The following reactions have been examined: chlorine addition to ethylene to form 2-chloroethyl radical, and hydrogen addition to chloroethylene to form 1-chloroethyl radical and to form 2-chloroethyl radical. Equilibrium geometries and transition structures were fully optimized with 3-21G and 6-31G* basis sets, and energies were computed with Hartree-Fock and Merller-Plesset methods. The 2-chloroethyl radical adopts an antiperiplanar conformation and has a rotation barrier of 4 kcal mol-'. It

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... s predicted not to have the low-frequency CH stretch mode considered characteristic of radicals with P-hydrogens. A barrier of less than 0.5 kcal mol-' is found for chlorine addition to ethylene. For hydrogen addition to the unsubstituted carbon of chloroethylene, the barrier is ca. 1 kcal mol-'; for attack on the substituted carbon the barrier is 4-6 kcal mol-'. The C-CI dissociation,energy of 2-chloroethyl radical is calculated to be 17 kcal mol-'. Compared to ethyl radical, the C-H dissociation energy for 1-chloroethyl radical is 1.4 kcal mol-' higher while that of 2-chloroethyl radical is 2.5 lower.