Reappraisal of Empirical Solvent Polarity Scales for Organic Solvents
Stefan Spange, Nadine Weiß, Caroline H. Schmidt, Katja Schreiter
Abstract
Abstract Correlations of Reichardt's E T (30), the Catalán SdP (solvent dipolarity), SP (solvent polarizability), SA (solvent acidity), SB (solvent basicity), Kamlet‐Taft π * (dipolarity/polarizability), α (hydrogen bond donating ability) and β (hydrogen bond accepting ability) polarity parameters with the molar concentration of 161 pure organic solvents are presented. Mostly, linear relationships of the polarity parameter as a function of molar concentration are obtained as long as each individual solvent class is considered separately. A physically different interpretation of the E T (30), Kamlet‐Taft π * and α as well as Catalán SA and SB parameters has been proposed. Furthermore, the Hildebrand solubility parameter in combination with the diffraction index is used for the correlation analysis with the above‐mentioned solvent parameters. It can be concluded that empirical polarity parameters derived from solvatochromic UV/Vis measurements are inherently a function of the molecular structure of the probe.