Ionic Liquids Beyond Simple Solvents: Glimpses at the State of the Art in Organic Chemistry

Abstract

Within the last 25 years ionic liquids have written a tremendous success story, which is documented in a nearly uncountable amount of original research papers, reviews, and numerous applications in research and industry. These days, ionic liquids can be considered as a mature class of compounds for many different applications. Frequently, they are used as neoteric solvents for chemical tansformations, and the number of reviews on this field of research is huge. In this focused review, though, we are trying to evaluate the state of the art of ionic liquid chemistry beyond using them simply as solvents for chemical transformations. It is not meant to be a comprehensive overview on the topic; the choice of emphasis and examples rather refects the authors’ personal view on the field. We are especially highlighting fields in which we believe the most fundamental developments within the next five years will take place: biomass processing, (chiral) ionic liquids from natural sources, biotransformations, and organic synthesis.

Acid‐Catalyzed Conversion of Carbohydrates into Value‐Added Small Molecules in Aqueous Media and Ionic Liquids

“…ILs are referred to as ac lass of alternative solvents that consist solely of ions andh ave melting points below 100 8C. Over the past few decades, there has been significant focus on the chemistry of ILs [135] and chemical processes in IL media, [135][136][137][138] with respect to their specific properties and the wide range of applications, including the synthesis of platform molecules. [138] Chemical transformations of carbohydrates in alternative solvents possess manifoldb enefits, compared with reactions in aqueous systems.…”

Aggregation Behavior of Several Ionic Liquids in Molecular Solvents of Low Polarity—Indication of a Bimodal Distribution

“…Ionic liquids( ILs) have been defined ass alts that are liquids below 100 8C. [1] They have become at opic of intense research as am edium for chemical synthesis, [2][3][4] electrochemistry, [5,6] and catalysis [7,8] to name just af ew applications. In many of their applications,I Ls come in contact with other components such as traditional solvents, andt herefore an umber of thermophysical properties, for example, volumetric properties, [9] viscosity, [10] anda coustic properties [11] of as ignificant number of binary IL-molecular solvents ystemsc ontinue to be studied with attempts to classify and correlate these to the structure of the IL and the molecular solvent.…”

Synthesis, Analysis and Thermoelectrochemical Applications of Ionic Liquids

“…In the history of ILs, the first synthesized ionic liquid was ethanolammonium nitrate, reported by Gabriel and Weiner in 1888 [29]. The first protic IL at RT was ethylammonium nitrate with a melting point of 12 °C, which was reported by Walden in 1914 [30]. Back then, this topic did not receive much attention from the scientific community because of its instability, poor solubility in water, and limited application areas.…”