SUBSTITUENT DISTRIBUTION ON O, N-CARBOXYMETHYLCHITOSANS BY H-1-NMR AND C-13 NMR

The use of the n.m.r. method in the investigation of chitosan carboxymethylation was evaluated. It seems to be the most effective technique to determine concurrently the degree and the position of substitution of the carboxymethylated chitosan derivatives. The C-13-n.m.r., by the DEPT method, H-1-H-1 and H-1-C-13-n.m.r. correlations give much valuable information from the chemical shifts of the complex carboxymethylchitosan spectra. The relative reactivity of the functional groups of chitosan towards carboxymethylation was also determined assuming a higher reactivity of the C-6 position.