The field of ionic liquids (ILs) has recently gained huge worldwide scientific and industrial recognition due to the many beneficial properties of these materials. The ability to tailor the physical, chemical and biological properties of ILs has been the major driving force behind the surge of interest in this rapidly growing field of chemistry. In this mini-review, the history of ILs, their description, properties and applications are discussed. Although ILs are often represented as a new class of solvents, the concept of low melting ILs is not new but goes back to the 19th century. It is generally acknowledged that the birth of room temperature ionic liquids (RTILs) took place in 1914, when Walden reported ethyl ammonium nitrate a salt that is liquid at room temperature [1]. However, this discovery did not trigger any significant interest in ILs at the time, as this compound was highly reactive. The first discoveries of striking ILs were the aluminum chloride-based salts that drew attention for their use in electroplating in the 1940s [2]. The second discovery of prominent ILs were the alkylimidazolium salts introduced in the early 1980s [2]. It was the introduction of 1- ethyl-3-methylimidazolium-based chloroaluminate 2- in 1982 which led to the quest for RTILs. This IL turned out to be one of the most widely studied IL of its era. Unfortunately, the chloroaluminate-based ILs were reactive in water. The third major discovery was the advent of less corrosive, air and water stable ILs in 1992 [2, 3], which propelled new developments in this field and led to the current growth in academic and industrial research. Indeed the number of publications on the exciting fundamental developments of ILs has grown exponentially in the last decade as shown in fig.ure 1. This has been closely followed by a significant increase in the number of published patents on technological applications of ILs. This surge in the number of publications is indicative of the growing interest in IL technology by the scientific community. The historical pathway toward the development of ILs is summarized in figure 2.
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