Chloranil

Chloranil
	source ↗
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;
UN number	3077
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
Density	1.97 g⋅cm−3
Melting point	298.3 °C (568.9 °F; 571.5 K)
Boiling point	Sublimes
Solubility in water	0.25 g/kg (20 °C (68 °F))
Solubility in Ethanol	Slightly soluble
Solubility in Chloroform	Slightly soluble
Solubility in Diethyl ether	Soluble
log P	2.3 (20 °C (68 °F))
Vapor pressure	1 hPa (71 °C (160 °F))
Magnetic susceptibility (χ)	−112.6×10−6 cm3/mol
Structure
Crystal structure	Monoclinic
Space group	P21/c (C5; 2h)
Point group	2/m
Lattice constant	a = 8.86 Å, b = 5.83 Å, c = 8.76 Å α = 90°, β = 72.6°, γ = 90°
Formula units (Z)	2
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H315, H317, H318, H410
Precautionary statements	P261, P264, P272, P273, P280, P302+P352, P305+P351+P338+P310, P333+P313, P362, P391, P501
NFPA 704 (fire diamond)	source ↗ 3 1 0
Flash point	>100 °C (212 °F)
Autoignition; temperature	>400 °C (752 °F)
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	4000 mg/kg (rat, oral)
LC50 (median concentration)	24.85 mg/m3 (rat, inhalation, 4h)
	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

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 molecule⁵ 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:⁶

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.⁷

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.

References

"SDS - Tetrachloro-p-benzoquinone". www.fishersci.com. Revision 6. ThermoFisher Scientific. 19 December 2025. p. 3. Retrieved 5 June 2026.
Sigma-Aldrich Co., Tetrachloro-1,4-benzoquinone.
Haynes, William M., ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). Boca Raton, Florida: CRC Press. pp. 3–496. ISBN 9781498754293.
Ueda, Ikuhiko (June 1961). "The Crystal Structure of Chloranil and Bromanil". Journal of the Physical Society of Japan. 16 (6): 1185–1194. doi:10.1143/JPSJ.16.1185.
Lü, Jian-Ming; Rosokha, Sergiy V.; Neretin, Ivan S.; Kochi, Jay K. (1 December 2006). "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. 128 (51): 16708–16719. doi:10.1021/ja066471o.
Muller, François; Caillard, Liliane (2011). "Chlorophenols". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a07_001.pub2. ISBN 978-3-527-30673-2.
Buckle, Derek R. (15 April 2001). "Chloranil". Encyclopedia of Reagents for Organic Synthesis. John Wiley. doi:10.1002/047084289X.rc057.

External links

Chloranil in the Pesticide Properties DataBase (PPDB)

[FisherSDS-1] "SDS - Tetrachloro-p-benzoquinone". www.fishersci.com. Revision 6. ThermoFisher Scientific. 19 December 2025. p. 3. Retrieved 5 June 2026.

[Sigma-2] Sigma-Aldrich Co., Tetrachloro-1,4-benzoquinone.

[CRC97-3] Haynes, William M., ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). Boca Raton, Florida: CRC Press. pp. 3–496. ISBN 9781498754293.

[4] Ueda, Ikuhiko (June 1961). "The Crystal Structure of Chloranil and Bromanil". Journal of the Physical Society of Japan. 16 (6): 1185–1194. doi:10.1143/JPSJ.16.1185.

[Kochi-5] Lü, Jian-Ming; Rosokha, Sergiy V.; Neretin, Ivan S.; Kochi, Jay K. (1 December 2006). "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. 128 (51): 16708–16719. doi:10.1021/ja066471o.

[6] Muller, François; Caillard, Liliane (2011). "Chlorophenols". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a07_001.pub2. ISBN 978-3-527-30673-2.

[7] Buckle, Derek R. (15 April 2001). "Chloranil". Encyclopedia of Reagents for Organic Synthesis. John Wiley. doi:10.1002/047084289X.rc057.

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Names
source ↗
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
UN number	3077
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
Properties³
Chemical formula	C₆Cl₄O₂
Molar mass	245.86 g·mol⁻¹
Appearance	Yellow solid
Density	1.97 g⋅cm⁻³¹
Melting point	298.3 °C (568.9 °F; 571.5 K)
Boiling point	Sublimes
Solubility in water	0.25 g/kg (20 °C (68 °F))
Solubility in Ethanol	Slightly soluble
Solubility in Chloroform	Slightly soluble
Solubility in Diethyl ether	Soluble
log P	2.3 (20 °C (68 °F))²
Vapor pressure	1 hPa (71 °C (160 °F))¹
Magnetic susceptibility (χ)	−112.6×10⁻⁶ cm³/mol
Structure⁴
Crystal structure	Monoclinic
Space group	P2₁/c (C⁵ _2h)
Point group	2/m
Lattice constant	a = 8.86 Å, b = 5.83 Å, c = 8.76 Å α = 90°, β = 72.6°, γ = 90°
Formula units (Z)	2
Hazards²
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H315, H317, H318, H410
Precautionary statements	P261, P264, P272, P273, P280, P302+P352, P305+P351+P338+P310, P333+P313, P362, P391, P501
NFPA 704 (fire diamond)	¹ source ↗ 3 1 0
Flash point	>100 °C (212 °F)¹
Autoignition temperature	>400 °C (752 °F)
Lethal dose or concentration (LD, LC):
LD₅₀ (median dose)	4000 mg/kg (rat, oral)
LC₅₀ (median concentration)	24.85 mg/m³ (rat, inhalation, 4h)
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

Commercial applications

See also

References

External links