Thermophysical properties of triazolium based ionic liquids

R. Gardas1, A. Gupta1 and P. Chhotaray1

1Department of Chemistry, Indian Institute of Technology Madras, India

Keywords: ionic liquid
property: density; viscosity; speed of sound
material: triazole

Ionic liquids (ILs) are novel class of molten salts and due to their unique properties, like negligible vapour pressure, large liquidus range, wide electrochemical window, high ionic conductivity and high solvating capacity for organic and inorganic compounds, received much attention from both academic and industrial research groups [1]. The research areas on ILs are growing very rapidly, and the potential applications of ILs are numerous [2,3]. Many of these require a thorough knowledge of their thermophysical properties. Thermophysical properties are also essential for the process and product design calculations involving separations, heat transfer, mass transfer and fluid flow. In this work, several ionic liquids having triazolium as cation and halide, tetrafluoro borate, hexafluoro phosphate or acetate as anion have been synthesized, purified and characterized. The temperature dependence, in the range of 293.15 to 363.15 K, of density, viscosity and speed of sound for the studied ILs are measured by using Anton Paar digital density and sound velocity meter and AMVn automated viscometer. Experimental data are used to calculate several derived thermodynamic properties, such as isothermal compressibility, isobaric expansivity, and thermal pressure coefficient. The influence of IL anions on studied properties is discussed. On the basis of experimental data, the QSPR (quantitative structure−property relationship) correlations and group contribution methods for thermophysical properties of triazolium based ILs have been developed, which form the basis for the development of the computer-aided molecular design (CAMD) [4,5] of studied ILs. It has also been demonstrated that the predictive data obtained by correlation methods are in good agreement with the experimental data.

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