Hydrolysis of Mustard Derivatives in Aqueous Acetone-Water and Ethanol-Water Mixtures

Article abstract of DOI:10.1021/jo00364a025

The hydrolyses of two mustard derivatives, 2-chloroethyl ethyl sulfide (CEES) and 2-chloroethyl methyl sulfide (CEMS), were investigated and compared with the hydrolysis of tert-butyl chloride (TBC) in aqueous binary mixtures of acetone and ethanol from 0 to 45 deg C.The solvent effect on rates and on activation parameters provided further evidence for an SN1 mechanism with anchimeric assistance of the sulfur atom to form a cyclic sulfonium ion as the reaction intermediate.Lower ΔH(excit.) and ΔS(excit.) values of both CEES and CEMS relative to that of TBC reflected the S-C bond formation and the strained structure of the intermediate.A finite and negative ΔC_p(excit.) was detected.The observed ΔH(excit.) was corrected for the cosolvent effect by adopting Fagley's model and was consistent with the value in pure water.