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

, a coupling reaction is a type of reaction in which two reactant molecules are bonded together. Such reactions often require the aid of a metal

catalyst Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...

. In one important reaction type, a main group

organometallic compound Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and ...

of the type R-M (where R = organic group, M = main group centre metal atom) reacts with an organic halide of the type R'-X with formation of a new

carbon–carbon bond A carbon–carbon bond is a covalent bond between two carbon atoms. The most common form is the single bond: a bond composed of two electrons, one from each of the two atoms. The carbon–carbon single bond is a sigma bond and is formed between on ...

in the product R-R'. The most common type of coupling reaction is the

cross coupling reaction In organic chemistry, a cross-coupling reaction is a reaction where two different fragments are joined. Cross-couplings are a subset of the more general coupling reactions. Often cross-coupling reactions require metal catalysts. One important reac ...

Richard F. Heck Richard Frederick Heck (August 15, 1931 – October 9, 2015) was an American chemist noted for the discovery and development of the Heck reaction, which uses palladium to catalyze organic chemical reactions that couple aryl halides with alken ...

Ei-ichi Negishi was a Japanese chemist who was best known for his discovery of the Negishi coupling. He spent most of his career at Purdue University in the United States, where he was the Herbert C. Brown Distinguished Professor and the director of the Negi ...

, and

Akira Suzuki is a Japanese chemist and Nobel Prize Laureate (2010), who first published the Suzuki reaction, the organic reaction of an aryl- or vinyl- boronic acid with an aryl- or vinyl- halide catalyzed by a palladium(0) complex, in 1979. Early life a ...

were awarded the 2010

Nobel Prize in Chemistry The Nobel Prize in Chemistry () is awarded annually by the Royal Swedish Academy of Sciences to scientists in the various fields of chemistry. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895, awarded for outst ...

for developing palladium-catalyzed cross coupling reactions. Broadly speaking, two types of coupling reactions are recognized: *Homocouplings joining two identical partners. The product is symmetrical *Heterocouplings joining two different partners. These reactions are also called

cross-coupling reaction In organic chemistry, a cross-coupling reaction is a reaction where two different fragments are joined. Cross-couplings are a subset of the more general coupling reactions. Often cross-coupling reactions require metal catalysts. One important re ...

s. The product is unsymmetrical, .

Homo-coupling types

Coupling reactions are illustrated by the Ullmann reaction:

Cross-coupling types

Applications

Coupling reactions are routinely employed in the preparation of pharmaceuticals. Conjugated polymers are prepared using this technology as well.

References

{{DEFAULTSORT:Coupling Reaction Organometallic chemistry Carbon-carbon bond forming reactions Catalysis