Basicity of nitrogen-sulphur(Vi) compounds. part 5.¹ ionization of trisubstituted sulphamides

The ionization equilibria in base of 27 trisubstituted sulphamides, mainly represented by the following series: X-C₆H₄NHSO₂NR²R¹, where NR²R¹ = piperidyl, morpholinyl, and NPrⁿ₂, and RHNSO₂NR²R¹, where R, R¹, and R² are cyclo-C₆H₁₁, Ac, and X-C₆H₄ and X-C₆H₄, Ac, and X-C₆H₄, have been studied in 60% v/v ethanol-water using the potentiometric method. In a few cases pK_a values have been determined by the u.v. method. The effect of substituents has been correlated in Hammett plots and values are generally ca. 2.6 (as for an aryl linked nitrogen in sulphonanilide ionizations). The acid-strengthening effect of the acetyl group and the acid-weakening effect of the methyl group are seen in some series.