Oxidation of cellulose under controlled conditions

Detailed studies on the sodium metaperiodate oxidation of cellulose to yield 2,3-dialdehyde cellulose were carried out to ascertain the effects of concentration of periodate relative to cellulose, temperature of reaction, pH of the medium, effect of morphology of the cellulose, and effect of homogenous versus heterogenous reaction conditions. Microcrystalline cellulose had slightly higher reactivity then cellulose due to its greater purity and lower molecular weight, which gave rise to more reactive end groups. There were no significant changes in the reactivity of cellulose with periodate in buffer solutions of pH 2-5, or of homogenous oxidation of methylcellulose and carboxymethylcellulose as compared to heterogenous oxidation of cellulose powder. It was found that only controlling the concentration of periodate used and the temperature could easily control the rate and extent of oxidation of cellulose. The conclusion is that in order to achieve higher extent of oxidation of cellulose it is preferable to use higher concentration of periodate at 55 degreesC for short reaction time, instead of stoichiometric periodate concentration for longer reaction times. (C) 2002 Elsevier Science Ltd. All rights reserved.