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Application of the Flory theory and of the Kirkwod-Buff formalism to the study of orientational effects in 1-alkanol + linear or cyclic monoether mixtures / Juan Antonio Gonzalez in Industrial & engineering chemistry research, Vol. 48 N° 15 (Août 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7417–7429 Titre : Application of the Flory theory and of the Kirkwod-Buff formalism to the study of orientational effects in 1-alkanol + linear or cyclic monoether mixtures Type de document : texte imprimé Auteurs : Juan Antonio Gonzalez, Auteur ; Nicolás Riesco, Auteur ; Ismael Mozo, Auteur Année de publication : 2009 Article en page(s) : pp. 7417–7429 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Orientational  effects  1-alkanols  Cyclic  monoethers  Flory  mode  Kirkwood−Buff  formalism Résumé : Orientational effects present in binary mixtures of 1-alkanols with linear or cyclic monoethers have been studied using the Flory model and the Kirkwood−Buff formalism. The alcohols considered are those from methanol to 1-decanol, and the ethers are the following: dimethylether (DME), diethylether (DEE), dipropylether (DPE), dibutylether (DBE), tetrahydrofuran (THF), and tetrahydropyran (THP). In terms of the Flory model, orientational effects have been investigated by analyzing the concentration dependence of the interaction parameter, X12, and comparing the deviations obtained between experimental molar excess enthalpies, HmE, and calculated values with an X12 parameter determined from HmE measurements at equimolar composition. Due to the facts that structural effects are relevant for many of the considered mixtures and their excess molar volumes, VmE, are negative, we have also determined the excess molar internal energies, UV,mE, and X12 parameters from these data. From the X12 variation with the alkanol size, we have shown than interactions between unlike molecules are nearly constant along a homologous series with a given ether. In the framework of the Kirkwood−Buff theory, the study has been developed through the Kirkwood−Buff integrals and related local mole fractions, obtained from vapor−liquid equilibria and VmE data available in the literature. Ideal compressibilities for the mixtures were assumed. Although the Flory model does not describe the complex structural effects present in the investigated mixtures and fails when predicting VmE, both theories provide consistent results on the orientational effects in these solutions. In addition, the results are in agreement with those previously obtained from the ERAS model. Systems involving linear monoethers are mainly characterized by orientational effects related to the self-association of the alcohol, in such way that the mentioned effects decrease when the size of the alcohol is increased in solutions with a given ether. Orientational effects become more relevant when the chain length of the linear monoether mixed with a fixed 1-alkanol increases. It has been shown that dispersive interactions merely differ by size effects for solutions of 1-alkanol (from 1-propanol) and DPE, or DBE. Systems with cyclic monoethers are characterized by a strengthening of dipolar interactions and a weakening of association effects. As a result, orientational effects are weaker in this type of solution. It is remarkable that mixtures with the longer 1-alkanols (from 1-hexanol) show a behavior close to random mixing. Random mixing is also observed when the temperature increases, as in the case of 1-propanol or 1-butanol + diethylether systems at 323.15 K. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004354 [article] Application of the Flory theory and of the Kirkwod-Buff formalism to the study of orientational effects in 1-alkanol + linear or cyclic monoether mixtures [texte imprimé] / Juan Antonio Gonzalez, Auteur ; Nicolás Riesco, Auteur ; Ismael Mozo, Auteur . - 2009 . - pp. 7417–7429. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7417–7429 Mots-clés : Orientational  effects  1-alkanols  Cyclic  monoethers  Flory  mode  Kirkwood−Buff  formalism Résumé : Orientational effects present in binary mixtures of 1-alkanols with linear or cyclic monoethers have been studied using the Flory model and the Kirkwood−Buff formalism. The alcohols considered are those from methanol to 1-decanol, and the ethers are the following: dimethylether (DME), diethylether (DEE), dipropylether (DPE), dibutylether (DBE), tetrahydrofuran (THF), and tetrahydropyran (THP). In terms of the Flory model, orientational effects have been investigated by analyzing the concentration dependence of the interaction parameter, X12, and comparing the deviations obtained between experimental molar excess enthalpies, HmE, and calculated values with an X12 parameter determined from HmE measurements at equimolar composition. Due to the facts that structural effects are relevant for many of the considered mixtures and their