The Course of the Oxidation of the Aldose Sugars by Bromine Water

The optical rotation of a buffered glucose solution upon bromine oxidation rises to a point which corresponds approximately with the rotation of the delta gluconic lactone; then the rotation decreases to a minimum value at a rate corresponding to the hydrolysis of the delta lactone; and finally the rotation slowly increases to a point corresponding to the equilibrium rotation of gluconic acid. These changes agree qualitatively with the hypothesis that the delta gluconic lactone is formed in solution immediately after the oxidation of the sugar by bromine water. Apparently the 1, 5 ring form of glucose is oxidized directly to the 1, 5 gluconic lactone, but the authors believe that further data must be obtained before this mechanism is definitely established. The oxidation of various sugars was followed by the same method and similar changes were observed which indicate that the aldose sugars in general are oxidized by bromine water in slightly acid solution to the delta lactones rather than to the sugar acids as previously believed. CONTENTS Page