Radiation Chemistry of Carbohydrates, VI: γ-Radiolysis of Glucose in Deoxygenated N2O Saturated Aqueous Solution

Abstract

In the γ-radiolysis of deoxygenated N2O -saturated aqueous solutions of D-glucose (10-2 M, 1 · 1019 - 4 · 1019 eV/g, dose rate 4.3 · 1018 eV/g · h at 25°C), the following products have been identified: Gluconic acid (1), 2-deoxy-gluconic acid (2), arabinose (3), 2-deoxy-ribose (4), 5-deoxy-gluconic acid (5), glucosone (6), 3-deoxy-glucosone (7), 3-keto-glucose (8), [2-deoxy-3-keto-glucose (9), 4-deoxy-3-keto-glucose (10)]3, 4-ketoglucose (11), 3-deoxy-4-keto-glucose (12), 5-deoxy-4-keto-glucose (13), 5-keto-glucose (14), 2-deoxy-5-keto-glucose (15), 4-deoxy-5-keto-glucose (16), 6-deoxy-5-keto-glucose (17), glueo-hexodialdose (18), 5-deoxy-xylo-hexodialdose (19), ribose (20), xylose (21), erythrose (22), threose (28), 3-deoxy-pentulose (24), 2-butanone-(l,4)-diol (25), and dihydroxy - acetone (26). G-values were also determined. In the primary processes OH radicals and H atoms from the radiolysis of the solvent water abstract carbon bound hydrogen atoms from D-glucose to give all six possible primary glucosyl radicals. The observed products are formed in disproportionation reactions of the primary glucosyl radicals (1, 6, 8, 11, 14, 18) or of sugar radicals which originate from the primary glucosyl radicals by water elimination (2, 4, 7, 9, 10, 12, 13, 15, 16, 17, 19), rearrangements (5, 14, 15), or loss of carbon monoxide (3, 4, 20). Products 1-5 and probably 20 have primary glucosyl radicals with the odd electron at C-l as precursors. Radicals with the free spin at C-2 give rise to the products 6 and 7. Attack at C-3 yield products 8-10, at C-4 products 11-13, at C-5 products 14-17, and an attack at C-6 products 18 and 19. Products 21-26 are formed in very low yields and hence are of minor importance. Their mechanism of formation has not been investigated. © 1975, Walter de Gruyter. All rights reserved.