Conversion effect on the reaction CF 3 + HCN. Analysis of I 2 and I participation with CF 3 I as radical source

The gas‐phase reaction of CF 3 with HCN has been examined over a wide conversion range using CF 3 I as a thermal and photolytic source of radicals. Quantitative and qualitative results show a significant increase of the specific rate constant for the hydrogen abstraction reaction relative to CF 3 recombination when reaction is carried out under ultraviolet irradiation. This “extra” formation of the reaction product, CF 3 H, has been assigned to the participation of iodine in this system through the formation of a (I‐HCN) intermediate. Arrhenius parameters obtained for the addition mechanism of I to HCN do not seem to conform to a single reaction step, on the contrary, they correspond to a more complex reaction scheme.