Reactivity of some sugars and sugar phosphates towards gold(III) in sodium acetate-acetic acid buffer medium

The kinetics of the oxidation of some aldoses and aldose phosphates have been studied spectrophotometrically in sodium acetate-acetic acid buffer medium at different temperatures. The reactions are first order with respect to Au(III)] and substrate]. Both H+ and Cl- ions retard the reaction. The reactions appear to involve different gold(III) species, viz. AuCl4-, AuCl3(OH2) and AuCl3(OH)- . The results are interpreted in terms of the probable intermediate formation of free radicals and Au(II). Aldoses react with gold(III) in the order: triose > tetrose > pentose > hexose. The sugar phosphates react with gold(III) at a faster rate than the parent sugars except glucose-1-phosphate, which reacts at slower rates than glucose. A tentative reaction mechanism leading to the formation of products has been suggested.