A review of ionic liquids: Applications towards catalytic organic transformations

Ionic liquids (ILs) offer a wide range of promising applications because of their much enhanced properties. However, further development of such materials depends on the fundamental understanding of their hierarchical structures and behaviors, which requires multiscale strategies to provide coupling among various length scales. In this review, we first introduce the structures and properties of these typical ILs. Then, we introduce the multiscale modeling methods that have been applied to the ILs, covering from molecular scale (QM/MM), to mesoscale (CG, DPD), to macroscale (CFD for unit scale and thermodynamics COSMO-RS model and environmental assessment GD method for process scale). In the following section, we discuss in some detail their applications to the four scales of ILs, including molecular scale structures, mesoscale aggregates and dynamics, and unit scale reactor design and process design and optimization of typical IL applications. Finally, we address the concluding remarks of multiscale strat...

Multiscale Studies on Ionic Liquids

CO2 separation plays an important role in energy saving and CO2 emission reduction, both of which are necessary to address the issue of global warming Ionic liquids (ILs) have been proposed to be “green” solvents for CO2 separation Unfortunately, the high cost, toxicity, and poor biodegradability of these compounds limit their large-scale application Deep eutectic solvents (DESs) were recently considered a new type of IL with additional advantages in terms of cost, environmental impact, and synthesis DESs based on choline salts (ie, choline-based DESs) are promising candidates for CO2 separation In this work, the microstructures, physicochemical properties, and water effect of choline-based DESs are surveyed and compared with those of conventional ILs The properties of choline-based DESs are similar to those of conventional ILs, but research on the latter remains limited Further study on the microstructures, properties, and separation performance of choline-based DESs considering dynamic factors must be carried out through experimental measurements and model development Thermodynamic analysis based on Gibbs free energy change is conducted to investigate the performances of choline-based-DESs during CO2 separation from biogas Choline-based-DESs are screened on the basis of energy use and amount of absorbent needed The performances of the screened choline-based-DESs are further compared with those of conventional ILs screened in our previous work, as well as commercial CO2 absorbents Comparisons indicate that the screened DES-based absorbents show great application potential due to their nonvolatility, low energy use, or low amount required The performances of physical choline-based-DES and 30 wt% MEA for CO2 separation from other gas streams (eg, flue gas, lime kiln gas, and bio-syngas) are discussed Considering the high amounts of physical absorbents required to enable separation, further study with techno-economic analysis needs to be carried out

Choline-based deep eutectic solvents for CO2 separation: Review and thermodynamic analysis

A new insight into pure and water-saturated quaternary phosphonium-based carboxylate ionic liquids: Density, heat capacity, ionic conductivity, thermogravimetric analysis, thermal conductivity and viscosity

Thermophysical properties of glycerol and polyethylene glycol (PEG 600) based DES

The practical aspects and prospects of application of ionic liquids as heat transfer fluids are discussed. The physicochemical properties of ionic liquids (heat capacity, thermal conductivity, thermal and radiation stability, viscosity, density, saturated vapour pressure and corrosion activity) are compared with the properties of some commercial heat transfer fluids. The issues of toxicity of ionic liquids are considered. Much attention is paid to known organosilicon heat transfer fluids, which are considered to have much in common with ionic liquids in the set of properties and are used in the review as reference materials. The bibliography includes 132 references.

https://iopscience.iop.org/article/10.1070/RCR4510/pdf

Ionic liquids as heat transfer fluids: comparison with known systems, possible applications, advantages and disadvantages

Five new ionic liquids formed by doubly charged cations containing a siloxane moiety and bis(trifluoromethylsulfonyl) imide anion are synthesized and characterized. Their thermal stability is studied by means of TGA; melting points (glass transition temperatures) and densities are measured. The temperature dependences of kinematic viscosity of the obtained ionic liquids are presented along with their approximations by the Vogel–Tammann–Fulcher equation.

Synthesis and properties of dicationic ionic liquids containing a siloxane structural moiety

Four novel ionic liquids with siloxane-functionalized cations were synthesized and characterized. Their thermal stability was studied by the TG method; glass transition points, viscosities, and densities were also measured.

Synthesis and properties of ionic liquids with siloxane-functionalized cations

Two series of imidazolium ionic liquids with the bis(trifluoromethylsulfonyl)imide anion were synthesized, which differ by the presence of a hydroxyl group at the ω-position of the alkyl substituent in the cation structure (nC = 2–8). The properties of the liquids were studied by DSC, TGA, and IR and NMR spectroscopy. Their thermal stability was studied, and the melting points, viscosity, and volatility in vacuum were measured. The effect of OH groups in the structure of the ionic liquid on its properties was evaluated.

Effect of Hydroxyl Groups in a Cation Structure on the Properties of Ionic Liquids

Dicationic ionic liquids with bis(trifluoromethylsulfonyl)imide anions and dimethylimidazolic moieties linked by the polymeric siloxane chain in the cation structure have been synthesized. Thermal stability of the compounds synthesised was studied by TGA; glass transition temperatures, viscosities and volatility in vacuo were measured. Applicability of these ionic liquids as heat carriers under high dynamic vacuum conditions is shown.

A. A. Koroteev

Papers

Ionic liquids as heat transfer fluids: comparison with known systems, possible applications, advantages and disadvantages

Synthesis and properties of dicationic ionic liquids containing a siloxane structural moiety

Synthesis and properties of ionic liquids with siloxane-functionalized cations

Effect of Hydroxyl Groups in a Cation Structure on the Properties of Ionic Liquids

Dicationic polysiloxane ionic liquids