excess molar volumes, VmE, are negative, we have also determined the excess molar internal energies, UV,mE, and X12 parameters from these data. From the X12 variation with the alkanol size, we have shown than interactions between unlike molecules are nearly constant along a homologous series with a given ether. In the framework of the Kirkwood−Buff theory, the study has been developed through the Kirkwood−Buff integrals and related local mole fractions, obtained from vapor−liquid equilibria and VmE data available in the literature. Ideal compressibilities for the mixtures were assumed. Although the Flory model does not describe the complex structural effects present in the investigated mixtures and fails when predicting VmE, both theories provide consistent results on the orientational effects in these solutions. In addition, the results are in agreement with those previously obtained from the ERAS model. Systems involving linear monoethers are mainly characterized by orientational effects related to the self-association of the alcohol, in such way that the mentioned effects decrease when the size of the alcohol is increased in solutions with a given ether. Orientational effects become more relevant when the chain length of the linear monoether mixed with a fixed 1-alkanol increases. It has been shown that dispersive interactions merely differ by size effects for solutions of 1-alkanol (from 1-propanol) and DPE, or DBE. Systems with cyclic monoethers are characterized by a strengthening of dipolar interactions and a weakening of association effects. As a result, orientational effects are weaker in this type of solution. It is remarkable that mixtures with the longer 1-alkanols (from 1-hexanol) show a behavior close to random mixing. Random mixing is also observed when the temperature increases, as in the case of 1-propanol or 1-butanol + diethylether systems at 323.15 K. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9004354

Thermodynamics of mixtures containing amines. X. systems with cyclic amines or morpholine / Juan Antonio Gonzalez in Industrial & engineering chemistry research, Vol. 50 N° 16 (Août 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 16 (Août 2011) . - pp. 9810-9820 Titre : Thermodynamics of mixtures containing amines. X. systems with cyclic amines or morpholine Type de document : texte imprimé Auteurs : Juan Antonio Gonzalez, Auteur Année de publication : 2011 Article en page(s) : pp. 9810-9820 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : thermodynamic  Amines  Morpholine Résumé : Cyclic amine or morpholine + organic solvent mixtures have been investigated in terms of DISQUAC and of the Kirkwood―Buffformalism. The amines considered are cyclohexylamine; (c-CH2)uNH (u = 2―7) and (c-CH2)uN―CH3 (u = 4,5). The organic solvents are alkanes and methanol or ethanol. The DISQUAC interaction parameters are reported. The model describes correctly a whole set of thermodynamic properties: vapor―liquid equilibria (VLE); excess Gibbs energies, GEm; excess enthalpies, HEm; excess heat capacities at constant pressure, CEP,m; and partial excess enthalpies at infinite dilution, HE,∞1, as well as the main features of the Kirkwood―Buff integrak. In (c-CH2)uNH + C6H12 mixtures, amine-amine interactions become weaker with increased u values. This is supported by the corresponding decrease of HEm and HE,∞1 and of the effective dipole moment. Interactions between amine molecules are also weakened when passing from a primary cyclic amine to an isomeric tertiary cyclic amine. The existence of an aromatic ring in the amine, as in aniline or pyridine, leads to stronger amine―amine interactions. Dipolar interactions between morpholine molecules are stronger than those between piperidine molecules, and reveal the existence of proximity effects between the two groups of morpholine. In systems with alkanes, interactions between amine molecules are preferred to those between unlike molecules. In piperidine + methanol and pyrrolidine + ethanol systems, the mixture structure is close to random mixing. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201120h [article] Thermodynamics of mixtures containing amines. X. systems with cyclic amines or morpholine [texte imprimé] / Juan Antonio Gonzalez, Auteur . - 2011 . - pp. 9810-9820. