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Producción Científica, The CH3(CH2)uCOO(CH2)vCH3 + n-alkane mixtures have been investigated on the basis of an experimental database containing effective dipole moments of esters, and excess molar functions of the systems: enthalpies (HEm), volumes (VEm ), isobaric heat capacities (CEpm ) and isochoric internal energies (UEVm ) and by means of the application of the Flory model and the Kirkwood-Buff formalism. The situation of the mixtures within theGEm (excess molar Gibbs energy) vs. HEm diagram has also been briefly considered. Results indicate that dispersive interactions are dominant and that steric effects can explain some differences between solutions containing heptane and isomeric esters. Proximity and orientational effects are also discussed in diester + hexane mixtures. In the case of systems with a given alkane and different isomeric polar compounds, orientational effects become weaker in the order: n-alkanone > dialkyl carbonate > n-alkanoate. Results from the Kirkwood-Buff formalism indicate that the number of ester-ester interactions decreases in systems with alkyl ethanoates when the alkyl size increases and that preferential solvation between polar molecules decreases as follows: dialkyl carbonate > n-alkanone > n-alkanoate., Ministerio de Ciencia e Innovación /AEI/10.13039/501100011033/ FEDER (PID2022-137104NA-I00)

Producción Científica, The mixtures 2-propanol or 2-butanol + n-alkanone, or + acetophenone, or + linear monoether, or + cyclic ether, or + linear organic carbonate, or + propylene carbonate have been investigated using thermodynamic data, and in terms of the Flory theory, and the Kirkwood-Buff integrals. The data considered are: excess molar enthalpies (), volumes, entropies, and the temperature dependence of. The enthalpy of the 2-alkanol-solvent interactions have been determined, and the different contributions to discussed. It is shown that values of the 2-alkanol (fixed) + n-alkanone, or + linear carbonate mixtures change in the same manner that for n-alkanone, or linear carbonate + n-alkane (fixed) systems. In contrast, values of 2-alkanol (fixed) + linear monoether or + n-alkane mixtures change similarly. This set of results suggests that solvent–solvent interactions are determinant in systems with n-alkanone or linear carbonate, while interactions between alcohol molecules are determinant in mixtures with linear monoethers. According to the Flory model, orientational effects in systems with a given 2-alkanol become weaker in the sequence: linear monoether > linear organic carbonate > n-alkanone, and are stronger in solutions with a cyclic monoether than in those with cyclic diethers, and in systems with acetophenone or propylene carbonate than in the mixtures with the corresponding linear solvents. Results obtained from the Kirkwood-Buff integrals are consistent with these findings. The application of Flory model reveals that orientational effects are similar in systems with 1- or 2-alkanols, with the exception of solutions with linear monoethers, where such effects are stronger in mixtures containing 1-alkanols. For the examined systems, the formalism of the Kirkwood-Buff integrals makes no meaningful distinction between solutions with 1-alkanols or 2-alkanols.

El estudio de sistemas formados por un componente aromático polar con alcanos desarrollado en este TGF es original y requiere gran destreza experimental y amplios conocimientos termodinámicos. Esto ha culminado con el estudio de la influencia de la la longitud de la cadena alifática unida al anillo aromático en la miscibilidad cuando se mezcla con un alcano. Los datos experimentales se han obtenido mediante la utilización de un dispositivo (de diseño y fabricación propia) de medición de la opalescencia crítica. El equipo se ha calibrado y testeado midiendo un sistema test y se ha comparado los resultados con los encontrados en la bibliografía., Departamento de Física Aplicada, Grado en Física

The systems C6H5Cl, or C6H5Br, or 1-chloronaphthalene, or 1,2,4-trichlorobenzene, or 1-methylnaphthalene, or 1,2,4-trimethylbenzene + alkane have been investigated by means of the their excess molar properties, including, when the needed data are available, those at constant volume, internal energies (U_Vm^E) and heat capacities (C_Vm^E), and using the DISQUAC, and Flory models, and the concentration-concentration structure factor formalism. The position of the mixtures within the G_m^E (excess molar Gibbs energy) vs. H_m^E (excess molar enthalpy) diagram has been also determined. Interactions between C6H5X molecules become stronger in the sequence X = H ≈ F≈Cl < Br. These interactions are weaker than those between 1-chloronaphtahlene or 1,2,4-trichlorobenzene molecules. It is shown that the considered systems have some common features: dispersive interactions are dominant, structural effects for solutions with shorter n-alkanes are large and U_Vm^Edecreases when the number (n) of C atoms of the alkane increases. This variation is held when an n-alkane is replaced by a branched alkane with the same n in systems with C6H5Cl or 1-chloronaphthalene. This suggests that larger alkanes are poorer breakers of the interactions between aromatic halogenated compounds. Viscosity and C_Vm^E data support this conclusion. The parabolic dependence of C_Vm^E with n indicates that the short orientational order of long n-alkanes is destroyed. Aromaticity and proximity effects are discussed., Project VA100G19 (Apoyo a GIR), Castilla y Leon Regional Grant

