An improved method for synthesizing N,N′-dicarboxymethylchitosan

Fully substituted N,N′-dicarboxymethylchitosan was obtained by the alkylation of chitosan at pH 8–8.5 and 90 °C using a monochloroacetic acid:chitosan weight ratio of 4:1. The water-soluble derivative is a chelating agent suitable for treatment of osteogenis or other applications involving chelation.