Features of the adsorption of aryl- and hetaryl-substituted 1,3,4-oxadiazoles from solutions on the surface of porous graphitic carbon in Henry's range

Adsorption in Henry's range of structurally related aryl- and hetaryl-substituted 1,3,4-oxadiazoles from n-hexane-dichloromethane and water-acetonitrile solutions on the surface of porous graphitic carbon (PGC) under the conditions close to equilibrium is studied by high-performance liquid chromatography. The characteristics of sorption of 1,3,4-oxadiazoles from solutions on the surface of this adsorbent, octadecyl silica gel, and on hypercrosslinked polystyrene are compared. It is shown that the structure of the molecules and their Van der Waals surface area and polarity affect adsorption on a PGC surface. A variant of the mechanism of adsorption of the polar molecules on the PGC surface, explaining the anomalously high values of their Henry constants of adsorption and based on the planar location of the 1,3,4-oxadiazoles molecules with respect to the adsorbent surface and the specific adsorbate-adsorbent intermolecular interaction in addition to the background dispersion interactions, is proposed. It is established that the linear the Gibbs energy relationship upon the adsorption of the studied compounds from n-hexane-dichloromethane and water-acetonitrile solutions on the PGC surface holds.