F.M. Royo

Thermophysic comparative study of two isomeric pyridinium-based ionic liquids.

A comprehensive thermophysical study of isomeric room-temperature ionic liquids n-butyl-3-methyl-pyridinium tetrafluoroborate and n-butyl-4-methyl-pyridinium tetrafluoroborate has been performed. This paper reports various experimental data including density, speed of sound, refractive index, surface tension, isobaric molar heat capacity, and kinematic viscosity. From the experimental results, coefficients of thermal expansion, dynamic viscosities and molar refractions of the studied ionic liquids have been determined. Results have been analyzed paying special attention to the different features of the isomers and their structural differences. Several theories and empirical relations have been applied in order to predict physical properties of ionic liquids. A good agreement between experimental and calculated data has been found. Furthermore, a study about the versatility and application of the different relationships has been carried out finding that in general density and coefficients of thermal expansion can be estimated with relatively good accuracy.

Anion influence on thermophysical properties of ionic liquids: 1-butylpyridinium tetrafluoroborate and 1-butylpyridinium triflate.

The thermophysical properties of two pyridinium-based ionic liquids, 1-butylpyridinium tetrafluoroborate and 1-butylpyridinium triflate, have been measured. Thus, densities, refractive indices, speeds of sound, viscosities, surface tensions, isobaric molar heat capacities, and thermal properties have been experimentally determined over a wide range of temperatures. The comparison of the properties of the two ionic liquids has allowed us to analyze in detail the anion influence. Moreover, useful derived properties have been calculated from the results. On the other hand, the influence of the lack of a substituent in the cation has been evaluated when properties of 1-butylpyridinium tetrafluoroborate have been contrasted to those of 1-butyl-n-methylpyridinium tetrafluoroborate, (n = 2, 3, or 4). The study has been carried out paying special attention to interactions between ions in order to elucidate the desired relationship between properties and structural characteristics of ionic liquids.

HmE, VmE, and GmE of {xCl2HCCHCl2 + (1 − x)C6H14} at several temperatures

Excess molar enthalpies, excess molar volumes, and vapour pressures of (1,1,2,2-tetrachloroethane + n-hexane) between 288.15 and 318.15 K (298.15 to 308.15 K for the vapour pressures) were determined. Activity coefficients and excess molar Gibbs free energies were calculated by Barkers method. Both the strong endothermic character and the positive excess entropy of the mixture suggest an orientational order in 1,1,2,2-tetrachloroethane that is destroyed in the mixing process.

Density and Speed of Sound for Binary Mixtures of a Cyclic Ether with a Butanol Isomer

Densities and speeds of sound of the binary mixtures 1,3-dioxolane + 1-butanol, 1,3-dioxolane + 2-butanol, 1,4-dioxane + 1-butanol, and 1,4-dioxane + 2-butanol have been measured at 25 and 40°C. The excess molar volumes and excess isentropic compressibility coefficients were calculated from experimental data and fitted to a Redlich–Kister polynomial function. Results were analyzed in terms of molecular interactions and compared with literature data.

HmE and VmE of some (1-chlorobutane + alkanol or cyclohexanol) mixtures

Abstract Excess molar enthalpies and excess molar volumes of (1-chlorobutane + an alkanol or cyclohexanol) at 298.15 K (also 308.15 K in some case), were measured. The results were “explained” in terms of interactions involving the chlorine atom. Volumetric behaviour of mixtures containing 2-methylpropan-2-ol is analysed by taking into account the high proportion of cyclic structures in this alcohol and the conversion of linear into cyclic multimers when the mixture is formed.

Excess thermodynamic properties of isomeric butanols with 2-methyl-tetrahydrofuran

Abstract Excess molar volumes, VmE, excess isentropic compressibilities, gkSE, of 1-butanol, 2-butanol, 2-methyl-1-propanol or 2-methyl-2-propanol with 2-methyl-tetrahydrofuran have been determined at the temperatures 298.15 K and 313.15 K. Excess molar enthalpies, HmE, for these mixtures are given at 298.15 K. The results obtained here are compared with those of 1-butanol or 2-butanol with tetrahydrofuran.

Viscosities of the ternary mixture (2-butanol+n-hexane+1-butylamine) at 298.15 and 313.15 K

Abstract Viscosities of the ternary mixture (2-butanol+ n -hexane+1-butylamine) and of the binary mixtures (2-butanol+ n -hexane) at 298.15 and 313.15 K, and (2-butanol+1-butylamine) at 313.15 K have been measured at atmospheric pressure. Viscosity deviations and excess Gibbs energy of activation of viscous flow for the binary and ternary systems were fitted to Redlich–Kisters and Cibulkas equations, respectively. To correlate experimental data of ternary system from binary ones, different empirical and semiempirical equations have been used (Nissan and Grunberg, Hind, Frenkel, McAllister, Katti and Chaudhri, Heric and Iulan) and their parameters have been calculated. The “viscosity-thermodynamic” model (UNIMOD) has been applied to correlate experimental data for the binary mixtures and to predict the viscosity for the ternary system. The Group Contribution-Thermodynamic Viscosity model (GC-UNIMOD), and the group contribution method proposed by Wu have been employed to predict the viscosity for the binary and ternary systems.

Viscosities of the ternary mixture (1-butanol + n-hexane + 1-butylamine) at the temperatures 298.15 and 313.15 K

Abstract Viscosities of the ternary mixture {1-butanol + n -hexane + 1-butylamine} and the binary mixtures {1-butanol + n -hexane}, {1-butanol + 1-butylamine} and { n -hexane + 1-butylamine} have been measured at 298.15 and 313.15 K. Viscosity deviations for the binary and ternary systems were fitted to Redlich-Kisters and Cibulkas equations, respectively. The “viscosity-thermodynamic” model (UNIMOD) has been used to correlate experimental data for the binary mixtures and to predict the viscosities for the ternary system. The Group-Contribution Thermodynamic-Viscosity model (GC-UNIMOD), and the group contribution method proposed by Wu have been used to predict the viscosity of the binary and ternary systems.

Refractive indices and molar refractions for isomeric chlorobutanes with isomeric butanols

Experimental refractive indices and molar refractions for the binary mixtures of each of the isomers of chlorobutane with each of the isomers of butanol are given at 298.15 K. From these data the refractive index deviations were calculated. The experimental refractive index results were compared with those predicted by several mixing rules: Lorentz–Lorenz, Gladstone–Dale, Arago–Biot, Wiener and Heller.

Excess volumes and excess viscosities of binary mixtures of cyclohexane+picoline

Abstract The densities and viscosities of binary mixtures of cyclohexane + picoline have been measured at 298.15 and 313.15 K over the whole composition range. From these, excess volumes VE, excess viscosities ηE and excess energies of activation for viscous flow G∗E have been calculated. VE is positive and both ηE and G∗E are negative. These results are consistent with the self-association of picolines and the non-polar character of cyclohexane, which produces the dissociation of the picolines.