The Baeyer–Emmerling indole synthesis is a method for synthesizing
indole
Indole is an aromatic heterocyclic organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other c ...
from a (substituted) ''ortho''-nitrocinnamic acid and
iron
Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...
powder in strongly basic solution. This reaction was discovered by
Adolf von Baeyer
Johann Friedrich Wilhelm Adolf von Baeyer (; 31 October 1835 – 20 August 1917) was a German chemist who synthesised indigo and developed a nomenclature for cyclic compounds (that was subsequently extended and adopted as part of the IUPAC org ...
and
Adolph Emmerling
Adolph Emmerling (13 June 1842, Freiburg im Breisgau – 17 March 1906, Baden-Baden) was a German chemist, known for his research in the field of agricultural chemistry.
He studied chemistry at the University of Freiburg, receiving his doctora ...
in 1869.
Reaction mechanism
The reaction of iron powder with ''o''-nitrocinnamic acid reduces the
nitro group
In organic chemistry, nitro compounds are organic compounds that contain one or more nitro functional groups (). The nitro group is one of the most common explosophores (functional group that makes a compound explosive) used globally. The nitr ...
to a
nitroso
In organic chemistry, nitroso refers to a functional group in which the nitric oxide () group is attached to an organic moiety (chemistry), moiety. As such, various nitroso groups can be categorized as ''C''-nitroso compounds (e.g., nitrosoalkane ...
. The nitrogen then condenses with a carbon on the
alkene
In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond.
Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...
chain with loss of a molecule of water to form a ring.
Decarboxylation gives indole.
See also
*
Baeyer–Drewson indigo synthesis
The Baeyer–Drewson indigo synthesis (1882) is an organic reaction in which indigo is prepared from 2-nitrobenzaldehyde and acetone The reaction was developed by von Baeyer in 1880 to produce the first synthetic indigo at laboratory ...
References
{{DEFAULTSORT:Baeyer-Emmerling Indole Synthesis
Indole forming reactions
Organic reactions
Name reactions