This paper reports on the synthesis and the physical properties of the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate (EMISE). Experimental densities, speeds of sound and refractive indices were determined from (288.15 to 343.15) K. Dynamic viscosities were measured from (298.15 to 343.15) K and surface tension were measured from (288.15 to 313.15) K for pure ionic liquid. Densities, dynamic viscosities, speeds of sound, and isentropic compressibilities have been determined over the whole composition range for ethanol (1) + EMISE (2) and water (1) + EMISE (2) binary systems at T ) (298.15, 313.15, and 328.15) K and atmospheric pressure. Excess molar volumes, viscosity deviations, and deviations in isentropic compressibility for the binary systems were fitted to a Redlich-Kister equation to determine the fitting parameters and the root mean square deviations. Refractive indices were measured at 298.15 K over the whole composition range for the ethanol (1) + EMISE (2) and water (1) + EMISE (2) binary systems. The results were used to calculate deviations in the refractive index.

Dynamic viscosities, densities, and refractive indices have been measured from T = 298.15 K to T = 343.15 K for 1-hexyl-3-methylimidazolium chloride, [C6mim][Cl], and 1-methyl-3-octylimidazolium chloride, [C8mim][Cl]. Dynamic viscosities and densities have been determined over the whole composition range for water + [C6mim][Cl] and water + [C8mim][Cl] at T = (298.15, 313.15, 328.15, and 343.15) K and 0.1 MPa of pressure. Excess molar volumes and viscosity deviations for the binary systems at the above-mentioned temperatures were fitted to a Redlich−Kister equation to determine the fitting parameters and the root mean square deviations. Densities and viscosities of water + 1-butyl-3-methylimidazolium chloride, [C4mim][Cl], at T = (298.15, 313.15, 328.15, and 343.15) K and 0.1 MPa of pressure have been measured, and apparent molar volumes were determined.

Density, speed of sound, refractive index, dynamic viscosity, and surface tension measurements of 1-butyl-3methylimidazolium methyl sulfate have been made as a function of temperature. The synthesis of the ionic liquid is given. The low viscosity of the ionic liquid suggests its use as a solvent in the extraction process for the separation of azeotropic mixtures. The thermal expansion coefficient of the ionic liquid was calculated from the density, and the results are discussed. An analysis of the influence of the alkyl chain length of the cation on the density was performed by comparison with recently published values.

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This paper reports on the synthesis of the ionic liquid 1,3-dimethylimidazolium methyl sulfate [MMIM][MeSO 4 ]. Experimental densities, speed of sounds, and refractive indices were determined from (283.15 to 343.15) K. Dynamic viscosities were measured from (293.15 to 343.15) K. Surface tensions were measured from (288.15 to 313.15) K. The coefficient of thermal expansion and molecular volume of [MMIM][MeSO 4 ] were calculated from experimental values of density.

Ionic liquids (ILs) formed by multivalent cations are generally of higher thermal and electrochemical stability, which makes them attractive for use in high-temperature applications. Whereas the influence of structural elements on the physicochemical properties of dicationic ILs (DILs) is well established, such systematic investigations on their ecotoxicity and biodegradablility are still lacking. The present study investigates the influence of the dicationic structural elements on these characteristics and addresses the question whether already established structure-activity relationships of common ILs can be applied to DILs.Therefore, a set of 10 DILs with different linkage chain length, terminal alkyl side chain length, linkage chain polarity and head groups were synthesized and studied in several biodegradation and toxicity tests. The results showed that the acute toxicity was in many cases below the levels observed for monocationic ILs. However, none of the DILs could be degraded within the performed biodegradation experiments. Hence, DILs are a potential less toxic alternative to monocationic ILs, but further work on their design is necessary.

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