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Densities, $$\rho$$, and kinematic viscosities, $$\nu$$, have been determined at atmospheric pressure and at 293.15–303.15 K for binary mixtures formed by methanol and one linear polyether of the type CH3–O–(CH2CH2O)n–CH3 (n = 2, 3, 4). Measurements on $$\rho$$ and $$\nu$$ were carried out, respectively, using an Anton Paar DMA 602 vibrating-tube densimeter and an Ubbelohde viscosimeter. The $$\rho$$ values were used to compute excess molar volumes, $$V_{{\text{m}}}^{{\text{E}}}$$, and, together with the $$\nu$$ results, dynamic viscosities ($$\eta$$). Deviations from linear dependence on mole fraction for viscosity, $$\Delta \eta$$, are also provided. Different semi-empirical equations have been employed to correlate viscosity data. Particularly, the equations used are the: Grunberg–Nissan, Hind, Frenkel, Katti–Chaudhri, McAllister and Heric. Calculations show that better results are obtained from the Hind equation. The $$V_{{\text{m}}}^{{\text{E}}}$$ values are large and negative and contrast with the positive excess molar enthalpies, $$H_{{\text{m}}}^{{\text{E}}}$$, available in the literature, for these systems. This indicates that structural effects are dominant. The $$\Delta \eta$$ results are positive and correlate well with the difference in volumes of the mixture compounds, confirming the importance of structural effects. The temperature dependences of $$\eta$$ and of the molar volume have been used to calculate enthalpies, entropies and Gibbs energies, $$\Delta G^{*}$$, of viscous flow. It is demonstrated that $$\Delta G^{*}$$ is essentially determined by enthalpic effects. Methanol + CH3–O–(CH2CH2O)n–CH3 mixtures have been treated in the framework of the ERAS model. Results for $$H_{{\text{m}}}^{{\text{E}}}$$ are acceptable, while the composition dependence of the $$V_{{\text{m}}}^{{\text{E}}}$$ curves is poorly represented. This has been ascribed to the existence of strong dipolar and structural effects in the present solutions.

The liquid-liquid equilibrium (LLE) curves have been determined for the 2-hydroxyl-benzaldehyde (salicylaldehyde, SAC) + CH3(CH2)nCH3 mixtures (n = 5,6,7,8,9). The equilibrium temperatures were determined observing, by means of a laser scattering technique, the turbidity produced on cooling when a second phase takes place. All the systems show an upper critical solution temperature, which linearly increases with n. Intermolecular effects have been investigated in alkanol + benzaldehyde systems using data from the literature. Interactions in 1-alkanol mixtures are mainly of dipolar type. The corresponding excess molar enthalpies, H m E , are large and positive, which reveals that interactions between like molecules are dominant. Interactions between unlike molecules are stronger for the methanol-containing system. For the other mixtures, the enthalpy of the 1-alkanol-benzaldehyde interactions remains more or less constant. At 298.15 K and equimolar composition, the replacement of a linear polar solvent by the isomeric aromatic one leads to increased H m E values in systems with a given 1-alkanol. The phenol + benzaldehyde system shows strongly negative deviations from the Raoult’s law. Proximity effects have been examined in SAC + hydrocarbon mixtures. Alkane-containing systems are essentially characterized by dipolar interactions, while dispersive interactions are prevalent in the solution with benzene. All the mixtures have been treated in terms of DISQUAC. The interaction parameters for the OH/CHO contacts and for the SAC/aromatic and SAC/alkane contacts have been reported. DISQUAC provides a correct description of the thermodynamic properties considered. In the case of SAC systems, this is done by defining a new specific group HO–C–C–CHO for salicylaldehyde.

