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 ...