Deep eutectic solvents (DESs) are a promising class of mixtures known for their significantly lower melting points compared to their individual constituents. They share similar physical properties with ionic liquids (ILs) but offer more advantageous characteristics such as low cost, easy preparation, and environmental friendliness. This review provides a brief account of various types of DESs and their potential applications in organic transformations and metal-extraction studies. In particular, natural deep eutectic solvents (NADESs) have demonstrated their importance in various fields of research, including biocatalysis, depollution, electrochemistry, and biomedical applications. However, it is imperative to explore the advantages of NADESs over conventional volatile organic solvents and ILs in terms of cost-effectiveness, green and sustainable nature, promising designability, biosafety profiles, and correlations between the compositions and combinations of constituents. Without a doubt, addressing these tasks will improve the understanding of this novel class of solvents at the molecular level and thereby enable new ways to utilize the special features of NADESs in future applications.
Rajput et al. (Sun,) studied this question.