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. DDQ decomposes in water, but is stable in aqueous mineral acid.

Preparation

Synthesis of DDQ involves

cyanation In organic synthesis, cyanation is the attachment or substitution of a cyanide group on various substrates. Such transformations are high-value because they generate C-C bond. Furthermore nitriles are versatile functional groups. Cyanation to f ...

of chloranil. J. Thiele and F. 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.

Reactions

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

naphthalene Naphthalene is an organic compound with formula . It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromati ...

: :2 C₆Cl₂(CN)₂O₂ + C₁₀H₁₂ → 2 C₆Cl₂(CN)₂(OH)₂ + C₁₀H₈ The resulting hydroquinone is poorly soluble in typical reaction solvents (dioxane, benzene, alkanes), which facilitates workup. Solutions of DDQ in benzene are red, due to the formation of a charge-transfer complex.

Dehydrogenation

Aromatization

Cross-Dehydrogenative Coupling

Safety

DDQ reacts with water to release highly toxic

hydrogen cyanide Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on an ...

(HCN). A low-temperature and weakly acidic environment increases the stability of DDQ.

References

External links

"Like Neurons in the Brain": A Molecular Computer that Evolves
{{DEFAULTSORT:Dichloro-5, 6-Dicyano-1, 4-Benzoquinone, 2, 3- Nitriles Organochlorides 1,4-Benzoquinones Oxidizing agents Reagents for organic chemistry