title: N-(2-Carboxyethyl)chitosans: regioselective synthesis, characterisation and protolytic equilibria.
abstract: N-(2-Carboxyethyl)chitosans were obtained by reaction of low molecular weight chitosan with a low degree of acetylation and 3-halopropionic acids under mild alkaline media (pH 8-9, NaHCO3) at 60 degrees C. The chemical structure of the derivatives obtained was determined by 1H and 13C NMR spectroscopies. It was found that alkylation of chitosan by 3-halopropionic acids proceeds exclusively at the amino groups. The products obtained are described in terms of their degrees of carboxyethylation and ratio of mono-, di-substitution and free amine content. The protonation constants of amino and carboxylate groups of a series of N-(2-carboxyethyl)chitosans were determined by pH-titration at ionic strength 0.1 M KNO3 and 25 degrees C.
authors.affiliation: Laquipai, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre 687, P-4169-007, Porto, Portugal. yury_skorik@mail.ru
authors.forename: Yury A
authors.initials: YA
authors.lastname: Skorik
authors.forename: Carlos A R
authors.initials: CA
authors.lastname: Gomes
authors.forename: M Teresa S D
authors.initials: MT
authors.lastname: Vasconcelos
authors.forename: Yury G
authors.initials: YG
authors.lastname: Yatluk
mesh_terms: D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry; D002686:Chitin / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry; D048271:Chitosan; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D055672:Static Electricity
chemical_list: D001672:Biocompatible Materials; D002686:Chitin; D048271:Chitosan