Mechanisms of alkaline degradation of sucrose. Relative rates of alkaline degradation of some sucrose derivatives

Abstract

An earlier study of the relative rates of degradation of several sucrose derivatives has been refined and extended. The results support a novel hypothesis to explain the unusual alkali-lability of sucrose (1). In this hypothesis the first and rate-determining step in the degradation is an S_N1cB displacement effected at the C1 anomeric centre of the glucose moiety by an oxyanion derived from the C1' hydroxyl (10), to produce 1-(α-D-glucopyranosyl)fructose (11). The latter is then very rapidly degraded, mainly to lactic acid. The possibility of analogous competing displacements involving the 3' and 6' oxyanions remains for further investigation.