The Hofmann–Martius rearrangement in

organic chemistry Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; ...

is a

rearrangement reaction In organic chemistry, a rearrangement reaction is a broad class of organic reactions where the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. Often a substituent moves from one atom to another ...

converting an N-alkylated

aniline Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine In organic chemistry, an aromatic amine is an organic compound consisting of an aroma ...

to the corresponding ortho and / or

para Para, or PARA, may refer to: Businesses and organizations * Paramount Global, traded as PARA on the Nasdaq stock exchange * Para Group, the former name of CT Corp * Para Rubber, now Skellerup, a New Zealand manufacturer * Para USA, formerly ...

aryl In organic chemistry, an aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar" is used as ...

-alkylated aniline. The reaction requires heat, and the

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

is an acid like

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

. : When the catalyst is a metal halide the reaction is also called the Reilly–Hickinbottom rearrangement. The reaction is also known to work for aryl ethers and two conceptually related reactions are the

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 aryl ...

and the

Fischer–Hepp rearrangement The Fischer–Hepp rearrangement is a rearrangement reaction in which an aromatic N-nitroso or nitrosamine converts to a carbon nitroso compound: This organic reaction was first described by the German chemist Otto Philipp Fischer (1852–1932) ...

. Its

reaction mechanism In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical change occurs. A chemical mechanism is a theoretical conjecture that tries to describe in detail what takes place at each stage of ...

centers around dissociation of the reactant with the positively charged organic residue R attacking the aniline ring in a Friedel–Crafts alkylation. In one study this rearrangement was applied to a 3-N(CH₃)(C₆H₅)-2-oxindole:heating 1 in

toluene Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon. It is a colorless, water-insoluble liquid with the smell associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a methyl group (CH3) at ...

at 80 °C gives 30% 2-o (ortho) and 37% 2-p (para) : The reaction is named after German chemists

August Wilhelm von Hofmann August Wilhelm von Hofmann (8 April 18185 May 1892) was a German chemist who made considerable contributions to organic chemistry. His research on aniline helped lay the basis of the aniline-dye industry, and his research on coal tar laid the g ...

and Carl Alexander von Martius.

References

{{DEFAULTSORT:Hofmann-Martius Rearrangement Rearrangement reactions

See also

References