Catalytic Depolymerization of Chitin with Retention of N‐Acetyl Group

Abstract Chitin, a polymer of N ‐acetylglucosamine units with β‐1,4‐glycosidic linkages, is the most abundant marine biomass. Chitin monomers containing N ‐acetyl groups are useful precursors to various fine chemicals and medicines. However, the selective conversion of robust chitin to N ‐acetylated monomers currently requires a large excess of acid or a long reaction time, which limits its application. We demonstrate a fast catalytic transformation of chitin to monomers with retention of N ‐acetyl groups by combining mechanochemistry and homogeneous catalysis. Mechanical‐force‐assisted depolymerization of chitin with a catalytic amount of H 2 SO 4 gave soluble short‐chain oligomers. Subsequent hydrolysis of the ball‐milled sample provided N ‐acetylglucosamine in 53 % yield, and methanolysis afforded 1‐ O ‐methyl‐ N ‐acetylglucosamine in yields of up to 70 %. Our process can greatly reduce the use of acid compared to the conventional process.