Physicochemical Properties of N-Butyl-N-methyl-2-oxopyrrolidonium Bromide and Its Binary Mixtures with Water or Methanol

Novel N-butyl-N-methyl-2-oxopyrrolidonium bromide ([BMpyr]⁺[Br]^-) ionic liquid was synthesized and characterized by different techniques such as NMR (¹H and ¹³C), FTIR, and HPLC. The measurements of thermophysical properties such as density, sound velocity, refractive index, viscosity, and conductivity of pure [BMpyr]⁺[Br]^- were carried out at different temperatures from 293.15 to 343.15 K. Density, sound velocity, refractive index, and viscosity values decreases with increase in temperature whereas conductivity values increases. The density, sound velocity, refractive index, and conductivity data were fitted to the linear equation. Molecular volume data for cation and anion constituents of [BMpyr]⁺[Br]^- were proposed from density correlation. On the basis of viscosity, some related parameters, like Vogel-Tammann-Fulcher, were calculated. Densities for the binary systems of the [BMpyr]⁺[Br]^- with water or methanol were also measured at different temperatures. The intermolecular interactions between [BMpyr]⁺[Br]^- and water or methanol were discussed.