One-step preparation of 2,3,6-tricarboxy cellulose

•2,3,6-Tricarboxy cellulose (TCC) was prepared in one step from regenerated cellulose.•AZADO was used as a catalyst under aqueous and alkaline conditions.•TCC is a mesotartaric acid/hydrated glyoxilic acid alternating co-polyacetal.•Sodium salt of the TCC (NaTCC) had a molecular mass of 10,700 or a DP of 39.•NMR analysis showed that the NaTCC had an almost homogeneous chemical structure.

Water-soluble sodium 2,3,6-tricarboxylate cellulose (NaTCC) or sodium mesotartarate/monohydrated glyoxilate alternating co-polyacetal was prepared from regenerated cellulose in a yield of 82% by one-step oxidation with catalytic amounts of 2-azaadamantane N-oxyl (AZADO), NaBr, and excess NaOCl in water at room temperature under alkaline conditions. The AZADO-oxidized product was shown to have an almost homogeneous NaTCC chemical structure by its 1H and 13C NMR spectra. The weight- and number-average molecular masses of the obtained NaTCC were 10,700 and 7000. When AZADO-mediated oxidation was applied to softwood bleached kraft pulp, a water-soluble oxidized product was obtained. However, it had a more heterogeneous chemical structure showing that the complete oxidation of the C2, C3, and C6 hydroxyls to carboxyls is difficult to achieve in native cellulose.