Chloranil is a
quinone
The quinones are a class of organic compounds that are formally "derived from aromatic compounds uch as benzene or naphthalene">benzene.html" ;"title="uch as benzene">uch as benzene or naphthalene] by conversion of an even number of –CH= group ...
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 ("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 p ...
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 and diaziquone (AZQ), a cancer chemotherapeutic agent.
See also
*
Chloranilic acid
*
2,3-Dichloro-5,6-dicyano-1,4-benzoquinone
2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (or DDQ) is the chemical reagent with formula C6Cl2(CN)2O2. This oxidant is useful for the dehydrogenation of alcohols, phenols, and steroid ketones. DDQ decomposes in water, but is stable in aqueous mine ...
(DDQ)
References
External links
* {{PPDB, 1297
Organochlorides
Fungicides
1,4-Benzoquinones
Oxidizing agents