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 H2SO4 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.

Production of Glucosamine from Chitin by Co‐solvent Promoted Hydrolysis and Deacetylation

“…Very recently, a mechanocatalytic depolymerization of chitin was reported, in which chitin was ground together with a catalytic amount of H 2 SO 4 in a ball‐mill to obtain soluble oligomers. Subsequent hydrolysis at 170 to 190 °C without additional acid led to NAG (53 %) as the main product, suggesting that the acetyl group is robust under the applied conditions . Therefore, effective transformation of chitin into GlcN by tandem hydrolysis–deacetylation steps with a small amount of acid catalyst in a single step remains a challenge.…”

“…Subsequenth ydrolysis at 170 to 190 8Cw ithouta dditional acid led to NAG (53 %) as the main product, suggesting that the acetyl group is robust under the applied conditions. [11] Therefore, effective transformation of chitin into GlcN by tandem hydrolysis-deacetylation steps with as mall amount of acid catalyst in as ingle step remains achallenge.…”

Valorization of Oceanic Waste Biomass: A Catalytic Perspective

“…This increase was attributed to enhanced reactivity of the substrate and stability of the product. Mechanical forces were found to be essential for selective catalytic depolymerization of chitin . After optimizing the reaction conditions for depolymerization they tested the hydrogenation of NAG.…”

Shell Biorefinery: Dream or Reality?

“…Mechanocatalytic conversions of lignocellulosic biomass have been increasing in popularity recently . To this end, Fukuoka and co‐workers reported a new strategy for selective chitin hydrolysis into GlcNAc by combined physical and chemical forces . Chitin was first impregnated with a catalytic amount of H 2 SO 4 .…”