Products from microwave and ultrasonic wave assisted acid hydrolysis of chitin.

Hydrolysis of α-chitin in concentrated hydrochloric acid under elevated temperature is a general preparation of a nutrapharmaceutical glucosamine hydrochloride (GlcN.HCl). In this study, the microwave and ultrasonic wave assisted acid hydrolysis of shrimp shell α-chitin are investigated with an aim to improve the reaction rate and selectivity. Microwave heating shortens the hydrolysis time from 120 min in the conventional heating process to 12 min to afford GlcN.HCl in 57% yield. Sonication can be used to assist chitin dissolution in 38% HCl prior to the hydrolysis at 120 °C for 120 min to produce GlcN.HCl in 62% yield. The selective hydrolysis of glycosidic bond of chitin is achievable at 30 °C for 4 h to give N-acetyl glucosamine (GlcNAc) in 37% yield.