Kinetics of the hydrogen abstraction •CH3 plus alkane→CH4 plus alkyl reaction class:: An application of the reaction class transition state theory

Kinetics of the hydrogen abstraction reaction center dot CH3 + CH4 -> CH4 + center dot CH3 is studied by a direct dynamics method. Thermal rate constants in the temperature range of 300-2500 K are evaluated by the canonical variational transition state theory (CVT) incorporating corrections from tunneling using the multidimensional semiclassical small-curvature tunneling (SCT) method and from the hindered rotations. These results are used in conjunction with the Reaction Class Transition State Theory/Linear Energy Relationship (RC-TST/ LER) to predict thermal rate constants of any reaction in the hydrogen abstraction class of center dot CH3 + alkanes. Our analyses indicate that less than 40% systematic errors on the average exist in the predicted rate constants using the RC-TST/LER method while comparing to explicit rate calculations the differences are less than 100% or a factor of 2 on the average.