Probing molecular interactions between Choline Acetate Ionic Liquid and Alcohols: A comparable thermophysical study of Choline Acetate Ionic Liquid with change in solvent polarities

Abstract

In order to understand the effect of solvent permittivity on the molecular interactions in solutions, various thermophysical parameters such as density ρ, ultrasonic sound velocity u, refractive index nD, and specific conductivity ˄m of 2-hydroxyethyl-trimethylammonium Acetate; [(C2H4OH)-(CH3)3N] [Acetate] or Choline Acetate in alcohols viz. ethanol, 1-propanol and 1-butanol have been investigated over the entire concentration range at temperatures ranging from (293.15 to 323.15) K at atmospheric pressure. Further, derived thermodynamic properties and parameters at infinite dilution such as apparent molar volumes Vϕ, apparent molar compressibilities KSϕ, apparent molar volume at infinite dilution Vϕ0, limiting apparent molar expansibilities ϕE0, limiting isentropic compression KSϕ0 have been calculated. The “Kosmotropic” or “structure making” ability of Choline Acetate decreases for each additional alcohol CH2 group revealing that the Choline Acetate shows greater order-making effect in ethanol. The results further have been verified by calculating molar refraction RM and limiting molar conductance˄mo values which showed that Choline Acetate has greater interaction with the solvent having high polarity i.e. ethanol. The experimental observations have been also supported by DFT calculations which are in agreement with more structural modification of Choline Acetate in Ethanol than in 1-propanol and 1-butanol.