Theoretical investigation of the decarboxylation reaction of CH 3CO 2 radical

Abstract

A theoretical study on the decarboxylation reaction of CH 3CO 2 radical at the MP2 level of theory has been carried out. It is found that the thermal reaction CH 3CO 2 → CH 3 + CO 2 may occur on the 2A′(A′) potential energy surface of CH 3CO 2 via a reaction barrier of 4.2 kcal/mol at the PMP4/6-311+G(3df,3pd)//MP2/6-311+G(2df,2p) level of theory. Another possible reaction path is the CH 3CO 2(A′) transform into the CH 3CO 2(A 1) and thus undergo a barrier-less dissociation into the products CH 3 + CO 2. The thermal rate constants of channel CH 3CO 2(A′) → CH 3 + CO 2.were evaluated based on the electronic structure and energy information from the PMP4/6-311+G(3df,3pd)//MP2/6-311+G(2df,2p) level of theory with microcanonical variational transition state theory (μVT) in the temperature range of 200–3000 K. The fitted Arrhenius expression from the forward μVT rate constants within the calculated temperature range is K μ VT = 2.196 × 10 11 T 0.294 e ( - 2.304 × 10 3 / T ) s - 1 . It is also found that the geometry of the CH 3CO 2 radical is sensitive to the basis set used.