Determination of molecular structure parameters on the basis of gas-adsorption chromatography data. Part 2.—Determination of potential barriers and equilibrium angles of internal rotation for methyl derivatives of biphenyl and for terphenyls

Abstract

The adsorption method developed earlier has been used to determine potential barriers of internal rotation for free molecules of 2-methyl-, 4-methyl-, 4,4′-dimethyl-, 2,6-dimethyl- and 2,6,2′,6′-tetramethyl-biphenyls and for ortho-, meta- and para-terphenyls. The method has also been used to determine equilibrium angles of internal rotation for free molecules of 2-methyl, 2,6-dimethyl- and 2,6,2′,6′-tetramethyl-biphenyls and for o-terphenyl. The parameters obtained for the internal rotation potential functions agree with the sequences of their values which follow from general theoretical considerations. The equilibrium angles of internal rotation of the free molecules are close to the angles of internal rotation at which the Henry's-constant values for adsorption equilibrium on graphitized thermal carbon black (calculated by the molecular-statistical method for a quasi-rigid model of the molecule) are equal to the corresponding experimental values.