KINETICS AND MECHANISM OF OXIDATION OF ERYTHRO-SERIES PENTOSES AND HEXOSES BY N-CHLORO-P-TOLUENESULFONAMIDE

The kinetics and mechanism of oxidation of D-glucose, D-mannose, D-fru ctose, D-arabinose, and D-ribose with chloramine-T in alkaline medium were studied. The rate law, rate = k [Chloramine-T] [Sugar] [HO-](2), was observed. The rate of the reaction was influenced by a change in i onic strength of the medium, and the dielectric effect was found to be negative. The latter enabled the computation of d(AB), the size of th e activated complex. The reaction rate was almost doubled in deuterium oxide. Activation energies were calculated from the Arrhenius plots. HPLC and GLC-MS analyses of the products indicated that the sugars wer e oxidized to a mixture of aldonic acids, consisting of arabinonic, ri bonic, erythronic, and glyceric acids. Based on these data, a plausibl e mechanism involving the aldo-enolic anions of pentoses and keto-enol ic anions of hexoses is suggested. (C) 1998 Elsevier Science Ltd. All rights reserved.