Contribution to the study of the mechanism of the Ullmann biaryl condensation. The reaction of 2,3-dichloronitrobenzene

Abstract

The reaction of 2,3-dichloronitrobenzene with copper bronze gives, in a total yield of 100%, 1,5-dinitrobiphenylene and 1,5,9-trinitrotriphenylene. The formation of these compounds necessarily implies an initial ortho–meta coupling, which rules out a free-radical process, and a mechanism involving the coupling of two molecules of an organocopper intermediate. The results are, on the contrary, in good accord with the ionic mechanism, proposed by Fanta, according to which the organocopper intermediate reacts with a molecule of the aryl halide.