MEASUREMENT OF SOLUTE DIPOLARITY POLARIZABILITY AND HYDROGEN-BOND ACIDITY BY INVERSE GAS-CHROMATOGRAPHY

Solvatochromically based linear solvation energy relationships (LSERs) have been studied for more than ten years and been applied to the study of a very wide variety of chemical phenomena. During the past several years they have been used to explore retention processes and characterize gas chromatographic stationary phases. However, the general application of this method is limited by the complex and tedious methods needed to measure the explanatory variables and by the limited accuracy of the a priori parameter estimation rules. In this paper we have investigated the use of retention data for a wide variety of solutes on more than a dozen very different gas chromatographic stationary phases, including a number of extremely basic phases. These data are the basis for a method of rapidly estimating two of the explanatory variables commonly encountered in solvatochromic LSERs. Using the above approach, the polarity/polarizability parameters and the hydrogen bond donor acidity parameters for more than 200 compounds have been estimated. The results suggest that these two parameters can be estimated with a precision, and perhaps accuracy, at least as good as the more time-consuming methods. We have demonstrated that the Martin equation and LSER equations based on these parameters are compatible. Finally we have shown for the first time that the coefficients of the LSER, as required by basic theory, are proportional to the liquid phase solvatochromic parameters.