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The Bamberger rearrangement is the 
The starting phenylhydroxylamines are typically synthesized by the
chemical reaction
A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...
of phenylhydroxylamine
Phenylhydroxylamine is the organic compound with the formula C6H5NHOH. It is an intermediate in the redox-related pair C6H5NH2 and C6H5NO. Phenylhydroxylamine should not be confused with its isomer α-phenylhydroxylamine or ''O''-phenylhydroxyl ...
s with strong aqueous
An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), in water would be re ...
acid, which will rearrange to give 4-aminophenols. It is named for the German chemist Eugen Bamberger (1857–1932).
The starting phenylhydroxylamines are typically synthesized by the transfer hydrogenation
In chemistry, transfer hydrogenation is a chemical reaction involving the addition of hydrogen to a compound from a source other than molecular . It is applied in laboratory and industrial organic synthesis to saturate organic compounds and redu ...
of nitrobenzenes using rhodium
Rhodium is a chemical element with the symbol Rh and atomic number 45. It is a very rare, silvery-white, hard, corrosion-resistant transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring i ...
or zinc
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
catalysts.
Application: Fenhexamide
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 thenitrenium ion
A nitrenium ion (also called: aminylium ion or imidonium ion (obsolete)) in organic chemistry is a reactive intermediate based on nitrogen with both an electron lone pair and a positive charge and with two substituents (). Nitrenium ions are isoel ...
4, which can react with nucleophiles ( H2O) to form the desired 4-aminophenol 5.
See also
* Friedel–Crafts alkylation-like reactions: ** Hofmann-Martius rearrangement **Fries rearrangement
The Fries rearrangement, named for the German chemist Karl Theophil Fries, is a rearrangement reaction of a phenolic ester to a hydroxy aryl ketone by catalysis of Lewis acids.
It involves migration of an acyl group of phenol ester to the ar ...
** Fischer–Hepp rearrangement
** Wallach rearrangement
References
{{DEFAULTSORT:Bamberger rearrangement Rearrangement reactions Name reactions