El estudio de sistemas formados por un componente aromático polar con alcanos desarrollado en este TGF es original y requiere gran destreza experimental y amplios conocimientos termodinámicos. Esto ha culminado con el estudio de la influencia de la la longitud de la cadena alifática unida al anillo aromático en la miscibilidad cuando se mezcla con un alcano. Los datos experimentales se han obtenido mediante la utilización de un dispositivo (de diseño y fabricación propia) de medición de la opalescencia crítica. El equipo se ha calibrado y testeado midiendo un sistema test y se ha comparado los resultados con los encontrados en la bibliografía., Departamento de Física Aplicada, Grado en Física

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 (SCC(0)) formalism. DISQUAC interaction parameters SCC (0) 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 excess molar enthalpy (HmE) 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 excess molar isobaric heat capacity (CpmE) of solutions involving n-alkanes, or on HmE 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 CpmE values of these systems. It is shown that structural effects can contribute largely to HmE. This is investigated in terms of the excess molar internal energy at constant volume, UVmE , whose values are determined for the investigated solutions. For mixtures with a given n-alkane, the relative variation of HmE and UVmE with the fluorohydrocarbons is different. HmE valuesn change in the sequence C6F6 > 1,4-C6H4F2> C6H6 > C6H5F, while UVmE changes in the order: 1,4-C6H4F2> C6H6 ≈ C6H5F > C6F6 . C6F6 + aromatic hydrocarbon mixtures are characterized by interactions between unlike mol, Project VA100G19 (Apoyo a GIR), Castilla y Leon Regional Grant

Systems of the type linear primary or secondary amine + cyclohexane, or + polar (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, HmE, and vapour-liquid and solid-liquid equilibria of the studied mixtures and improves calculations on HmE 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 HmE 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 HmE 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., Project VA100G19 (Apoyo a GIR), Castilla y Leon Regional Grant

Densities and kinematic viscosities of binary mixtures of methanol + 2,5,8-trioxanonane, or + 2,5,8,11-tetraoxadodecane, or + 2,5,8,11,14-pentaoxapentadecane have been measured over the whole composition range at 293.15, 298.15 and 303.15 K and atmospheric pressure. Densities were determined using a vibrating-tube density meter and viscosities were measured with an automatic Ubbelohde capillary viscometer. The experimental results have been used to calculate the excess molar volumes, V E m , and the deviations of dynamic viscosity, . Moreover, viscosity data were correlated by some semi-empirical equations (Grunberg-Nissan, Hind, Frenkel, Katti- Chaudhri, McAllister and Heric). The large and negative V E m and the positive values obtained seem to remark the predominant contribution of free volume effects on interactional effects to these thermophysical properties., Departamento de Física Aplicada, Máster en Física

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, HmE , are large and positive, which reveal 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 HmE 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, TS_m^E, isobaric heat capacities, C_pm^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 vapor-liquid equilibria data. Many systems under consideration are characterized by dipolar interactions between like molecules as it is indicated by LLE data. In addition, in the diagram G_m^E vs. H_m^E, they are located between the lines G_m^E=H_m^E/2 andG_m^E=H_m^E, which is the region where systems such as n-alkanone, or linear organic carbonate, or N-methylpyrrolidone + alkane are encountered. Consequently, they have H_m^E> 0, C_pm^E> 0 andTS_m^E> 0. 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 systems containing NM, or NTBz, or BzCN or SULF or the mixture 1-octanol + EtN, are characterized by interactions between like molecules, which is in agreement with the available LLE data for these solutions. For DMSO systems or mixtures formed by EtN and shorter 1-alkanols, the local mole fractions do not differ from the bulk ones and the mixture structure can be ascribed to orienta

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, Junta de Castilla y León Regional Grant BU034U16, Ministerio de Educación, Cultura y Deporte (MECD): Grant FPU14/04104

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 (HE m), isochoric internal energies (UE Vm), isobaric heat capacities (CEpm) and volumes (VEm), and the Kirkwood’s correlation factor. Due to proximity effects between thephenyl and the CN groups, dipolar interactions between molecules of aromatic nitriles are stronger thanthose 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, CEpm of benzonitrile + hydrocarbon mixtures and HEm of benzonitrile + cyclohexane, or 1-alkanol systems. Large differences encountered between theoretical HEm 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 HEm of these systems. The Vem curves of solutions with longer 1-alkanols are more poorly described, which has been explained in terms of the existence of structural effects., Junta de Castilla y León Regional Grant BU034U16, Ministerio de Educación, Cultura y Deporte (MECD): Grant FPU14/04104

