Thermophysical Study of 1-Butyl-2-Methylpyridinium Tetrafluoroborate Ionic Liquid.

A thermophysical study of 1-butyl-2-methylpyridinium tetrafluoroborate in a wide range of temperatures has been performed. Thus, density, speed of sound, refractive index, kinematic viscosity, surface tension, and thermal properties have been measured, whereas coefficients of thermal expansion, molar refractions, dynamic viscosities, and entropies and enthalpies of surface formation per unit surface area at the studied temperatures have been calculated. Experimental results have been compared with those obtained for 1-butyl-3-methylpyridinium tetrafluoroborate and 1-butyl-4-methylpyridinium tetrafluoroborate to analyze the effect of the positional isomeric cationic structure on properties. A systematic characterization leads to understand the behavior of such compounds, being a fundamental step to develop their potential as new solvents.