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2,3-Dichloro-5,6-dicyano-1,4-benzoquinone

2,3-Dichloro-5,6-dicyano-1,4-benzoquinone
Structural formula of dichlorodicyanobenzoquinone
Space-filling model of the dichlorodicyanobenzoquinone molecule
Names
Preferred IUPAC name
4,5-Dichloro-3,6-dioxocyclohexa-1,4-diene-1,2-dicarbonitrile
Other names
  • 2,3-Dichloro-5,6-dicyano-p-benzoquinone
  • 4,5-Dichloro-3,6-dioxo-1,4-cyclohexadiene-1,2-dicarbonitrile
  • Dichlorodicyanobenzoquinone
Identifiers
3D model (JSmol)
Abbreviations DDQ
ChemSpider
ECHA InfoCard 100.001.402
EC Number 201-542-2
PubChem CID
RTECS number GU4825000
Properties
C8Cl2N2O2
Molar mass 227.00 g·mol−1
Appearance yellow to orange powder
Density 1.7g/cm3
Melting point 210 to 215 °C (410 to 419 °F; 483 to 488 K) (decomposes)
Boiling point 301.8 °C (575.2 °F; 575.0 K) at 760mmHg
reacts
Hazards
R-phrases (outdated) R25 R29
S-phrases (outdated) S22 S24/25 S37 S45
Flash point 136.3 °C (277.3 °F; 409.4 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY  (what is YesYN ?)
Infobox references

2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (or DDQ) is the chemical reagent with formula C6Cl2(CN)2O2. This oxidant is useful for the dehydrogenation of alcohols, phenols, and steroid ketones in organic chemistry. DDQ decomposes in water, but is stable in aqueous mineral acid.

Synthesis of DDQ involves cyanation of chloranil. Thiele and Günther first reported a 6-step preparation in 1906. The substance did not receive interest until its potential as a dehydrogenation agent was discovered. A single-step chlorination from 2,3-dicyanohydroquinone was reported in 1965.

The reagent removes pairs of H atoms from organic molecules. The stoichiometry of its action is illustrated by the conversion of tetralin to naphthalene:

The resulting hydroquinone is poorly soluble in typical reaction solvents (dioxane, alkanes), which facilitates workup.

DDQ reacts with water with release of hydrogen cyanide (HCN), which is highly toxic. A low-temperature and weakly acidic environment increases the stability of DDQ.


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