Grupo Especializado en Termodinámica de los Equilibrios entre Fasesenglish versionGETEF emblema


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Año 1996

  • Domanska, U; Gonzalez, JA; Solid-liquid equilibria for systems containing long-chain 1-alkanols. I. Experimental data for 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol or 1-icosanol-benzene or -toluene mixtures. Characterization in terms of DISQUAC; Fluid Phase Equilibr, 119 (1-2) 1996 131-151
Solid-liquid equilibrium temperatures for binary mixtures of long-chain 1-alkanols (1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol and 1-icosanol) and benzene or toluene have been measured by a dynamic method between 276 K and the melting point of the alcohol. These data are used, taking into consideration the two solid-solid first-order transitions observed in the 1-alkanols, to characterize in terms of DISQUAC the hydroxyl-aromatic interactions present in the investigated mixtures. The relative standard deviations for the equilibrium temperatures are less than 0.01 for most of the systems.
  • Gonzalez, JA; de la Fuente, IG; Cobos, JC; Domanska, U; Thermodynamics of branched alcohols. I. Extension of DISQUAC to tert-alcohols-n-alkanes or tert-alcohols-cyclohexane mixtures; Fluid Phase Equilibr, 119 (1-2) 1996 81-96.
DISQUAC interchange coefficients for the contacts tertiary OH-aliphatic and tertiary OH-cyclohexane are reported. The quasichemical parameters are independent of the alkane; the first and third quasichemical parameters are common for the alkanols investigated, whereas the second depends on the position of the OH group. Therefore, two ensembles of alcohols are distinguished: 2-methyl-2-alkanols and 3-methyl-3-alkanols. Tert-butanol behaves differently owing to its high melting point. Dispersive parameters change with the alcohol. This behaviour is compared with that observed for other contacts. Vapor-liquid equilibria and excess functions, even the excess heat capacity, are well represented by the model. In contrast, partial molar excess quantities at infinite dilution are poorly described.
  • Gonzalez, JA; de la Fuente, IG; Cobos, JC; DISQUAC analysis of binary liquid organic mixtures containing cyclic or linear alkanols and cycloalkanes or n-alkanes; Thermochima Acta, 278 1996 57-69
Literature data for cycloalkanol + cycloalkane or n-alkane mixtures are critically reviewed and characterized in terms of the DISQUAC model incorporating intramolecular effects related to the inclusion of a functional group, OH, in an aliphatic ring.
Although the interaction parameters follow similar rules to those encountered for other heterocycles (amines, ethers, ketones), some differences are found, e.g., the quasichemical coefficients are independent not only (as usual) of the alkane, but also of the cycloalkanol.
It is shown that for such systems steric effects are less important than ring strain.
A treatment of 1-alkanols + cycloalkanes (except C6H12) mixtures using the interaction parameters determined previously for cyclohexane is included.
  • Domanska, U; Gonzalez, JA; Solid-liquid equilibria for systems containing long-chain 1-alkanols. II. Experimental data for 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol or 1-eicosanol plus CCl4 or plus cyclohexane mixtures. Characterization in terms of DISQUAC; Fluid Phase Equilibr, 123 (1-2) 1996 167-187
Solid-liquid equilibrium (SLE) temperatures for 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol or 1-eicosanol + CCl4 mixtures and for 1-dodecanol or 1-tetradecanol + cyclohexane systems have been measured by a dynamic method between 273 K to the melting point of the alcohol. First order transitions between different crystal forms (α, β, γ) of the alcohols were observed, The solid-solid transitions of these long-chain alcohols changed with the solvent as result of solute-solvent interactions. This behaviour is also encountered in many other systems. The hydroxyl/cyclohexane and hydroxyl/CCl4 interactions present in the investigated systems were characterized in terms of DISQUAC, reporting the interchange coefficients for such contacts. It is remarkable that these interchange coefficients remain constant for a given alcohol: from 1-octadecanol for mixtures with cyclohexane, and from 1-hexadecanol for those systems containing CCl4. Calculations were developed taking into account the solid-solid transitions of the 1-alkanols. This is important because of the large value of the molar heat of the α → β transition. For mixtures containing alcohols other than 1-eicosanol the relative standard deviations for the equilibrium temperatures were less than 0.009. For mixtures containing 1-eicosanol the relative standard deviations were close to 0.020, because the model cannot, using the proposed interaction parameters, reproduce their negative deviations from Raoult's law.
