Static and shock tube pyrolyses of alkyl fluorides. Part III. The thermal decomposition of 1-chloro-2-fluoroethane, 1,1-difluoroethane, and 1,1,1-trifluoroethane

Abstract

The thermal decompositions of 1-chloro-2-fluoroethane, 1,1-difluoroethane, and 1,1,1-trifluoroethane to yield the corresponding alkenes and hydrogen halides have been studied by use of a comparative shock tube technique. 1-Chloro-2-fluoroethane has also been studied in a static system. The rate constants log k/s^–1 obtained were as follows: 1-Chloro-2-fluoroethane (a) by shock tube, (13·47 ± 0·34)-(63,800 ± 1200)/2·3RT(HCl elimination); (12·93 ± 0·32)-(60,800 ± 1100)/2·3RT(HF elimination); (b) static, (13·59 ± 0·32)-(62,250 ± 1100)/2·3RT(HCl elimination, maximum inhibited value); (12·95 ± 0·30)-(60,000 ± 1000)/2·3RT(HF elimination): 1,1-Difluoroethane, by shock tube, (13·53 ± 0·30)-(64,973 ± 935)/2·3RT: 1,1,1-Trifluoroethane by shock tube, (13·80 ± 0·30)-(73,638 ± 4138)/2·3RT, where R= 1·987 cal mol^–1 K^–1. The rates of these decompositions are compared with those of similar halogenated compounds and discussed in terms of the ion-pair model.