摘要
用量子化学MP2 (full)方法 ,在 6 3 11+ +G 基组水平上研究了CH2 CH(2 A′)自由基与臭氧反应的机理 ,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QCISD(T ,full) /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 .研究结果表明 :CH2 CH(2 A′)自由基与臭氧反应有两条可行的反应通道 ,分别为 :CH2 CH(2 A′) +O3 →TS1→M1→TS2→O2 +OCH2 CH→TS4+O2 →O2 (3 Σg) +CH2 CHO(2 A″)和CH2 CH(2 A′)+O3 →M2 →TS3→O2 (3 Σg) +CH2 CHO(2 A″) .后一个反应通道较易发生 ,而且反应活化能小 (2 97kJ/mol) ,说明CH2 CH(2 A′)
The geometries of reactants, transition states, intermediates and products on the reaction of CH2CH((2)A') + O-3 have been optimized at the MP2 (full)/6-311 + + G** level. The transition states and intermediates of the reactions were verified by frequency analysis. The relative single-point energies were further calculated at the QCISD (T, full)/6-311 + + G** level, based on the MP2(full)/6-311 + + G** optimized structures. The zero point energy (ZPE) corrections and the rate constants of reaction were also obtained. The. results show that there are two reaction channels, CH2CH((2)A') + O-3 --> TS1 --> M1 --> TS2 --> O-2 + OCH2CH --> TS4 + O-2 --> O-2((3)Sigmag) + CH2CHO((2)A') and CH2CH((2)A') + O-3 --> M2 --> TS3 --> O-2((3)Sigmag) + CH2CHO((2)A'), respectively. The latter reacts more easily of which the reaction barrier is lower (2.97 kJ/mol) and reaction activity is higher. Therefore, the results of theoretical study indicate that CH2CH((2)A') radicals in the atmosphere are able to greatly deplete ozone and the reaction of CH2CH((2)A') radicals with ozone is strongly exothermic.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2003年第8期1256-1260,共5页
Acta Chimica Sinica
基金
国家自然科学基金 (No.2 98730 2 9)资助项目
