Dissolution and depolymerization of barley starch in selected ionic liquids.

Katja Lappalainen, Johanna Kärkkäinen, Marja Lajunen

Department of Chemistry, University of Oulu, PO Box 3000, FIN-90014, Finland.

Carbohydrate polymers 2013 Mar 1

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Polysaccharides like starch are poorly soluble in common solvents. However, certain ionic liquids (ILs) have been found to dissolve them, although some depolymerization happens during the dissolution. Dissolution and depolymerization of barley starch in ten ionic liquids have been studied with p-TsOH as a catalyst under controlled microwave heating. Dissolution time and the extent of the depolymerization of starch, determined by using HPLC-ELSD, were specific to each IL. Dialkylimidazolium halide ILs dissolved starch fast and depolymerized it substantially producing 79-100% water-soluble starch oligomers with the average molecular weight of 1000-2000Da. 1-Ethyl-3-methylimidazolium phosphate ([EMIM][Me2PO4]) and 2-hydroxyethylammonium formate ([NH3CH2CH2OH][HCOO]) dissolved starch slowly and depolymerized it least among the tested ILs. For the slow depolymerization of starch these ILs can be considered as suitable solvents for starch modifications where its depolymerization should be avoided. Copyright © 2012 Elsevier Ltd. All rights reserved.

Citation

Katja Lappalainen, Johanna Kärkkäinen, Marja Lajunen. Dissolution and depolymerization of barley starch in selected ionic liquids. Carbohydrate polymers. 2013 Mar 1;93(1):89-94