Abstract:
The overall reactions CF3Br + HBr → CF3H + Br2, C2F5Br + HBr → C2F5H + Br2 have been studied competitively over the range 195–476°C. Reaction was initiated by bromine atoms generated both thermally and photochemically. Initiation reactions are Br + CF3Br → Br2+ CF3(3), Br + C2F5Br → Br2+ C2F5(4) for which log k3/k4=(0.264 ± 0.075)–(2330 ± 220)/θ where θ= 2.303 RT/cal mol–1. This confirms previous work on reactions (3) and (4) studied separately. The relevnce of the results to the determination of the bond dissociation energies D(CF3—Br) and D(C2F5—Br) is discussed.
