Eliminations promoted by thiolate ions. Part II. Reactions of cyclohexyl halides and cyclohexyl toluene-p-sulphonate

Abstract

The rate constants of the bimolecular elimation reactions of cyclohexyl halides, 1,1-dihalogenocyclohexanes, and cyclohexyl toluene-p-sulphonate promoted by ethoxide and benzenethiolate ions in ethanol are reported. Reactions with substituted benzenethiolates as bases enable Brönsted coefficients for each reaction series to be calculated. These coefficients are used to diagnose the nature of the E2 transition states, and the benzenethiolate; ethoxide rate ratios are found to be dependent on transition state character. An argument is advanced against the operation of the “merged” substitution–elimation mechanism in any of the reactions studied.