Research on the Design and Application of Natural Deep Eutectic Solvents

Green technology actively seeks new solvents to replace common organic solvents. Over the past two decades, ionic liquids (ILs) have gained enormous attention from the scientific community, and the number of reported articles in the literature has grown exponentially. Nevertheless, IL “greenness” is often challenged, mainly due to their poor biodegradability, biocompatibility, and sustainability. An alternative to ILs are deep eutectic solvents (DESs). DESs are defined as a mixture of two or more components, which may be solid or liquid and that at a particular composition present a high melting point depression becoming liquids at room temperature. When compounds that constitute the DESs are primary metabolites, the DESs are so called NADESs. NADESs fully represent green chemistry principles. The current state of the art concerning the advances made on these solvents in the past few years is reviewed in this paper, and future perspectives on the major directions toward which the research on NADESs is envisaged are here discussed, and these comprised undoubtedly a wide range of chemically related subjects.