%0 Journal Article
%T Ionic Liquids: Synthesis and Applications in Catalysis
%A Rajni Ratti
%J Advances in Chemistry
%D 2014
%R 10.1155/2014/729842
%X Ionic liquids have emerged as an environmentally friendly alternative to the volatile organic solvents. Being designer solvents, they can be modulated to suit the reaction conditions, therefore earning the name ˇ°task specific ionic liquids.ˇ± Though primarily used as solvents, they are now finding applications in various fields like catalysis, electrochemistry, spectroscopy, and material science to mention a few. The present review is aimed at exploring the applications of ionic liquids in catalysis as acid, base, and organocatalysts and as soluble supports for catalysts. 1. Introduction One of the twelve principles of green chemistry is that the use of auxiliary substances such as solvents and separation agents should be made unnecessary and if used should be innocuous [1]. The toxic and hazardous properties of many solvents particularly chlorinated hydrocarbons pose crucial environmental concerns such as atmospheric emissions and contamination of water effluents. It is recognized that employing the use of nonconventional solvents as alternatives for environmentally unfriendly traditional solvents can reduce waste solvent production and hence reduce the negative impact on environment to a great extent [2]. The most prevalent of these new solvent systems includes, but not exclusively, water, supercritical fluids (like supercritical CO2), ionic liquids, solventless processes, and fluorous techniques [3]. Of all the above mentioned nonconventional solvents of interest, ionic liquids have emerged as a promising alternative [4]. Ionic liquid is defined as a salt with melting point below the boiling point of water [5]. Ionic liquids are known by several different names like neoteric solvents, designer solvents, ionic fluids, and molten salts. Most of the ionic liquids are composed of organic cation and inorganic anions. In order to be liquid at room temperature, the cation should preferably be unsymmetrical; that is, the alkyl groups should be different. Polarity and hydrophilicity/hydrophobicity of ionic liquids can be tuned by suitable combination of cation and anion. It is this property of ionic liquids which has earned them the accolade ˇ°designer solvents.ˇ± As solvents, ionic liquids have found applications in a number of reactions [6¨C16]. Dupont et al. extensively reviewed the application of ionic liquids as catalytic phase in various organometallic reactions [17]. Catalytic applications of metal nanoparticles have been explored in ionic liquid media by Migowski and Dupont [18, 19]. Besides the use of ionic liquids as alternate solvents, lately further
%U http://www.hindawi.com/journals/ac/2014/729842/