A comparative study of the protonation of myo-inositol hexakis(phosphate)

Abstract

Numerous studies of the protonation of myo-inositol hexakis(phosphate)(IP₆) have lead to divergent results. Our values of the constants determined at 25 °C in 0.1 mol dm^–3 Et₄NClO₄ or Bu₄NBr media are sometimes several orders of magnitude higher than those previously published. The reason for the discrepancy between the results is found from an examination of the theoretical titration curves computed with the protonation constants measured in the presence of various support electrolytes at different ionic strengths. It is reasonable to suppose that complexation equilibria, involving alkali-metal cations, are superimposed on the protonation equilibria.