Theoretical study of H-abstraction reaction of C₂H₅OH with NCO

A direct dynamics method is employed to study the mechanism and kinetics of the hydrogen abstraction reaction of C₂H₅OH with NCO. The optimized geometries and frequencies of the stationary points and the minimum-energy paths (MEPs) are obtained at the MP2/6-311G(d,p) level. In order to obtain more accurate potential energy surface (PES) information and provide more credible energy data for kinetic calculation, the single-point energies along the MEPs are further computed at QCISD(T)/6-311+G(d,p)//MP2/6-311G(d,p) level. The rate constants for three channels of title reaction are calculated by canonical variational transition state theory (CVT) with small-curvature tunneling (SCT) contributions over the wide temperature region 220-1500 K. The theoretical overall rate constants are in good agreement with the available experimental data. For the title reaction, the methylene-H abstraction channel is dominant, while the hydroxyl-H and methyl-H abstraction channels are negligible over the whole temperature region.