Chloranil is a
quinone
The quinones are a class of organic compounds that are formally "derived from aromatic compounds uch as benzene or naphthalene
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by conversion of an even number of –CH= groups into –C(=O)– groups with any necessary rearrangement of double ...
with the molecular formula C
6Cl
4O
2. Also known as tetrachloro-1,4-benzoquinone, it is a yellow solid. Like the parent benzoquinone, chloranil is a planar molecule
[ J.-M. Lü, S. V. Rosokha, I. S. Neretin and J. K. Kochi, "Quinones as Electron Acceptors. X-Ray Structures, Spectral (EPR, UV-vis) Characteristics and Electron-Transfer Reactivities of Their Reduced Anion Radicals as Separated vs Contact Ion Pairs" Journal of the American Chemical Society 2006 128, 16708-16719.] that functions as a mild oxidant.
Synthesis and use as reagent
Chloranil is produced by chlorination of phenol to give
hexachlorocyclohexa-2,5-dien-1-one
Hexachlorocyclohexa-2,5-dien-1-one, sometimes informally called hexachlorophenol (HCP) is an organochlorine compound. It can be prepared from phenol. Despite the informal name, the compound is not a phenol but is a ketone. The informal name is der ...
("hexachlorophenol"). Hydrolysis of the dichloromethylene group in this dienone gives chloranil:
:C
6H
5OH + 6 Cl
2 → C
6Cl
6O + 6 HCl
:C
6Cl
6O + H
2O → C
6Cl
4O
2 + 2 HCl
Chloroanil serves as a hydrogen acceptor. It is more electrophilic than quinone itself. It is used for the aromatization reactions, such as the conversion of
cyclohexadiene Cyclohexadiene may refer to:
* 1,3-Cyclohexadiene,
* 1,4-Cyclohexadiene,
See also
* Benzene or its theoretical isomer ''1,3,5-Cyclohexatriene''
* Cyclohexene
Cyclohexene is a hydrocarbon with the formula C6H10. This cycloalkene is a colorle ...
s to the benzene derivatives.
[Derek R. Buckle "Chloranil" in ''Encyclopedia of Reagents for Organic Synthesis'', 2001, John Wiley. ]
Chloranil is used to test for free secondary amines. This test is useful for checking for the presence of
proline
Proline (symbol Pro or P) is an organic acid classed as a proteinogenic amino acid (used in the biosynthesis of proteins), although it does not contain the amino group but is rather a secondary amine. The secondary amine nitrogen is in the prot ...
derivatives. It is also a good test for the successful deprotection of a secondary amine. Secondary amines react with chloranil to give a brown/red/orange derivative, the colour depending on the amine. In these reactions, the amine displaces chloride from the ring of the quinone.
Commercial applications
It is a precursor to many dyes, such as
pigment violet 23
Pigment violet 23 is an organic compound that is a commercial pigment. It is member of the di oxazine family of heterocyclic compounds, but derived from carbazoles. It is prepared by condensation of chloranil and 3-amino-''N''-ethylcarbazole. It ...
and diaziquone (AZQ), a cancer chemotherapeutic agent.
See also
*
Chloranilic acid
Chloranilic acid is an organic Chemical compound, compound with the chemical formula . It is a red-orange solid. The compound is obtained by hydrolysis of chloranil:
:
It is centrosymmetric, planar molecule. It also crystallizes as a dihydrate ...
*
2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)
References
External links
* {{PPDB, 1297
Organochlorides
Fungicides
1,4-Benzoquinones
Oxidizing agents