Selectivity of the Aromatic Plumbylation Reaction

Article abstract of DOI:10.1021/jo01311a019

The plumbylation of toluene in dichloroacetic acid yields initially 5.4percent 2-, 1.8percent 3-, and 92.7percent 4-methylphenyllead(IV) dichloroacetates.The toluene to benzene rate ratio under these conditions is 59.9.The partial rate factors are o^Me_f = 9.64, m^Me_f = 3.21, p^Me_f = 331.The plumbylation of toluene in trifluoroacetic acid yields aryl trifluoroacetates and biaryls.Analysis of these products suggest that the plumbylation reaction yields 17.9percent 2-, 3.2percent 3-, and 78.9percent 4-methylphenyllead (IV) trifluoroacetates in the initial step of the reaction.The toluene to benzene rate ratio is 114 under these conditions.The partial rate factors are o^Me_f = 61.2, m^Me_f = 10.8, and p^Me_f = 540.These observations suggest that the plumbylation reaction is a typical electrophilic substitution and that the reaction is significantly more selective than thallation or mercuration.