Mixtures formed by 1-alkanol and one strongly polar compound, nitromethane (NM), ethanenitrile (EtN), dimethyl sulfoxide (DMSO, sulfolane (SULF), nitrobenzene (NTBz) or benzonitrile (BzCN), have been investigated on the basis of a set of thermophysical data, which includes: excess molar functions, enthalpies, H m E , Gibbs energies, G m E , entropies, T S m E , isobaric heat capacities, C p m E , volumes, V m E ; liquid-liquid equilibria (LLE), excess permittivies and deviations from the linearity of dynamic viscosities. In addition, calculations have been conducted to determine the Kirkwood-Buff integrals and the Kirkwood correlations factors, g K , of the investigated mixtures. In the former case, DISQUAC has been employed for modeling the needed vapour-liquid equilibria data. Many systems under consideration are characterized by dipolar interactions between like molecules and have positive values of H m E , C p m E and T S m E . On the other hand, alkanol-solvent interactions, for mixtures with a fixed 1-alkanol, become weakened in the sequence: DMSO ≈ SULF > EtN > NM > BzCN > NTBz. In systems with a given solvent, such interactions become also weaker when the chain length of the 1-alkanol is increased. Interestingly, the considered mixtures also show strong structural effects. Results on Kirkwood-Buff integrals reveal that nitriles are more preferred than nitroalkanes around a central alcohol molecule. Calculations on g K show that, in terms of the mixture polarization, the systems are rather unstructured, and that this trend becomes more important when the 1-alkanol size increases in solutions with a given solvent.

Densities (ρ) and speeds of sound (c) at a temperature T = 298.15 K, relative permittivities at 1 MHz (er) and refractive indices at the sodium D-line (nD) at T = (293.15 K to 303.15 K), all of them at a pressure p = 0.1 MPa, are reported for binary liquid mixtures alkan-1-ol + aniline. The alkan-1-ols considered are methanol, propan-1-ol and pentan-1-ol. Also, the values of the excess molar volume (VmE), excess isentropic compressibility (κSE), excess speed of sound (cE), excess refractive index (nDE), excess relative permittivity (erE) and its temperature derivative (∂erE/∂T)p are calculated and fitted to Redlich-Kister polynomials. The agreement among the reported data and other literature sources is analysed by comparing VmE, nDE, erE and the deviation of c from mole-fraction linearity (Δc). The positive excess molar internal energies at constant volume (Um, VE) show the dominance of the breaking of interactions between like molecules in the energy balance on mixing, particularly the breaking of strong dipolar interactions between aniline molecules. This contribution is also dominant for the erE values, as they are negative and decrease with the length of the alkan-1-ol chain. Calculations on the concentration-concentration structure factor are consistent with these statements, revealing homocoordination in the studied systems. The VmE are negative, which together with the positive Um, VE indicate the existence of important structural effects in the studied mixtures. The application of the Kirkwood-Frohlich model shows that the average relative orientation of neighbouring dipoles is similar in the mixtures methanol + aniline or + pyridine, in spite of the different character of the predominant interactions in the latter mixture (heterocoordination).

Systems of the type linear primary or secondary amine + cyclohexane, or + polar compound (namely, linear or cyclic monoether, + 1,4-dioxane, + N,N-dialkylamide, or + ethanitrile) have been investigated using literature data, and by means of DISQUAC. Interaction parameters for the contacts amine/ether, amine/amide and amine/nitrile are provided. For a given contact, the QUAC interchange coefficients remain practically constant along each homologous series. A similar trend has been encountered in other many previous studies. DISQUAC correctly describes excess molar enthalpies, H m E , and vapour-liquid and solid-liquid equilibria of the studied mixtures and improves calculations on H m E from the UNIFAC (Dortmund) model. The experimental data have been used to determine the enthalpy of the interactions between unlike molecules, which are stronger in systems with N,N-dialkylamides or ethanenitrile than in mixtures with ethers. On the other hand, it is shown that H m E values of amine + C6H12 mixtures are closely related to the amine self-association, and that interactions between molecules of the polar compounds are determinant on H m E results of the mixtures amine + fixed polar compound or of the systems fixed amine + polar compound (no linear monoether). Structural effects are relevant in the di-n-butylamine + linear ether systems. The application of the Flory model reveals that orientational effects are rather weak in the investigated solutions. This is in agreement with previous studies on this type of mixtures using the ERAS model.

