Carbon acidity. 78. Extended cesium ion pair indicator scale in tetrahydrofuran

Aggregation and Alkylation of the Cesium Enolate of 2-p-Biphenylylcyclohexanone1

“…The ion pair acidity is defined by eq 4 relative to an appropriate indicator in the proton-transfer equilibrium, eq 5. The indicator ion pair scale for cesium salts in THF was published earlier …”

“…The cesium ion pair acidity of BPCH was measured against the indicators 9-dimethylaminophenylfluorene (9-DMAPhFl, λ max = 376 nm, ε max = 28 700, p K = 19.28) and 9-biphenylylfluorene (9-BpFl, λ max = 455 nm, ε max = 29 400, p K a = 17.72) . The equilibrium 5 is defined for the monomer; any aggregation reduces the concentration of the monomer below the formal concentration of the substrate and reduces the apparent p K of the substrate.…”

The Brønsted correlation for phenalene hydrocarbons

“…6 The acidity of 4 was measured in THF 7 and is part of our table of cesium ion pair acidities in THF. 5 The cesium salt of 4 has λ max = 533 nm (ε=53600), values close to those in THF, λ max = 538 nm (ε=57800). Results of several equilibrium acidity determinations with 4 in CHA are shown in Table 2.…”

“…We will also use the relative acidities of the cesium ion pairs in THF. 5 For delocalized carbanions, ion pair pK's in CHA are known to correspond closely to the cesium ion pairs in THF. Accordingly, Brønsted correlations between the kinetic acidities in methanol and the cesium/THF ion pair pK's are essentially unchanged (vide infra).…”

Carbon acidity. 97. Cesium ion pair acidity of some sulfones in cyclohexylamine

“…number of compounds as their cesium salts in cyclohexylamine (CHA) [14] and in tetrahydrofuran (THF) [15]. The "ion pair" acidities are defined by the transmetallation equilibrium:…”