Molecular oxygen, oxidation aromatic

Phenolic compounds are commonplace natural products Figure 24 2 presents a sampling of some naturally occurring phenols Phenolic natural products can arise by a number of different biosynthetic pathways In animals aromatic rings are hydroxylated by way of arene oxide intermediates formed by the enzyme catalyzed reaction between an aromatic ring and molecular oxygen... 

E. F. J. de. Vries, L. Ploeg, M. Colao, J. Brussee, A. van der Gen, Enantioselective Oxidation of Aromatic Ketones by Molecular Oxygen, Catalyzed by Chiral Monoaza-Crown Ethers , Tetrahedron Asymmetry 1995, 6, 1123-1132. 

Ishii and coworkers have demonstrated that V-hydroxyphtalimide (NHPI) is an effective mediator for the oxidation of inactive hydrocarbons, alcohols, olefins and aromatic compounds by molecular oxygen, since the corresponding V-oxyl (PINO) generated from NHPI is an active species for their oxidation" . Before the aerobic oxidation by Ishii... 

The three-dimensional structures, or part of it, are also known for Desulfovibrio vulgaris and Anacystis nidulans flavodoxins. These results, including those obtained on C.MP., were recently summarized by Adman . Hence, these results will be discussed only briefly. The x-ray structures show that the isoalloxazine ring is embedded in a hydrophobic pocket of the apoprotein, i.e. flanked by at least one aromatic amino acid residue. During the redox transitions, especially from the oxidized to the semiquinone state, small conformational changes occur and contacts with the isoalloxazine ring are formed or broken. These conformational transitions form probably a kinetic barrier so that the semiquinone state is trapped by the apoprotein and, therefore, rather stable towards oxidation by molecular oxygen. 

Exclusive ring-nitration occurs with alkylbenzenes. The nitration of toluene in the presence of H-ZSM-5 and molecular oxygen shows a remarkable enhancement of para selectivity (ortho para ratio = 0.08).268 A review is available for the nitration of aromatics by nitrogen oxides on zeolite catalysts.269... 

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