Novel choline-chloride-based deep-eutectic-solvents with renewable hydrogen bond donors: levulinic acid and sugar-based polyols

Abstract

Choline chloride (ChCl) has been combined with renewable hydrogen bond donors (HBD) to form novel deep eutectic solvents (DES) with melting points lower than 100 °C. In some cases (e.g. sorbitol or isosorbide as HBDs) chiral DES can be easily produced. Moreover, the addition of glycerol decreases the viscosity of DES significantly. In the ChCl?:?levulinic acid DES case, singular properties were observed. Thus, equimolecular mixtures of ChCl?:?levulinic acid (1?:?1) formed a crystal at room temperature, rapidly melting in contact with air humidity. Addition of excess of acetone to ChCl?:?levulinic acid (1?:?2) leads to the almost quantitative precipitation of choline chloride, which can be used again to form a DES.