摘要
用量子化学MP2方法 ,在 6 311++G(d ,p)基组水平上研究了烯烃CH2 CHF与臭氧反应的机理 ,对氟代乙烯臭氧化反应Criegee机理进行了系统的计算 ,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QCISD(T) / 6 311++G(d ,p)水平上计算了它们的能量 .并对它们进行了频率分析 ,以确定中间体和过渡态的真实性 .研究结果表明 ,氟代乙烯与臭氧反应沿Criegee机理是可信的、合理的 .同时研究还发现 ,就氟代乙烯与臭氧反应活性而言 ,其控制步骤的位垒较低 ,可以说氟代乙烯与臭氧反应活性较强 ,也就是说氟代乙烯对臭氧的损耗较大 .
The ozone layer absorbs more than 90% UV-C ( 100 similar to 295 nm) and UV-B (295 similar to 320 nm) which are harmful for the livings on the earth an let the living things exist and multiply safely. So the depletion of the ozone layer and mechanism of the ozone hole have been the fatefully and globally environmental problems. Nowadays, many chemicals depleting ozone, such as CH4, Cl, F, NH2 and so on, have been discussed by theoretical or experimental methods. The ab initio MP2 method has been employed to study the Criegee reaction mechanism of CH2CHF with ozone at the 6-311 ++ G ** base level, to optimize the geometry configurations of reactants, products, intermediates, and transition states. Reaction various compounds energies have been calculated using the QCISD (T) method at the 6-311 ++ G ** base sets level. Intermediates and transition states of the reaction were verified by the frequency analysis and the intrinsic reaction coordinate (IRC) calculation was also performed for getting the further credible results. The results show that the Criegee reaction mechanism of CH2CHF with ozone is reasonable. That means the reaction is a three-step process and the second step is the controlling step, namely, M2-->TS2-->M3. The barriers of the controlling step during the CH2CHF with ozone reaction are not high, only 38.22 kJ/mol. That is to say, the CH2CHF with ozone reaction has a strong activity and the fluoro-ethylene may deplete ozone. Thus, such a research has the greatly theoretical significance for protecting the ozone layer.
基金
ProjectedsupportedbySichuanProvincialEducationCommitteeKeyResearchprogram
