[Phenoxenium ions: generations and reactions].
The acid-catalyzed reaction of N-acyl- and N-sulfonylhydroxylamines with benzene proceeded smoothly to give C-C products; 2- and 4-hydroxybiphenyls. The reaction and the thermolysis of N-aryloxypyridinium salts involve common intermediates. The results of product analysis, the orientation of the reaction, effects of substituents on the nitrogen atom and on the phenyl ring suggested a mechanism involving a phenoxenium ion. The positive charge of the phenoxenium ion localized not on the oxygen atom but on the ortho and para carbons of the benzene ring. C-O product: diphenylethers are formed when the heterolysis of the N-O bonds is slow and the aromatic solvent has high nucleophilicity, suggesting an SN2-like reaction on the oxygen atom. The phenoxenium ions are also concerned with a rearrangement of O-arylhydroxylamine to 2-aminophenol. An ion-molecule pair involving phenoxenium ion and ammonia as an intermediate of the intramolecular ortho rearrangement.
Endo
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Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
Shudo
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D002384:Catalysis; D006898:Hydroxylamines; D010636:Phenols / Q000737:chemistry*
D006898:Hydroxylamines; D010636:Phenols; C012484:phenylhydroxylamine; C042329:phenoxy radical