EMPIRICAL PARAMETERS OF SOLVENT POLARITY AS LINEAR FREE-ENERGY RELATIONSHIPS

Although the effect of solvent on the rate and the position of equilibrium of chemical reactions has been known since the last century, there are still no reliable and exact methods for a quantitative description and prediction of such solvent effects. Empirical parameters of solvent polarity are of great value in this respect and can be derived with the aid of the principle of “linear relationships between free energies” (LFE relationships). The present article deals with the possibilities of establishing reaction and absorption series using solvent‐dependent standard reactions or standard absorptions of organic compounds. Particular attention is merited by the summary of the 24 most important empirical parameters of solvent polarity and the table of ET(30) values for 151 solvents. In addition to examples of the application of these values, attempts to improve the LFE correlations of singular empirical parameters of solvent polarity with the aid of multiparametric equations are described. Copyright © 1979 by Verlag Chemie, GmbH, Germany