Theoretical study on the OH + CH₃NHC(O)OCH₃ reaction

The multiple-channel reactions OH + CH₃NHC(O)OCH₃ → products are investigated by direct dynamics method. The optimized geometries, frequencies, and minimum energy path are all obtained at the MP2/6-311+G(d,p) level, and energetic information is further refined by the BMC-CCSD (single-point) method. The rate constants for every reaction channels, R1, R2, R3, and R4, are calculated by canonical variational transition state theory with small-curvature tunneling correction over the temperature range 200-1000 K. The total rate constants are in good agreement with the available experimental data and the two-parameter expression k(T) = 3.95 × 10 ^-12 exp(15.41/T) cm³ molecule^-1 s^-1 over the temperature range 200-1000 K is given. Our calculations indicate that hydrogen abstraction channels R1 and R2 are the major channels due to the smaller barrier height among four channels considered, and the other two channels to yield CH₃NC(O)OCH₃ + H₂O and CH₃NHC(O)(OH)OCH₃ + H₂O are minor channels over the whole temperature range.