131544-01-9Relevant academic research and scientific papers
Carbon Acidity. 78. Extended Cesium Ion Pair Indicator Scale in Tetrahydrofuran
Streitwieser, Andrew,Ciula, James C.,Krom, James A.,Thiele, Georg
, p. 1074 - 1076 (1991)
A revised cesium ion pair acidity scale relative to fluorene at pKa = 22.90 is presented.The range of the scale is extended 3 pK units by including more acidic indicators and now encompasses pKas 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 (pKa = 40.9).Comparisons are drawn to ionic acidities in dimethyl sulfoxide.
Basicity of a stable carbene, 1,3-di-tert-butylimidazol-2-ylidene, in THF
Kim, Yeong-Joon,Streitwieser, Andrew
, p. 5757 - 5761 (2007/10/03)
The basicity of 1,3-di-tert-butylimidazol-2-ylidene (1) was measured in THF against three hydrocarbon indicators. Both ion pairs and free ions were found and the corresponding equilibrium constants were measured. Homoconjugation was not found in either THF or DMSO. The carbene is effectively more basic in DMSO by several pK units, probably because of hydrogen bonding of 1-H+ to DMSO. Model ab initio computations are consistent with these results.
