Preparation of water-soluble sodium polyglucuronates from water-insoluble glucans by NaBr-free TEMPO-catalyzed oxidation with sodium dichloroisocyanurate in water

NaBr-free TEMPO-catalyzed oxidation with sodium dichloroisocyanurate (NaDCC) used as the consumed co -oxidant in water and room temperature was applied to water-insoluble polyglucans, such as a commercial regenerated cellulose (Bemliese), curdlan, α-(1 → 3)-glucan, corn starch, and 20% NaOH-treated/never-dried ramie. Water-soluble oxidized products with degrees of oxidation (DO) of >0.8 were obtained from Bemliese, curdlan, α-(1 → 3)-glucan, and corn starch by the TEMPO/NaDCC system at pH 9. The mass-average degrees of polymerization (DP w ) of the oxidized products were higher than those prepared by the conventional TEMPO/NaBr/NaClO system at pH 10. In the case of 20% NaOH-treated and never-dried ramie, DOs were only ~0.6 and water-soluble oxidized products could not be obtained quantitatively. Consequently, the TEMPO/NaDCC system in water at pH 9 is advantageous for preparation of water-soluble oxidized products with higher DP w values from water-insoluble glucans, such as Bemliese, curdlan, α-(1 → 3)-glucan, and corn starch, by suppression of depolymerization probably because of no NaOBr present in the system. The water-soluble oxidized products or sodium polyglucuronates are possible to be used as biodegradable and metabolizable polymeric builders in laundry detergents.