Baeyer-Emmerling indole synthesis
Encyclopedia
The Baeyer-Emmerling indole synthesis is a method for synthesizing indole
from a (substituted) ortho-nitrocinnamic acid and iron
powder in strongly basic solution. This reaction was discovered by Adolf von Baeyer
and A. Emmerling in 1869.
. The intermediate hydroxylamine then condenses with the 2nd carbon on the 1-position to yield indole-2-carboxylc acid, giving off H2O in the process. This carboxylic acid can be decarboxylated to yield indole.
Indole
Indole is an aromatic heterocyclic organic compound. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered nitrogen-containing pyrrole ring. Indole is a popular component of fragrances and the precursor to many pharmaceuticals. Compounds that contain an...
from a (substituted) ortho-nitrocinnamic acid and iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
powder in strongly basic solution. This reaction was discovered by Adolf von Baeyer
Adolf von Baeyer
Johann Friedrich Wilhelm Adolf von Baeyer was a German chemist who synthesized indigo, and was the 1905 recipient of the Nobel Prize in Chemistry. Born in Berlin, he initially studied mathematics and physics at Berlin University before moving to Heidelberg to study chemistry with Robert Bunsen...
and A. Emmerling in 1869.
Reaction Mechanism
The reaction of iron powder upon o-nitrocinnamic acid first yields a substituted hydroxylamineHydroxylamine
Hydroxylamine is an inorganic compound with the formula NH2OH. The pure material is a white, unstable crystalline, hygroscopic compound. However, hydroxylamine is almost always provided and used as an aqueous solution. It is used to prepare oximes, an important functional group. It is also an...
. The intermediate hydroxylamine then condenses with the 2nd carbon on the 1-position to yield indole-2-carboxylc acid, giving off H2O in the process. This carboxylic acid can be decarboxylated to yield indole.
Related links
- Adolf von BaeyerAdolf von BaeyerJohann Friedrich Wilhelm Adolf von Baeyer was a German chemist who synthesized indigo, and was the 1905 recipient of the Nobel Prize in Chemistry. Born in Berlin, he initially studied mathematics and physics at Berlin University before moving to Heidelberg to study chemistry with Robert Bunsen...
- Baeyer-Drewson indigo synthesisBaeyer-Drewson indigo synthesisThe Baeyer–Drewson indigo synthesis is an organic reaction in which indigo is prepared from 2-nitrobenzaldehyde and acetone The reaction is classified as a Aldol condensation...
- IndoleIndoleIndole is an aromatic heterocyclic organic compound. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered nitrogen-containing pyrrole ring. Indole is a popular component of fragrances and the precursor to many pharmaceuticals. Compounds that contain an...
- IndigoIndigo dyeIndigo dye is an organic compound with a distinctive blue color . Historically, indigo was a natural dye extracted from plants, and this process was important economically because blue dyes were once rare. Nearly all indigo dye produced today — several thousand tons each year — is synthetic...