Solvation properties and limiting activity coefficients of halogenated hydrocarbons in C78H158 branched saturated alkane solvent

Kováts’ retention indices were determined for 41 halogenated compounds by gas–liquid chromatography (GLC) at temperatures from 373 to 433 K using fused silica open tubular capillary columns coated with 19,24-dioctadecyldotetracontane (C78H158, C78) as stationary phase. Gas–liquid equilibrium parameters (specific retention volumes, standard Gibbs energy differences and limiting activity coefficients) were calculated for 1-F-, 1-Cl-, 1-Br- and 1,1,1-trifluoroalkanes, F-, Cl-, Br-, I-, hexafluoro- and trifluoromethylbenzenes on the basis of absolute retention data of n-alkanes determined by GLC using packed columns with the same stationary phase. The experimental standard Gibbs free energy differences data obtained correlated well by a Kirchhoff-type temperature function and the thermodynamic parameters (partial molar standard enthalpy, entropy and heat capacity differences) of the solvation are determined. It was concluded that capillary columns coated with non-volatile stationary liquid phase are suitable for the determination of vapour–liquid equilibrium data.