  • Gonzalez, JA; de la Fuente, IG; Cobos, JC; Estimation of DISQUAC interchange energy parameters for linear secondary alcohols plus n-alkanes or plus cyclohexane mixtures; Fluid Phase Equilibr, 123 (1-2) 1996 39-57
The data available in die literature on vapor-liquid equilibria (VLE), molar excess Gibbs energies (GE), molar enthalpies (HE), molar excess heat capacities (CPE), activity coefficients (γi) and partial molar excess enthalpies (HiE,∞) at infinite dilution of linear secondary alkanols (1) + n-alkanes (2) or + cyclohexane (2) systems are examined on the basis of the DISQUAC group contribution model.
The components in the mixtures are characterized by three types of groups of surfaces: hydroxyl (OH group); aliphatic (CH3, CH2 and CH groups); and cyclohexane(c-CH2 group). The purely dispersive parameters of the aliphatic/cyclohexane contacts are available in the literature. The parameters for the secondary OH/aliphatic and secondary OH/cyclohexane interactions are reported in this work. The quasi-chemical parameters are independent of the alkane. The first and third parameters are common for the alkanols investigated. The second quasi-chemical parameter depends on the position of the OH group. So, on the basis of available data, two groups of alcohols are distinguished: 2-alkanols and 3-alkanols. The dispersive parameters change with the alcohol.
The model describes consistently the phase equilibria and molar excess functions. Dependence on temperature of CPE is well represented, except at very low temperatures. The absolute mean deviation for γi is about 6.6%, For i = 1, the deviation is 9.2%; for i = 2, it is 3.9%, DISQUAC cannot represent HiE,∞, i.e. the calculated HE curves vs. x1, the mole fraction, are not as steep as the experimental ones at very high dilution of the alcohol. This may be considered the major limitation of the model.
So, in terms of DISQUAC, the investigated mixtures behave similarly to 1-alkanol (1) + alkane (2) systems.
  • Gonzalez, JA; Martinez, JMF; de la Fuente, IG; Cobos, JC; DISQUAC characterization of the carbonyl-oxygen interactions in binary liquid organic mixtures containing linear molecules: Ketones and a monoether, diether, or triether; Can J Chem-Rev Can Chim, 74 (10) 1996 1815-1823
The available data in the literature on vapor-liquid equilibria, excess Gibbs energies, and excess enthalpies for linear ketones + linear mono- or poly-ether mixtures are examined in terms of the DISQUAC group contribution model. Interaction parameters are reported. The quasichemical interchange coefficients are independent of the compounds in the systems; the dispersive interchange coefficients depend on the intramolecular environment of the carbonyl and (or) oxygen groups. Proximity effects, which seem to lead to an important increase of the interaction parameters, are briefly considered in treating systems including 1-methoxy-2-propanone or dimethyl carbonate molecules. DISQUAC consistently describes the experimental data of the mixtures investigated. The rather good representation obtained for vapor-liquid equilibria at high temperatures is noteworthy. A discussion in terms of effective and reduced dipole moments of binary mixtures containing carbonyl and oxygen groups in the same or different molecules is also presented.
  • Gonzalez, JA; de la Fuente, IG; Cobos, JC; Application of a purely physical model (DISQUAC) to binary mixtures of phenol and organic solvents; Ber Bunsen-Ges Phys Chem Chem Phys, 100 (10) 1996 1746-1751
A whole set of literature data on phase equilibria, vapor-liquid equilibria, VLE, liquid-liquid equilibria, LLE, and solid-liquid equilibria, SLE, and on molar excess Gibbs energies, GE, molar excess enthalpies, HE and on activity coefficients at infinite dilution for phenol + organic solvents mixtures are examined in terms of the DISQUAC group contribution model. The interchange coefficients for OH(phenol)/aromatic; OH(phenol)/aliphatic and for OH(phenol)/C6H12 interactions are reported.
DISQUAC yields a good representation of VLE, GE and HE, as well as of the temperature dependence of GE. DISQUAC predictions on SLE are similar to those encountered in other alcoholic solutions previously investigated, and are slightly worse than those given by the mean association number theory. LLE data are critically reviewed. The necessity of different third interchange coefficients for the OH(phenol)/aliphatic interactions in the series phenol + n-alkanes for the longer n-alkanes in order to improve LLE predictions is discussed. The larger discrepancies are found when predicting activity coefficients at infinite dilution.



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