Ab Initio Chemical Kinetics for Self- and Cross-Reactions of anti - and syn -CH ₃ CHOO Conformers

The mechanisms for the self- and cross-reactions of anti-CH₃CHOO and syn-CH₃CHOO conformers have been investigated by ab initio quantum-chemical and statistical-theory calculations. The results of the study indicate that at 298 K under 5-Torr He pressure, the self-reaction of anti-CH₃CHOO is the fastest with kaa = 4.90 × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹, the anti-syn cross-reaction with kas = 1.82 × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹, and the self-reaction of syn-CH₃CHOO with kss = 1.28 × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹. The theoretical results, including the deactivation of internally excited dimers formed by initial bimolecular association reactions accounting for more than 50% of the predicted rates, agree with the recent experimental data within reported errors measured at 298 K and 2-10 Torr He pressure.