碳前驱体CH3ArCH2NH2热解反应的热力学和动力学DFT研究

在实验研究基础上 ,通过量子化学理论计算对碳前驱体 CH3 Ar CH2 NH2 的热裂解机理作了进一步的研究 .利用 Gaussian98程序包中 AM1方法及 DFT UB3 LYP/3 -2 1 G*方法 ,对化合物 5种可能热裂解路径的热力学和动力学计算结果表明 ,CH3 Ar CH2 NH2 热裂解的主反应路径为生成自由基 CH3 Ar CH2 ·和 NH2 · ,其主反应路径 AM1计算的活化能 Ea=2 3 0 .78k J/mol,DFT计算的活化能 Ea=3 2 1 .1 8k J/mol;比较键焓计算的数据与相应的实验数据 ,发现 DFT计算结果与实验结果吻合得较好 ;通过分析优化的反应物及产物自由基的部分结构参数 ,了解了理论支持主反应的原因 ;计算的产物自由基的空间构型表明主反应路径生成的产物自由基相互间若进行稠环缩合反应 ,将获得分子平面取向性很好的稠环芳烃产物

Studies on Thermodynamics and Kinetics about Pyrolysis Mechanism of Carbon Matrix Precursor CH3ArCH2NH2

Based on the experiment, the pyrolysis mechanism of carbon matrix precursor CH3ArCH2NH2 was further studied by quantum chemistry computation. Using the AM1 and DFT UB3LYP/3-21G* method in Gaussian 98 program package, thermodynamic and kinetic data were calculated for 5 designed pyrolysis paths of the compound. The calculation result shows that the reaction producing CH3ArCH2*and NH2*is the main pyrolysis reaction path and the calculated activation energy is Ea=230.78 kJ/mol by AM1 method and is Ea=321.18 kJ/mol by DFT method, which could be understood by analyzing the geometry parameters, spin densities and charges of some atoms in reactants and free radicals produced. Compared with experimental data of bond enthalpy, the calculated results by DFT coincide well. The geometry parameters of the produced free radicals also shows that, after the compound CH3ArCH2NH2 as carbon matrix compound are pyrolyzed, the plane orientation of the produced free radicals will benefit the formation of a fused aromatic ring structure.