An electron spin resonance study of proton transfer equilibria involving the pyrogallol semiquinone radical

Abstract

The electron spin resonance spectrum of the pyrogallol semiquinone radical has been measured in aqueous solutions of varying pH, a rapid flow system being employed for production of the radicals. Distinct spectra are obtained from species possessing two, one and zero hydroxyl protons and the first and second acid dissociation constants of the pyrogallol radical cation are estimated. It is possible to set upper limits on the rate of hydroxyl proton exchange between the radical species and the solvent.