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臭氧层损耗是人类面临的重要环境问题之一。平流层中氟氯烃类化合物受紫外线光解所产生的氯代次甲基会消耗臭氧。为了弄清该自由基消耗臭氧的机制,用量子化学计算的方法详细地研究了CCI+O_3反应在二重态势能面上的反应机理。本文在B3LYP/6-311 G(d,p)水平上优化了反应物、中间体、过渡态和产物的几何构型,得到了相应的振动频率和能量值,并在相同水平上用内禀反应坐标计算方法确认了过渡态和中间体之间的联系,理清了该反应详细的路径。研究发现CCI+O_3反应有5种产物通道:CICO+O_2、CO_2+Cl+O、CO_2+CIO、CO+O_2+CI和OCO_2+Cl,通过对各反应路径上的驻点的能量分析得出CICO+O_2是主要的通道,CO_2+Cl+O、CO_2+CIO和OCO_2+Cl是次要通道,通道CO+O_2+Cl在动力学上是最少的。本研究工作将为控制氯代次甲基对臭氧层的破坏提供理论依据。
Ozone depletion is one of the major environmental issues facing mankind. Chlorinated methine radicals produced by UV photodissociation of HCFCs in the stratosphere ozone depleting ozone. In order to understand the ozone-depleting mechanism of the free radical, the reaction mechanism of the CCI + O 3 reaction on the dipole potential energy surface has been studied in detail using quantum chemistry calculations. In this paper, the geometries of reactants, intermediates, transition states and products were optimized at the B3LYP / 6-311 G (d, p) level. The corresponding vibrational frequencies and energies were obtained. At the same level, The reaction coordinate calculation method confirmed the relationship between the transition state and the intermediates and clarified the detailed path of the reaction. It is found that there are five product channels in CCI + O_3 reaction: CICO + O_2, CO_2 + Cl + O, CO_2 + CIO, CO + O_2 + CI and OCO_2 + Cl. Through energy analysis of stagnation points on each reaction path CICO + O_2 is the main channel, CO_2 + Cl + O, CO_2 + CIO and OCO_2 + Cl are the secondary channels, channel CO + O_2 + Cl is the least kinetic. This work will provide a theoretical basis for controlling the destruction of the ozone layer by chloromethine.