Relative permittivities at 1 MHz, er, and refractive indices at the sodium D-line, nD, are reported at 0.1 MPa and at (293.15–303.15) K for the binary systems 1-alkanol + di-n-propylamine (DPA). Their corresponding excess functions are calculated and correlated. For the methanol mixture, positive values of the excess permittivities, erE, are found. Except at high concentrations of the alcohol in the 1-propanol mixture, the remaining systems show negative values of this property. This fact reveals that the creation of (1-alkanol)-DPA interactions contributes positively to erE, being this contribution dominant in the methanol mixture. The negative contributions arising from the disruption of interactions between like molecules are prevalent in the other mixtures. At ϕ1 (volume fraction) = 0.5, erE changes in the sequence: methanol > 1-propanol > 1-butanol > 1-pentanol

Data on density, ρ, speed of sound, c, and refractive index, nD, have been reported at (293–303.15) K for the N,N-dimethylacetamide (DMA) + CH3CO(CH2)u − 1CH3 (u = 1, 2, 3) systems, and at 298.15 K for the mixture with u = 5. These data have been used to compute excess molar volumes, VmE, excess adiabatic compressibilities, κSE, and excess speeds of sound cE. Negative VmE values indicate the existence of structural effects and interactions between unlike molecules. From molar excess enthalpies, HmE, available in the literature for N,N-dimethylformamide (DMF), or N-methylpyrrolidone (NMP) + n-alkanone systems, it is shown: (i) amide-ketone interactions are stronger in DMF systems than in those with NMP; (ii) they become weaker when u increases in mixtures with a given amide. Structural effects largely contribute toHmE and are more relevant in mixtures containing NMP. The application of the Flory's model reveals that the random mixing hypothesis is valid in large extent for DMF solutions, while NMP systems are characterized by rather strong orientational effects. From values of molar refraction and of the product PintVm (where Pint is the internal pressure and Vm the molar volume), it is concluded that dispersive interactions increase with u, or when DMF is replaced by DMA in mixtures with a fixed ketone., Junta de Castilla y León, under Project BU034U16

Interactions and structure of organic carbonate + alkane, and 1-alkanol + organic carbonate mixtures have been investigated by means of a set of molar excess functions, enthalpies ( H m E ), volumes ( V m E ), isobaric heat capacities, ( C p m E ) or entropies; and considering internal pressure ( P int ); liquid-liquid equilibria or permittivity data. In addition, the mentioned systems have been studied using the Flory model and the concentration-concentration structure factor S CC ( 0 ) , formalism. The mixtures under consideration are characterized by dipolar interactions and by homocoordination (that is, by interactions between like molecules). In systems with a given solvent, dipolar interactions are weakened in the order: propylene carbonate (PC) > dimethyl carbonate (DMC) > diethyl carbonate (DEC). Comparison of mixtures containing DMC or DEC with those involving 2-propanone or 3-pentanone shows that dipolar interactions are not determined merely by values of the dipole moment, but they also depend on the size group. The enthalpies of the alkanol-carbonate interactions have been evaluated from calorimetric data. They are stronger in DMC solutions, and become weaker when the alcohol size increases in mixtures with a given carbonate. Application of the Flory model to 43 systems of the type 1-alkanol + carbonate provides a mean relative standard deviation for H m E equal to 0.107. Results reveal that orientational effects decrease in the order DEC > PC > DMC. Orientational effects are particularly relevant in methanol or ethanol + DEC mixtures. Interestingly, the mentioned effects are weaker in 1-alkanol + DMC mixtures than in DMC + alkane systems. A similar trend is observed in DEC solutions when the considered alcohol is longer than ethanol.

