Equilibrium acidities of substituted methanes in dimethyl sulfoxide

Perhaps the data that provide the best basis for comparison between these groups in terms of internal consistency are those of Bordwell and co-workers/ These workers determined relative equilibrium acidities of the substituted methanes with reference to aromatic hydrocarbon indicators in DMSO. The data are given in Table 7.3. The ordering N02 C=0 S02 CN is established by these data. Both inductive and resonance effects are involved in the ability of these functional groups to stabilize the negative charge. The inductive effect is probably dominant for sulfones  

Carbanions derived from carbonyl compounds are often referred to by the name etiolate. This name is derived from the name for the enol tautomer of carbonyl compounds. The resonance-stabilized enolate anion is the conjugate base of both the keto and the enol forms of carbonyl compounds  

There have been numerous studies of the rates of deprotonation of carbonyl compounds. These data are of interest not only because they define the relationship between thermodynamic and kinetic acidity in these compounds, but also because they are necessary for defining mechanisms of reactions in which enolates are involved as intermediates. Rates of enolate formation can be measured conveniently by following isotopic exchange using either deuterium or tritium  

Another technique is to measure the rate of halogenation of the carbonyl compound. Ketones and aldehydes in their carbonyl forms do not react rapidly with the halogens but the enolate is rapidly attacked. The rate of halogenation is therefore a measure of 

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Table 7.3. Equilibrium Acidities of Substituted Methanes in Dimethyl Sulfoxide"...

Equilibrium acidities of substituted methanes in dimethyl sulfoxide... 

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