Bamberger rearrangement

Eugen Bamberger (1857–1932)

The Bamberger rearrangement is a reaction from the field of organic chemistry and named after its discoverer, the German chemist Eugen Bamberger (1857–1932). The reaction is used to synthesize para - hydroxyaniline derivatives from phenylhydroxylamine derivatives in the presence of strong aqueous acids .

Reaction mechanism

The reaction begins with the reversible protonation of phenylhydroxylamine 1 . Protonation of the nitrogen atom is preferred and leads to 2 , but is unproductive for the desired reaction. If the hydroxy oxygen is protonated ( 3 ), water can be split off with the formation of a mesomeric stabilized nitrenium ion 4 . This is followed by a nucleophilic attack by a water molecule on the aromatic . This results in product 5 after rearomatization .

Individual evidence

↑ Eug. Bamberger: About the phenylhydroxylamine. In: Reports of the German Chemical Society. 27, No. 2, 1894, pp. 1548-1557, doi : 10.1002 / cber.18940270276 .
↑ PW Oxley, BM Adger, MJ Sasse, MA Forth: N-Acetyl-N-phenylhydroxylamine via Catalytic Transfer Hydrogenation of Nitrobenzene using Hydrazine and Rhodium on Carbon In: Organic Syntheses . 67, 1989, p. 187, doi : 10.15227 / orgsyn.067.0187 ; Coll. Vol. 8, 1993, p. 16 ( PDF ).
↑ Takaaki Sone, Kazuhiro Hamamoto, Yoshiyuki Seiji, Seiji Shinkai, Osamu Manabe: Kinetics and mechanisms of the Bamberger rearrangement. Part 4. Rearrangement of sterically hindered phenylhydroxylamines to 4-aminophenols in aqueous sulphuric acid solution. In: Journal of the Chemical Society, Perkin Transactions 2. No. 12, 1981, pp. 1596-1598, doi : 10.1039 / p29810001596 .
↑ George Kohnstam, W. Andrew Petch, D. Lyn H. Williams: Kinetic substitute and isotope effects in the acid-catalysed rearrangement of N-phenylhydroxylamines. Are nitrenium lons involved? In: Journal of the Chemical Society, Perkin Transactions 2. No. 3, 1984, pp. 423-427, doi : 10.1039 / P29840000423 .

Web links

Commons : Bamberger rearrangement - collection of images, videos and audio files

[1] Eug. Bamberger: About the phenylhydroxylamine. In: Reports of the German Chemical Society. 27, No. 2, 1894, pp. 1548-1557, doi : 10.1002 / cber.18940270276 .

[2] PW Oxley, BM Adger, MJ Sasse, MA Forth: N-Acetyl-N-phenylhydroxylamine via Catalytic Transfer Hydrogenation of Nitrobenzene using Hydrazine and Rhodium on Carbon In: Organic Syntheses . 67, 1989, p. 187, doi : 10.15227 / orgsyn.067.0187 ; Coll. Vol. 8, 1993, p. 16 ( PDF ).

[3] Takaaki Sone, Kazuhiro Hamamoto, Yoshiyuki Seiji, Seiji Shinkai, Osamu Manabe: Kinetics and mechanisms of the Bamberger rearrangement. Part 4. Rearrangement of sterically hindered phenylhydroxylamines to 4-aminophenols in aqueous sulphuric acid solution. In: Journal of the Chemical Society, Perkin Transactions 2. No. 12, 1981, pp. 1596-1598, doi : 10.1039 / p29810001596 .

[4] George Kohnstam, W. Andrew Petch, D. Lyn H. Williams: Kinetic substitute and isotope effects in the acid-catalysed rearrangement of N-phenylhydroxylamines. Are nitrenium lons involved? In: Journal of the Chemical Society, Perkin Transactions 2. No. 3, 1984, pp. 423-427, doi : 10.1039 / P29840000423 .