Laser‐induced chemical kinetics: Absolute rate constants for the reactions Ċ2F2 + Br2 → C2F5Br + Ḃr and n‐Ċ3F7 + Br2 → n‐C3F7Br + Ḃr

Abstract Absolute rate constants at room temperature for the metathesis reaction C~FS + Br2 C2FSBr + Br and nd3F7 + Br2 CzFTBr + Br have been measured under VLPP conditions: k 1 = (2.0 f 0.5) X l@M-'.s-', k2 = (3.0 f 0.7) 108M-'-s-'. The radicals were generated through collisionless infrared-multiphoton decomposition of the corresponding iodides by irradiation from a high-power C02-TEA laser. The reaction of k2F~ and &F7 with NO2 are briefly discussed in relation to the reaction of ks with NO2, which had been measured previ- ously. Introduction Rate constants for metathetical reactions of radicals with small molecules have been studied quite extensively over the past few years, often by measurement relative to the recombination reaction of the radical, which has been assumed to recombine in a temperature-independent reaction [ 11. These studies have resulted in relative Arrhenius parameters mainly for slow hydrogen-transfer reactions. For many fast metathetical reactions (e.g.,