The gas‐phase kinetics of the reaction of 1,1‐difluoroiodoethane with hydrogen iodide: The C–I bond dissociation energy in 1,1‐difluoroiodoethane

The kinetics of gas‐phase reaction of CH 3 CF 2 I with HI were studied from 496 to 549K and have been shown to be consistent with the following mechanism:A least squares treatment of the data gave\documentclass{article}\pagestyle{empty}\begin{document}$$\log k_1 (M^{- 1} \cdot \sec ^{- 1}) = (11.4 \pm 0.3) - \frac{{(15.7 \pm 0.8)}}{\theta}$$\end{document} where θ = 2.303 RT kcal/mole. The observed activation energy E 1 was combined with E 2 = 0 ± 1 kcal/mole to yield\documentclass{article}\pagestyle{empty}\begin{document}$$DH^ \circ ({\rm CH}_{\rm 3} {\rm CF}_2 - {\rm I}) = 52.1 \pm 1.0{\rm kcal}/{\rm mole}$$\end{document} The result, combined with data for several CI bond dissociation energies, leads us to conclude that the C( sp 3 )I bond is relatively insensitive to F for H substitution and that the C( sp 2 )–I bond has considerable double‐bond character.