Density, Surface Tension, and Refractive Index of Ionic Liquids Homologue of 1-Alkyl-3-methylimidazolium Tetrafluoroborate [C_nmim][BF₄] (n = 2,3,4,5,6)

Abstract

The values of density, surface tension, and refractive index were measured for a classic series of air and water stable ionic liquids (ILs) based on tetrafluoroborate, [C n mim][BF 4 ](n = 2,3,4,5,6)(1-alkyl-3-methylimidazolium tetrafluoroborate) in the temperature range of (298.15 to 338.15 ± 0.02) K. In terms of Glasser's theory, the standard molar entropy and lattice energy of the ILs were calculated. Using Kabo's method, the molar enthalpy of vaporization of the IL, Δ l g H m 0 (298 K), was estimated. According to the interstice model, the thermal expansion coefficient of ILs [C n mim][BF 4 ] (n = 2,3,4,5,6), α, were calculated, and in comparison with experimental value, their magnitude order is in good agreement. To test this new concept of ionic parachor, [BF 4 ] − was chosen as a reference ion and its individual value of ionic parachor was determined in terms of extrathermodynamic assumption. Then, using ionic parachor of [BF 4 ] − , the ionic parachors for all corresponding imidazolium cations, [C n mim] + , were calculated and in good agreement with those obtained by Guan's estimation, and the 17 anion ionic parachors were also obtained. In terms of ionic parachor, the surface tension and refractive index of the investigated ionic liquids were estimated, and the estimated values correlate quite well with their matching experimental values.

Study on the thermodynamic properties for ionic liquid [C6mim][OAc](1-hexyl-3-methylimidazolium acetate)

“…The density, surface tension, and other physicochemical properties for the homologue of AcAILs were previously reported [7][8][9]. As a continuation of our previous investigation [7][8][9][10][11][12][13], this paper sol H Â m , for [C 6 mim] [OAc] in the temperature range of (288.15 to 308.15 ± 0.01) K were obtained according to of Archer's method [14], and the hydration enthalpy of cation and anion in infinite dilution aqueous [C 6 …”

Measurement of vaporization enthalpy by isothermogravimetrical method and prediction of the polarity for 1-alkyl-3-methylimidazolium acetate {[Cnmim][OAc] (n = 4, 6)} ionic liquids

“…As listed in Table 3, the values of d m decrease with increasing the number of methylene (-CH 2 -) group in the alkyl chains of the ILs, that is, polarity of the ILs reduces with increasing the number of the methylene. Using the values of literature, 11,30,36,37,41,42 11,28,30,36,37,[41][42][43] as shown in Table 3. The polarity order of ILs in Table 3 is consistent with the magnitude of d obtained by Schröder's method.…”

Study on thermodynamic properties and estimation of polarity of ionic liquids {[Cnmmim][NTf2] (n = 2, 4)}

“…As we all know, the polarity of ILs is oen assessed with the dielectric constant, for example, the values of dielectric constant of [C 37 If d m is used as criterion, it is easy to determine the order of polarity for the two ILs. According to the eqn (8), ( 9) and (12), using the values of literature 26,[39][40][41][42]…”