Relative permittivities at 1 MHz, er, and at (293.15–303.15) K, are reported for the binary systems N,N-dimethylformamide (DMF) + N-propylpropan-1-amine (DPA), + N-butylbutan-1-amine (DBA), + butan-1-amine (BA) or + hexan-1-amine (HxA). The values of the excess relative permittivities, erE, have also been determined for these solutions. The measurements were realized by means of a precision impedance analyser 4294A, to which a 16452A cell connected using a 16048G test lead, all of them from Agilent. The erE values are large and negative, and diminish when the size of the amine increases along a homologous series, which has been ascribed mainly to the rupture of interactions between like molecules along mixing. Calculations on excess molar orientational polarizabilities support this conclusion, indicating a dominant contribution to erE from the orientational polarizability of the molecules in the mixture. The analysis of excess relative Kirkwood correlation factors shows that the correlation between dipoles is effectively decreased along the mixing process.

International audience; Sulfur dioxide (SO2) and nitrogen monoxide (NO) are some of the gas impurities present in the carbon dioxide (CO2) separated from fume using post combustion capture process. Even in a small amount, these impurities may have an impact on storage process development. The dissolution of such gases in aqueous phase is part of the studies carried out to develop processes and analyse the risks in case of geological storage. The enthalpies of solution of SO2 and NO in water were here investigated by calorimetry, using a flow calorimetric technique. The enthalpies of solution were determined at 323.15 K and 373.15 K for sulfur dioxide, and at 323.15 K for nitrogen monoxide. The experimental enthalpy data were used together with available solubility data to test thermodynamic models representative of vapour-liquid equilibrium.

Producción Científica, Excess molar enthalpies, HEm, over the whole composition range have been determined for the liquid mixtures N,N-dimethylformamide (DMF) or N,N-dimethylacetamide (DMA) + butan-1-amine (BA), or + hexan-1-amine (HxA), or + N-propylpropan-1-amine (DPA), or N-butylbutan-1-amine (DBA) at 298.15 K and at 0.1 MPa using a BT2.15 calorimeter from Setaram adapted to work in dynamic mode at constant temperature and pressure. All the HEm values are positive, indicating that interactions between like molecules are predominant. The replacement of DMF by DMA in systems with a given amine leads to lower HEm results, which have been ascribed to stronger amide-amide interactions in DMF mixtures. The replacement of HxA by DPA in systems with a given amide leads to slightly higher HEm values, as interactions between unlike molecules are weaker for the latter. Structural effects in the investigated solutions are also present, since the corresponding excess molar volumes (VEm), previously determined, are negative or slightly positive. The systems have been characterized in terms of the ERAS model reporting the interaction parameters. The model correctly describes both HEm and VEm. The application of the model suggests that, in the systems under study, solvation effects are of minor importance and that physical interactions are dominant., Consejería de Educación, Junta de Castilla y León: Project VA100G19 (Apoyo a GIR, BDNS: 425389), Ministerio de Educación, Cultura y Deporte (MECD): Grant FPU14/04104, Ministerio de Educación, Cultura y Deporte (MECD): Complementary Grants EST16/00824 and EST17/00292

