Electrophilic additions to alkenes, part V. Substituent effects on the rates of reaction of arylsulphenyl chlorides with cyclohexene

Abstract

The rates of addition of a series of 4-substituted 2-nitrobenzenesulphenyl chlorides to cyclohexene in acetic acid solution increase with increasing electron-release from the 4-substituent, and a value of –0·715 is obtained for the reaction constant, ρ⁺, at 25°. The ρ⁺ correlation is in agreement with the mechanism proposed for this reaction, which postulates an episulphonium ion rather than an open carbonium ion as the cationic intermediate. The relative rates of reaction follow the expected order of stability of the intermediate episulphonium ions. In contrast to other electrophilic reagents, the magnitude of the initial positive charge on the electrophilic atom is not of fundamental importance in determining the relative rate of reaction.