Ab initio and RRKM studies of the unimolecular reactions of CH2XCHFO (X=H,F) radicals

The unimolecular reaction mechanism of the CH2XCHFO (X = H, F) radicals was studied using the ab initio G2(MP2, SVP) theory. Three kinds of reaction p athways, namely bond scission, three-center elimination of HF and isomeriza tion, were examined. Both the energy-specific rate constant [k(E)] and the thermal rate constant [k (T, P)] were evaluated using the RRKM theory and t he ab initio data. These theoretical calculations support the proposal that the C-C bond scissions dominate the decomposition of CH2XCHFO (X = H, F). The major products of the unimolecular reactions should be CH2X and CHFO. F urthermore, it is concluded that the lifetimes of CH3CHFO and CH2FCHFO are both very short in the atmosphere.