On the kinetic mechanism of the hydrogen abstraction reactions of the hydroxyl radical with CH 3 CF 2 Cl and CH 3 CFCl 2 : A dual level direct dynamics study

• Published in: Journal of computational chemistry 2010-02, Vol.31 (3), p.510-519
• Main Authors: Ji, Yue‐Meng, Cao, Fenglei, Gao, Hui, Li, Xiangzhi, Zhao, Cunyuan, Su, Chengyong, Liu, Jing‐Yao, Li, Ze‐Sheng
• Format: Article
• Language: English
• ISSN: 0192-8651; 1096-987X
• DOI: 10.1002/jcc.21343

By means of the dual‐level direct dynamics method, the mechanisms of the reactions, CH 3 CF 2 Cl + OH → products (R1) and CH 3 CFCl 2 + OH → products (R2), are studied over a wide temperature range 200–2000 K. The optimized geometries and frequencies of the stationary points are calculated at the MP2/6‐311G(d,p) level, and then the energy profiles of the reactions are refined with the interpolated single‐point energy method at the G3(MP2) level. The canonical variational transition‐state theory with the small‐curvature tunneling (SCT) correction method is used to calculate the rate constants. For the title reactions, three reaction channels are identified and the H‐abstraction channel is the major pathway. The results indicate that F substitution has a significant (reductive) effect on hydrochlorofluorocarbon reactivity. Also, for all H‐abstraction reaction channels the variational effect is small and the SCT effect is only important in the lower temperature range on the rate constants calculation. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010