Synthesis of Highly Substituted Butyryl Chitin in the Presence of Perchloric Acid

Perchloric acid was used as a catalyst for butyrylation of krill chitin. Esterification was carried out under heterogeneous conditions using a large excess of butyric anhydride at 20°C and 40°C. The effect of catalyst concentration and duration of the reaction on molecular weight and yield of butyryl chitin was investigated. Butyryl chitin with a degree of substitution of 2 in 90% yield were obtained. These butyryl chitins were soluble in various organic solvents and formed strong transparent films and fibers. The butyryl chitin also shows good resistance to gamma irradiation.