Fluorobenzene, or 1,4-difluorobenzene or hexafluorobenzene + alkane mixtures and hexafluorobenzene + benzene, or + toluene, or + 1,4-dimethylbenzene systems have been investigated using thermodynamic properties from the literature and through the application of the DISQUAC and UNIFAC (Dortmund) models and the concentration-concentration structure factor ( S CC ( 0 ) ) formalism. DISQUAC interaction parameters for the contacts F/alkane and F/aromatic have been determined. UNIFAC interaction parameters available in the literature for these contacts have been used along calculations. Both models predict double azeotropy for the C6F6 + C6H6 system, although in different temperature ranges. The H m E values of the fluorobenzene, or 1,4-difluorobenzene + n-alkane systems are positive and are accurately described by the models using interaction parameters independent of the n-alkane. This means that no Patterson’s effect exists in such mixtures. DISQUAC calculations allow state that such conclusion is still valid for C6F6 + n-alkane mixtures. DISQUAC provides better results than UNIFAC on C pm E of solutions involving n-alkanes, or on H m E of C6F6 + aromatic hydrocarbon systems. Mixtures with alkanes are characterized by interactions between like molecules, which are mainly of dispersive type, which is supported, e.g, by the negative C pm E values of these systems. It is shown that structural effects can contribute largely to H m E . This is investigated in terms of the excess molar internal energy at constant volume, U V m E , whose values are determined for the investigated solutions. For mixtures with a given n-alkane, the relative variation of H m E and U V m E with the fluorohydrocarbons is different. H m E values change in the sequence C6F6 > 1,4-C6H4F2 > C6H6 > C6H5F, while U V m E changes in the order: 1,4-C6H4F2 > C6H6 ≈ C6H5F > C6F6 . C6F6 + aromatic hydrocarbon mixtures are characterized by interactions between unlike molecules as it is demonstrated by their negative H m E values. The application of the S CC ( 0 ) formalism reveals that homocoordination is more important in C6F6 + n-alkane mixtures than in the corresponding systems with C6H5F, and that heterocoordination is dominant in the solutions of C6F6 with an aromatic hydrocarbon.

Excess molar enthalpies, H m E , have been measured using a Tian-Calvet microcalorimeter for the systems CH3(CH2)u-1OH (u = 1,2,3,4,7,10) + cyclohexylamine at 298.15 K and 0.1 MPa. The H m E values are large and negative, indicating the existence of strong interactions between unlike molecules, which is consistent with the also large and negative excess molar volumes, V m E of these solutions, previously measured by us. The contribution from the equation of state term to H m E has been evaluated for the 1-alkanol + cyclohexylamine, or + 1-hexylamine, or + aniline mixtures, and the corresponding excess molar internal energies at constant volumes, U m, V E , determined. It is shown that such contribution is particularly important for the methanol + aniline system, in such way that the excess functions H m E and U m, V E have different sign at x1 = 0.5. The DISQUAC and ERAS models have been applied to the cyclohexylamine systems, and the interaction parameters reported. DISQUAC improves ERAS results on H m E . The latter model describes correctly the V m E curves. The variation of H m E of CH3(CH2)u-1OH + cyclohexylamine, or + 1-hexylamine, or + aniline mixtures with u along a homologous series with a given amine, or with the amine in mixtures with a given 1-alkanol is discussed in terms of the different interactional contributions to H m E .

Densities, ρ, speeds of sound, c, and refractive indices, nD, have been measured for the systems N,N-dimethylformamide (DMF) + propanone, +2-butanone, or +2-pentanone in the temperature range from (293.15 to 303.15) K and at T = 298.15 K for the DMF + 2-heptanone mixture. Due to the high volatility of acetone, the corresponding nD measurements were developed at T = (293.15 and 298.15) K. The direct experimental data were used to determine the excess molar volumes, V m E , and the excess refractive indices, n D E , at the working temperatures. Values of the excess functions at T = 298.15 K, for the speed of sound, cE, the isentropic compressibility, κ S E and for the excess thermal expansion coefficient, α p E , were also calculated. The investigated systems are characterised by strong (amide + ketone) interactions, which become weaker when the alkanone size is increased. This is supported by negative V m E values; by the dependence on temperature and pressure of V m E , and by positive P int E (excess internal pressure) values. Analysis of the systems in terms of the Rao’s constant indicates that there is no complex formation. In addition, negative V m E values also reveal the existence of structural effects, which largely contribute to the excess molar enthalpy, H m E . V m E and H m E values increase with the chain length of the 2-alkanone. It allows conclude that the relative V m E variation with the ketone size is closely related to that of the interactional contribution to this excess function. Molar refraction values, Rm, show that dispersive interactions become more relevant for the systems including longer 2-alkanones.

