Hydrolysis of condensed phosphates in an anion-exchange resin

Abstract

The alkaline hydrolysis of diphosphate, triphosphate and cyclo-triphosphate sorbed into anion-exchange resins has been investigated using ³¹P NMR spectroscopy. Well resolved ³¹P NMR spectra of the sample species and their hydrolysis products within the resin phase were observed. For diphosphate and triphosphate systems, the rate constant and activation parameters for each hydrolysis reaction are quite similar, both in the resin phase and in a basic solution. For the cyclo-triphosphate system, however, the hydrolysis is significantly retarded compared to that in a solution of tetramethylammonium hydroxide. This retardation is shown to be entirely due to a much more unfavourable ΔH^‡ for the reaction in the resin phase. The relationship between mechanisms and reactivities of the hydrolysis in the resin phase is discussed.