The study of molecular interactions in 1-ethyl-3-methylimidazolium trifluoromethanesulfonate + 1-pentanol from density, speed of sound and refractive index measurements

A molecular interaction study is carried out between the ionic liquid (IL) 1-ethyl-3-methylimidazolium trifluoromethanesulfonate and 1-pentanol using the experimental values of density, speed of sound and refractive index measurements over the whole composition range as a function of temperature between (298.15 and 328.15) K at atmospheric pressure. The excess/deviation properties, such as molar volumes V_m^E, partial molar volumes (V¯_m^E), partial molar volumes at infinite dilution V¯_m^E,∞, isentropic compressibility K_s^E, free length (L_f^E, speeds of sound (u^E), refractive index (Δ_Pdbln_D) and isobaric thermal expansion coefficient (α_P^E) obtained from the experimental values are fitted into the Redlich-Kister type equation to obtain the binary coefficients and the standard deviations. The negative values of excess properties such as V_m^E, K_S^E, L_f^E, α_P^E and the positive values of u^E, Δ_Pdbln_D clearly indicated the existence of strong molecular interactions between the studied components. The values of (∂V_m^E/∂T)_Pand (∂H_m^E/∂P)_T are also calculated to support the existing interactions. A quantitative analysis of these parameters is further supported by IR spectroscopic analysis.