title: Carboxyalkylation of chitosan in the gel state.
abstract: This study presents a new approach for direct carboxyalkylation of chitosan in the gel state by using aza-Michael addition and substitution reactions. Various reagents were applied including acrylic and crotonic acids, and α-, β-, γ-, δ-, and ɛ-halocarboxylic acids. The reaction of chitosan with γ- and δ-halocarboxylic acids showed no target product formation either in solution or in the gel state. In the case of acrylic, crotonic, α- and β-halocarboxylic acids, the reaction performed in the gel state (concentration of chitosan 20-40%) shows higher degree of substitution at lower reaction time and temperature than in diluted solutions (concentration of chitosan 0.5-2%). The results were discussed in terms of kinetics of the target and side reactions. (1)H and (13)C NMR confirmed that in all cases the carboxyalkylation of chitosan proceeds exclusively at the amino groups.
authors: St. Petersburg State Chemical Pharmaceutical Academy, 14 Prof. Popov St., St. Petersburg 197022, Russia. yury_skorik@mail.ru
authors: Yury A
authors: YA
authors: Skorik
authors: Alexander V
authors: AV
authors: Pestov
authors: Mikhail I
authors: MI
authors: Kodess
authors: Yury G
authors: YG
authors: Yatluk
mesh_terms: D000477:Alkylating Agents / Q000494:pharmacology*; D000478:Alkylation; D002245:Carbon Dioxide / Q000378:metabolism; D002384:Catalysis; D048271:Chitosan / Q000737:chemistry* / Q000378:metabolism*; D005782:Gels / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008954:Models, Biological; D012996:Solutions
chemical_list: D000477:Alkylating Agents; D005782:Gels; D012996:Solutions; D002245:Carbon Dioxide; C041069:carboxyl radical; D048271:Chitosan