Thermodynamics of chlorobenzene, or bromobenzene, or 1-chloronaphthalene or 1,2,4-trichlorobenzene + alkane mixtures

Abstract

The systems C6H5Cl, or C6H5Br, or 1-chloronaphthalene, or 1,2,4-trichlorobenzene, or 1-methylnaphthalene, or 1,2,4-trimethylbenzene + alkane have been investigated by means of the their excess molar properties, including, when the needed data are available, those at constant volume, internal energies (UVmE) and heat capacities (CVmE), and using the DISQUAC, and Flory models, and the concentration-concentration structure factor formalism. The position of the mixtures within the GmE (excess molar Gibbs energy) vs. HmE(excess molar enthalpy) diagram has been also determined. Interactions between C6H5X molecules become stronger in the sequence X = H ≈ F ≈ Cl < Br. These interactions are weaker than those between 1-chloronaphtahlene or 1,2,4-trichlorobenzene molecules. It is shown that the considered systems have some common features: dispersive interactions are dominant, structural effects for solutions with shorter n-alkanes are large and UVmE decreases when the number (n) of C atoms of the alkane increases. This variation is held when an n-alkane is replaced by a branched alkane with the same n in systems with C6H5Cl or 1-chloronaphthalene. This suggests that larger alkanes are poorer breakers of the interactions between aromatic halogenated compounds. Viscosity and CVmE data support this conclusión. The parabolic dependence of CVmE with n indicates that the short orientational order of long n-alkanes is destroyed. Aromacity and proximity effects are discussed.