ADSORPTION AND RETENTION PATTERNS FOR HALOGEN ADAMANTANES ON THE GRAPHITE-LIKE ADSORBENT HYPERCARB UNDER HPLC CONDITIONS

Thermodynamic characteristics of sorption (retention factors, heat and entropy factors of sorption) of various chlorine, bromine, and iodine derivatives of adamantanes from water-methanol eluent on the graphite-like material Hypercarb and octyl silica gel (SiO2-C8) are determined experimentally under HPLC conditions. Hypercarb is shown be characterized by the highest structural selectivity in HPLC with respect to stereoisomers of halogen adamantanes. It is established that the order of elution of isomeric chlorine, bromine, and iodine derivatives of adamantanes from the polar eluent medium on Hypercarb under HPLC fully coincides with the retention patterns of these compounds on columns with graphitized thermal soot in gas chromatography. The retention of the considered halogen adamantanes and halogenoarenes on Hypercarb is described by the adsorption mechanism of sorption, with the principal contribution to the retention being made by dispersive interactions of sorbate molecules with the adsorbent surface. The dependence of the heat and entropy factors of sorption on the composition and structure of halogen adamantanes on Hypercarb is noted to be described by the molecular polarizability and molecular site values of the sorbates and by the lipophilicity of the compounds in the case of sorption on SiO2-C8. It is concluded that the found regularities of halogen adamantane sorption under HPLC conditions allow referring Hypercarb and SiO2-C8 to sorbents with 2D- and 3D-types of structural selectivity, respectively.