Hydrogen Atom Attack on 1,2-Dichlorotetrafluoroethane: Rates of Halogen Abstraction

Hydrogen atom attack on 1,2-dichlorotetrafluoroethane (DCFE) at temperatures between 970 and 1140 K and pressures of about 200−500 kPa (2−5 bar) has been studied with a single-pulse shock tube reactor. The observed products show that chlorine is readily abstracted, while fluorine is removed in at most trace quantities only. This is despite the greater exothermicity of the fluorine abstraction channel. Relative to the standard reaction of displacement of methyl from 1,3,5-trimethylbenzene, for which k [H + (CH 3 ) 3 C 6 H 3 → (CH 3 ) 2 C 6 H 4 + CH 3 ] = 6.7 × 10 13 exp(−3255/ T ) cm 3 mol -1 s -1, k (H + DCFE → CF 2 CF 2 Cl + HCl) = 2.1 × 10 14 exp(−5839/ T ) cm 3 mol -1 s -1 and k (H + DCFE → CFClCF 2 Cl + HF, 1100 K) ≤ 7 × 10 9 cm 3 mol -1 s -1 . Uncertainties are estimated to be factors of 1.1 and 1.4 on relative and absolute bases, respectively. Comparisons with relevant literature data are made. The slow rate of F abstraction implies that reaction of fluorinated compounds via this pathway will be unimportant except in compounds unable to react via other channels. Implications with regard to the destruction of fluorinated compounds in pyrolytic and combustion systems are discussed.