Heterogeneous chloroacetylation of chitosan powder in the presence of sodium bicarbonate

Because of the importance of the chloroacetyl group to carbohydrate synthes is, the objective of this work is to disclose a method that has been found useful for the heterogeneous chloroacetylation of chitosan powder in which sodium bicarbonate is used as the base for the neutralization of the acid b yproduct. A series of reactions were conducted to determine the more optima l conditions under which to perform acylation. The three varied aspects of the reaction were the acylating reagent (chloroacetyl chloride and chloroac etic anhydride), the solvent (methylene chloride and N,N-dimethylformamide) , and the temperature (0 or 44 degreesC). According to Fourier transform in frared (FTIR), the chitosan powder being refluxed in methylene chloride in the presence of chloroacetic anhydride constituted the best conditions. By incorporating these conditions and increasing the amount of the base, we ob tained a chloroacetylated chitosan powder that, characterized by FTIR, soli d-state cross-polarity/magic-angle spinning C-13 NMR, and elemental analysi s, had degrees of N- and O-chloroacetylation of 0.32 and 0.15, respectively . (C) 2001 John Wiley & Sons, Inc.