Natural deep eutectic solvents

Natural deep eutectic solvents (NADES) are bio-based ionic liquids and deep eutectic solvents which are composed of two or more compounds that are generally plant based primary metabolites, i.e. organic acids, sugars, alcohols, amines and amino acids. Ionic liquids are salts, liquid at room temperature, characterized by ionic bonds which have at least one large organic ion and a cation with a low degree of symmetry. The positive and negatively charged ions in the liquid are thus kept far apart so that they reduce the attractive forces between them and hinder crystallization, lowering the melting point and resulting in a completely ionic liquid at room temperature. Deep eutectic solvents (DES) are mixtures of solid compounds that form liquids due to a large depression of the melting point; the charge delocalization in the case of DES is caused by hydrogen bonding forming a non-aqueous liquid at room temperature. Work done by Choi, Spronsen et al. showed that water can be present as part of the solvent, being strongly retained in the liquid and which cannot be evaporated.