Mechanism and kinetics properties for the reaction: Chloroethane with atomic O (3P)

In this paper, we present direct dynamics calculations for the multiple-channel reaction of CH3CH2Cl with atomic O (3P) in a wide temperature range (200-3000 K), based on canonical variational transition state theory including small curvature corrections. Four distinct saddle points, one for α-abstraction and three for β-abstraction, have been located for this reaction. The potential energy surface information has been calculated at the MP2/6-311G(d,p) level. The energies along the minimum energy path have been further improved by single-point energy calculations at the G3MP2 level. In the β-abstraction channel, Jahn-Teller effect has been found. Changes of geometries, generalized normal-mode vibrational frequencies, and potential energies along the reaction paths for all channels have been discussed and compared. The calculated total rate constants match the available experimental values reasonable well over the measured temperature range. The results show the variational effect can be negligible and the small curvature tunneling contribution plays an important role for the calculation of the rate constant. At low temperature α-abstraction may be the major reaction channel, while β-abstraction will have more contribution to the whole reaction rate as the temperature increase.