Basicity of nitrogen–sulphur(VI) compounds. Part 4. Ionization of di- and tri-substituted sulphamides

Abstract

Potentiometric and u.v. methods have been used to study the ionization equilibria of di- and tri-substituted sulphamides: RNHSO2NHR [graphic omitted] R[graphic omitted]SO2NHR [graphic omitted] R[graphic omitted]SO2[graphic omitted]R RNSHO2NME2 [graphic omitted] R[graphic omitted]SO2NMe2 pKa 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 pKa values. The agreement between the pKa values obtained by the various methods is good. The effect of substituents on both equilibria (a and b) is similar.