Anharmonic effect of the dissociation rate constant of the unimolecular reactions of CH2XCHFO (X = H, F)

This study examines six unimolecular reactions of CH2XCHFO (X H, F). The geometries of the reactions are optimized with Gaussian 03. The calculated barrier heights show that bond C-C' scission, CH2XCHFO (X = H, F) -> CH2X+CHFO (R1), dominates the decomposition of CH2XCHFO. For X = F and X = F, the barrier heights of (R1) are 13.37 and 9.67 kcal mol(-1), respectively. The YL (Yao and Lin) method is used to calculate the anharmonic and harmonic rate constants of the unimolecular reactions. The results clearly demonstrate the anharmonic effect of these reactions. In the microcanonical case, for (R1) (X = H), the total energy is from 42.78 to 144.84 kcal mol(-1). The corresponding anharmonic rate constants are from 1.57 x 10(12) to 2.52 x 10(13) s(-1) and the harmonic rate constants are from 1.52 x 10(12) to 2.52 x 10(13) s(-1).