ABSTRACT
β-Chitin is interesting because of the unique properties different from those of α-chitin. β-Chitin is isolated from squid pens by treating with acid and alkali in a manner similar to that for β-chitin from shrimp or crab shells. Ordinary α-chitin is very resistive toward acetylation, and it is difficult to attain high degrees of acetylation. Chitin derivatives having p-toluenesulfonyl groups are versatile precursors for controlled further modifications, since they are soluble in organic solvents and highly reactive. β-Chitin has thus been confirmed to be useful as a starting material for designing a sophisticated molecular environment leading to the development of advanced functions. Acetolysis of α-chitin with acetic anhydride in concentrated sulfuric acid is one of the common methods for preparing a mixture of peracetylated chitooligosaccharides. The triphenylmethyl group is typically used to protect primary hydroxyl groups, and 6-O-tritylated chitin is a key intermediate that enables discrimination of two kinds of hydroxyl groups of chitin for regioselective substitutions.
