A physical study of the degradation of periodate–oxidized amylose

Changes in the viscosity of amylose that had been oxidized In an aqueous medium at pH 3.0 by sodium metaperiodate were followed as a function of time. Levels of 20, 40, 60, 80, and 100% periodate oxidation were attained. The rate of hydroxyl ion cleavage of the periodate oxidized amylose [(d1/[η]2)/dt = k] is proportional to the square of the degree of oxidation. That is, the hydroxyl ion hydrolysis of periodate oxyamylose occurs predominately at the site where two or more oxidized units exist side by side. A reaction mechanism is postulated to account for this slow breakdown of an isolated oxidized unit and for the fast degradation of two adjacent oxidized glucose; units. When two or more oxidized units exist side by side, the free aldehyde at carbon atom 3 is believed to be in equilibrium with a hydrate instead of a hemiacetal structure as in the case of a single, isolated, oxyglucose unit in amylose. The greater reversibility of the hydrate to the free aldehyde structure results in a greater possibility of β‐alkoxycarbonyl elimination at sites where two or more oxidized glucose units exist side by side.