Synthesis and property studies of N‐carboxymethyl chitosan

N ‐carboxymethyl chitosans ( N ‐CMC) were synthesized from chitosan in water with chloroacetic acid instead of comparatively expensive glyoxylic acid. The optimal reaction conditions were 90°C and 4 h with a ratio of chloroacetic acid to chitosan 5 : 1(w/w). The degree of substitution of product exceeded 1.32. The N ‐carboxymethyl chitosans were characterized by XRD, FTIR, 1 H‐NMR, and the water solubility and isoelectric point of N ‐CMC with different degrees of substitution were determined. FTIR and 1 H‐NMR data has confirmed that the substitution reaction occurred on the amino groups.