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Isaías García De La Fuente - One of the best experts on this subject based on the ideXlab platform.
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liquid liquid equilibria for 2 hydroxy benzaldehyde n alkane mixtures intermolecular and proximity effects in systems containing hydroxyl and aldehyde groups
The Journal of Chemical Thermodynamics, 2019Co-Authors: J A Gonzalez, Fernando Hevia, L. F. Sanz, Cristina Alonsotristan, Isaías García De La FuenteAbstract:Abstract 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.
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Thermodynamics of mixtures with strongly negative deviations from Raoult's law. XVI. Permittivities and refractive indices for 1-Alkanol + di-n-propylamine systems at (293.15–303.15) K. Application of the Kirkwood-Fröhlich model
Journal of Molecular Liquids, 2018Co-Authors: Fernando Hevia, Ana Cobos, Juan Antonio González, Isaías García De La Fuente, L. F. SanzAbstract:Abstract 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
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thermodynamics of mixtures containing a very strongly polar compound 12 systems with nitrobenzene or 1 nitroalkane and hydrocarbons or 1 Alkanols
Fluid Phase Equilibria, 2018Co-Authors: Juan Antonio González, Fernando Hevia, Isaías García De La Fuente, Luis Felipe . Sanz, Cristina AlonsotristanAbstract:Abstract 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.
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liquid liquid equilibria for acetophenone n alkane mixtures and characterization of acetophenone systems using disquac
Fluid Phase Equilibria, 2015Co-Authors: J A Gonzalez, Isaías García De La Fuente, Cristina Alonsotristan, José Carlos CobosAbstract:Abstract Liquid–liquid equilibrium (LLE) temperatures have been determined for acetophenone + CH3(CH2)uCH3 (u = 8,10,12,14) mixtures by means of the opalescence method using a laser scattering technique. All the solutions show an upper critical solution temperature (UCST), which increases almost linearly with u. Acetophenone + benzene, or +alkane, or +1-Alkanol mixtures have been treated by means of the DISQUAC model. The corresponding dispersive and quasi-chemical interaction parameters for the contacts CO/aromatic; CO/aliphatic; CO/c-CH2 and CO/hydroxyl are reported. The model correctly describes LLE diagrams and excess molar enthalpies, H m E , of the investigated solutions, over a wide range of temperature using the same set of interaction parameters. Mixtures with alkanes are mainly characterized by dipolar interactions. From the analysis of molar excess functions: H m E , volumes, V m E , and internal energies at constant volume, U V m E , and on LLE for such systems, it is shown that interactions between acetophenone molecules are stronger than those between 2-hexanone or 2-octanone molecules and that they are similar to acetone–acetone interactions. Thus, the phenyl ring in acetophenone leads to strengthened interactions between alkanone molecules. Dipolar interactions are also important in mixtures containing 1-Alkanols, and become more relevant in solutions with longer 1-Alkanols. The enthalpy of the alcohol–acetophenone interactions, ΔHOH–CO, were determined. This magnitude increases with the Alkanol size and remains practically constant from 1-butanol.
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thermodynamics of mixtures containing a very strongly polar compound 11 1 Alkanol alkanenitrile systems
Thermochimica Acta, 2015Co-Authors: J A Gonzalez, Fernando Hevia, Ana Cobos, Isaías García De La Fuente, Cristina AlonsotristanAbstract:Abstract 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.
J A Gonzalez - One of the best experts on this subject based on the ideXlab platform.
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liquid liquid equilibria for 2 hydroxy benzaldehyde n alkane mixtures intermolecular and proximity effects in systems containing hydroxyl and aldehyde groups
The Journal of Chemical Thermodynamics, 2019Co-Authors: J A Gonzalez, Fernando Hevia, L. F. Sanz, Cristina Alonsotristan, Isaías García De La FuenteAbstract:Abstract 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.
