Chemical Activation and Nonequilibrium Unimolecular Reactions of C2H5Cl and 1,2-C2H4Cl2 Molecules

A gas-phase chemical activation technique employing the H and Cl abstraction reactions by methylene from chloromethanes has been developed for the production of chloroethanes in the energy range between 85 and 95 kcal mole−1. In this paper the results from the reaction of methylene with chloromethane are reported. The abstraction reactions serve as a clean source of methyl and chloromethyl radicals; combination of these radicals at 25°C produces C2H5Cl and 1,2-C2H4Cl2 at energies near 90 kcal mole−1. Since the critical energy for the unimolecular HCl elimination reactions is about 55 kcal mole−1, the molecules will react by this pathway unless deactivated by collisions with the bath molecules. By studying the system in the appropriate pressure ranges, the nonequilibrium rate constants were measured at 25°C as 3×109 and 1.8×108 sec−1 for C2H5Cl and 1,2-C2H4Cl2, respectively.