Linear free energy relationship hydrogen exchange

In this chapter it is clearly impossible to do more than sample the extensive literature on the carbon acidity of sulfinyl and sulfonyl compounds, as it illuminates the electronic effects of these groups, particularly in connection with linear free-energy relationships. There are three main areas to cover first, as already indicated, equilibrium acidities (pKa values) second, the kinetics of ionization, usually studied through hydrogen isotopic exchange and finally, the kinetics of other reactions proceeding via carbanionic intermediates. 

Kinetic acidity is defined as the relative rate of proton abstraction by a base and is often measured by hydrogen isotope exchange. The linear free energy relationship often found between equilibrium and kinetic acidities for related groups of compounds is usually referred to as a Br nsted relationship (equation 4). 

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