The kinetics of the thermal gas‐phase reaction Br 2 + C 6 F 5 I → BrI + C 6 F 5 Br. An attempt to determine the bond dissociation energy D (C 6 F 5 ‐I)

The kinetics of the thermal bromination reaction equation image have been studied in the range of 261°–391°C. The observed rate law is compatible with initiation by the step equation image for which we obtain where Θ = 2.303 RT cal/mol. Using the above value of E 6 , we have This result disagrees with values of D (C 6 F 5 ‐I) obtained in other ways and we conclude that reaction (3) probably does not involve initiation by reaction (6). Instead, initiation may involve an addition of Br to the ring in C 6 F 5 I followed by decomposition of the adduct to give C 6 F 5 Br. If correct, this implies that the Arrhenius parameters above refer to the addition reaction rather than to reaction (6).