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Ionic liquids are designer molecules which can efficiently replace the conventional organic solvents used in chemical processes and operations. Although a number of such applications have been reported in the literature for almost a decade, very few have actually been commercialized. This paper details the different applications claimed and examines the issues and barriers which obstruct the rapid commercialization of ionic liquids. It identifies further courses of action required for the assessment and realization of the advantages of ionic liquids. PreambleFor the past ten years, ionic liquids (ILs) have been looked upon as a revolutionary replacement for conventional organic solvents, as a medium which can be designed and used to carry out a number of chemical reactions and operations at comparatively lower temperature and pressure conditions, and which do not affect the environment. However, thus far only a few ILs have been manufactured and utilized on a commercial scale. This paper examines the claimed uses of ILs, the issues and barriers for their commercialization and the course of action required to explore their utilization. Ionic LiquidsIonic liquids are defined as room temperature fluids composed entirely of ions that are typically large organic cations and small inorganic or organic anions [1]. The thermodynamics and reaction kinetics of processes carried out in ionic liquids are different from those in conventional media. This creates new opportunities for catalytic reactions, separations, electrochemistry and combined reaction/separation processes. ILs have negligible vapor pressures near room temperature and the emission of volatile organic compounds, which is substantial for conventional organic solvents, is negligible for ILs. This leads to cleaner chemical processes and operations.Ionic liquid salts can be mixed with other salts including inorganic salts to form multicomponent ILs. Suitable cations and anions can be chosen to obtain ILs with the desired properties for specific application and there can be innumerable mixtures. It is possible to design an IL for a particular application by combining a cation with an organic or inorganic anion, as shown in Fig. 1, to obtain desired melting points, viscosity, density, hydrophobicity, miscibility, etc. The estimated number of IL mixtures currently available is 1018 [2]. PropertiesBy choosing the anion or alkyl chain of the cation, one can vary the hydrophobicity, viscosity, density, and solvation of the ionic liquid system. The contamination of ILs by impurities such as water, halides, and metal ions often affects the physical properties. The physical and thermodynamic properties of some ILs are given in Tab. 1 [3] 1) . DensityIonic liquids generally have a higher density than water. Traces of water in the ionic liquids appear to act as a diluent, and therefore, lower the density. However, such traces have a relatively small effect. ViscosityViscosity is an important physical property. ILs are generally viscous, compared to molecular solvents. How...

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The world market of lactic acid is growing every year, mainly as a solvent and precursor to poly(lactic acid) (PLA). The cost of renewable biomass-derived PLA will have to compete with other synthetic polymers, if it is to grab a significant and sustainable fraction of the market share. It is thus necessary to have efficient and cost-effective technology for the production of puregrade lactic acid (LA). In this article, a novel cost-effective, eco-friendly continuous process for the production of high-quality lactic acid at pilot plant scale has been demonstrated. The novelty of this process is that, for the first time, we report and use the concept of inverse reactive distillation for the esterification of crude concentrated LA in a continuous countercurrent packed column mode. This allows us to operate the column at higher temperatures, improving the kinetic rate process and leading to shorter columns. This is followed by the hydrolysis of methyl lactate (MLA) in a series of three continuously stirred tank reactors (CSTRs), where LA itself acts as a catalyst. The LA obtained in the pilot plant process shows 99.81% purity (by weight) on water-free basis and has an optical purity of 99.9%. The pilot scale experimental results pertaining to the autocatalytic esterification of LA and hydrolysis of MLA have been compared and validated, with respect to simulated results. The innovations reported here can make the process economically viable for commercial use.