Hydrophobicity parameters determined by reversed-phase liquid chromatography: VIII. Hydrogen-bond effects of ester and amide groups in heteroaromatic compounds on the relationship between the capacity factor and the octanol—water partition coefficient

Abstract

The logarithms of the capacity factors, log k′, for several heteroaromatic systems (furan, pyrrole, benzofuran, indole, benzene and their alkyl, ester and amide derivatives) were determined on a Capcell Pak C 18 column using methanol—buffer (pH 7.4) mobile phases of different compositions. These results and the log k w values, derived by a linear extrapolation of the plot of log k′ against the volume fraction of methanol to 0% methanol, were correlated with experimental log P values by taking into account the hydrogen-acceptor and hydrogen-donor effects. Whereas the hydrogen-donor effect was found to be minimized by using the log k w parameter, the hydrogen-acceptor effect was found to become insignificant in an eluent containing 50% methanol. Isocratic data determined at this eluent composition gave the simplest and best correlation.