A kinetic study of d-glucose oxidation by bromine in aqueous solutions

The kinetics of the oxidation of d-glucose to d-gluconic acid by bromine in aqueous solution were studied using potentiometric techniques and theoretical considerations of complex bromine–bromide–pH equilibria. The pH has a strong influence on reaction rate. At pH < 8 the reaction is very slow, while in the pH range pH 8–9.5 the reaction is sufficiently fast and seems optimal for the reaction. The proposed active species at that pH region is hypobromous acid. At pH > 9.5, the reaction is further accelerated due to the formation of hypobromite.The proposed kinetics expression for gluconic acid formation, based on the determined kinetic parameters at pH 9.24, is of the formdc(GA)/dt = 160c2(G)c0(HOBr)c0(H+)c0(Br−)

pH dependence of the slopes for d-glucose oxidation with bromine, obtained from linear parts of the potential changes during time, compared with theoretical distribution curves of bromine species.Figure optionsDownload as PowerPoint slide