Chemoselective protection of the amino groups of chitosan by controlled phthaloylation: facile preparation of a precursor useful for chemical modifications.
A simple and convenient procedure for chemoselectively protecting the amino groups of chitosan has been developed to provide N-phthaloyl-chitosan that is indispensable as a soluble N-protected precursor for further controlled modification reactions of chitosan. Although the conventional N-phthaloylation of chitosan in N,N-dimethylformamide was accompanied by partial phthaloylation of the hydroxy groups, the addition of a small amount of hydroxy-containing compounds effectively suppressed the O-phthaloylation. Of some compounds examined, water proved particularly suitable, resulting in the formation of chemoselectively N-phthaloylated chitosan without any appreciable O-phthaloyl groups. The resulting N-phthaloyl-chitosan was found to be crystalline despite the presence of a bulky substituent. A solubility test indicated that N-phthaloyl-chitosan exhibited considerable affinity for organic solvents.
Kurita
Keisuke
K
Department of Applied Chemistry, Faculty of Engineering, Seikei University, Musashino-shi, Tokyo 180-8633, Japan.
Ikeda
Hiroyuki
H
Yoshida
Yuya
Y
Shimojoh
Manabu
M
Harata
Manabu
M
D000107:Acetylation; D002686:Chitin / Q000031:analogs & derivatives* / Q000737:chemistry; D004187:Disaccharides / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D010795:Phthalic Acids / Q000737:chemistry*; D012995:Solubility; D013055:Spectrophotometry, Infrared; D014961:X-Ray Diffraction
D004187:Disaccharides; D010795:Phthalic Acids; D002686:Chitin; C012492:phthalonic acid