Ionic Liquids as Green Solvents for Sustainable Approaches

Abstract: The rising demand for environmentally friendly alternatives in chemical processing has made ionic liquids (ILs) a promising class of green solvents. ILs are liquid at room temperature due to the compound';s asymmetry, which lowers the lattice energy of the crystalline structure and, consequently, the melting points of salts. ILs possess a long shelf life. Despite certain limitations in toxicity data and largescale implementation, they hold immense promise as green solvents due to their excellent thermal stability, negligible or lower vapour pressure, tunable solvating capacity, density and viscosity control, product recovery ability, recycling capabilities, decreased evaporation, and reduced risk of environmental contamination compared to traditional organic solvents. Their high capacity to dissolve a variety of substrates, particularly highly polar ones, is noteworthy. ILs are employed as useful solvent systems in chemical reactions, extractions, separations, electroanalytical applications, and chemical sensing, among other uses. The applications of ILs range across organic synthesis, nanoparticle fabrication, biomass processing, catalysis, metal ion remediation, and biofuel extraction, highlighting their role in a sustainable chemical industry. ILs also play an increasing role in biotechnological and pharmaceutical fields, providing biocompatible media for enzymatic reactions and drug delivery. Advancing the design and developing environment-friendly synthesis methods are important steps toward unlocking the potential of ILs in promoting sustainable development and supporting a circular economy. The current review article presents an overview of ILs as green solvents for sustainable approaches, where the structure, properties, synthesis, applications, regulatory considerations and environmental policies, limitations, sustainable industrial applications, and technological scalability of ILs are discussed.