title: Reductive N-alkylation of chitosan with acetone and levulinic acid in aqueous media.
abstract: 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.
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, Biomaterial Sciences, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kurita
authors.forename: A
authors.initials: A
authors.lastname: Isogai
mesh_terms: D000096:Acetone / Q000737:chemistry*; D000478:Alkylation; D001894:Borohydrides / Q000737:chemistry; D048271:Chitosan / Q000737:chemistry*; D002850:Chromatography, Gel; D006863:Hydrogen-Ion Concentration; D007834:Lasers; D007982:Levulinic Acids / Q000737:chemistry*; D008027:Light; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D010084:Oxidation-Reduction; D012542:Scattering, Radiation; D014867:Water / Q000737:chemistry*
chemical_list: D001894:Borohydrides; D007982:Levulinic Acids; D014867:Water; D000096:Acetone; D048271:Chitosan; C009282:sodium cyanoborohydride; C032246:levulinic acid