Excess Enthalpies for Binary Mixtures of o-Xylene + o-Disubstituted Isomers

Abstract

The excess enthalpies for binary mixtures of o-xylene+ o-disubstituted isomers (ethyltoluene, methoxytoluene, fluorotoluene, chlorotoluene, bromotoluene, iodotoluene, tolylacetonitrile, fluoroiodobenzene, bromofluorobenzene, chlorofluorobenzene, fluoronitrobenzene, aminofluorobenzene) were measured at 298.15 K. The excess enthalpies are small for these binary systems except systems of (xylene + fluoronitrobenzene) and (xylene + aminofluorobenzene), which show larger positive excess enthalpies. The experimental results were compared according to the group contribution method UNIFAC (Dortmund), regular solution theory and COSMORS of DFT. UNIFAC predictions were positive and differed significantly from the observed results. However, excess enthalpies calculated by the COSMO-RS model showed better agreement than the others. There was a correlation between excess enthalpies and dipole-dipole interaction energy by the Keesom-Israelachvili equation.