The Chugaev elimination is a chemical reaction that involves the elimination of water from

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...

s to produce

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 ...

s. The intermediate is a

xanthate 150px, Sodium salt of ethyl xanthate Xanthate usually refers to a salt with the formula (R = alkyl; M+ = Na+, K+), thus they are the metal-thioate/''O''-esters of dithiocarbonate. The name ''xanthates'' is derived from Ancient Greek ''xanthos'' ...

. It is named for its discoverer, the Russian chemist

Lev Aleksandrovich Chugaev Lev Aleksandrovich Chugaev (16 October 1873 – 26 September 1922) was a Russian chemist. At the height of his career, he was professor of chemistry at the University of Petersburg, being the successor to Dmitri Mendeleev. He was active in the f ...

(1873-1922), who first reported the reaction sequence in 1899. In the first step, a xanthate salt is formed out of the

alkoxide In chemistry, an alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. They are written as , where R is the organic substituent. Alkoxides are strong bases and, whe ...

and

carbon disulfide Carbon disulfide (also spelled as carbon disulphide) is a neurotoxic, colorless, volatile liquid with the formula and structure . The compound is used frequently as a building block in organic chemistry as well as an industrial and chemical non ...

(CS₂). With the addition of

iodomethane Iodomethane, also called methyl iodide, and commonly abbreviated "MeI", is the chemical compound with the formula CH3I. It is a dense, colorless, volatile liquid. In terms of chemical structure, it is related to methane by replacement of one h ...

, the alkoxide is transformed into a methyl xanthate. At about 200 °C, the alkene is formed by an intramolecular elimination. In a 6-membered cyclic transition state the hydrogen atom is removed from the carbon atom β to the xanthate oxygen in a ''syn''-elimination. The side product decomposes to

carbonyl sulfide Carbonyl sulfide is the chemical compound with the linear formula OCS. It is a colorless flammable gas with an unpleasant odor. It is a linear molecule consisting of a carbonyl group double bonded to a sulfur atom. Carbonyl sulfide can be conside ...

(OCS) and

methanethiol Methanethiol (also known as methyl mercaptan) is an organosulfur compound with the chemical formula . It is a colorless gas with a distinctive putrid smell. It is a natural substance found in the blood, brain and feces of animals (including hum ...

. The Chugaev elimination is similar in mechanism to other thermal elimination reactions such as the

Cope elimination The Cope reaction or Cope elimination, developed by Arthur C. Cope, is an elimination reaction of the N-oxide to form an alkene and a hydroxylamine. Mechanism and applications The reaction mechanism involves an intramolecular 5-membered cyclic tr ...

and

ester pyrolysis Ester pyrolysis in organic chemistry is a vacuum pyrolysis reaction converting esters containing a β-hydrogen atom into the corresponding carboxylic acid and the alkene. The reaction is an Ei elimination, Ei elimination and operates in a syn fashio ...

. Xanthates typically undergo elimination from 120 to 200 °C, while esters typically require 400 to 500 °C and amine oxides routinely react between 80 and 160 °C.

References

* * {{Organic reactions

External links

Animation of the mechanism of the Chugaev elimination
Elimination reactions Olefination reactions Name reactions

See also

References

External links