A spectroscopic index for the polarity of solvents, such as Dimroth and Reichardt's ET, is also a measure of the solvating ability of these solvents toward anions. Few data for protic solvents, in particular acidic ones, have been reported in the literature. Measurements of ET have been made with the betaine dye 2,6-diphenyl-4-(2′,4′,6′-triphenyl-1-pyridino)phenoxide for over 40 protic solvents, such as the alcohols from methanol to dodecanol and various substituted phenols, and with the dye 4-(2′,4′,6′-triphenyl-1-pyridino)phenoxide for some 20 of these solvents. For some more acidic solvents, such as carboxylic acids, Kosower's Z values have been determined with 4-cyano-1-ethylpyridinium iodide, and Mayer, Gutmann, and Gerger's AN values with tributylphosphine oxide. The values were intercompared, and the effects of the presence of base (triethylamine) and water on the ET values have been studied. These indexes have been correlated with structural factors for the alcohols and phenols, and with the acidity of the phenols. These correspondences permit the prediction of ET and the solvation properties of solvents which have not been studied yet.
ASJC Scopus subject areas
- Engineering (all)
- Physical and Theoretical Chemistry