A SEMIEMPIRICAL STUDY OF 2,2'-DICHLORODIETHYL SULFIDE S(N)2 AND NEIGHBORING GROUP HYDROLYSIS REACTION-MECHANISMS IN THE GAS-PHASE AND IN AQUEOUS-SOLUTION

A PM3 and SM3-PM3 semiempirical molecular orbital study of the 2,2'-di chlorodiethyl sulfide conventional S(N)2 and neighboring group hydroly sis reaction mechanisms in the gas phase and in aqueous solution is de scribed. The calculations predict substantially faster reactions in aq ueous solution, with the neighboring group mechanism always being pref erred. Detailed consideration is given to the geometries, relative ene rgies, and partial atomic charges of all species involved in the react ion mechanisms considered and the extent to which aqueous solvation im pacts these quantities. The results are consistent with expectation an d with reported calculations concerning the intramolecular S(N)2 react ion of 2-chloroethyl methyl sulfide. We also present the lowest energy mustard chlorohydrin structures according to PM3 and AM1 conformation al analysis.