Improved synthesis of cellulose carbamates without by-products

The synthesis of cellulose carbamates in dimethylacetamide with dibutyltin dilaurate as a catalyst is reported. The new method gives cellulose carbamates without by-products. The reaction was carried out under mild conditions and low excess of isocyanate to prevent di- and trimerization of isocyanates and reaction of isocyanates with carbamates. Since the method takes place under anhydrous conditions it is also suited for silyl celluloses. The surface of cellulose crystallites was carbanilated using toluene as non-swelling reaction medium. For carbanilated silyl celluloses and cellulose crystallites carbanilated on the surface the degree of substitution (DS) could be determined from the weight loss in thermogravimetric analysis.