(61a) Ionic Liquids: Are They Worth Their Salt?

Ionic liquids are non-volatile organic salts that have low melting points, frequently below room temperature. Typical compounds are comprised of a quaternary ammonium, quaternary phosphonium, imidazolium or pyridinium cation with a wide variety of common anions. Since they cannot evaporate and cause air pollution, they are being vigorously investigated as promising alternatives to volatile organic solvents. We will discuss the physical and chemical properties of ionic liquids and show how these properties can be tailored or tuned by judicious choice of cation, anion and substituents. Although water-stable ionic liquids have only been known for about fifteen years, they have already been introduced in numerous industrial processes. They are being investigated for many more applications, including as solvents for reactions, as nonvolatile electrolytes in batteries and solar cells, for gas and liquid separations, and as heat transfer fluids and high temperature lubricants. We will discuss these applications, with particular emphasis on our own work developing ionic liquids for removal of carbon dioxide from flue gas.