Cobalt catalysis aromatic substitution

Catalysis by cobalt(III) has been the subject of several papers.185-187 The N.N-bis(sahcyldene)ethylnediaminocobalt(III)-catalysed oxidative carbonylation of o-, m-and -substituted primary aromatic amines in MeOH gives ureas, isocyanates, carbamates, and azo derivatives. A Hammett p value of —0.5 for the reaction indicates that electrophilic attack of CO at a nitrogen anion complexed to Co in the TS is... 

Benzylic oxidation of aromatic side-chains is also a well established technology in the bulk chemicals arena, e. g. toluene to benzoic acid and p-xylene to ter-ephthalic acid [1,2]. These processes involve homogeneous catalysis by, e. g., cobalt compounds, however, and also fall outside the scope of this book. Ammoxi-dation of methyl-substituted aromatic and heteroaromatic compounds is performed over heterogeneous catalysts in the gas phase but this reaction is treated elsewhere (Section 9.5). Transition metal-substituted molecular sieves have been widely studied as heterogeneous catalysts for oxidation of aromatic side-chains in the liquid phase, but there are serious doubts about their heterogeneity [5,6]. Here again, a cursory examination of the literature reveals that supported palladium seems to be the only heterogeneous catalyst with synthetic utility [4]. 

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