Properties Of Room Temperature Ionic Liquids Research Articles

Low viscous and highly conductive phosphonium ionic liquids based on bis(fluorosulfonyl)amide anion as potential electrolytes

The physical and electrochemical properties of room-temperature ionic liquids based on quaternary phosphonium cations together with a bis(fluorosulfonyl)amide anion are presented in this report. The bis(fluorosulfonyl)amide-based phosphonium ionic liquids were relatively low-melting, low viscous and highly conductive when compared to those of the corresponding bis(trifluoromethylsulfonyl)amide-based ionic liquids. Particularly, the ionic liquids containing a methoxy group in the phosphonium cations indicated very low viscosities and high conductivities. The FSA-based phosphonium RTILs were thermally stable up to nearly 300°C. The voltammetric analysis suggested that the bis(fluorosulfonyl)amide-based phosphonium ionic liquids showed high electrochemical stability similar to the corresponding bis(trifluoromethylsulfonyl)amide-based ionic liquids.

High-pressure study of solvation properties of room-temperature ionic liquids

The solvation properties of some room-temperature ionic liquids consisting of imidazolium cations and various anions were examined by means of the high-pressure spectroscopy with solvatochromic probes. We measured the pressure dependence of Kamlet-Taft solvatochromic parameters (π*, β) and microviscosity (η). It was found that π* and β were not so sensitive to the types of imidazolium cations and polyatomic anions, but the type of monoatomic anions. The pressure dependence of microviscosity was found to obey the empirical power-law equation.

Effects of cation and anion on physical properties of room-temperature ionic liquids

To investigate the effects of the cation and anion on the physical properties of room-temperature ionic liquids, the temperature dependences of the viscosity and density of 12 (7 cationic, 6 anionic) room-temperature ionic liquids were measured and analyzed. The effects of the cation were investigated using chainlike and cyclic (aromatic and non-aromatic) nitrogen-based room-temperature ionic liquids, and amide-type (N(SO 2C x F 2 x + 1 ) 2, x = 0, 1, 2) anions and anions of various shapes were used to investigate the effects of the anion.

Room-Temperature Ionic Liquid-Organic Solvent Mixtures: Conductivity and Ionic Association

Ion-transport properties of room-temperature ionic liquids (RTILs), N, N-diethyl-N-methoxyethyl-N-methyl ammonium (DEME) with different anions, BF4 and (CF3SO2)2N, as well as their mixed systems with two different organic solvents, propylene carbonate (PC) and 1,2-dichloroethane (DCE), have been explored by means of conductometry and pulsed-field-gradient spin-echo (PGSE) NMR diffusivity measurements. In a highly concentrated range from the neat ionic liquids to 1 mol dm−3 solution, an increase in the organic solvent content contributes to an increase in the ionic diffusion coefficients, which is reflected in enhancement of the ionic conductivity. Such increase in the solvent content, on the other hand, promotes the ionic association, even if highly polar PC is introduced as the solvent.

1-Alkyl-3-methylimidazolium Bis(perfluoroalkylsulfonyl)imide Water-Immiscible Ionic Liquids: Electrochemical Properties at Liquid-Liquid Interfaces

This study presents the electrochemical properties of room-temperature ionic liquids (RTILs) at a variety of liquid-liquid interfaces. The RTILs used here consist of 1-alkyl-3-methylimidazolium (, ) cations with bis(perfluoromethylsulfonyl)imide (BMSI) and bis(perfluoroethylsulfonyl)imide (BETI) anions. Ion transfer across the polarizable 1,2-dichloroethane/water and the neat RTIL/water interfaces were examined. The ion-transfer experiments suggested that the RTILs made with and BMSI or BETI are moderately hydrophobic with polarizable potential windows as large as for in 1,2-dichloroethane and for the neat interface. In addition, the effect of the junction potential at the aqueous reference electrode/RTIL interface was studied using the oxidation/reduction of ferrocene and decamethylferrocene. The junction potential at the reference electrode was found to decrease as a function of the cation chain length for both anions studied. The of transfer found for all the systems studied was per group of the cation.

A New Class of Solvents for CCC: The Room Temperature Ionic Liquids

Room temperature ionic liquids (RTILs) are salts with melting point close or below room temperature. Changing the nature of the anion or the cation produces a new salt that may or may not be a RTIL. The physico chemical properties of RTILs are briefly reviewed. The partitioning of 38 aromatic derivatives with acid, base, or neutral functionalities was studied between the biphasic liquid system 1‐butyl‐3‐methyl imidazolium hexafluorophosphate (BMIM PF6) and water. It was found that the viscosity of pure RTILs is too high for direct use as a liquid phase in countercurrent chromatography (CCC). The addition of a third solvent was needed to decrease viscosity. The ternary phase diagrams of BMIM PF6–water and acetonitrile, methanol, ethanol, 1‐propanol, and 2‐propanol are presented in mass and mole percentages. The organic solvent‐RTIL–water systems form two liquid phases with a viscosity low enough to allow CCC operation which was not done, due to the low amount of RTIL prepared.

Influence of chloride, water, and organic solvents on the physical properties of ionic liquids

Abstract We report here the first systematic study of the effect of impurities and additives (e.g., water, chloride, and cosolvents) on the physical properties of room-temperature ionic liquids. Remarkably, it was discovered that the viscosity of mixtures was dependent mainly on the mole fraction of added molecular solvents and only to a lesser extent upon their identity, allowing viscosity changes during the course of a reaction to be entirely predictable. While the addition of such molecular solvents decreases the viscosity and density, chloride impurities, arising from the preparation of the ionic liquids, increase viscosity dramatically. The commonly used methods of preparation were validated with respect to chloride impurity.