The Effect of Solvent oh the Oxygen Oxidation of Polysaccharides

Abstract

The extent to which oxygen can stabilize polysaccharides against alkaline degradation was studied. The conversion of aldehyde end groups to aldonic acid groups mainly arabinonic and erythronic acids) was accelerated markedly when cellobiose, hydro-cellulose, or wood chips were treated in aqueous alkali with oxygen in the presence of anthraquinone monosulfonate. Change of the solvent to aqueous ethanol gave an even more pronounced effect without any additive. Other alcohols (methanol, n-propanol, n-hexanol, and ethylene glycol) gave a similar effect. After an oxidative pretreatment, the alkali stability of hydrocellulose (at 100 C) was increased from about 50 % to more than 90 %. When the pretreated chips were pulped in soda-AQ liquor, the rate of delignification was substantially increased. The effect of oxidation on the stabilization of wood polysaccharides, however, was small because of the low stability of the aldonic acid end groups formed at higher temperatures.