Chloranil

Chloranil 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^[2] that functions as a mild oxidant.

Chloranil^[1]

Names
IUPAC name 2,3,5,6-Tetrachlorocyclohexa-2,5-diene-1,4-dione
Other names p-Chloranil; Tetrachloro-1,4-benzoquinone; Tetrachloro-p-benzoquinone
Identifiers
CAS Number	118-75-2 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:36703 Y
ChEMBL	ChEMBL192627 Y
ChemSpider	8068 Y
ECHA InfoCard	100.003.887
EC Number	204-274-4
KEGG	C18933 N
PubChem CID	8371
RTECS number	DK6825000
UNII	01W5X7N5XV Y
CompTox Dashboard (EPA)	DTXSID2020266
InChI InChI=1S/C6Cl4O2/c7-1-2(8)6(12)4(10)3(9)5(1)11 Y Key: UGNWTBMOAKPKBL-UHFFFAOYSA-N Y InChI=1/C6Cl4O2/c7-1-2(8)6(12)4(10)3(9)5(1)11 Key: UGNWTBMOAKPKBL-UHFFFAOYAV
SMILES ClC=1C(=O)C(\Cl)=C(\Cl)C(=O)C=1Cl
Properties
Chemical formula	C6Cl4O2
Molar mass	245.86 g·mol−1
Appearance	Yellow solid
Melting point	295 to 296 °C (563 to 565 °F; 568 to 569 K)
Magnetic susceptibility (χ)	−112.6·10−6 cm3/mol
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H410
Precautionary statements	P264, P273, P280, P302+P352, P305+P351+P338, P321, P332+P313, P337+P313, P362, P391, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

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:^[3]

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 cyclohexadienes to the benzene derivatives.^[4]

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.

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 (DDQ)