Carbon Acidity. 78. Extended Cesium Ion Pair Indicator Scale in Tetrahydrofuran

Article abstract of DOI:10.1021/jo00003a031

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_as 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.Broensted 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.