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thermodynamics of mixtures with strong negative deviations from raoult s law xiii relative permittivities for 1 Alkanol cyclohexylamine systems and dielectric study of 1 Alkanol polar compound amine amide or ether mixtures
The Journal of Chemical Thermodynamics, 2015Co-Authors: J A Gonzalez, Isasías García De La Fuente, L. F. Sanz, José Carlos CobosAbstract:Abstract Relative permittivities, e r , at 1 MHz have been measured for (1-Alkanol + cyclohexylamine) systems at T = (293.15 to 303.15) K and atmospheric pressure. The excess permittivity values, e r E , Kirkwood’s correlation factors, g K , and the excess values of this magnitude, g K E , have been also determined for these solutions and, using measurements available in the literature, for mixtures containing a number of 1-Alkanols and n-propylamine, n-butylamine, aniline, N-methylaniline, pyridine, di-n-ethylamine, N,N-dimethylformamide, N,N-dimethylacetamide, di-n-propylether, di-n-butylether, 2,5,8,11,14-pentaoxapentadecane, or propanal. At ϕ 1 (volume fraction) = 0.5, e r E values of cyclohexylamine solutions change in the sequence: 1-propanol > 1-butanol > 1-heptanol e r E curves becomes skewed to higher ϕ 1 values when the alcohol size increases. This seems to be a rather general behavior as is also encountered for many of the systems investigated. It can be explained in terms of the weaker and lower self-association of longer 1-Alkanols. The analysis of g K data shows that cyclohexylamine solutions including shorter alcohols are more structured. In addition, mixtures with this cyclic amine are more structured than those containing a linear amine or aniline. The e r E ( ϕ 1 ) and g K E ( ϕ 1 ) curves of (1-Alkanol + amine) mixtures show similar patterns. Thus, negative e r E values can be ascribed to the real mixture is less structured than the ideal solution; positive e r E values are due to the system is more structured than the ideal solution. We have also determined the orientational polarization and the corresponding excess values, P m E . The P m E and g K E functions have the same sign That is, negative values of such magnitudes suggest that the loss of structure of the real mixture compared with that of the ideal solution can be ascribed, at least in part, to a weakening of the orientational polarization.
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liquid liquid equilibria for acetophenone n alkane mixtures and characterization of acetophenone systems using disquac
Fluid Phase Equilibria, 2015Co-Authors: J A Gonzalez, Isaías García De La Fuente, Cristina Alonsotristan, José Carlos CobosAbstract:Abstract Liquid–liquid equilibrium (LLE) temperatures have been determined for acetophenone + CH3(CH2)uCH3 (u = 8,10,12,14) mixtures by means of the opalescence method using a laser scattering technique. All the solutions show an upper critical solution temperature (UCST), which increases almost linearly with u. Acetophenone + benzene, or +alkane, or +1-Alkanol mixtures have been treated by means of the DISQUAC model. The corresponding dispersive and quasi-chemical interaction parameters for the contacts CO/aromatic; CO/aliphatic; CO/c-CH2 and CO/hydroxyl are reported. The model correctly describes LLE diagrams and excess molar enthalpies, H m E , of the investigated solutions, over a wide range of temperature using the same set of interaction parameters. Mixtures with alkanes are mainly characterized by dipolar interactions. From the analysis of molar excess functions: H m E , volumes, V m E , and internal energies at constant volume, U V m E , and on LLE for such systems, it is shown that interactions between acetophenone molecules are stronger than those between 2-hexanone or 2-octanone molecules and that they are similar to acetone–acetone interactions. Thus, the phenyl ring in acetophenone leads to strengthened interactions between alkanone molecules. Dipolar interactions are also important in mixtures containing 1-Alkanols, and become more relevant in solutions with longer 1-Alkanols. The enthalpy of the alcohol–acetophenone interactions, ΔHOH–CO, were determined. This magnitude increases with the Alkanol size and remains practically constant from 1-butanol.
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thermodynamics of mixtures containing a very strongly polar compound 11 1 Alkanol alkanenitrile systems
Thermochimica Acta, 2015Co-Authors: J A Gonzalez, Fernando Hevia, Ana Cobos, Isaías García De La Fuente, Cristina AlonsotristanAbstract:Abstract 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.
