Natalia Plechkova and Kenneth Seddon at the Queen's University Ionic Liquids (QUILL) Research Centre, Belfast, examine how ionic liquids are being applied in the real world

Ionic liquids are liquids composed solely of ions, in contrast to conventional solvents comprised of covalent molecules. Their properties mean they are intrinsically excellent candidates for industrial applications compared to volatile organic solvents. Organic solvents have been known for several centuries, and therefore occupy most of the solvent market in industry. If the properties of ionic liquids and organic solvents are to be compared, however, it could be anticipated that industry may be a natural environment for ionic liquids. At the current level of development, ionic liquids can nicely complement, and even sometimes work better than, organic solvents in a number of industrial processes. This statement should not diminish the fact that ionic liquids have plenty of academic applications.

The field of ionic liquids is growing at a rate that was unpredictable even five years ago - there were over 2000 papers published in 2006 - and the range of commercial applications is quite staggering; not just in the number, but in their wide diversity, arising from close cooperation between academia and industry. Of all the industrial giants, BASF have done the most publicly to implement ionic liquid technology. They possess the largest patent portfolio, have the broadest range of applications, and work openly with leading academics. Currently, the most successful example of an industrial process using ionic liquid technology is the BASIL^TM (biphasic acid scavenging utilising ionic liquids) process. This first commercial publicly-announced process was introduced to the BASF site in Ludwigshafen, Germany, in 2002. The BASIL^TM process is used for the production of the generic photoinitiator precursor alkoxyphenylphosphines.

Read more in Natalia Plechkova and Ken Seddon's critical review 'Applications of ionic liquids in the chemical industry' in January's  Chemical Society Reviews.