Efficient synthesis of polysaccharide with high selenium content mediated by imidazole-based acidic ionic liquids

Exploring new solvents or catalysts has great prospect for the derivatization of poorly soluble natural polysaccharides as bio-resources which were extracted from food or industrial waste residue, as compared to traditional reaction system. In this work, selenized Artemisia sphaerocephala polysaccharide (SePAS) was synthesized by using imidazolium-based acidic ionic liquids (AILs) as catalyst. The results showed the highest Se content increased to 20438 mu g/g compared to conventional method (1703 mu g/g), indicating AILs could enhance selenylation reactivity and Se content was controlled by the acidity due to the protonation effect of H2SeO3 by AILs. FT-IR, X-ray photo-electron spectroscopy (XPS) and C-13 NMR results exhibited that seleno-group exists in SePAS and the substitution position was at C-6. The hydrogen bonding effect and acidity of AILs showed regulation on weight average molecular mass of SePAS. Therefore, AILs with excellent catalytic efficiency could be as potential catalyst for full use of polysaccharide-rich resources.