CH_2X(X=H,F,Cl)与臭氧反应机理的量子化学研究

Study on the Quantum Chemistry of CH_2X (X=H, F, Cl) and O_3 Reaction Mechanism

用量子化学UMP2方法 ,在 6 3 11+ +G 基组水平上研究了CH2 X (X =H ,F ,Cl)与臭氧反应机理 ,全参数优化了反应过程中反应物、中间体、过渡态和产物的几何构型 ,在UQCISD(T) / 6 3 11+ +G 水平上计算了它们的能量 ,并对它们进行了振动分析 ,以确定中间体和过渡态的真实性 .从CH2 X (X =H ,F ,Cl)与O3 的反应机理的研究结果看 ,它们与O3 反应的活性都比较强 ,相对而言 ,活性大小顺序为CH2 F >CH3 >CH2 Cl,也就是说 ,CH2 F自由基与臭氧间的反应活性最强 ,对大气臭氧的损耗将是最大的 .同时研究还发现CH2 X (X =H ,F ,Cl)系列自由基与O3

Quantum chemistry UMP2 method was performed to stu dy the reaction mechanism of the reactions of CH 2X (X=H, F, Cl) with O 3. The g eometric configurations of reactants, intermediates, transition states and produ cts were optimized by UMP2 method at 6-311++G ** level and the energies o f stationary points along the pathways were calculated at UQCISD(t)/6-311++G ** level. Intermediates and transition states were confirmed by vibration an alysis. From the results of the reaction mechanism of the reactions of CH 2X (X =H, F, Cl) with O 3, one can see that they are active radicals depleting ozone and the order of activity is CH 2F>CH 3>CH 2Cl. That is to say, CH 2F is t he most active chemical of the three radicals depleting the ozone layer. It is a lso found that the reactions of CH 2X (X=H, F, Cl) with O 3 are strongly e xothermic.