苯胺重氮化-席曼反应热危险性的理论研究

Theoretical Study on Thermal Hazards of Balz-Schiemann Reaction of Aniline

为研究苯胺重氮化-席曼反应的热危险性,采用Gaussian98软件,运用密度泛函理论(DFT)B3LYP,在6-31G(D)基组水平上,研究气相条件下重氮化-席曼反应的反应过程及微观机理,得到反应路径以及反应物、中间体、过渡态、产物全优化几何构型,探讨结构与性能的关系,解释重氮化-席曼反应的历程。通过热力学和动力学计算,获得标准热力学函数,分析反应的热危险性。理论计算结果表明:苯胺重氮化-席曼反应是剧烈的放热反应,这与重氮化反应剧烈以及重氮盐的热不稳定性的试验结果相吻合。

The process and mechanism of gas phase Balz-Schiemann of aniline leading to fluorobenzene were studied using Gaussian 98 program and DFT method at the B3LYP/6 -31G（D） level. The reaction pathway and the mechanism and the confirmation of reactants, intermediates, transition states and products were obtained. In order to explain the process of Balz-Schiemann reaction, the relationship was analyzed between structure and properties. According to thermodynamic and kinetic calculations, standard thermo- dynamic functions were obtained and thermal safety of the process was discussed. The calculation results reveal that the diazotization is a violent, exothermal reaction and the diazonium salt is instable, which agrees with experimental results.