Chloranilic acid is an organic compound with the chemical formula C6Cl2O2(OH)2. It is a red-orange solid. The compound is obtained by hydrolysis of chloranil:

Chloranilic acid[1]
Skeletal formula of chloranilic acid
Ball-and-stick model of chloranilic acid
Names
Preferred IUPAC name
2,5-Dichloro-3,6-dihydroxycyclohexa-2,5-diene-1,4-dione
Other names
2,5-Dichloro-3,6-dihydroxy-1,4-benzoquinone
2,5-Dichloro-3,6-dihydroxybenzoquinone
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.001.619 Edit this at Wikidata
EC Number
  • 201-780-7
UNII
  • InChI=1/C6H2Cl2O4/c7-1-3(9)5(11)2(8)6(12)4(1)10/h9,12H
    Key: IPPWILKGXFOXHO-UHFFFAOYAU
  • Cl\C1=C(/O)C(=O)C(\Cl)=C(\O)C1=O
Properties
C6H2Cl2O4
Molar mass 208.98 g/mol
Appearance orange or red crystals or powder
Density 1.96 g/cm3[2]
Melting point ≥300 °C
Acidity (pKa) 2.95, 4.97[3]
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H315, H319, H335
P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501
Flash point 135.4 °C (275.7 °F; 408.5 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
C6Cl4O2 + 2 H2O → C6Cl2O2(OH)2 + 2 HCl

It is centrosymmetric, planar molecule. It also crystallizes as a dihydrate.[2]

Chloranilic acid is a noteworthy hydroxyquinone that is somewhat acidic owing to the presence of the two chloride substituents. The conjugate base, C6H2Cl2O42- readily forms coordination complexes often linking pairs of many metal ions.[3]

See also

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References

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  1. ^ "Chloranilic acid". Sigma-Aldrich.
  2. ^ a b Andersen, E. K. (1967). "The Crystal and Molecular Structure of Hydroxyquinones and Salts of Hydroxyquinones. I. Chloranilic Acid". Acta Crystallographica. 22 (2): 188–191. doi:10.1107/S0365110X67000325.
  3. ^ a b Mostafa, S. I. (1999). "Complexes of 2,5-Dihydroxy-1,4-Benzoquinone and Chloranilic Acid with Second and Third Row Transition Elements". Transition Metal Chemistry. 24 (3): 306–310. doi:10.1023/A:1006944124791. S2CID 91429728.