HOMOGENEOUS ACETYLATION OF CHITOSAN IN IONIC LIQUIDS

Homogeneous acetylation of chitosan was carried out with acetyl chloride in 1-allyl-3-methylimidozolium chloride (AmimCl) ionic liquid. The dissolution process of chitosan in AmimCl was observed by polarized optical microscopy. The optimal reaction conditions were achieved by screening the effect of temperature, reaction time and acylating reagents on recovery yield of acetylated chitosan and degree of substitution (DS), which was determined by IR spectra analysis using baseline method. Acetylated chitosan could be separated easily by water precipitation followed by filtration. The acetylation process was further confirmed by IR spectra, and the crystal structure was changed after the acetylation detected by XRD spectroscopy. Compared with traditional acetylation of chitosan, the homogeneous system, mild condition, and simply workup make this methodology more accessible to the demand of sustainable green biomass chemistry.