Preparation and characterization of carboxymethylchitosan

Chitosan was reacted with monochloroacetic acid at room temperature for different reaction times (3h, 5h, 7h and 10h) and employing two chitosan/monochloroacetic acid molar ratios (1:4.3 or 1:8.6). The carboxymethylation of chitosan was confirmed by ¹H NMR and 13C NMR spectroscopy. The carboxymethylchitosans had average degrees of substitution ranging from 0.52 to 1.44 as determined by potentiometric and conductimetric analysis. The occurrence of N,O-carboxymethylation was also observed in all cases.