<br />Ionic Liquids as Green Solvents:<br />Progress and Prospects <br /> By<br /> Prof. Dr. Nada Saadoon Ahmedzeki <br />Similar to all salts, ILs are made up of separate cationic and anionic species, but unlike common salts, ILs have a low tendency to crystallize due to their bulky and asymmetrical cation structure. The nearly infinite combinations of suitable cations and anions lead to the possibility of tailoring the IL properties, with the anion responsible for such qualities as air and water stability and the cation responsible for melting temperature and organic solubility. They are also known as “designer solvents” since they give the opportunity to tune their specific properties for aparticular need. The researchers can design a specific IL by choosing negatively charged small anions like [Tf 2 N] − , PF 6 − , or PF 4 − and positively charged large cations of alkylimidazolium, alkylpyridinium, alkylpyrrolidinium, alkylphosphonium, or alkylmorpholinium. <br /> <br /><br />Ionic liquids (ILs) as “green” solvents reside in their extremely low vapor pressure and high thermal stability, which offers advantages such as ease of containment, product recovery, and recycling ability. In addition, ILs show considerable variation in their stability to moisture and their miscibility with molecular liquids. Properties such as density, melting point, water and cosolvent miscibility, viscosity, polarity, acid/base character, and coordinating ability can be tailored by the appropriate selection of the cation and/or anion component.<br />ILs have been implemented as solvent systems in chemical reactions, separations, extractions, electroanalytical applications and chemical sensing, among many others. Also, they have high ionic character that enhances the reaction rates to a great extent in many reactions. These features allow ILs to be used as potential alternative solvents to VOS in a wide variety of industrial chemical processes. Furthermore, the use of ILs as industrial solvents can result in economical, social, and ecological impact due to their effect on the human health and environment.<br />Volatile organic solvents, which have caused concerns on increasing air pollution and worker’s health, are common reaction media for commercial production of different chemicals. It is an enormous challenge to reduce the amount of volatile organic compounds (VOCs) used in chemical and industrial processes. Governmental policies for the control of emissions of different substances which are released into the environment will become more restrictive as pollution increases worldwide. Therefore, the development of more efficient and environmentally friendly processes will be obligatory in the coming years.<br />ILs have been rather sanguinely viewed as environmentally friendly or “green” solvents. Because of multiplicity of their uses, attention in ILs suddenly increased. ILs are organic salts that are liquid at ambient temperatures, preferably at room temperature. The reason why ILs are liquid at room temperature is still not fully understood. Application of ILs are as solvents for polymerization processes, development of ILs as green reaction media and catalysts ILs for the convenient synthesis of functional nanoparticles and other inorganic nanostructures , ILs in catalysis, green solvents for nonaqueous biocatalysis, ILs in chemical analysis , ILs solvent properties and organic reactivity , metal-containing ILs and ILs crystals based on imidazolium moiety,Pd-benzothiazol-2-ylidene complex in ILs, molten salts, and concentrated electrolyte solutions, use of ILs as “green” solvents for extractions, application of chromatographic and electrophoretic methods for the analysis of imidazolium and pyridinium cations as used in ILs , analytical applications of room-temperature ILs , catalysis in ILs, dissolution of cellulose with ILs and its application , electrophilic reactions of aromatic and heteroaromatic compounds in ILs, energetic nitrogen-rich salts and ILs , enzyme-catalyzed reactions in ILs, functionalized imidazolium salts for task-specific ILs and their applications, ILs: an environmentally friendly media for nucleophilic substitution reactions, ILs as solvents for catalyzed oxidations of organic compounds. ILs show considerable variation in their stability to moisture and their miscibility with molecular liquids. Properties such as density, melting point, water and cosolvent miscibility, viscosity, polarity, acid/base character, and coordinating ability can be tailored by the appropriate selection of the cation and/or anion component. These features allow ILs to be used as potential alternative solvents to VOS in a wide variety of industrial chemical processes. The main reason for believing ILs to be nontoxic results from their nonvolatile properties, which makes them potential green substitutes for conventional volatile organic solvents. Furthermore, the use of ILs as industrial solvents can result in economical, social, and ecological impact due to their effect on the human health and environment. <br />