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 16 (Août 2011) . - pp. 9810-9820 Mots-clés : thermodynamic  Amines  Morpholine Résumé : Cyclic amine or morpholine + organic solvent mixtures have been investigated in terms of DISQUAC and of the Kirkwood―Buffformalism. The amines considered are cyclohexylamine; (c-CH2)uNH (u = 2―7) and (c-CH2)uN―CH3 (u = 4,5). The organic solvents are alkanes and methanol or ethanol. The DISQUAC interaction parameters are reported. The model describes correctly a whole set of thermodynamic properties: vapor―liquid equilibria (VLE); excess Gibbs energies, GEm; excess enthalpies, HEm; excess heat capacities at constant pressure, CEP,m; and partial excess enthalpies at infinite dilution, HE,∞1, as well as the main features of the Kirkwood―Buff integrak. In (c-CH2)uNH + C6H12 mixtures, amine-amine interactions become weaker with increased u values. This is supported by the corresponding decrease of HEm and HE,∞1 and of the effective dipole moment. Interactions between amine molecules are also weakened when passing from a primary cyclic amine to an isomeric tertiary cyclic amine. The existence of an aromatic ring in the amine, as in aniline or pyridine, leads to stronger amine―amine interactions. Dipolar interactions between morpholine molecules are stronger than those between piperidine molecules, and reveal the existence of proximity effects between the two groups of morpholine. In systems with alkanes, interactions between amine molecules are preferred to those between unlike molecules. In piperidine + methanol and pyrrolidine + ethanol systems, the mixture structure is close to random mixing. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201120h

Thermodynamics of mixtures containing oxaalkanes. 4. / Juan Antonio Gonzalez in Industrial & engineering chemistry research, Vol. 49 N° 19 (Octobre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 19 (Octobre 2010) . - pp. 9511–9524 Titre : Thermodynamics of mixtures containing oxaalkanes. 4. : Random mixing and orientational effects in ether + alkane systems Type de document : texte imprimé Auteurs : Juan Antonio Gonzalez, Auteur Année de publication : 2010 Article en page(s) : pp. 9511–9524 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Thermodynamics  Ether  Alkane  systems Résumé : Molar excess enthalpies, HmE, and volumes, VmE, of linear or cyclic ether + n-alkane systems have been discussed in terms of the effective dipole moment, μ̅, of the ether, differences of standard enthalpies of vaporization of the ether and of the isomeric alkane, the number and relative positions of the oxygen atoms, the shape of the ether, and the relative size of the mixture compounds. The mentioned solutions have also been studied using the Flory model and the Kirkwood−Buff formalism. Both theories provide consistent results. At 298.15 K, the random mixing hypothesis is a good approximation for mixtures including linear or cyclic monoethers or linear diethers. Orientational effects become stronger in solutions with 2,5,8-trioxanonane, 2,5,8,11-tetraoxadodecane, or 2,5,8,11,14-pentaoxapentadecane. In the case of 1,3-dioxolane mixtures, this type of effect is more relevant than in systems with 1,4-dioxane. This is supported by W-shaped Cp,mE curves, large variations of the Flory interaction parameter, X12, with x1, the oxaalkane concentration, and local mole fractions of the ether−ether type that are higher than the bulk ones, particularly at lower x1 values. The latter means that orientational effects are more important at this condition, and this is confirmed by large X12 variations with x1 in the region of low x1 values. At equimolar composition, X12 values of solutions containing 2,5,8,11-tetraoxadodecane or cyclic ethers remain nearly constant with the number of C atoms of the alkane, which reveals that systems with such oxaalkanes are similar from an interactional point of view. From values of the internal excess energies at constant volume, UVmE, it is shown that interactions between like molecules are usually overestimated. Nevertheless, the general trends observed are independent of the HmE or UVmE data considered. Structural effects are present in mixtures with components that differ largely in size (e.g., dipropyl ether + hexadecane or 2,5,8,11,14-pentaoxapentadecane + hexane). ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101264p [article] Thermodynamics of mixtures containing oxaalkanes. 4. : Random mixing and orientational effects in ether + alkane systems [texte imprimé] / Juan Antonio Gonzalez, Auteur . - 2010 . - pp. 9511–9524. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 19 (Octobre 2010) . - pp. 9511–9524 Mots-clés : Thermodynamics  Ether  Alkane  systems Résumé : Molar excess enthalpies, HmE, and volumes, VmE, of linear or cyclic ether + n-alkane systems have been discussed in terms of the effective dipole moment, μ̅, of the ether, differences of standard enthalpies of vaporization of the ether and of the isomeric alkane, the number and relative positions of the oxygen atoms, the shape of the ether, and the relative size of the mixture compounds. The mentioned solutions have also been studied using the Flory model and the Kirkwood−Buff formalism. Both theories provide consistent results. At 298.15 K, the random mixing hypothesis is a good approximation for mixtures including linear or cyclic monoethers or linear diethers. Orientational effects become stronger in solutions with 2,5,8-trioxanonane, 2,5,8,11-tetraoxadodecane, or 2,5,8,11,14-pentaoxapentadecane. In the case of 1,3-dioxolane mixtures, this type of effect