Preparation and physicochemical properties of imidazolium acetates and the conductivities of their aqueous and ethanol solutions

Abstract

The ionic liquids 1-methylimidazolium acetate ([Mim]Ac), 1,3-dimethylimidazolium acetate ([Mmim]Ac), and 1-ethyl-3-methylimidazolium acetate ([Emim]Ac) were prepared and their densities, conductivities, and absolute viscosities were measured at temperatures ranging from 293.15 to 338.14 K. Their corresponding molar conductivities and kinematic viscosities were also calculated. The dependence of densities, conductivities, molar conductivities, absolute viscosities, and kinematic viscosities on temperature were obtained using the least-squares method. The influence of the alkyl chains at the 3-position N atom of the imidazole ring on the above five physicochemical properties of these imidazolium acetates were discussed. The conductivities of binary solutions of [Mim]Ac {or [Mmim]Ac or [Emim]Ac} (1)- H2O (or EtOH) (2) were measured for a full set of mole fractions and the corresponding molar conductivities of the three imidazolium acetates in the six binary solutions were also calculated. In water and ethanol solutions we found that the conductivities and the molar conductivities increased initially and then decreased with an increase in the mole fraction of the imidazolium acetates. At the same concentration a longer alkyl chain at the 3-position of the imidazole ring resulted in higher conductivity and molar conductivity for the imidazolium acetates. Furthermore, the conductivities and molar conductivities of the aqueous solutions are always far higher than those of ethanol solutions. © Editorial office of Acta Physico-Chimica Sinica.