Kinetics of the gas‐phase reaction CH₃F + I₂ ⇆ CH₂FI + HI: The CH bond dissociation energy in methyl and methylene fluorides

Abstract

Abstract The kinetics of the gas‐phase reaction of CH 3 F with I 2 have been studied spectrophotometrically from 629 to 710 K, and were determined to be consistent with the following mechanism: equation image A least‐squares analysis of the kinetic data taken in the initial stages of reaction resulted in where θ = 4.575 T /1000 kcal/mol. The errors represent one standard deviation. The experimental activation energy E 4 = 30.8 ± 0.2 kcal/mol was combined with the assumption E 3 = 1 ± 1 kcal/mol and estimated heat capacities to obtain The enthalpy change at 298 K was combined with selected thermochemical data to derive The kinetic studies of ĊHF 2 and CH 2 F 2 have been reevaluated to yield These results are combined with literature data to yield the CH, CF, and CCl bond dissociation energies in their respective fluoromethanes, and the effect of α‐fluorine substitution is discussed.