Phase equilibrium study of the binary systems (N-hexyl-3-methylpyridinium tosylate ionic liquid + water, or organic solvent)

Highlights: → Synthesis, DSC, and measurements of phase equilibrium of N-hexyl-3-methylpyridinium tosylate. → Solvents used: water, alcohols, benzene, alkylbenzenes, and aliphatic hydrocarbons. → Correlation with UNIQUAC, Wilson and NRTL models. → Comparison with different tosylate-based ILs. - Abstract: The (solid + liquid) phase equilibrium (SLE) and (liquid + liquid) phase equilibrium (LLE) for the binary systems ionic liquid (IL) N-hexyl-3-methylpyridinium tosylate (p-toluenesulfonate), {([HM3Py][TOS] + water, or an alcohol (1-butanol, or 1-hexanol, or 1-octanol, or 1-decanol), or an aromatic hydrocarbon (benzene, toluene, or ethylbenzene, or propylbenzene), or an alkane (n-hexane, n-heptane, n-octane)} have been determined at ambient pressure using a dynamic method. Simple eutectic systems with complete miscibility in the liquid phase were observed for the systems involving water and alcohols. The phase equilibrium diagrams of IL and aromatic or aliphatic hydrocarbons exhibit eutectic systems with immiscibility in the liquid phase with an upper critical solution temperature as for most of the ILs. The correlation of the experimental data has been carried out using the UNIQUAC, Wilson and the non-random two liquid (NRTL) correlation equations. The results reported here have been compared with analogous phase diagrams reported by our group previously for systems containing the tosylate-based ILs.