Direct conversion of chitin into a N-containing furan derivative

Abstract

This paper describes the direct conversion of chitin into a nitrogen-containing (N-containing) furan derivative (3A5AF) for the first time. Under optimized conditions, the yield of 3A5AF reaches 7.5% with ca. 50% chitin conversion by using boric acid and alkaline chlorides as additives, and NMP as a solvent. A variety of other compounds, including levoglucosenone, 4-(acetylamino)-1,3-benzenediol, acetic acid and chitin–humins, have been identified as side products, based on which a plausible reaction network involved in the process is proposed. Mechanistic investigation by NMR studies and poison tests confirms the formation of a boron complex intermediate during the reaction, shedding light on the promotional effects of boric acid. Kinetic studies show that the depolymerization of the chitin crystalline region is rate-determining, and therefore disruption of the hydrogen bonding in the crystalline region of chitin, either before or during the reaction, is the key to further improving the reaction yields.