Effect of the number, position and length of alkyl chains on the physical and thermal properties of poly-substituted pyridinium ionic liquids

Abstract

The knowledge of the physical properties of ionic liquids is of high importance in order to evaluate theirpotential applicability for a given purpose. In the last few years, ionic liquids have been proposed aspromising solvents for extractive desulfurization of fuels. Among them, recent studies have shown thationic liquids derived from pyridinium affords excellent S-compounds removal capacity. In this work,the thermal analysis of five ionic liquids derived from pyridinium cation polysubstituted with differentalkyl chains was carried out by Differencial Scanning Calorimetry (DSC) and Thermal GravimetricAnalysis (TGA). Furthermore, the density, speed of sound, refractive index and dynamic viscosity for allthe pure ionic liquids were also measured from T = (298.15 to 343.15) K. The effect of the number ofcation alkyl chains, their length, and their position on the pyridinium ring, on the ionic liquid physicalproperties is also analyzed and discussed.