sodium-cyanoborohydride and levulinic-acid

Reductive N-alkylation with acetone and levulinic acid in the presence of sodium cyanoborohydride was applied to chitosan to prepare N-isopropyl and 5-methyl-pyrrolidinone chitosans, respectively. These chitosan derivatives were obtained quantitatively, and the highest degrees of substitution (DS) were achieved for chitosan solutions at the initial pH 4.5-5.0. When the molar ratio of the primary amino groups of chitosan, NaBH(3)CN and either acetone or levulinic acid was 1:10:3, reaction ratios at the primary amino groups reached about 100% and 41% for N-isopropyl and 5-methyl-pyrrolidinone chitosans, respectively, after the reaction at room temperature for 72h. No depolymerization occurred on chitosan molecules under the reductive N-alkylation conditions used.

Topics: Acetone; Alkylation; Borohydrides; Chitosan; Chromatography, Gel; Hydrogen-Ion Concentration; Lasers; Levulinic Acids; Light; Magnetic Resonance Spectroscopy; Molecular Weight; Oxidation-Reduction; Scattering, Radiation; Water