26—The Oxidation of the Aldehyde Groups in Periodate Oxycelluloses by Chlorous Acid

The effects of pH, temperature, and chlorite concentration on the oxidation of the aldehyde groups in periodate oxycelluloses by acidified chlorite solutions have been investigated . From the results it is concluded that a maximum conversion of aldehyde to carboxyl groups is obtained by treatment of the oxycelluloses at 20°C with chlorite solution acidified to pH 3 ; the chlorite concentration and the length of the treatment that are required depend upon the extent of the periodate oxidation . This chlorite treatment has been applied to a series of sixteen periodate oxycelluloses, and it has been found that the final products contained, on the average 1·78 carboxyl groups for every atom of oxygen consumed in the perioaate oxidation. This yield of carboxyl, although considerably higher than those obtained by earlier workers, is still significantly less than the theoretical value of 2 ; possible reasons for the discrepancy are discussed. Evidence is presented which suggests that one of the two aldehyde groups in a chain-unit of a periodate oxycellulose is preferentially oxidized by chlorous acid, and that this group reduces more copper in the copper number determination, and contributes more to the alkali-sensitivity of the oxidized chain-molecule, than the other.