Volumetric characterization of pyridinium-based ionic liquids

Densities for 1-propylpyridinium tetrafluoroborate, 1-butylpyridinium tetrafluoroborate, 1-butylpyridinium triflate, 1-butyl-3-methylpyridinium dicyanamide, and 1-octyl-3-methylpyridinium tetrafluoroborate are reported in a broad range of temperatures (283.15–333.15 K) and pressures (0.1–65 MPa). The pressure–volume–temperature behaviours of these fluids have been correlated successfully with the empirical TRIDEN equation; then, relevant derived properties such as the coefficient of thermal expansion, and the isothermal compressibility have been calculated. A comparison of the results has been carried out to analyse their properties in structural and energetic terms.

► Densities as a function of temperature and pressure for 5 ionic liquids are reported.
► TRIDEN equation has been used to correlate experimental data.
► Derived properties have been calculated from densities using TRIDEN equation.
► The influence of the ionic structures on their behaviour has been analysed.