REACTIVITY CHARACTERISTICS OF SQUID BETA-CHITIN AS COMPARED WITH THOSE OF SHRIMP CHITIN - HIGH POTENTIALS OF SQUID CHITIN AS A STARTING MATERIAL FOR FACILE CHEMICAL MODIFICATIONS

Chemical reactivity of beta-chitin isolated from squid pens has been e xamined in various reactions to elucidate the possibility of facile mo difications in simple manners leading to the preparation of derivative s with well-defined structures. beta-Chitin swelled in common solvents such as methanol and pyridine unlike the ordinary alpha-chitin and ex hibited much higher reactivity than alpha-chitin. Free amino groups pr esent in beta-chitin were easily and selectively acetylated with aceti c 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 t he presence of 4-dimethylaminopyridine as the catalyst, even full acet ylation was achieved under mild conditions. Tosylation was also quite efficient in pyridine without side reactions such as N-deacetylation w hich is unavoidable in the tosylation of alpha-chitin. beta-Chitin als o enabled direct tritylation in pyridine in the presence of 4-dimethyl aminopyridine. All these reactions were quite sluggish with alpha-chit in, and no reactions or only very low extents of substitution were obs erved, indicating the high potential of beta-chitin as a versatile sta rting material for facile modification reactions. (C) 1994 John Wiley & Sons, Inc.