Kinetics of the Disappearance of <i>N</i>-Acetyl-D-glucosamine in Subcritical Aqueous Ethanol

Abstract

N-Acetyl-D -glucosamine (GlcNAc) was treated in subcritical fluids with ethanol contents of 0% -80% (w/w) using a tubular reactor at 190℃. The disappearance of GlcNAc in all the aqueous ethanol fluids obeyed first-order kinetics, and the rate constant was roughly proportional to the water molarity of the aqueous ethanol; this indicates that water plays an important role in the disappearance of GlcNAc. The pH of the reaction mixture decreased as the reaction proceeded and then plateaued because of the formation of a buf fer system by glucosamine and the acetic acid liberated from GlcNAc. The ultraviolet absorption spectra of the reactor effluents suggested the formation of both carboxylic acids and furfurals. The formation of furfurals and color development were suppressed at higher ethanol contents.