Studies on dissolution of carbohydrates in ionic liquids and extraction from aqueous phase

An extended study on the solubility of the carbohydrates glucose, fructose, sucrose and lactose in twenty eight different ionic liquids (ILs) was performed. These ILs were based on the combination of tetraalkylammonium, tetraalkylphosphonium, 1-methyl-3-alkylimidazolium and dimethyl-tetraalkylguanidinium cations containing alkyl and ether pendant substituent groups, and anions of chloride, dicyanamide, saccharine, acesulfame, acetate or thiocyanate. It was possible to achieve solubilities, at 35 °C, of each carbohydrate up to 43.9, 49.0, 17.1 and 16.6% (g of carbohydrate per 100 g of IL), respectively. The possibility to extract carbohydrates from an aqueous phase by hydrophobic ILs was also demonstrated. Besides, some selectivity for a mixture of two carbohydrates was also observed.