Versatile Applications of the Ionic Liquid

Abstract

The first ionic liquid Ethyl ammonium nitrate was discovered in the year 1914. Ionic liquids are organic salt that is composed of organic cations and organic or inorganic anions. Ionic liquids subsist as liquid below the 100˚C or in the room temperature. A huge number of ionic liquid can be synthesized by the amalgamation of the various anions and cations through numerous kind of bonds. Ionic liquids are considered as green solvents because of non-volatility, lowviscosity, colourless, polar, wide range of solubility of biopolymers, absorption and desorption of gases. The environmental factor (E-factor), atom efficiency also supported the greenness of the ionic liquid. In chemistry, ionic liquid can replace the usual volatile organic solvents, mineral acids, solid acids etc., due to the non-corrosive green nature. For this reason, ionic liquids can be employed to numerous organic syntheses. The synthesis of ionic liquids can be done in single or multiple steps. Microwave irradiations and ultrasound assisted reactions are commonly employed to synthesise the green ionic liquids. Purification of ionic liquids can be done through crystallisation, extraction, distillation, biphasic separation and also through composed method of centrifugation or membrane separation followed by distillation. Broadly, ionic liquids are classified as basic ionic liquids, protic ionic liquids, neutral ionic liquids, chiral ionic liquids, metallic ionic liquids, poly ionic liquids, bio-ionic liquids, task specific ionic liquids etc. The major application of ionic liquids in the field of solvents and catalysts, electrochemistry, physical chemistry, analytical chemistry, pharmaceutical, biological, engineering field is well documented in this paper.