Active-sodium-promoted Reductive Cleavage of Halogenated Benzoic Acids

The outcome of the reaction between 1,2-diaryl-1,2-disodioethanes and halogenated benzoic acids
strongly depends on the nature of both reaction partners. Indeed, whilst chloro-, bromo- and iodobenzoic
acids are easily dehalogenated, the reductive cleavage of fluorobenzoic acids proceeds to a high
extent only in the presence of the dianions endowed with more powerful reducing properties. Moreover,
it was observed that ortho-substituted benzoic acids are more easily dehalogenated than the corresponding
para or meta isomers. These observations allowed the development of reaction conditions for
the exhaustive or regioselective cleavage of selected polyhalogenated benzoic acids.