A theoretical investigation for the reaction of CH3CH2SH with atomic H: Mechanism and kinetics properties

The multiple-channel reaction of CH3CH2SH with atomic H has been investigated theoretically using ab initio molecular orbital theory for the first time. The profile of the potential energy surface was constructed at the QCISD(T)/6-311 + G(3df, 2p)//MP2/6-311G(2d, p) level. Two kinds of channels have been identified: abstraction and substitution. ion involved in three channels: H abstraction from CH3 group, H abstraction from CH2 group, and H abstraction from SH group. The substitution channel will lead to the products of CH3CH2 and H2S. On the basis of ab initio calculation, the rate constants have been deduced using canonical variational transition-state theory with small curvature tunneling contribution over a wide temperature range (200-3000 K). The kinetics properties along the reaction path for each channel have been analyzed and compared. The calculated total rate constants match the available experimental values reasonably well over the measured temperature range. The results show that, the channel of H abstraction from SH group dominant this reaction, while substitution channel will be a strong competitive reaction as the temperature increases.