Hydrolysis of chitosan under microwave irradiation in ionic liquids promoted by sulfonic acid-functionalized ionic liquids

Hydrolysis of chitosan in ionic liquids was carried out under microwave irradiation (MW) using sulfonic acid-functionalized ionic liquids (SFILs) as catalysts. The effect of microwave power, irradiation time, dosage of SFILs and DMSO was investigated by orthogonal tests. Under the optimal reaction conditions, the yield of total reducing sugars (TRS) reached over 90% within 2 min. The viscosity-average molecular weight of degraded chitosan was determined by viscosity method. The structures of the original and degraded chitosan were characterized by Fourier-transform infrared (FUR) spectra, X-ray powder diffraction (XRD) analysis and carbon-13 nuclear magnetic resonance spectroscopy (C-13 NMR). The influence of microwave power and irradiation time on the TRS and M-v was further studied. This method can dramatically reduce reaction time. (C) 2011 Elsevier Ltd. All rights reserved.