A Decenary Update on the Deep Eutectic Solvents in Heterocyclic Scaffold Synthesis-A Green Solvent Approach

Deep eutectic solvents (DESs) are a mixture of two or more chemicals (hydrogen bond donors and acceptors) that are solid at room temperature, but combined at a unique molar ratio, presenting a melting point recession and becoming liquid. These solvents emerged as an alternative to hazardous solvents employed in various organic transformations and fulfilled the green chemistry concept. The convenience of synthesis, recyclability, inexpensiveness, non-toxicity, high solvent capacity, high biodegradation, low volatile organic character, and environmentally benign nature give DESs an edge over other solvents. Due to the numerous benefits to present environmental concerns and the necessity to replace hazardous solvents, the DESs solvent system is appealing to chemists in recent decades. The most important role played by the DESs showed component interactions via covalent or ionic bonds, and is thus considered a good candidate to replace ionic liquids or traditional solvents. The present review article focuses mainly on recent highlights of DESs, preparation, properties and applications to various heterocyclic molecule construction for the period 2012 to 2022.