Linear solvation energy relationships. Part 3. Some reinterpretations of solvent effects based on correlations with solvent π* and α values

Solvent polarity and hydrogen bonding effects on a number of physical and chemical properties and reaction parameters are unravelled and rationalized by means of the solvatochromic comparison method and equations of the form XYZ=XYZ0+sπ*+aα, where π* is a measure of solvent polarity and α a measure of solvent hydrogen bond donor acidity. XYZ's considered include ET values for eight electronic spectral transitions, two sets of nitrogen hyperfine splitting constants, a set of fluorescence lifetimes, logarithms of rate constants for four nucleophilic substitution reactions, and the ‘electrophilicity parameter,’E, of Koppel and Palm.