DISQUAC structure-dependent interaction parameters for mixtures containing sec-alkanols and benzene, toluene, or n-alkanones

1998 ◽  
Vol 76 (10) ◽  
pp. 1418-1428 ◽  
Author(s):  
Juan Antonio González ◽  
I García de la Fuente ◽  
J C Cobos

Mixtures containing sec-alkanols and benzene, toluene, or n-alkanones are characterized in terms of DISQUAC by means of structure-dependent interaction parameters. The quasichemical (QUAC) interchange coefficients are independent of the size alcohol for a given organic solvent; while the dispersive (DIS) ones change with the size of the alcohol. This behaviour has been found for other many alcoholic solutions. DISQUAC represents well the thermodynamic properties of these mixtures: vapor-liquid equilibria, VLE, molar excess Gibbs energies, GE, and molar excess enthalpies, HE. So, the mean deviations between experimental and calculated results are about 2% for pressure, and 8% for HE. A short comparison between DISQUAC results and those given by the Dortmund version of UNIFAC, the UNIQUAC association theory and other similar model is also presented. In the case of the Dortmund version of UNIFAC, poorer predictions are obtained for HE, as this property is more sensitive to molecular structure. Association theories provide better results because are used as correlation equations.Key words: thermodynamics, 2-alkanols, group contributions, interactions.

2000 ◽  
Vol 78 (10) ◽  
pp. 1272-1284 ◽  
Author(s):  
Juan Antonio González ◽  
Isaias Garcia de la Fuente ◽  
Jose Carlos Cobos

Binary mixtures of triethylamine (TEA) and alkanols have been investigated in the framework of DISQUAC. The systems are built by three contacts: aliphatic–hydroxyl, aliphatic–nitrogen, and hydroxyl–nitrogen. The corresponding interaction parameters are reported and discussed. The former are avalilable in the literature but were modified (particularly the third dispersive (DIS) and quasichemical (QUAC) interchange coefficients) for sec- and tert-alkanols + n-alkanes using recent data on excess heat capacities at constant pressure (CEP) for systems of these alkanols with n-heptane. The interaction parameters for aliphatic-nitrogen contacts are purely dispersive. The structure dependence of the DIS and QUAC interchange coefficients of the hydroxyl-nitrogen contacts in 1-alkanols + TEA systems is similar to that found in other solutions previously investigated. The QUAC interchange coefficients remain constant from ethanol and are also valid for 2-alkanols and tert-butanol. Methanol behaves differently. A short discussion in terms of effective dipole moments is also included. DISQUAC represents well the thermodynamic properties examined: vapor-liquid equilibria (VLE), molar excess Gibbs energies (GE) and molar excess enthalpies (HE). DISQUAC provides better results than the Dortmund version of UNIFAC using the published geometrical and interaction parameters. ERAS parameters for 1-alkanols + TEA systems are also reported. Interactions between unlike molecules are stronger for solutions with methanol or ethanol. DISQUAC improves ERAS results on HE, while both models give similar results for GE. However, ERAS needs an specific parameter, with unknown temperature-dependence, to describe properly GE. The main advantage of ERAS is its ability to provide information on VE. Its main limitation is that can be only applied to those systems where association is expected. DISQUAC, a purely physical model, can be applied to any type of binary mixture, as it is followed from this and previous studies.Key words: theory, liquids, associated, thermodynamics, group contributions.


1999 ◽  
Vol 64 (12) ◽  
pp. 765-774 ◽  
Author(s):  
Dragana Zivkovic ◽  
Zivan Zivkovic

The results of the determination of the thermodynamic properties for ternary systems Cr.Co.Me (Me = Mo, Al) using a new general solution model for the predictions are presented in this work. For five sections (with mole ratio Co :Me = 2:8, 4:6, 5:5, 6:4, 8:2) investigated in each ternary system at temperature of 2000 K, integral molar excess Gibbs energies and partial molar thermodynamic properties of chromium were calculated.


2005 ◽  
Vol 83 (10) ◽  
pp. 1812-1825 ◽  
Author(s):  
Juan Antonio González ◽  
Ismael Mozo ◽  
Isaías García de la Fuente ◽  
José Carlos Cobos

Binary mixtures of aniline with benzene, toluene, alkane, alkanol, or N,N-dialkylamide have been investigated in the framework of the DISQUAC model. The reported interaction parameters change regularly with the molecular structure of the mixture components. The model consistently describes a set of thermodynamic properties including liquid–liquid equilibria, vapor–liquid equilibria, and molar excess enthalpies. The two latter properties for ternary systems are well-represented by DISQUAC using binary parameters only (i.e., neglecting ternary interactions). A comparison of DISQUAC results and those obtained from the UNIFAC (Dortmund version) and ERAS models is also shown. The experimental molar excess enthalpies for binary and ternary mixtures are better described by DISQUAC than by UNIFAC. ERAS fails when representing molar excess enthalpies of those binary systems including methanol or ethanol. This may be due to the existence of strong dipolar interactions among aniline molecules as well as to effects related to the equation of state term, evaluated comparing molar excess enthalpies, and molar excess internal energies at constant volume. The study of the aniline systems in terms of the concentration–concentration structure factor also underlines the importance of dipolar interactions in solutions with alkanes or alcohols, which may be due to the high polarizability of the aniline molecule.Key words: thermodynamics, mixtures, aniline, dipolar interactions, structural effects.


2015 ◽  
Vol 386 ◽  
pp. 1-6 ◽  
Author(s):  
Aouicha Belabbaci ◽  
Chahrazed Ghezouali ◽  
Rosa M. Villamañán ◽  
Jose J. Segovia ◽  
Miguel A. Villamañán ◽  
...  

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