Preparation of water-soluble sodium deoxycellulosesulfonate from homogeneously prepared tosylcellulose

Water-soluble sodium deoxycellulosesulfonate (DCS-Na) was prepared by nucleophilic substitution of the p-toluenesulfonyl (tosyl) groups of cellulose p-toluenesulfonate (tosylcellulose) by a sulfonate group in aqueous Na2SO3 solution. In the substitution, the yield and degree of substitution (DS) by the sulfonate group (DSsul) were found to increase with increasing reaction temperature and with reaction time, and reached up to 80% and 0.28, respectively, at 100 °C for 72 h. Although the DS of the tosyl group (DStosyl) decreased with increasing reaction temperature and with reaction time, a respectable amount of tosyl group still remained even at 100 °C for 72 h. Furthermore, the intrinsic viscosity, [η], of the DCS-Na obtained decreased considerably with increasing reaction temperature and with reaction time. The decreases in DStosyl and [η] were very similar to each other in that increasing DSsul was independent of the reaction temperature and the reaction time. The similarity of the decreases suggests that the mechanisms of scission of the cellulose backbone and the leaving of the tosyl groups (from tosylcellulose) in the nucleophilic substitution were closely related to each other. The partial conversion of the tosyl group in the tosylcellulose to the sulfonate group, by the nucleophilic substitution, was also confirmed by the change in the IR absorption spectrum. The product could be considered to be a ter-polymer from the point of view of the AGU (anhydro glucose unit). Thus, we have AGU-co-DAGUS-Na-tosyl AGU as possible options