Ionization constants of some Schiff's bases in 80%(w/w) dimethyl sulphoxide–water solvent at 25 °C

Abstract

pK Determination in 80%(w/w) dimethyl sulphoxide–water solvent at 25 °C has been used as a means of studying the tautomerism in a series of Schiff's bases derived from some C-acylhydroxypyrones. While their much lower acidities compared with the corresponding parent compounds indicate a predominance of ketoamine tautomers, their higher acidities compared with amides and other nitrogen acids suggest significant contributions from dipolar structures. Correlation of the wide range of pK values with the structures is discussed.