The Reaction of OH Radicals with 1,1‐di‐, tri‐ and tetrachloroethylene

The kinetics and product formation of the homogeneous gas‐phase reactions of the OH radical with 1,1‐di‐, tri‐ and tetrachloroethylene were investigated at temperatures between 298–459 K, in the pressure range of 0.5–5.6 mbar. Measurements were made in a discharge‐flow apparatus, using helium as the carrier gas. The OH radical and the reaction products were detected by mass spectrometry. The rate constants were observed to be pressure independent in the case of 1,1‐di‐ and tetrachloroethylene but slightly pressure dependent in the case of trichloroethylene. The temperature dependencies can be expressed by the Arrhenius equation (in units of 10 12 cm 3 mol −1 s −1 ). k(T) = (0.136 ± 0.016) exp[(9.5 ± 0.4) kJ mol −1 / RT ] for 1,1‐dichloroethylene, k(T) = (0.470 ± 0.051) exp[(2.0 ± 0.5) kJ mol −1 / RT ] for trichloroethylene, and k(T) = (3.33 ± 0.19) exp[−(8.6 ± 0.1) kJ mol −1 / RT ] for tetrachloroethylene. The major products are: CH 2 OH — CCl 2 for 1,1‐dichloroethylene; 2,2‐dichloroethenol and Cl for trichloroethylene; trichloroethenol, dichloroacetyl chloride, Cl, CHCl 2 and phosgene for tetrachloroethylene.