Derivatives have been formed from chitins and chitosans in which the amine residues on the polyglucosamine have been modified to form the groups: (a) --N.dbd.CHR or --NHCH.sub.2 R (b) --NHR' (c) --NHR" and (d) --NH--CH.sub.2 CO.sub.2 H or --NH--glyceryl where R is an aromatic moiety having at least one hydroxyl or carboxyl group, or a macrocyclic ligand R' is an aldose or ketose residue, and, R" is an organometallic aldehyde residue. These derivatives are useful in chelating metals, in pharmaceutical formulations, in cosmetics, in chromatographic separations, in enzyme immobilization, as catalysts, etc. Galactomannans having selected amine-containing side chains have also been prepared by reductive amination.