Oxidative transformations in cellulose molecules

Abstract

AbstractIt is shown that in all cellulose specimens isolated from plant tissues there are non‐hydroxyl groups in the 1‐, 2‐, 3‐, and 6‐positions of some of the glucose repeating unite. The presence of trace amounts of these groups changes the physical and chemical properties of the cellulose. For the purpose of studying the effect of the functional groups on the stability of the glucoside bond in the cellulose molecule and also to obtain oxidized products of importance by themselves, we have investigated the possible paths of cellulose oxidation. As an extension of previous work devoted to the primary oxidative reactions of cellulose we have studied oxidation by sodium periodate with subsequent oxidation by nitrogen oxides. This procedure yielded products containing 220 COOH groups per 100 glucose residues. These groups are in the 2‐, 3‐, and 6‐positions. The reactions showed that in opened pyran rings there is hindrance to the oxidation of primary OH groups. In contrast to other methods, which give products with not more than 50% of the theoretical number of dicarboxyl groups, the successive oxidation of cellulose by sodium periodiate yielded theoretical amounts of dicarboxycellulose with respect to carboxyl group content. The oxidation products obtained have a fibrous structure, dissolve in dilute aqueous sodium hydroxide, are relatively resistant to acid hydrolysis, are stable in air, and contain only traces of nitrogen, in contrast to dicarboxy‐ and monocarboxycelluloses. This type of oxidized cellulose, which we have termed tricarboxycellulose, possesses high and selective ion exchange properties, allowing cations, among them proteins, to be separated. This new type of oxidized fibrous cellulose permits a new direction to be developed in paper chromatography.