Relative permittivities at 1 MHz, , and refractive indices at the sodium D-line, , are reported at 0.1 MPa and at (293.15–303.15) K for the binary systems 1-alkanol + n-hexylamine (HxA). Also, their corresponding excess functions are calculated and correlated. Positive values of the excess permittivities, , are encountered for the methanol system, whereas the remaining mixtures show negative values. This reveals that interactions between unlike molecules contribute positively to . This contribution is dominant for the methanol mixture, while those arising from the breaking of interactions between like molecules are prevalent for the remaining mixtures. At (volume fraction) = 0.5, changes in the order: methanol > 1-propanol > 1-butanol > 1-pentanol < 1-heptanol. Similar variation with the chain length of the 1-alkanol is observed for mixtures such as 1-alkanol + heptane, or + cyclohexylamine, and can be explained in terms of the lower and weaker self-association of longer 1-alkanols. The effect of the replacement of HxA by cyclohexylamine, or by aniline, is also shown. Calculations on molar refractions indicate that dispersive interactions in the systems under study increase with the length of the 1-alkanol. The mixtures are studied by means of the application of the Kirkwood-Fröhlich model, and the Kirkwood correlation factors, including the corresponding excess values, are reported., Ministerio de Educación, Cultura y Deporte for the grants FPU14/04104 and FPU15/05456 respectively. The authors gratefully acknowledge the financial support received from the Consejería de Educación y Cultura of Junta de Castilla y León, under Project BU034U16.

Mixtures involving nitrobenzene and hydrocarbons, or 1-alkanols and 1-nitroalkane, or nitrobenzene have been investigated on the basis of a whole set of thermophysical properties available in the literature. The properties considered are: excess molar functions (enthalpies, entropies, isobaric heat capacities, and volumes), vapour-liquid and liquid-liquid equilibria, permittivities or dynamic viscosities. In addition, the mixtures have been studied by means of the application of the DISQUAC, ERAS, and UNIFAC models, and using the formalism of the concentration-concentration structure factor. The corresponding interaction parameters in the framework of the DISQUAC and ERAS models are reported. In alkane mixtures, dipolar interactions between 1-nitroalkane molecules are weakened when the size of the polar compound increases, accordingly with the relative variation of their effective dipolar moment. Dipolar interactions are stronger in nitrobenzene solutions than in those containing the smaller 1-nitropropane, although both nitroalkanes have very similar effective dipole moment (aromaticity effect). Systems with 1-alkanols are characterized by dipolar interactions between like molecules which sharply increases when the alkanol size increases. Simultaneously, interactions between unlike molecules become weaker, as the OH group is then more sterically hindered. Interactions between unlike molecules are stronger in systems with nitromethane than in nitrobenzene solutions. The replacement of nitromethane by nitroethane in systems with a given 1-alkanol leads to strengthen those effects related with the alcohol self-association. Permittivity data and results on Kirkwood's correlation factors show that the addition of 1-alkanol to a nitroalkane leads to cooperative effects, which increase the dipolar polarization of the solution, in such way that the destruction of the existing structure in pure liquids is partially counterbalanced. This effect is less important when longer 1-alkanols are involved., Consejería de Educacion y Cultura of Junta deCastilla y Leon, under Project BU034U16

Values of density (ρ), speed of sound (c) and refractive index (nD) for N,N-dimethylformamide (DMF) + N-propylpropan-1-amine (DPA) or + butan-1-amine (BA) mixtures at (293.15−303.15) K, and for DMF + N-butylbutan-1-amine (DBA) or hexan-1-amine (HxA) mixtures at 298.15 K are reported. Density and speed of sound measurements were conducted using a vibrating-tube densimeter and sound analyser, Anton Paar model DSA5000; refractive index values, nD values were obtained by means of a RFM970 refractometer from Bellingham+Stanley. The experimental ρ, c and nD values have been used to determine excess molar volumes, VmE, excess adiabatic compressibilities, κSE, excess speeds of sound, cE, excess thermal expansion coefficients, αpE, and excess refractive indices, nDE. This set of data shows the existence of interactions between unlike molecules and of structural effects in the mixtures under study. VmE values of solutions including linear secondary amines are lower than those of mixtures with linear primary amines....

