Mechanism and Kinetics of the Hydrogen Abstraction Reaction of C2H3 with CH3F

A dual-level direct dynamics method was employed to study the hydrogen abstraction reaction of C2H3 with CH3F. The calculated potential barriers (Delta E-#) of reaction channels R1, R2, and R3 are 43.2, 43.9, and 44.1 kJ.mol(-1), respectively, and the reaction energy is -38.2 kJ.mol(-1) at the QCISD(T)/6-311++ G(d, p)//B3LYP/6-311G(d, p) level. In addition, the rate constants of the reaction were evaluated by means of the conventional transition-state theory (TST) and canonical variational transition-state theory (CVT) with or without small curvature tunneling corrections (SCT) over a wide temperature range of 200-3000 K. The results indicate that the rate constants of the three hydrogen abstraction reaction channels exhibit a positive temperature dependence, in which the variational effect is negligible for all the channels, whereas the tunneling effect is considerable at lower temperatures. Moreover, the reaction R1 is the dominant channel. Reaction R2 competes kinetically with R1 as the temperature increases, whereas the contribution from R3 is small.