Basicity of nitrogen-sulphur(VI) compounds. Part 4.¹ Ionization of di- and tri-substituted sulphamides

pK_a Values for equilibrium a have been determined for nine di- and five tri-substituted sulphamides, sulphamide, and phenylsulphamide in 60% v/v ethanol-water. Ionization data for equilibrium b have been measured for seven diarylsulphamides in aqueous potassium hydroxide. Since neither H₋ nor H₂₋ acidity functions are suitable for describing the ionizations occurring a number of other methods, e.g. the modified Marziano-Cimino-Passerini method, have been used to obtain thermodynamic pK_a values. The agreement between the pK_a values obtained by the various methods is good. The effect of substituents on both equilibria (a and b) is similar.