https://www.chem.ccu.edu.tw/~joyce/referance/gump/IL/Chem.%20Rev.%201999,%2099,%202071.pdf

Room-Temperature Ionic Liquids. Solvents for Synthesis and Catalysis

Ionic liquids are salts that are liquid at low temperature (<100 degrees C) which represent a new class of solvents with nonmolecular, ionic character. Even though the first representative has been known since 1914, ionic liquids have only been investigated as solvents for transition metal catalysis in the past ten years. Publications to date show that replacing an organic solvent by an ionic liquid can lead to remarkable improvements in well-known processes. Ionic liquids form biphasic systems with many organic product mixtures. This gives rise to the possibility of a multiphase reaction procedure with easy isolation and recovery of homogeneous catalysts. In addition, ionic liquids have practically no vapor pressure which facilitates product separation by distillation. There are also indications that switching from a normal organic solvent to an ionic liquid can lead to novel and unusual chemical reactivity. This opens up a wide field for future investigations into this new class of solvents in catalytic applications.

Ionic Liquids-New "Solutions" for Transition Metal Catalysis.

In contrast to a recently expressed, and widely cited, view that “Ionic liquids are starting to leave academic labs and find their way into a wide variety of industrial applications”, we demonstrate in this critical review that there have been parallel and collaborative exchanges between academic research and industrial developments since the materials were first reported in 1914 (148 references)

Applications of ionic liquids in the chemical industry

http://pubs.acs.org/doi/pdfplus/10.1021/cr300162p

Deep Eutectic Solvents (DESs) and Their Applications

Within the framework of green chemistry, solvents occupy a strategic place. To be qualified as a green medium, these solvents have to meet different criteria such as availability, non-toxicity, biodegradability, recyclability, flammability, and low price among others. Up to now, the number of available green solvents are rather limited. Here we wish to discuss a new family of ionic fluids, so-called Deep Eutectic Solvents (DES), that are now rapidly emerging in the current literature. A DES is a fluid generally composed of two or three cheap and safe components that are capable of self-association, often through hydrogen bond interactions, to form a eutectic mixture with a melting point lower than that of each individual component. DESs are generally liquid at temperatures lower than 100 °C. These DESs exhibit similar physico-chemical properties to the traditionally used ionic liquids, while being much cheaper and environmentally friendlier. Owing to these remarkable advantages, DESs are now of growing interest in many fields of research. In this review, we report the major contributions of DESs in catalysis, organic synthesis, dissolution and extraction processes, electrochemistry and material chemistry. All works discussed in this review aim at demonstrating that DESs not only allow the design of eco-efficient processes but also open a straightforward access to new chemicals and materials.

Deep eutectic solvents: syntheses, properties and applications

A series of novel air and water stable low melting salts based upon the 1-ethyl-3-methylimidazolium cation (EtMeim+) have been prepared and characterized; two salts, [EtMeim]BF4 and [EtMeim]MeCO2, are liquids under ambient conditions.

/pdf/air-and-water-stable-1-ethyl-3-methylimidazolium-based-ionic-3sx9hec5ln.pdf

Air and water stable 1-ethyl-3-methylimidazolium based ionic liquids

Air and Water Stable 1‐Ethyl‐3‐methylimidazolium Based Ionic Liquids.

X-ray crystallographic investigation of the tertiary structure of simple 1-methylimidazolium (1-Meim) salts reveals that cation—cation face-to-face π—stacking with interplanar separations in the range typically seen for molecule—molecule and molecule—cation interactions are possible. Two salts are reported. 1-Meim-CF3SO3, 1, exists as a centrosymmetric dimer with an interplanar separation of only 3.16 A. The two imidazolium rings are slipped to the extent that the interaction can be regarded as a manifestation of C—H…C—H dipole interactions. 1-Meim-NO3 exists as a one-dimensional (1-D) polymer with interplanar separations of 3.65 A. The cations are not as severely slipped as for 1 and the interactions can be regarded as the result of cation—cation and anion—anion complementary electrostatics. Semi-empirical calculations are used to rationalize the π-π stacking in both 1 and 2. Crystal data: 1-Meim-CF3SO3, 1, triclinic, P1, a=6.416(3) A, b=7.617(4) A, c=9.569(4) A, α=85.36(4)°, β=86.08(3)°, γ=85.1...

Manifestations of noncovalent interactions in the solid state. Dimeric and polymeric self-assembly in imidazolium salts via face-to-face cation—cation π-stacking

John S. Wilkes

Papers

Air and water stable 1-ethyl-3-methylimidazolium based ionic liquids

Air and Water Stable 1‐Ethyl‐3‐methylimidazolium Based Ionic Liquids.

Manifestations of noncovalent interactions in the solid state. Dimeric and polymeric self-assembly in imidazolium salts via face-to-face cation—cation π-stacking