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thermodynamics of mixtures containing amines xvi of 1 butanol 1 octanol or 1 decanol benzylamine systems at 298 15 308 15 318 15 and 333 15 k
Thermochimica Acta, 2015Co-Authors: Ricardo Paramo, J A Gonzalez, Isaías García De La Fuente, C Casanova, José Carlos CobosAbstract:Abstract Molar isobaric heat capacities, C pm , and molar excess isobaric heat capacities, C pm E , are reported for 1-butanol, 1-octanol or 1-decanol + benzylamine systems at (293.15, 308.15, 318.15, 333.15) K. C pm E values were measured with a Setaram Micro DSC II microcalorimeter using a scanning method. The investigated mixtures are characterized by large and positive C pm E ( x 1 = 0.5 ) values at 298.15 K, which remarks that self-association and/or solvation effects are predominant in such solutions. The C pm E curves are skewed towards higher mole fractions of the alcohol, which suggests that alcohol-amine interactions are more probable in that region. In addition, for a given 1-Alkanol, C pm E ( x 1 = 0.5 ) decreases when temperature increases, due to alcohol dissociation is larger at elevated temperatures. The lower self-association of longer 1-Alkanols and lower solvation effects may explain that the C pm E ( x 1 = 0.5 ) change with temperature is sharper for the solutions with the mentioned alcohols. The observed decrease of C pm E ( x 1 = 0.5 ) with the increasing of the chain length of the alcohol at enough high temperatures may be explained in similar terms.
Cristina Alonsotristan - One of the best experts on this subject based on the ideXlab platform.
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liquid liquid equilibria for 2 hydroxy benzaldehyde n alkane mixtures intermolecular and proximity effects in systems containing hydroxyl and aldehyde groups
The Journal of Chemical Thermodynamics, 2019Co-Authors: J A Gonzalez, Fernando Hevia, L. F. Sanz, Cristina Alonsotristan, Isaías García De La FuenteAbstract:Abstract 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.
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thermodynamics of mixtures containing a very strongly polar compound 12 systems with nitrobenzene or 1 nitroalkane and hydrocarbons or 1 Alkanols
Fluid Phase Equilibria, 2018Co-Authors: Juan Antonio González, Fernando Hevia, Isaías García De La Fuente, Luis Felipe . Sanz, Cristina AlonsotristanAbstract:Abstract 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.
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liquid liquid equilibria for acetophenone n alkane mixtures and characterization of acetophenone systems using disquac
Fluid Phase Equilibria, 2015Co-Authors: J A Gonzalez, Isaías García De La Fuente, Cristina Alonsotristan, José Carlos CobosAbstract:Abstract Liquid–liquid equilibrium (LLE) temperatures have been determined for acetophenone + CH3(CH2)uCH3 (u = 8,10,12,14) mixtures by means of the opalescence method using a laser scattering technique. All the solutions show an upper critical solution temperature (UCST), which increases almost linearly with u. Acetophenone + benzene, or +alkane, or +1-Alkanol mixtures have been treated by means of the DISQUAC model. The corresponding dispersive and quasi-chemical interaction parameters for the contacts CO/aromatic; CO/aliphatic; CO/c-CH2 and CO/hydroxyl are reported. The model correctly describes LLE diagrams and excess molar enthalpies, H m E , of the investigated solutions, over a wide range of temperature using the same set of interaction parameters. Mixtures with alkanes are mainly characterized by dipolar interactions. From the analysis of molar excess functions: H m E , volumes, V m E , and internal energies at constant volume, U V m E , and on LLE for such systems, it is shown that interactions between acetophenone molecules are stronger than those between 2-hexanone or 2-octanone molecules and that they are similar to acetone–acetone interactions. Thus, the phenyl ring in acetophenone leads to strengthened interactions between alkanone molecules. Dipolar interactions are also important in mixtures containing 1-Alkanols, and become more relevant in solutions with longer 1-Alkanols. The enthalpy of the alcohol–acetophenone interactions, ΔHOH–CO, were determined. This magnitude increases with the Alkanol size and remains practically constant from 1-butanol.