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_pm^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., Junta de Castilla y León Regional Grant BU034U16, Ministerio de Educación, Cultura y Deporte (MECD): Grant FPU14/04104

Mediante la medida experimental de la densidad, viscosidad, índice de refracción y permitividad a tres temperaturas (293.15, 298.15 y 303.15 K) y el cálculo de diferentes magnitudes derivadas, se ha procedido a estudiar las interacciones intermoleculares que se producen en las mezclas líquidas binarias de 1-alcohol (metanol, 1-propanol, 1-butanol, 1-heptanol y 1-decanol) con la ciclohexilamina., Departamento de Física Aplicada, Doctorado en Física

Aborda el estudio de mezclas binarias de líquidos y la medida directa de 5 propiedades termofísicas: - Permitividad - Índice de refracción - Densidad - Velocidad del sonido - Capacidad calorífica La primera parte, instrumental, explica: - Funcionamiento y fundamento físico de todos los aparatos. - Puesta a punto dos técnicas experimentales nuevas en el grupo: Permitividades e Índice de refracción - Calibración y sistema test para la evaluación de la precisión y exactitud de las medidas realizadas. La segunda parte expone los resultados de las medidas, sus correspondientes excesos respecto de la mezcla ideal y la discusión para los sistemas caracterizados, relativos a mezclas de los siguientes líquidos: - n-Heptano - n-Octano - Dibutiléter - 2,5,8,11,14-pentaoxapentadecano - Metanol - 1-Propanol - 1-Pentanol - Bencilamina - Anilina La tercera parte, incluye anexos con los programas informáticos creados al efecto para automatizar las medidas, así como los programas utilizados., Departamento de Física Aplicada

En este trabajo se hace un estudio experimental y teórico de mezclas binarias que incluyen N,N-Dimetilformamida + amina (Di-n-propilamina, Di-n-butilamina, n-Hexilamina). En concreto, se determinan densidades, velocidades del sonido, volúmenes molares de exceso, compresibilidades isoentrópicas de exceso, velocidades del sonido de exceso, coeficientes de dilatación térmica de exceso, presiones internas, índices de refracción de exceso, refracciones molares, etc. a diferentes composiciones, presión atmosférica y varias temperaturas. Los datos obtenidos se utilizan para investigar los efectos interaccionales y estructurales en los sistemas considerados. Se concluye que las mezclas están caracterizadas por interacciones importantes entre moléculas de amida y de amina y se ponen de relieve efectos estructurales relacionados sobre todo con el tamaño de las moléculas. El estudio realizado contribuye con nuevo conocimiento empírico al ya existente de las mezclas que contienen un componente fuertemente polar., Departamento de Física Aplicada, Máster en Instrumentación en Física

1-Alkanol + alkanenitrile 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, vapour-liquid (VLE), liquid-liquid (LLE) and solid-liquid (SLE) equilibria, molar excess functions, Gibbs energies,G_m^E, and enthalpies, H_m^E, and partial excess molar enthalpies at infinite dilution, H_mi^(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, TS_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 improvesH_m^Eresults from the ERAS model. ERAS results onH_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(x_1=0.5) with the 1-alkanol size for mixtures with a given nitrile, but the concentration dependence of this excess function is poorly represented.

Contribución Experimental: Calibrado y puesta a punto del densímetro Anton Paar DSA 5000 y del microcalorímetro Tian-Calvet. Determinación de los volúmenes, las compresibilidades isoentrópicas y las entalpías de exceso de mezclas amina + cetona o + n-alcano. El estudio se ha completado con el análisis espectroscópico de mezclas 2-butanona + amina. Contribución Teórica: Formulación de las ecuaciones de la Termodinámica de mezclas. Estudio mecánico-estadístico de líquidos y de mezclas de no electrolitos. Se han estudiado las hipótesis fundamentales de diferentes modelos y sus ecuaciones. Los modelos ERAS y DISQUAC se han aplicado a las mezclas estudiadas, lo que ha permitido obtener algunas conclusiones importantes acerca de sus propiedades. Haciendo uso de los resultados experimentales, se presenta la aplicación de los modelos anteriores para el estudio de mezclas amina + cetona o +n-alcano. Además, se han discutido las propiedades generales de las mezclas de interés en base a consideraciones puramente experimentales., Departamento de Física Aplicada