Competitive study of the reactions Br + R F I → IBr + R F and determination of bond dissociation energies D (R F −I) where R F = CF 3 , C 2 F 5 , n ‐;C 3 F 7 , i ‐C 3 F 7 , and n ‐C 4 F 9

The overall photobromination reactions have been studied using a competitive technique. Relative Arrhenius parameters were obtained for the rate‐determining step equation image These were placed on an absolute basis using previous‐absolute values of A and E for R F I=CF 3 I. The activation energies were used to calculate bond dissociation energies D (RI) with the following results: R F − E 16 D(R F −I)(kcal/mole) CF 3 I 10.8 52.6 C 2 F 5 I 8.8 50.6 n ‐C 3 F 7 I 7.4 49.2 i ‐C 3 F 7 I 7.5 49.2 n ‐C 4 F 9 I 6.7 48.4 E 16 from [1] The D (R I) are compared with related D (RI) and it is concluded that for a given alkyl group R H and the corresponding perfuloroalkyl group R F , D (R I) > D (R I) whereas it has previously been found that D (R X;) < D (R X) where X is not iodine.