechanism of Hofmann elimination 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-E2 elimination mechanism instead of trans-E2 one proposed by Ye Xiulin.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
1989年第4期398-402,共5页
Acta Physico-Chimica Sinica
