Ionic liquids–an Overview

Abstract

A virtually unprecedented exponential burst of activity resulted following the publication, in 1998, of an article by Michael Freeman (Freemantle, M. Chemical & Engineering News, 1998, March 30, 32), which speculated on the role and contribution that ionic liquids (ILs) might make in the future on the development of clean technology. Up until that time only a handful of researchers were routinely engaged in the study of ILs but frenzied activity followed that continues until the present day. Scientists from all disciplines related to Chemistry have now embarked on studies, including theoreticians who are immersed in the aim of improving the ''designer role'' so that they can tailor ILs to deliver specified properties. This article, whilst not in any sense attempting to be exhaustive, highlights the main features which characterise ILs, presenting these in a form readily assimilated by newcomers to this area of research. An extensive glossary is featured in this article as well as a chronological list which charts the major areas of development. What follows consists of a number of sections briefly describing the role of ILs as solvents, hypergolic fuels, their use in some electrochemical devices such as solar cells and lithium batteries and their use in polymerisation reactions, followed by a concise summary of some of the other roles that they are capable of playing. The role of empirical, volume-based thermodynamics procedures, as well as large scale computational studies on ILs is also highlighted. These developments which are described are remarkable in that they have been achieved in less than a decade and a half, although knowledge of these materials has existed for much longer.

Densities and conductivities of seven 1-allyl-3-methylimidazolium carboxylate ionic liquids

“…For 1:1 salts like the ILs investigated in the present work, I = 1, α = 83.3 kJ·mol −1 nm, and β = 157.3 kJ mol −1 [36][37][38]. The crystal energies for the ILs calculated from Eq.…”

An Overview of Coumarin as a Versatile and Readily Accessible Scaffold with Broad-Ranging Biological Activities

“…Ionic liquids (ILs) have become increasingly popular in the last decades as a safer alternative to classic solvent systems, in a perspective of more sustainable chemical processes. Most ILs possess a number of properties that made them appealing, proving to be non-flammable, to possess a negligible vapor-pressure, that means that solvent evaporation is eliminated and to dissolve a wide range of organic and inorganic compounds [ 305 ]. Furthermore, since ionic liquids are low-melting salts, they are made at least from two components which can be varied (the anion and the cation), thus the solvents could be designed with a particular end use in mind or possessing a particular set of properties [ 306 ].…”

Predictive thermodynamics for ionic solids and liquids

“…Room-temperature ionic liquids (RTILs) [38][39][40][41] can replace organic solvents used for the dissolution of both polar and non-polar solutes and for processing or extraction of materials, while also having useful catalytic features. 42 ILs are low-polluting, with low combustibility, good thermal stability and low vapour pressures.…”