A UNIFIED SCALE OF SOLVENT POLARITIES FOR SPECIFIC AND NONSPECIFIC INTERACTIONS

A unified scale for predicting non-specific solvent polarity employs the physicochemical properties of solutes, such as NMR, EPR, electronic transitions, etc., and the equation Delta(chi) = S'P + W in order to produce a scale of non-specific solvating ability. This approach is successful due to the exclusion of data for systems where donor-acceptor interactions exist. In this paper, the Unified Scale is extended to include systems in polar acceptor solvents by using the equation Delta(chi) = E(A)'E(B)* + C-A'C-B* + S'P + W, which takes into account both the non-specific and specific donor-acceptor interactions of these solvents with donor solute probes. An experimental procedure which leads to the separation of solute solvation into non-specific and specific components is described.