Yang Meng, Liao Caiyue, Tang Chenglong, Zhang Peng, Huang Zuohua, Li Jianling
State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, 710049, People's Republic of China.
Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
Phys Chem Chem Phys. 2021 Mar 4;23(8):4658-4668. doi: 10.1039/d0cp05935h.
The potential energy surfaces (PESs) of three nitrotoluene isomers, such as p-nitrotoluene, m-nitrotoluene, and o-nitrotoluene, have been theoretically built at the CCSD(T)/CBS level. The geometries of reactants, transition states (TSs) and products are optimized at the B3LYP/6-311++G(d,p) level. Results show that reactions of -NO2 isomerizing to ONO, and C-NO2 bond dissociation play important roles among all of the initial channels for p-nitrotoluene and m-nitrotoluene, and that the H atom migration and C-NO2 bond dissociation are dominant reactions for o-nitrotoluene. In addition, there exist pathways for three isomer conversions, but with high energy barriers. Rate constant calculations and branching ratio analyses further demonstrate that the isomerization reactions of O transfer are prominent at low to intermediate temperatures, whereas the direct C-NO2 bond dissociation reactions prevail at high temperatures for p-nitrotoluene and m-nitrotoluene, and that H atom migration is a predominant reaction for o-nitrotoluene, while C-NO2 bond dissociation becomes important by increasing the temperature.
在CCSD(T)/CBS水平上理论构建了对硝基甲苯、间硝基甲苯和邻硝基甲苯三种硝基甲苯异构体的势能面（PESs）。反应物、过渡态（TSs）和产物的几何结构在B3LYP/6-311++G(d,p)水平上进行了优化。结果表明，对于对硝基甲苯和间硝基甲苯，-NO2异构化为ONO以及C-NO2键解离反应在所有初始通道中起重要作用，而对于邻硝基甲苯，H原子迁移和C-NO2键解离是主要反应。此外，存在三种异构体相互转化的途径，但具有较高的能垒。速率常数计算和分支比分析进一步表明，对于对硝基甲苯和间硝基甲苯，O转移的异构化反应在低温至中温下较为突出，而直接的C-NO2键解离反应在高温下占主导，对于邻硝基甲苯，H原子迁移是主要反应，而C-NO2键解离随着温度升高变得重要。
