Determination Of The Vapor Pressure And Prediction Of The Polarity For Ionic Liquid {[C_nmim][Pro](n=4,5,6)}

In the last20years, as a new class of novel reaction medium and softfunctional materials, ionic liquids (ILs) have attracted more and more attentionfrom industrial and scientific communities. One of the most attractive features ofILs is their negligible vapor pressure at room temperature so that they are oftenconsidered as environmentally benign solvents which are promising replacementsfor volatile organic compounds used in many industrial processes. In this paperwe use the propionate ionic liquid {[Cnmim][Pro](n=4,5,6)} as the studyingobject, completed the following work:The ionic liquid (ILs){[Cnmim][Pro](n=4,5,6)} was prepared by theneutralization method and characterized by1H-NMR spectroscopy anddifferential scanning calorimetry (DSC). Using isothermogravimetrical analysis,the vapor pressures in the temperature range of423.15~463.15K and the enthalpyof vaporization at the average temperature, Tav, for the IL were determined. UsingVerevkin’s method, the difference of heat capacity between the vapor phase andthe liquid phase,of the ILS was calculated based on the statistical thermodynamics.Therefore, in terms of glCpom, the value of glHom(Tav) can be transformed intothe reference temperature298.15K. we calculated glHom(T), glSom(T), glGom(T)at different temperatures.In terms of Hildebrand solubility parameter theory, a new scale of polarityfor the IL was put forward.The solubility parameter, δ, has also been divided intotwo parts: one part is δncaused from inducted energy of liquid molecules; theother is δμcaused from orientation energy of the permanent dipole moment. δncan calculate according to Lawson-Ingham equation,δμcan be used as the scalingof polar liquid. According to the date δμprediction of ionic liquid polaritysequence consisten with experimental results very vell.