| Abstract: | Chemical reactivity of β-chitin isolated from squid pens has been examined in various reactions to elucidate the possibility of facile modifications in simple manners leading to the preparation of derivatives with well-defined structures. β-Chitin swelled in common solvents such as methanol and pyridine unlike the ordinary α-chitin and exhibited much higher reactivity than β-chitin. Free amino groups present in β-chitin were easily and selectively acetylated with acetic anhydride in methanol to give chitin with a uniform structure, poly(N-acetyl-D-glucosamine). When acetylation reaction was carried out in pyridine, O-acetylation proceeded smoothly besides N-acetylation. In the presence of 4-dimethylaminopyridine as the catalyst, even full acetylation was achieved under mild conditions. Tosylation was also quite efficient in pyridine without side reactions such as N-deacetylation which is unavoidable in the tosylation of α-chitin. β-Chitin also enabled direct tritylation in pyridine in the presence of 4-dimethylaminopyridine. All these reactions were quite sluggish with β-chitin, and no reactions or only very low extents of substitution were observed, indicating the high potential of β-chitin as a versatile starting material for facile modification reactions. © 1994 John Wiley & Sons, Inc. |
