The acid–base behaviour of sulphides

Abstract

The protonation equilibria of alkyl methyl sulphides have been studied in sulphuric acid solutions. Their –H₀ values at half protonation lie in the range –5·4 to –5·7 and their pK_BH⁺ values, as determined with the aid of the Bunnett and Olsen equation, in the range –6·7 to –6·9. Steric effects are not important even for the t-butyl derivative and the polar effects are small (ρ*= 0·86 ± 0·09). The solvation requirements of the protonated sulphides are small as evidenced by the negative ϕ values obtained (–0·26 to –0·29).