CH_3CHF自由基与HNCO的反应机理

The Reaction Mechanism for CH_3CHF Radical and HNCO

采用密度泛函理论的B3LYP方法,在6-311++G(d,p)基组水平上研究了CH3CHF自由基与HNCO的微观反应机理,优化了反应过程中的反应物、中间体、过渡态和产物,在QCISD(T)/6-311++G(d,p)水平上计算体系在反应通道各驻点的能量.振动分析结果和IRC分析结果证实了中间体和过渡态的真实性,计算所得的成键临界点电荷密度变化也确认了该反应过程,并找到了七条反应通道.其中生成氟代烷基酰亚胺稳定分子的通道活化能垒最低,在该反应体系中是与氢迁移平行竞争较易发生的一条反应通道.

The reaction mechanism of CH3CHF radical reacting with HNCO had been investigated by density functional theory （DFr）. The geometries and frequencies of reactants, intermediates, transition states and products had been calculated at the B3LYP/6-311＋＋G （d, p） level. To obtain more accurate energy result, single point energies were calculated at the QCISD（T）/6-311＋＋G（d,p） level. The vibration analysis and the IRC analysis approved the authenticity of intermediates and transition states, and the reaction processes were confirmed by the changes of charge density at bond-forming critical points. Seven feasible reaction pathways of this reaction had been found and studied. The results indicated that the pathway which produced the stable molecule fluoroalkyl imide had the lowest activation barrier and it was a competitive pathway that took place easier than the hydrogen transfer process.