CARBON ACIDITY .78. EXTENDED CESIUM ION-PAIR INDICATOR SCALE IN TETRAHYDROFURAN

A revised cesium ion pair acidity scale relative to fluorene at pK(a) = 22.90 is presented. The range of the scale is extended 3 pK units by including more acidic indicators and now encompasses pK(a)S from 15.62 to 38.73. The accuracy of the scale has been improved by multiple equilibria among indicators. Uncertainties between close lying indicators is generally less than +/- 0.01 pK unit. Bronsted plots are constructed for series of fluorenyl and arylmethyl hydrocarbons. From these plots, the acidity value for toluene in THF was extrapolated (pK(a) = 40.9). Comparisons are drawn to ionic acidities in dimethyl sulfoxide.