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

Renewable Resources Robert-Jan van Putten,†,‡ Jan C. van der Waal,† Ed de Jong,*,† Carolus B. Rasrendra,‡,⊥ Hero J. Heeres,*,‡ and Johannes G. de Vries* †Avantium Chemicals, Zekeringstraat 29, 1014 BV Amsterdam, the Netherlands ‡Department of Chemical Engineering, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands DSM Innovative Synthesis BV, P.O. Box 18, 6160 MD Geleen, the Netherlands Department of Chemical Engineering, Institut Teknologi Bandung, Ganesha 10, Bandung 40132, Indonesia

Hydroxymethylfurfural, A Versatile Platform Chemical Made from Renewable Resources

Ionic liquids as electrolytes

Dialkylimidazolium chloroaluminate melts: a new class of room-temperature ionic liquids for electrochemistry, spectroscopy and synthesis

Solution studies of halide complexes of the transition metals, of general type [MXn]y− (X=Cl or Br), have been severely hampered by the existence of both solvation and solvolysis phenomena1. We demonstrate here that the use of room-temperature ionic liquids (often misleadingly referred to as molten salts) as solvents circumvents both of these problems, and permits the first reliable solution spectra to be recorded for these species; in some cases the spectra exhibit quite remarkable resolution.

Room-temperature ionic liquids as solvents for electronic absorption spectroscopy of halide complexes

The chemical and electrochemical behavior of titanium was examined in the Lewis acidic aluminum chloride-1-ethyl-3-methylimidazolium chloride (AlCl 3 -EtMeImCl, molten salt at 353.2 K. Dissolved Ti(II), as TiCl 2 , was stable in the 66.7-33.3% mole fraction ( m/o composition of this melt. but slowly disproportionated in the 60.0-40.0 m/o melt. At low current densities, the anodic oxidation of Ti(0)did not lead to dissolved Ti (II). but to an insoluble passivating film of TiCl 3 . At high current densities or very positive potentials, Ti (0) was oxidized directly to Ti(IV); however, the electrogenerated Ti (IV) vaporized from the melt as TiCl 4 (g). As found by other researchers working in Lewis acidic AlCl 3 -NaCl, Ti(II) tended to form polymers as its concentration in the AlCl 3 - EtMeImCl melt was increased. The electrodeposition of Al-Ti alloys was investigated at Cu rotating disk and wire electrodes. Al-Ti alloys containing up to ∼19% atomic fraction (a/o) titanium could be electrodeposited from saturated solutions of Ti (II) in the 66.7-33.3 m/o melt at low current densities, but the titanium content of these alloys decreased as the reduction current density was increased. The pitting potentials of these electrodeposited Al-Ti alloys exhibited a positive shift with increasing titanium content comparable to that observed for alloys prepared by sputter deposition.

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Electrochemistry of Titanium and the Electrodeposition of Al-Ti Alloys in the Lewis Acidic Aluminum Chloride–1-Ethyl-3-methylimidazolium Chloride Melt

The constant current electrodeposition of bulk aluminum on copper substrates was investigated in the Lewis acidic [> 50 mole percent (m/o) AlCl 3 ] aluminum chloride-1-methyl-3-ethylimidazolium chloride room temperature molten salt (AlCl 3 -MeEtimeCl). Although aluminum can be electroplated from the neat molten salt, we have found that the quality of the electrodeposit is greatly enhanced by the addition of benzene as a cosolvent. Electrodeposits produced in such melts exhibited a grain size on the order of 5 to 15 μm. The lattice parameters of these electrodeposits were slightly smaller than the Joint Committee on Powder Diffraction Standards (JCPDS) value; this was attributed to the presence of vacancies in the aluminum lattice that were present at concentrations ranging from about 0.1 to 0.5 atomic percent (a/o). The copper substrate was found to have a slight (311) texture as determined by x-ray diffraction; however, all of the electrodeposits exhibited a preferred (220) crystallographic orientation with the intensity of the (311) reflection being equal to that of a randomly oriented sample. The (200) and (111) reflections were relatively weak. The relative intensity of the (220) reflection increased and those for the (311), (200), and (111) orientations decreased as the benzene concentration was increased. A Williamson-Hall treatment indicated that microstrain in the electrodeposits was essentially nonexistent.

Electrodeposition of Aluminum from the Aluminum Chloride‐1‐Methyl‐3‐ethylimidazolium Chloride Room Temperature Molten Salt + Benzene

The electrodeposition of Ni and Ni-Al alloys on glassy carbon was investigated in the 66.7--33.3 mole percent (m/o) Al chloride-1-methyl-3-ethylimidazolium chloride molten salt containing electrogenerated Ni(II) at 40 C. The electrodeposition of Ni on glassy carbon involves 3-D progressive nucleation on a finite number of active sites with hemispherical diffusion-controlled growth of the nuclei. At potentials slightly more negative than those needed to induce the reduction of Ni(II) to the metal, Al is codeposited with Ni to produce Ni-Al alloys. Controlled-potential and controlled-current experiments revealed that it is possible to produce alloy deposits containing up to approximately 40 atomic percent (a/o) Al under conditions that circumvent the bulk deposition of Al. The Al content of the Ni-Al deposit was found to vary linearly with the deposition potential but nonlinearly with the current density. The electrodeposited Ni-Al alloys are thermodynamically unstable with respect to Ni(II), i.e., immersion of the alloy deposit in melt containing Ni(II) under open-circuit conditions leads to a reduction in the Al content of the alloy. The mechanism of alloy formation appears to involve underpotential deposition of Al on the developing Ni deposit; however, alloy formation must be kinetically hindered because the Al content is always less thanmore » predicted from theoretical considerations. Ni-Al alloys produced at 0.30 V in melt containing Ni(II) and 20% (w/w) benzene as a cosolvent contained about 15 a/o Ni and were of high quality with a disordered fcc structure, but alloys produced at more negative potentials had the visual appearance of a loosely adherent, finely divided, black powder and were heavily contaminated with chloride, probably as a result of the occlusion of the molten salt solvent by the dendritic alloy deposit during deposit growth.« less

Charles L. Hussey

Papers

Dialkylimidazolium chloroaluminate melts: a new class of room-temperature ionic liquids for electrochemistry, spectroscopy and synthesis

Room-temperature ionic liquids as solvents for electronic absorption spectroscopy of halide complexes

Electrochemistry of Titanium and the Electrodeposition of Al-Ti Alloys in the Lewis Acidic Aluminum Chloride–1-Ethyl-3-methylimidazolium Chloride Melt

Electrodeposition of Aluminum from the Aluminum Chloride‐1‐Methyl‐3‐ethylimidazolium Chloride Room Temperature Molten Salt + Benzene

Electrodeposition of nickel-aluminum alloys from the aluminum chloride-1-methyl-3-ethylimidazolium chloride room temperature molten salt