The gas‐phase kinetics of the reaction of 1,1,1‐trifluoroethyl iodine with HI: The CI bond dissocation energy in 2,2,2‐trifluoroethyl iodide

The kinetics of the gas‐phase reaction of 2,2,2‐trifluoroethyl iodide with hydrogen iodide has been studied over the temperature range of 525°K to 602°K and a tenfold variation in the ratio of CF3CH2I/HI. The experimental results are in good agreement with the expected free radical‐mechanism: An analysis of the kinetic data yield: where θ =2.303RT in kcal/mol. If these results are combined with the assumption that E2 = 0 ± 1 kcal/mol, then one obtains DH (CF3CH2I) = 56.3 kcal/mol. This result may be compared with DH (CH3CH2I) = 52.9 kcal/mol and suggests that substitution of three fluorines for hydrogen in the beta position strengthens the CI bond slightly.