| Appearance = Yellow solid
| Density =
| MeltingPtC = 295 to 296
| MeltingPt_notes =
| BoilingPt =
| Solubility =
| MagSus = -112.6·10−6 cm3/mol
| MainHazards =
| FlashPt =
| AutoignitionPt =
| RPhrases =
| SPhrases =
is a quinone
with the molecular formula C6Cl4O2. 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:François Muller and Liliane Caillard "Chlorophenols" in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim, 2011.
C6H5OH + 6 Cl2 → C6Cl6O + 6 HCl
C6Cl6O + H2O → C6Cl4O2 + 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
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
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.
It is a precursor to many dyes, such as pigment violet 23
and diaziquone (AZQ), a cancer chemotherapeutic agent.