Thermodynamics of Organic Mixtures Containing Amines. VII. Study of Systems Containing Pyridines in Terms of the Kirkwood-Buff Formalism
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- 作者：Juan Antonio Gonzá ; lez ; Isaí ; as Garcí ; a de la Fuente ; Ismael Mozo ; José ; Carlos Cobos ; Nicolá ; s Riesco
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2008
- 出版时间：March 5, 2008
- 年：2008
- 卷：47
- 期：5
- 页码：1729 - 1737
- 全文大小：139K
- 年卷期：v.47,no.5(March 5, 2008)
- ISSN：1520-5045
文摘
Mixtures formed by a pyridine base and alkane, benzene, or 1-alkanol have been investigated in the frameworkof the Kirkwood-Buff theory. In this work, the derivatives of the molar excess Gibbs energies (GE), relativeto the mole fraction, needed for the determination of the Kirkwood-Buff integrals (Gij) and related quantitieswere calculated using the DISQUAC group contribution model. Systems with alkanes are characterized byinteractions between similar molecules (G12 < 0). Mixtures with pyridine or 4-methylpyridine show Gii curveswith a maximum at high amine concentrations, which indicates that amine-amine interactions are strongerthan in solutions with dimethyl or trimethylpyridines. For solutions with a given alkane, the increase of methylgroups in the aromatic ring of the pyridine leads to a decrease of G11 in the following sequences: pyridine> 4-methylpyridine and pyridine > 2-methylpyridine > 2,4-dimethylpyridine > 2,4,6-trimethylpyridine. Thesame variations are observed for the molar excess enthalpies (HE), and volumes (VE). Systems with benzeneor 1-alkanols show lower 
G12 values than those with alkanes. This has been ascribed to the existence ofinteractions between dissimilar molecules, which are of dipolar type. The comparison of G12 for 1-alkanol +pyridine base (or + benzene or + toluene) mixtures clearly reveals that the interactions between dissimilarmolecules are much more predominant in amine systems. However, their local mole fractions are scarcelydependent on the intermolecular interactions and the distribution of the molecules in the solution is practicallyrandom, even in methanol systems.
G12 values than those with alkanes. This has been ascribed to the existence ofinteractions between dissimilar molecules, which are of dipolar type. The comparison of G12 for 1-alkanol +pyridine base (or + benzene or + toluene) mixtures clearly reveals that the interactions between dissimilarmolecules are much more predominant in amine systems. However, their local mole fractions are scarcelydependent on the intermolecular interactions and the distribution of the molecules in the solution is practicallyrandom, even in methanol systems.