Chloranil

Chloranil
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
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.887 Edit this at Wikidata
EC Number
  • 204-274-4
KEGG
RTECS number
  • DK6825000
UNII
UN number 3077
  • InChI=1S/C6Cl4O2/c7-1-2(8)6(12)4(10)3(9)5(1)11 checkY
    Key: UGNWTBMOAKPKBL-UHFFFAOYSA-N checkY
  • InChI=1/C6Cl4O2/c7-1-2(8)6(12)4(10)3(9)5(1)11
    Key: UGNWTBMOAKPKBL-UHFFFAOYAV
  • ClC=1C(=O)C(\Cl)=C(\Cl)C(=O)C=1Cl
Properties
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
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))
−112.6×10−6 cm3/mol[citation needed]
Structure
Monoclinic
P21/c (C5
2h)
2/m
a = 8.86 Å, b = 5.83 Å, c = 8.76 Å
α = 90°, β = 72.6°, γ = 90°
2
Hazards
GHS labelling:
GHS05: CorrosiveGHS07: Exclamation markGHS09: Environmental hazard
Danger
H315, H317, H318, H410
P261, P264, P272, P273, P280, P302+P352, P305+P351+P338+P310, P333+P313, P362, P391, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
1
0
Flash point >100 °C (212 °F)
>400 °C (752 °F)
Lethal dose or concentration (LD, LC):
4000 mg/kg (rat, oral)
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).
X markN verify (what is checkYX markN ?)

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 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:

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.

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.[citation needed]

Commercial applications

It is a precursor to many dyes, such as pigment violet 23 and diaziquone (AZQ), a cancer chemotherapeutic agent.[citation needed]

See also

References

  1. ↑ Haynes, William M., ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). Boca Raton, Florida: CRC Press. pp. 3–496. ISBN 9781498754293.
  2. 1 2 3 4 "SDS - Tetrachloro-p-benzoquinone". www.fishersci.com. Revision 6. ThermoFisher Scientific. 19 December 2025. p. 3. Retrieved 5 June 2026.
  3. 1 2 Sigma-Aldrich Co., Tetrachloro-1,4-benzoquinone.
  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.
  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.