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Determination of Viscosity, Ionic Conductivity, and Diffusion Coefficients in Some Binary Systems: Ionic Liquids + Molecular Solvents

2006; American Chemical Society; Volume: 51; Issue: 2 Linguagem: Inglês

10.1021/je0504515

1520-5134

Clément Comminges, Rachid Barhdadi, Michel Laurent, Michel Troupel,

Thermodynamic properties of mixtures

Experimental data for viscosities, diffusion coefficients of ferrocene, and conductivities were obtained for three ionic liquid mixtures: 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4), N-methyl-N-butylpyrrolidinium bis(trifluoromethylsulfonyl)imide (bmpyNTf2), and N-methyl-N-hexylpyrrolidinium bis(trifluoromethylsulfonyl)imide (hmpyNTf2) + dimethylformamide (DMF) or + 3-picoline as cosolvents, in the range of temperature T = (295.2 to 325.2) K. At a given temperature, the viscosity decreases exponentially with the mole fraction of the added cosolvent, and the variation of the diffusion coefficient agrees with the Stokes−Einstein law. Concerning the conductivity, addition of the polar solvent dimethylformamide produces an increase much greater than the addition of 3-picoline. The viscosity, diffusion coefficient, and conductivity follow the Arrhenius model in the explored temperature range. Consequently, moderate heating and addition of a cosolvent are two good means for obtaining conditions well adapted to electrosynthetic applications in ionic liquids.