On the kinetic mechanism of reactions of hydroxyl radical with CHF2CH3 ? n F n (n = 1–3)

The potential energy surfaces of the reactions CHF₂CH_3 − n F _n (n = 1–3) + OH were investigated by MPWB1K and BMC-CCSD (single-point) methods. Furthermore, with the aid of canonical variational transition state theory including the small-curvature tunneling correction, the rate constants of the title reactions were calculated over a wide temperature range of 220–1,500 K. Agreement between the CVT/SCT rate constants and the experimental values is good. Our results show that the order of rate constants is CHF₂CH₂F + OH > CHF₂CHF₂ + OH > CHF₂CF₃ + OH. For reaction CHF₂CH₂F + OH, the 1-H-abstraction channel dominates the reaction at the whole temperature, while 2-H-abstraction channel appears to be competitive with the increase of temperature.