Estimation of aldehyde groups in hydrocellulose from cotton

Abstract

The aldehyde content of hydro cellulose may be readily estimated by titration with iodine in alkaline solution. Investigation of the rate of oxidation of hydrocellulose by iodine at 0° C and pH 10.6 showed that there is an initial rapid reaction in the first hour accompanied by a side reaction. This latter reaction continues after the rapid reaction has ceased and consumes iodine slowly at a constant rate. Purified cotton cellulose shows an initial reaction with iodine and after 1 hour exhibits a side reaction of the same rate as the hydrocellulose. By applying a correction for the amount of iodine consumed in the side reaction, it is possible to estimate the iodine utilized in the oxidation of aldehyde groups. Since iodine utilized in this way converts aldehyde to carboxyl groups, an, independent check on the value obtained with iodine is readily obtained by estimation of the carboxyl groups thus formed by titration with silver o-nitrophenolate. It is shown that the extent of hydrolytic degradation as determined by this method compared well with similar measurements by the viscosity method.