Density and Surface Tension of Ionic Liquids [H2N–C2mim][PF6] and [H2N–C3mim][PF6

Abstract

Two amino functionalized ionic liquids 1-(2-aminoethyl)-3-methylimidazolium hexafluorophosphate, [H2N–C2mim][PF6], and 1-(3-aminopropyl)-3-methylimidazolium hexafluorophosphate, [H2N–C3mim][PF6], were synthesized and characterized. The density and surface tension of these ionic liquids were measured from (293.15 to 343.15) K. Their values decreased with increasing temperature. The physical properties such as coefficient of thermal expansion, molecular volume, standard molar entropy, lattice energy, and molar enthalpy of vaporization were estimated using experimental data. The critical temperature of the ionic liquids was estimated using Eötvos equations. The values were then used to estimate the boiling temperature of the ionic liquids according to methods of Rebelo. The interstice model was used to predict the thermal expansion coefficient of the ionic liquids, α, and the result was in very good agreement with the experimental value. In addition, the parachor method was used to predict the physical properties of the ionic liquids [H2N–Cnmim][PF6] (n = 4, 5, 6).