Thermodynamics of mixtures containing a fluorinated benzene and a hydrocarbon

Juan Antonio González; Luis Felipe Sanz; Fernando Hevia; Isaías García de la Fuente; José Carlos Cobos

doi:10.1016/j.molliq.2021.116506

paper

Thermodynamics of mixtures containing a fluorinated benzene and a hydrocarbon

arXiv:2409.12664 · doi:10.1016/j.molliq.2021.116506

Abstract

Fluorobenzene, or 1,4-difluorobenzene or hexafluorobenzene + alkane mixtures and hexafluorobenzene + benzene, or + toluene, or + 1,4-dimethylbenzene systems have been studied using thermodynamic properties from the literature and through the application of the DISQUAC and UNIFAC (Dortmund) models and the concentration-concentration structure factor ( $S_{CC} (0)$ ). Interaction parameters for the contacts F/alkane and F/aromatic have been determined for DISQUAC, and they have been taken from the literature for UNIFAC. Both models predict double azeotropy for the C $_{6}$ F $_{6}$ + C $_{6}$ H $_{6}$ system, although in different temperature ranges. Excess molar enthalpies ( $H_{m}^{E}$ ) of the fluorobenzene, or 1,4-difluorobenzene + n-alkane systems are positive and are accurately described by the models using interaction parameters independent of the n-alkane, discarding Patterson's effect in such mixtures. DISQUAC calculations confirm that conclusion for C $_{6}$ F $_{6}$ + n-alkane mixtures. DISQUAC provides better results than UNIFAC on excess molar isobaric heat capacities ( $C_{p m}^{E}$ ) of solutions involving n-alkanes, or on $H_{m}^{E}$ of C $_{6}$ F $_{6}$ + aromatic hydrocarbon systems. For mixtures with a given n-alkane, the relative variation of excess molar internal energies at constant volume ( $U_{V m}^{E}$ ) and $H_{m}^{E}$ and with the fluorohydrocarbons is different, due to structural effects. C $_{6}$ F $_{6}$ + aromatic hydrocarbon mixtures are characterized by interactions between unlike molecules, as seen from their negative $H_{m}^{E}$ values. The $S_{CC} (0)$ formalism reveals that homocoordination is more important in C $_{6}$ F $_{6}$ + n-alkane mixtures than in the corresponding systems with C $_{6}$ H $_{5}$ F, and that heterocoordination is dominant in the solutions of C $_{6}$ F $_{6}$ with an aromatic hydrocarbon.

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Orientational effects in alkanone, alkanal or dialkyl carbonate + alkane mixtures and in alkanone + alkanone or + dialkyl carbonate systems

Thermodynamics of mixtures containing a fluorinated benzene and a hydrocarbon

Abstract

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