Kinetic calculation on the hydrogen abstraction reaction between H and CH_3NH_2

Hydrogen abstraction reaction between H and CH_3NH_2 is explored using the QCISD(T)/6-311++G(3df,3pd)//MP2/6-311 G(d,p) method.This reaction takes place through two channels:H abstraction from methyl group(CH_3)(R1)and amido group(NH_2)(R2).The potential barrier of R1 is about 17.41 kJ/mol lower than that of R2,which shows R1 is the major reaction channels.On the basis of the ab initio data,the rate constants for each channel were evaluated using canonical variational transition state theory(CVT)with the smallcurvature tunneling correction(SCT)method over a wide temperature range of 200~4000 K.The total rate constants are in excellent agreement with the experimental values.The kinetic calculation indicates that the variational effect on the calculation of rate constants is small over the whole temperature range and the trnneling correction plays an important role in the lower temperature range for all the channels.