1-Alkanol + alkanonitrile systems have been studied by means of the DISQUAC, ERAS and UNIFAC (Dortmund) models. DISQUAC and ERAS parameters for the alkanol/nitrile interactions are reported. DISQUAC describes a whole set of thermodynamic properties: phase equilibria, vapor–liquid (VLE), liquid–liquid (LLE) and solid–liquid (SLE) equilibria, molar excess functions: Gibbs energies, G m E , enthalpies, H m E , and partial excess molar enthalpies at infinite dilution, H m i E , ∞ using the same set of interaction parameters for each solution. The dependence on the molecular structure of the interaction parameters is similar to that observed in other previous applications to mixtures formed by 1-alkanols and a strongly polar compound, in such way that the quasichemical interchange coefficients can be kept constant from 1-propanol. However, methanol and ethanol solutions behave differently. From the analysis of experimental data for H m E , T S m E ( = H m E − G m E ) , and molar excess volumes, V m E , it is concluded that the studied systems are characterized by dipolar interactions and strong structural effects. The former are more relevant in acetonitrile solutions. Association effects are more important in butanenitrile mixtures. DISQUAC gives better results than the ERAS model. ERAS results on H m E for systems containing acetonitrile are also improved by UNIFAC. This remarks the importance of dipolar interactions in the investigated mixtures. ERAS describes the variation of V m E (x1 = 0.5) with the 1-alkanol size for mixtures with a given nitrile, but the concentration dependence of this excess function is poorly represented.

The coexistence curves of liquid-liquid equilibrium (LLE) for the mixtures: phenylacetonitrile + heptane, + octane, + nonane, + cyclooctane, or + 2,2,4-trimethylpentane and for 3-phenylpropionitrile + heptane, or + octane are reported. Aromatic nitrile + alkane, + aromatic hydrocarbon or + 1 alkanol systems are investigated using a set of thermophysical properties: phase equilibria (solid-liquid, SLE, vapour-liquid, VLE and LLE), excess molar functions, enthalpies (), isochoric internal energies (), isobaric heat capacities () and volumes (), and the Kirkwood’s correlation factor. Due to proximity effects between the phenyl and the CN groups, dipolar interactions between molecules of aromatic nitriles are stronger than those between molecules of isomeric linear nitriles. Dipolar interactions become weaker in the order: 3-phenylpropionitrile > phenylacetonitrile > benzonitrile. Benzonitrile + aromatic hydrocarbon mixtures are characterized by dispersive interactions and structural effects. The latter are more important in systems with phenylacetonitrile. Structural effects are also present in benzonitrile + n-alkane, or + 1-alkanol + mixtures. The systems mentioned above have been studied using DISQUAC. Interaction parameters for contacts where the CN group in aromatic nitriles participates are given. DISQUAC describes correctly any type of phase equilibria, of benzonitrile + hydrocarbon mixtures and of benzonitrile + cyclohexane, or 1-alkanol systems. Large differences encountered between theoretical values and experimental data for some solutions are discussed. 1-Alkanol + benzonitrile mixtures are also investigated by means of the ERAS model. ERAS represents well of these systems. The curves of solutions with longer 1-alkanols are more poorly described, which has been explained in terms of the existence of structural effects., Consejería de Educación y Cultura of Junta de Castilla y León, under Project BU034U16

