Mechanism of the oxidation of methylbenzenes by Pd(II)
The oxidation of methylbenzenes (toluene, p-xylene, mesitylene, durene) by palladium- (II) to diarylmethanes in CF3COOH proceeds according to a mechanism of one-electron transfer. In addition, there is an oxidation of arenes to diaryls according to the well-known two-electron mechanism, including electrophilic substitution in the ring of the arene.
The contribution of the one-electron mechanism increases with decreasing ionization potential of the arene and with increasing acidity of the medium.
Complexes of palladium(I) (probably dimers) are intermediates of the one-electron oxidation of methylbenzenes to diarylmethanes.
KeywordsOxidation Methylbenzene Acidity Palladium Ionization Potential
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