Solvation properties and limiting activity coefficients of halogenated hydrocarbons in C 78H 158 branched saturated alkane solvent

Abstract

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 (C 78H 158, 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.