BAMBERGER Phenylhydroxylamine rearrangement

BAMBERGER Phenylhydroxylamine Rearrangement Rearrangement of N-arylhydroxylamine to aminoptienol. 

Montmorillonite KIO clay and its various cation-exchanged forms have been found to promote the formation of an unexpected product, p-nitrosodiphenylamine, from iV-phenylhydroxylamine, rather than the typical Bamberger products. A Bamberger rearrangement has been shown to occur during the metabolism of 2,4,6-trinitrotoluene... 

Recently, a Bamberger rearrangement in gas phase was reported. The rearrangement of A-phenylhydroxylamine (210, R, R, R = H) into 4-aminophenol (214, R , R, R = H) occurred on the acid sites of H-ZSM-5 zeolite. However, A-phenylhydroxylamine with K-10 montmoriUonite clay and its various cation-exchanged forms failed to rearrange into aminophenols ... 

Nitrobenzenes also undergo the Bamberger rearrangement, being the most convenient and economical method for the synthesis of p-aminophenols, particularly on an industrial scale . The process is normally carried out by catalytic hydrogenation under highly acidic conditions, where Af-phenylhydroxylamine has been shown to be the intermediate (equation 65). 

The Bamberger Rearrangement, 116 (R=OH, R =H)- p-Aminophenol The Bamberger rearrangement is summarized by the transformation of A(-phenylhydroxylamine (118) to /)-aminophenol (122), and its para-selective mechanism is shown in Scheme 18.19. 

Sone, T., Y. Tokuda, T. Sakai, S. ShinkaiandO.Manabe. 1981. Kinetics and mechanisms of the Bamberger rearrangement. Part 3. Rearrangement of phenylhydroxylamines top-aminophenols in aqueous sulphuric acid solution. J. Chem. Soc. Perkin. Trans. II 1981 298-302. 

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