Topological investigations of binary mixtures containing 1-ethyl-3-methylimidazolium tetrafluoroborate and anilines

Abstract

The densities, ρ, speeds of sound, u of 1-ethyl-3-methylimidazolium tetrafluoroborate (i)+aniline or N-methylaniline or 2-methylaniline (j) binary mixtures at 293.15, 298.15, 303.15, and 308.15K and excess molar enthalpies, HE of the same mixtures at 298.15K have been measured over entire mole fraction using DSA-5000 and 2-Drop microcalorimeter respectively. Excess molar volumes, VE and excess isentropic compressibilities, κSE values have been predicted by utilizing the measured densities and speeds of sound data. The Graph theory which deals with the topology of the constituents of mixtures has been applied to predict (i) state of components of ionic liquid mixture in their pure and mixed state; (ii) nature and extent of interactions existing in mixtures; and (iii) VE, HE and κSE values. The analysis of VE data in terms of Graph theory suggests that while 1-ethyl-3-methylimidazolium tetrafluoroborate is characterized by electrostatic forces of attraction and exists as monomer; aniline or N-methylaniline or 2-methylaniline exists as associated molecular entities. Further, (i+j) mixtures are characterized by interactions between nitrogen and fluorine atoms of 1-ethyl-3-methylimidazolium tetrafluoroborate with nitrogen and hydrogen atoms of aniline or N-methylaniline or 2-methylaniline to form 1:1 molecular complex. The IR studies also support this view point. The VE, HE and κSE values predicted by Graph theory compare well with the experimental values.