The structural effect of some 1,3,4-oxadiazoles and 1,2,4,5-tetrazines on their thermodynamic characteristics of adsorption from aqueous organic solutions on phenyl-bonded silica gel

The thermodynamic characteristics of adsorption of substituted 1,3,4-oxadiazoles and 1,2,4,5-tetrazines from aqueous organic solutions on phenyl-bonded silica gel were determined in the Henry region via the method of high-performance liquid chromatography. The influence of the structure of the studied compounds on their thermodynamic characteristics of adsorption from binary aqueous organic solvents of different natures was examined. The correlation dependences of the standard differential molar changes in the Gibbs energy, enthalpy, and entropy of adsorption on the van der Waals surface area and reduced dipole moment of molecules of the examined compounds were found. The main factors in optimization of the separation techniques and adjustment of the adsorption selectivity of phenyl-bonded silica gel were determined under conditions of reversed-phase high-performance liquid chromatography.