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thermodynamics of mixtures containing a very strongly polar compound 11 1 Alkanol alkanenitrile systems
Thermochimica Acta, 2015Co-Authors: J A Gonzalez, Fernando Hevia, Ana Cobos, Isaías García De La Fuente, Cristina AlonsotristanAbstract:Abstract 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.
Fernando Hevia - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamics of mixtures containing a very strongly polar compound. 12. Systems with nitrobenzene or 1-nitroalkane and hydrocarbons or 1-Alkanols
Elsevier, 2020Co-Authors: Juan Antonio González, Fernando Hevia, Luis Felipe . Sanz, García De La Fuente, Isaías ., Alonso Tristán CristinaAbstract: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 Educacion y Cultura of Junta deCastilla y Leon, under Project BU034U1
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Thermodynamics of mixtures with strongly negative deviations from Raoult's law. XV. Permittivities and refractive indices for 1-Alkanol + n-hexylamine systems at (293.15–303.15) K. Application of the Kirkwood-Fröhlich model
Elsevier, 2020Co-Authors: Fernando Hevia, Ana Cobos, Juan Antonio González, García De La Fuente, Isaías ., Alonso Tristán CristinaAbstract: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
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liquid liquid equilibria for 2 hydroxy benzaldehyde n alkane mixtures intermolecular and proximity effects in systems containing hydroxyl and aldehyde groups
The Journal of Chemical Thermodynamics, 2019Co-Authors: J A Gonzalez, Fernando Hevia, L. F. Sanz, Cristina Alonsotristan, Isaías García De La FuenteAbstract:Abstract 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.
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Thermodynamics of mixtures with strongly negative deviations from Raoult's law. XVI. Permittivities and refractive indices for 1-Alkanol + di-n-propylamine systems at (293.15–303.15) K. Application of the Kirkwood-Fröhlich model
Journal of Molecular Liquids, 2018Co-Authors: Fernando Hevia, Ana Cobos, Juan Antonio González, Isaías García De La Fuente, L. F. SanzAbstract:Abstract 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
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thermodynamics of mixtures containing a very strongly polar compound 12 systems with nitrobenzene or 1 nitroalkane and hydrocarbons or 1 Alkanols
Fluid Phase Equilibria, 2018Co-Authors: Juan Antonio González, Fernando Hevia, Isaías García De La Fuente, Luis Felipe . Sanz, Cristina AlonsotristanAbstract:Abstract 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.
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1 o hexadecyl 2 desoxy 2 amino sn glycerol a substrate for human sphingosine kinase
Biochimica et Biophysica Acta, 2002Co-Authors: Sofie Gijsbers, Stanny Asselberghs, Piet Herdewijn, Paul P Van VeldhovenAbstract:The substrate specificity of human sphingosine kinase was investigated using a bacterially expressed poly(His)-tagged protein. Only the D-erythro isomer of the sphingoid bases, sphinganine and sphingenine, was effectively phosphorylated. Long chain 1-Alkanols, alkane-1,2-diols, 2-amino-1-Alkanol or 1-amino-2-Alkanol and short chain 2-amino-1,3-alkanediols were very poor substrates, indicating that the kinase is recognizing the chain length and the position of the amino and secondary hydroxy group. A free hydroxy group at carbon 3 is not a prerequisite, however, since 1-O-hexadecyl-2-desoxy-2-amino-sn-glycerol was an efficient substrate with an apparent K(m) value of 3.8 microM (versus 15.7 microM for sphingenine). This finding opens new perspectives to design sphingosine kinase inhibitors. It also calls for some caution since it cannot be excluded that this ether lipid analogue is formed from precursors that are frequently used in research on platelet activating factor or from phospholipid analogues which are less prone to degradation.