- Bamberger rearrangement
The Bamberger rearrangement is the
chemical reaction of N-phenylhydroxylamines with strongaqueous acid , which will rearrange to give 4-aminophenols.cite journal | last = Bamberger | first = E. | journal = Chem. Ber. | date = 1894 | volume = 27 | pages = 1347 & 1548–1557 | title = Uber das Phenylhydroxylamin | doi = 10.1002/cber.18940270276 | url = http://gallica.bnf.fr/ark:/12148/bpt6k907342/f376.table ] cite journal | last = Harman | first = R. E. | journal =Organic Syntheses | title = Chloro-p-benzoquinone | volume = 35 | pages = 22 | year = 1955 | url = http://www.orgsyn.org/orgsyn/prep.asp?prep=cv4p0148 "(also in the [http://www.orgsyn.org/orgsyn/pdfs/CV4P0148.pdf Collective Volume (1963) 4:148 (PDF)] )."] It is named for the German chemistEugen Bamberger (1857–1932).N-Phenylhydroxylamines are typically synthesized from
nitrobenzene s by reduction usingrhodium cite journal | author = Oxley, P. W.; Adger, B. M.; Sasse, M. J.; Forth, M. A. | journal =Organic Syntheses | url = http://www.orgsyn.org/orgsyn/prep.asp?prep=cv8p0016 | volume = 67 | pages = 187 | date = 1989 | title = N-Acetyl-N-phenylhydroxylamine via Catalytic Transfer Hydrogenation of Nitrobenzene using Hydrazine and Rhodium on Carbon "(also in the [http://www.orgsyn.org/orgsyn/pdfs/cv8p0016.pdf Collective Volume (1993) 8:16 (PDF)] )."] orzinc cite journal | last = Kamm | first = O. | journal =Organic Syntheses | url = http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0445 | volume = 4 | pages = 57 | date = 1925 | title = β-Phenylhydroxylamine "(also in the [http://www.orgsyn.org/orgsyn/pdfs/cv1p0445.pdf Collective Volume (1941) 1:445 (PDF)] )."] .Reaction mechanism
The mechanism of the Bamberger rearrangement proceeds from the monoprotonation of N-phenylhydroxylamine 1. N-protonation 2 is favored, but unproductive. O-protonation 3 can form the
nitrenium ion 4, which can react with nucleophiles (H2O) to form the desired 4-aminophenol 5.cite journal | author = Sone, Takaaki; Hamamoto, Kazuhiro; Seiji, Yoshiyuki; Shinkai, Seiji; Manabe, Osamu | title = Kinetics and mechanisms of the Bamberger rearrangement. Part 4. Rearrangement of sterically hindered phenylhydroxylamines to 4-aminophenols in aqueous sulphuric acid solution | journal = J. Chem. Soc. Perkin Trans. II | date = 1981 | pages = 1596–1598 | doi = 10.1039/P29810000298] cite journal | author = George Kohnstam, W. Andrew Petch and D. Lyn H. Williams | journal = J. Chem. Soc. Perkin Trans. II | date = 1984 | pages = 423–427 | title = Kinetic substituent and isotope effects in the acid-catalysed rearrangement of N-phenylhydroxylamines. Are nitrenium lons involved? | doi = 10.1039/P29840000423]References
ee also
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Hofmann-Martius rearrangement
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