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Synthesis of a novel N ‐selective ester functionalized chitin derivative and water‐soluble carboxyethylchitin
Author(s) -
Aoi Keigo,
Seki Taizo,
Okada Masahiko,
Sato Hiroaki,
Mizutani Shinichi,
Ohtani Hajime,
Tsuge Shin,
Shiogai Yoshiki
Publication year - 2000
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(20000901)201:14<1701::aid-macp1701>3.0.co;2-v
Subject(s) - chemistry , chitin , polymer chemistry , hydrolysis , ethyl acrylate , aqueous solution , nucleophilic substitution , methyl acrylate , acrylate , michael reaction , organic chemistry , nuclear chemistry , polymer , chitosan , monomer , copolymer , catalysis
A novel chitin derivative having a pendant ester function, 2‐ N ‐(2‐ethoxycarbonylethyl)chitin ( 2 ), was synthesized by a Michael‐type nucleophilic addition of an amino group of partially deacetylated chitin ( 1 ) to ethyl acrylate in phosphate buffer/methanol (5 : 3, v/v) at 40°C. N ‐Selective monosubstitution occurred exclusively in the polymer reaction, which was supported by a reaction of methyl 2‐amino‐2‐deoxy‐ D ‐glucopyranoside with ethyl acrylate to afford methyl 2‐ N ‐(2‐ethoxycarbonylethyl)‐2‐amino‐2‐deoxy‐ D ‐glucopyranoside. The degrees of substitution (DSs) of 2 were determined by 1 H NMR spectroscopy. T 1 analysis of 2 was carried out in order to clarify differences of signal intensities of the pendant ester protons and the pyranose ring protons. The result of the T 1 measurement suggested a relatively restricted molecular motion of the chitin backbone in comparison with the flexible pendant ethyl ester groups. Furthermore, 2‐ N ‐(2‐carboxyethyl)chitin sodium salt ( 3 ) was synthesized from ethyl acrylate and 1 by the Michael addition followed by hydrolysis in 0.1 N NaOH aq. at 40°C. The DSs of 3 were varied from 0.26 to 0.88, which were almost controlled by the reaction period of the Michael reaction from 6 to 168 h. 3 showed good solubility in water. Viscosity measured on a cone‐plate viscometer for the 1.0 wt.‐% aqueous solution of 3 (DS, 0.26) was 0.074 Pas·sec.