(Solid + liquid) and (liquid + liquid) phase equilibria study and correlation of the binary systems { N-butyl-3-methylpyridinium tosylate + water, or + an alcohol, or + a hydrocarbon}

Abstract

The ionic liquid N-butyl-3-methylpyridinium tosylate ([BM 3Py][TOS]) has been synthesized from β-picoline as a substrate. The work includes the characterization of the synthesized compound by elemental analysis, 1H NMR and 13C NMR spectra, water content, and by the differential scanning calorimetry. Phase diagrams for the binary systems {[BM 3Py][TOS] + water, or + an alcohol (1-butanol, 1-hexanol, 1-octanol, 1-decanol), or + an alkane ( n-hexane, n-heptane, n-octane), or + an aromatic hydrocarbons (benzene, toluene, ethylbenzene, n-propylbenzene)} have been determined at atmospheric pressure using a dynamic method. (Solid + liquid) phase equilibria with complete miscibility in the liquid phase region were observed for the systems involving water and the alcohols. The phase equilibria (solid, or liquid + liquid) for the binary systems containing a hydrocarbon reported here exhibit an upper critical solution temperature. The reduction of experimental data has been carried out using the non-random two liquid (NRTL) correlation equation. The phase diagrams reported here have been compared with analogous phase diagrams reported previously for systems containing the ionic liquid, N-butyl-4-methylpyridinium tosylate and other pyridinium-based ionic liquids. The influence of the asymmetry of the cation on the phase behaviour has been discussed.