Producción Científica, Relative permittivities at 1 MHz and at (293.15-303.15) K are reported for the binary systems N,N-dimethylacetamide (DMA) + N-propylpropan-1-amine (DPA), + N-butylbutan-1-amine (DBA), + butan-1-amine (BA) or + hexan-1-amine (HxA) and for N,N-dimethylformamide (DMF) + aniline. The excess permittivities are large and negative for systems with DMA, whereas they are large and positive for the aniline mixture. From the analysis of these excess permittivity data and of measurements previously reported, it is concluded: (i) the main contribution to the excess permittivity in systems with linear amines arises from the breaking of interactions between like molecules; (ii) in the DMF + aniline mixture, interactions between unlike molecules contribute positively to the excess permittivity, and such a contribution is dominant; (iii) longer linear amines are better breakers of the amide-amide interactions; (iv) interactions between unlike molecules are more easily formed when shorter linear amines, or DMF, participate. These findings are confirmed by a general study conducted in terms of excess values of molar orientational and induced polarizabilities and of the relative Kirkwood correlation factors for systems and components. The ERAS model is also applied to amide + amine mixtures. ERAS represents rather accurately the excess enthalpies and volumes of the mentioned systems. The variation of the cross-association equilibrium constants, determined using ERAS, with the molecular structure is in agreement with that observed for the excess permittivity., The authors gratefully acknowledge the financial support received from the Consejería de Educación y Cultura of Junta de Castilla y León, under Project BU034U16. F. Hevia and A. Cobos are grateful to Ministerio de Educación, Cultura y Deporte for the grants FPU14/04104 and FPU15/05456 respectively.

Interactions and structure of alkanone, or alkanal or dialkyl carbonate + alkane mixtures, or of 2-alkanone + 2-alkanone, or of ketone + dialkyl carbonate systems have been investigated by means of a set of thermodynamic properties and by the application of the Flory model. The properties considered are excess molar quantities: enthalpies, HmE, volumes, VmE, or isobaric heat capacities, CpmE, and liquid-liquid equilibria. Experimental data show that alkane mixtures are characterized by rather strong dipolar interactions. In the case of systems containing ketones with the same number of C atoms and a given alkane, dipolar interactions become weaker in the sequence: aromatic > cyclic > linear. In addition, the mentioned interactions become also weaker in the order: dialkyl carbonate > linear alkanone > linear alkanal. This is an important result, as carbonates show lower effective dipole moments than the other compounds, and it suggests that the group size may be relevant when evaluating thermodynamic properties of liquid mixtures. Results on HmE from the Flory model show that orientational effects (i.e., non-random mixing) are rather similar for systems with linear, cyclic or aromatic ketones or alkanals and alkanes. In contrast, orientational effects become weaker in dialkyl carbonate + alkane mixtures. The behavior of 2-alkanone + 2-alkanone systems and of mixtures of longer 2-alkanones or cyclohexanone with dialkyl carbonate is close to random mixing. Larger orientational effects are encountered in solutions of carbonates and shorter 2-alkanones., Consejería de Educación y Cultura of Junta de Castilla y León, under Project BU034U16.

Liquid−liquid equilibrium (LLE) phase diagrams have been determined, by means of the critical opalescence method with a laser scattering technique, for the mixtures 4-phenylbutan-2- one + CH3(CH2)nCH3 (n = 10,12,14) and for benzyl ethanoate + CH3(CH2)nCH3 (n = 12,14). The systems are characterized by having an upper critical solution temperature (UCST), which increases with n. The corresponding LLE curves show a rather horizontal top and become skewed toward higher mole fractions of the polar compound when n is increased. Calorimetric and LLE measurements show that, for mixtures with molecules with a given functional group, interactions between aromatic molecules are stronger than those between homomorphic linear molecules (aromaticity effect). This has been ascribed to proximity effects arising from the presence of the polar group and the aromatic ring within the same molecule. Proximity effects become weaker in the sequence 1-phenylpropan-2-one >4-phenylbutan-2-one >1-phenylethanone and are more important in benzyl ethanoate than in ethyl benzoate molecules. Values of the critical compositions and temperatures calculated with the DISQUAC group contribution model are in good agreement with the experimental results. Accordingly, the shape of the LLE curves is also correctly described by DISQUAC., Junta de Castilla y León, under Project BU034U16