Chromatostructural analysis (chromatoscopy) a new method of determination of molecular structure

Abstract

The intermolecular interaction of an isolated, adsorbed molecule with a homogeneous, flat solid surface and, thence, the thermodynamic characteristics of adsorption and adsorption chromatography at low (zero) surface coverage depend significantly on the molecular geometry of the adsorbate. Graphitized thermal carbon black (GTCB) is such a homogeneous solid and so may be used to determine some parameters of molecular structure. Use is made of the gas-chromatographically obtained Hery's constant for adsorption on GTCB with a semi-empirical molecular statistical theory of adsorption based on an atom–atom approximation for the potential function for intermolecular adsorbate–adsorbent interaction. The method is shown to be successful in determining, first, structural parameters for molecules of hexamethylbenzene, indane, 2- and 5-methylindanes, tetralin and, secondly, potential-function parameters for internal rotation in the molecules ethylbenzene and diphenyl and its methyl derivatives. By extension of the technique, experimentally obtained Henry's constants for adsorption on ion adsorbent–zeolite (NaX) have been used to determine the quadrupole moment of the cyclopropane molecule.