C_4烷基化反应机理的分子模拟

Molecular Simulation of Mechanism for C_4 Alkylation

采用基于密度泛函理论的量子化学方法计算了异丁烷/丁烯烷基化基元反应的反应能垒。结果表明,反应能垒最高的异丁烷氢负离子转移反应是烷基化反应的速率控制步骤。tert-C+4与丁烯反应主要得到目标产物三甲基戊烷,tert-C+4可由异丁烯质子化生成,或由sec-C+4骨架异构化生成,也可由正丁烯先异构化生成异丁烯,异丁烯进一步质子化生成,还可由异丁烷氢负离子转移反应生成。通过对反应过程中与C4烷基化目标产物C+8相关的异构化基元反应能垒的计算,得到C4烷基化反应中目标产物C8产物的生成路线,分子模拟所得的结果与实验所得的产物选择性结果相一致。

The quantum chemical method based on density functional theory （DFT） was used to calculate the reaction activation energy of isobutane alkylation with butene. The results showed that hydride transfer from isobutane with the highest reaction activation energy was the reaction rate controlling step. More ideal products of TMPs can be obtained from the reactions involving t-butyl carbenium ions derived from protonation of isobutene, skeletal isomerization of sec-butyl carbenium ions, isomerization of n-butene to isobutene then protonation and hydride transfer reaction, which was reinforced by molecular simulation. Also certain activation energy of isomerization reactions related to Ca products was calculated and the distribution of C8 products was predicted, which was consistent with experiment results.