Commercial Production of Ionic Liquids

Abstract

By 2019, a large number of different ionic liquidsIonic liquids(ILs) had been synthesized. There is a large uncertainty about the correct number, but there must be at least a couple thousand different ones described in the scientific literature and a similar number in labs of chemical companiesChemical companies. To synthesize ionic liquidsIonic liquids, numerous organic and inorganic compounds can be used and combined. A major goal of chemists who are designing novel ionic liquidsIonic liquidsis to predict ionic compounds that may be liquid at room temperature (or are at least liquid below a melting point of 100 °C, which is the common definition for ILs). A lot of experience is necessary to avoid the synthesis of too many substances that do not have sufficient properties. It is also possible to use efficient physico-chemical tools to design ionic liquidsIonic liquids, such as the “molecular volume approach” released by Krossing et al. in 2007 [1]. Using this method, it was possible to predict fundamental data, such as melting points, viscosities, conductivities, and densities, which matched very well with experimental data. As a consequence, over the past two decades ionic liquidsIonic liquidsbecame indeed “designer solventsSolvents” but also “designer electrolytesElectrolyte” and “designer (functional) materials.” Powerful tools combined with experience made it possible after more than 20 years of intensive research in many fields for ionic liquidsIonic liquidsto become industrially important productsIonic liquid products. As a consequence, the importance of methods for the commercial productionCommercial productionbecame more and more relevant. This overview for understandable reasons cannot be complete because the producers of ionic liquidsIonic liquidsare surely using numerous lab secrets and non-published information for their processes. Thus, in this chapter, the most prominently known production methods are summarized.