The reactive cellulose intermediate having free isocyanate groups (isocyanate cellulose) was synthesized by treatment of cellulose with 2, 4-tolylene diisocyanate (2, 4-TDI). The reaction of the isocyanate cellulose with amino acids and their esters were studied to obtain the cellulose derivatives containing amino acid residues. The reaction was carried out by heating mixtures of the isocyanate cellulose and amino acid derivatives under various reaction conditions. The free isocyanate groups were reacted with amino acid esters in dimethylsulfoxide (DMSO) at low temperature under nitrogen atmosphere, in high conversion to give cellulose derivatives containing amino acid residues. The amounts of amino acid esters bound to the isocyanate cellulose through the urea linkage were 0.35-1.07mmol/g.
The selective adsorption and chelate formation of metal ions onto cellulose derivatives containing amino acid residues were investigated. The results indicated that lysine-cellulose and cysteinecellulose, obtained by the saponification of the cellulose derivatives containing amino acid esters, had 0.051 and 0.056mmol/g of adsorption sites for copper (II) ion, respectively.