Electron Spin Resonance Spectra of γ-Irradiated Carbohydrates and α-Hydroxy Acids

Abstract

THE production of polymers¹ from a wide range-of carbohydrates and α-hydroxy acids induced by γ-irradiation of their de-aerated aqueous solutions posed the problem of identifying the monomer radicals responsible initially for such polymerizations. Measurement of the rates of dimerization of simple hydropyranols² and the polymer yields from some twenty model carbohydrates³ suggested that, with glucose, one of the primary reactions involved was a dimerization of the radical derived by abstraction of a hydrogen atom from the carbon of the hydroxymethyl group. The identification⁴ of the radical obtained on γ-irradiation of polycrystalline glycollic acid, using electron spin resonance spectra, and the presence of the same radical in the liquid phase, inferred from the isolation of tartaric acid⁵ from irradiated, de-aerated aqueous solutions of glycollic acid, suggested a close correlation between these systems. Moreover, recent work⁶ on single crystals has enabled the proton coupling tensor elements for protons in certain environments to be determined accurately. With glycollic acid the peak separation (∼61 Mc./sec.) of the polycrystalline sample corresponded closely with the average value (57 Mc./sec.) of the H(C) coupling which represents the isotropic part of interaction.