Solute-Stationary Phase Interaction in Gas Liquid Chromatography. Thermodynamic Parameters for Substituted Halogenobenzene Derivatives

Thermodynamic parameters were determined by variable temperature experiments on the gas liquid chromatography (GLC) relative retention values, log γ, of 3- and 4-substituted halogenobenzene derivatives under non-polar condition. These ΔΔHSº(R, X) had a compensational relation with the ΔΔSSº(R, X) values. The free energy change ΔΔGSº(R, X) which is estimated from the ΔΔHSº(R, X) and the ΔΔSSº(R, X) at 298 K is less than −23 kJ·mol-1. The ΔΔSSº(R) values could be explained by translational entropy change for the adsorbed active complex between the solute and stationary phase. It is suggested that the interaction could be mainly expressed by the physical adsorption exclusive of hydrogen bonding. The ΔΔGSº(R, X) values for each halogen derivative have been the excellent linear lines taking the same slopes for the monosubstituted benzene derivatives, ΔΔGSº(R). The regression analyses of their intercepts were given using the descriptor evaluated as the molecular volume σa(X) rather than σM(X). The regression analysis for polyhalogenobenzene was also given successfully using σa(Xn).