is more relevant than in systems with 1,4-dioxane. This is supported by W-shaped Cp,mE curves, large variations of the Flory interaction parameter, X12, with x1, the oxaalkane concentration, and local mole fractions of the ether−ether type that are higher than the bulk ones, particularly at lower x1 values. The latter means that orientational effects are more important at this condition, and this is confirmed by large X12 variations with x1 in the region of low x1 values. At equimolar composition, X12 values of solutions containing 2,5,8,11-tetraoxadodecane or cyclic ethers remain nearly constant with the number of C atoms of the alkane, which reveals that systems with such oxaalkanes are similar from an interactional point of view. From values of the internal excess energies at constant volume, UVmE, it is shown that interactions between like molecules are usually overestimated. Nevertheless, the general trends observed are independent of the HmE or UVmE data considered. Structural effects are present in mixtures with components that differ largely in size (e.g., dipropyl ether + hexadecane or 2,5,8,11,14-pentaoxapentadecane + hexane). ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101264p

Thermodynamics of mixtures containing oxaalkanes. 7. / Juan Antonio Gonzalez in Industrial & engineering chemistry research, Vol. 51 N° 13 (Avril 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 13 (Avril 2012) . - pp. 5108-5116 Titre : Thermodynamics of mixtures containing oxaalkanes. 7. : Random mixing in ether + CCl4 systems Type de document : texte imprimé Auteurs : Juan Antonio Gonzalez, Auteur ; Isaias García de la Fuente, Auteur ; José Carlos Cobos, Auteur Année de publication : 2012 Article en page(s) : pp. 5108-5116 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Thermodynamics  Mixing Résumé : Mixtures of a linear or cyclic ether + CCl4 have been studied using the Flory model and the Kirkwood-Buff integrals formalism. The relative variation of the molar excess enthalpy, HEm, along the homologous series of the investigated systems was investigated in terms of the contributions to HEm from the breaking of the ether-ether and CCl4-CCl4 interactions upon mixing and the formation of ether-CCl4 interactions. For CH3(CH2)u-l(CH2CH2O)v(CH2)u-lCH3 + CCl4 mixtures, an increase in u (v = 0) leads to a weakening of interactions between unlike molecules. In contrast, an increase in v (u fixed) or cyclization leads to stronger interactions between unlike molecules. For acetal mixtures, proximity effects weaken this type of interaction. From the application of the two models, it is shown that the structure of the mixtures is close to that of random mixing. Erroneously, strong orientational effects are predicted by the Flory model for 1,3-dioxolane or 1,3-dioxane + CCl4 systems, but this is because the theory cannot describe asymmetric HEm curves when the mixture compounds have similar values for Vi (molar volume) and for V*i (reduction parameter for volume). The Flory results on the excess molar volumes are discussed in terms of the interactional, curvature, and P* contributions to this excess function. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300094e [article] Thermodynamics of mixtures containing oxaalkanes. 7. : Random mixing in ether + CCl4 systems [texte imprimé] / Juan Antonio Gonzalez, Auteur ; Isaias García de la Fuente, Auteur ; José Carlos Cobos, Auteur . - 2012 . - pp. 5108-5116. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 13 (Avril 2012) . - pp. 5108-5116 Mots-clés : Thermodynamics  Mixing Résumé : Mixtures of a linear or cyclic ether + CCl4 have been studied using the Flory model and the Kirkwood-Buff integrals formalism. The relative variation of the molar excess enthalpy, HEm, along the homologous series of the investigated systems was investigated in terms of the contributions to HEm from the breaking of the ether-ether and CCl4-CCl4 interactions upon mixing and the formation of ether-CCl4 interactions. For CH3(CH2)u-l(CH2CH2O)v(CH2)u-lCH3 + CCl4 mixtures, an increase in u (v = 0) leads to a weakening of interactions between unlike molecules. In contrast, an increase in v (u fixed) or cyclization leads to stronger interactions between unlike molecules. For acetal mixtures, proximity effects weaken this type of interaction. From the application of the two models, it is shown that the structure of the mixtures is close to that of random mixing. Erroneously, strong orientational effects are predicted by the Flory model for 1,3-dioxolane or 1,3-dioxane + CCl4 systems, but this is because the theory cannot describe asymmetric HEm curves when the mixture compounds have similar values for Vi (molar volume) and for V*i (reduction parameter for volume). The Flory results on the excess molar volumes are discussed in terms of the interactional, curvature, and P* contributions to this excess function. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300094e