Carbon Acidity. 67. The Indicator Scale of Cesium Ion Pairs in Tetrahydrofuran

Article abstract of DOI:10.1021/ja00310a038

An equilibrium cesium ion-pair indicator scale relative to 9-phenylfluorene at pK_a = 18.49 has been established for 22 hydrocarbons in tetrahydrofuran.Comparison of this scale to those developed in Me2So and DME shows the scale to be independent of solvent.Visible absorbance spectral characteristics of the indicator anions are also reported and discussed in relation to other solvents.Thermodynamic studies of the equilibrium reactions were carried out over a temperature range of -20 to 25 deg C and reveal the importance of internal rotation on the entropy of reactions.Thermodynamic constants found for reaction between fluorenes show a complex behavior and are generally not interpretable at this time.