HPLC behavior and hydrophobic parameters of some anilides

The chromatographic behavior of para substituted anilides of 2,2-dimethylpr opanoic, benzoic and alpha -phenyl acetic acid has been studied by reversed -phase high performance liquid chromatography HPLC was performed on a C-18 column with various aqueous methanol mobile phases. The Influence on the re tention of anilide type and additional substituents in the molecule is disc ussed. Several chromatographic hydrophobicity parameters (CHP) have been calculate d by linear correlation between log k of the investigated compounds and the concentration of methanol in the mobile phase. The chromatographic hydroph obicity parameters were compared with the log P values calculated by Rekker 's fragmental method. The results show moderate correlations of CHIP with l og Mus, multiple linear regressions have been applied. It was found that be sides log P even the electronic effects of individual polar groups capable of hydrogen bonding proved to be very important in hydrophobic characteriza tion of the molecule.