EXTENSION OF THE UNIFIED SCALE OF SOLVENT POLARITIES TO ACCEPTOR PROBES - CONCERNS ABOUT BETA-PI-ASTERISK PARAMETERS

The previously reported unified scale of nonspecific solvation, S', is extended to acceptor probes in this article. Incomplete complexation of the acceptor in weak donor solvents is proposed with 4-nitroaniline. This proposal is supported by data for a series of other substituted nitroanilines. The Kamlet-Taft beta-pi* parameters are derived assuming complete complexation of the probe. Averaging in the effects of incomplete complexation into beta and pi* limits the utility of these parameters. In those instances where discrepancies exist in S' and pi*, a good correlation of S' and the Dimroth-Reichardt E(T)(30) parameters exists.