羟基自由基和三硝基甲苯反应的密度泛函理论研究

Study of Density Functional Theoretical of the Reaction of TNT with Hydroxyl Radical

采用密度泛函理论研究了羟基自由基与三硝基甲苯(TNT)的反应机理。在B3LYP/6-31G(d)水平下对反应复合物、过渡态和产物进行了几何结构优化,并进行了振动频率计算,分析了反应过程的几何构型的变化和稳定性。研究表明,羟基自由基加成反应中,TNT甲基间位碳位置加成是主反应通道;抽氢反应中,甲基氢的抽取是主反应通道.在羟基自由基与TNT反应形成的6条反应通道中,羟基自由基和甲基氢的反应活化能最低,为7.25 kJ/mol,预示优先发生甲基氢抽取反应。最后从热力学角度证明了羟基自由基和苯环上硝基反应相比加成和抽氢反应较难发生。

Uing the density functional theory（DFT）,the reaction mechanism for the TNT with ·OH reaction was studied.The geometries of all the molecules（reactants,trantion states and productions） were optimized,and the harmonic vibration frequencies and the energies were calculated as well at the B3LYP/6-31G（d） level.The changes of geometry and stability of reaction process were analyzed.The results showed that in hydroxyl radical addition reactions,the major channel was the addition reaction of TNT methyl carbon m-position.In hydroxyl radical hydrogen abstraction reactions,the major channel was abstraction reaction of the methyl hydrogen.Hydrogen abstraction channels activate energy was the lowst in the six reaction channels of hydrogen abstraction and addition of TNT with ·OH,7.25 kJ/mol,so the reaction of hydrogen abstraction should be the major channel.Hydroxyl radical direct oxidation Nitro was discussed from the role of reaction thermodynamics and the results showed that it was very difficult to reaction.