An E and C Modification of the β-π* Solvation Approach

The specific and nonspecific interactions between a solute and polar solvent are treated by an extension of the E and C equation to incorporate nonspecific solvation. An equation of the general form ΔX = E_A*E_B + C_A*C_B + SD* is offered where ΔX is the observable, E* and C* are parameters for the specific donor-acceptor interaction, and S and D* are solute and solvent parameters for the nonspecific solvation interaction. The treatment is compared to the Kamlet-Taft β-π* approach. Similarities and some very significant differences are discussed, indicating the limitations of a β-π* analysis. The fundamental cause of the limitations reported for Δν_OH-ΔH correlations of alcohols is discussed and the correlations are shown to be more general than some reports indicate. The analysis presented lends support to the Kamlet-Taft interpretation of the meaning of bβ, dramatically increases the E and C data base and provides support for the solvation minimized nature of the original E and C data base.