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

"DDQ" redirects here. For the Australian television station, see RTQ.

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,^[3] phenols,^[4] and steroid ketones.^[5] DDQ decomposes in water, but is stable in aqueous mineral acid.^[6]

2,3-Dichloro-5,6-dicyano-1,4-benzoquinone^[1]

Names
Preferred IUPAC name 4,5-Dichloro-3,6-dioxocyclohexa-1,4-diene-1,2-dicarbonitrile[2]
Other names 2,3-Dichloro-5,6-dicyano-p-benzoquinone 4,5-Dichloro-3,6-dioxo-1,4-cyclohexadiene-1,2-dicarbonitrile Dichlorodicyanobenzoquinone
Identifiers
CAS Number	84-58-2 Y
3D model (JSmol)	Interactive image
Abbreviations	DDQ
ChemSpider	6517 Y
ECHA InfoCard	100.001.402
EC Number	201-542-2
PubChem CID	6775
RTECS number	GU4825000
UNII	1H5KD39UH7 Y
CompTox Dashboard (EPA)	DTXSID7052577
InChI InChI=1S/C8Cl2N2O2/c9-5-6(10)8(14)4(2-12)3(1-11)7(5)13 Y Key: HZNVUJQVZSTENZ-UHFFFAOYSA-N Y InChI=1/C8Cl2N2O2/c9-5-6(10)8(14)4(2-12)3(1-11)7(5)13 Key: HZNVUJQVZSTENZ-UHFFFAOYAL
SMILES ClC=1C(=O)C(\C#N)=C(\C#N)C(=O)C=1Cl
Properties
Chemical formula	C8Cl2N2O2
Molar mass	227.00 g·mol−1
Appearance	yellow to orange powder
Density	1.7g/cm3
Melting point	210–215 °C (410–419 °F; 483–488 K) (decomposes)
Boiling point	301.8 °C (575.2 °F; 575.0 K) at 760mmHg
Solubility in water	reacts
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301
Precautionary statements	P264, P270, P301+P310, P321, P330, P405, P501
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). Y verify (what is YN ?) Infobox references

Preparation

Synthesis of DDQ involves cyanation of chloranil. J. Thiele and F. Günther first reported a 6-step preparation in 1906.^[7] 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.^[8]

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:

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.^[9]

Dehydrogenation

Aromatization

^[10]

Cross-Dehydrogenative Coupling

^[11]

Safety

DDQ reacts with water to release highly toxic hydrogen cyanide (HCN).^[6]

References

1. 2,3-Dichloro-5,6-dicyano-p-benzoquinone at Sigma-Aldrich
2. Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 50. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
3. Braude, E. A.; Linstead, R. P.; Wooldridge, K. R. H. (1956). "593. Hydrogen Transfer. Part IX The Selective Dehydrogenation of Unsaturated Alcohols by High-potential Quinones". Journal of the Chemical Society (Resumed). 1956: 3070–3074. doi:10.1039/JR9560003070.
4. Becker, H. D. (1965). "Quinone Dehydrogenation. I. Oxidation of Monohydric Phenols". Journal of Organic Chemistry. 30 (4): 982–989. doi:10.1021/jo01015a006.
5. Turner, A. B.; Ringold, H. J. (1967). "Applications of High-potential Quinones. Part I. The Mechanism of Dehydrogenation of Steroidal Ketones by 2,3-Dichloro-5,6-Dicyanobenzoquinone". Journal of the Chemical Society C: Organic. 1967: 1720–1730. doi:10.1039/J39670001720.
6. Buckle, Derek R.; Collier, Steven J.; McLaws, Mark D. (2005). "2,3-Dichloro-5,6-dicyano-1,4-benzoquinone". e-EROS Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rd114.pub2. ISBN 0471936235.
7. Thiele, J.; Günther, F. (1906). "Ueber Abkömmlinge des Dicyanhydrochinons". Justus Liebig's Annalen der Chemie. 349 (1): 45–66. doi:10.1002/jlac.19063490103.
8. Walker, D.; Waugh, T. D. (1965). "2,3-Dichloro-5,6-Dicyanobenzoquinone (DDQ). A New Preparation". The Journal of Organic Chemistry. 30 (9): 3240. doi:10.1021/jo01020a529.
9. Rathore, Rajendra; Kochi, Jay K. (2000), "Donor/acceptor organizations and the electron-transfer paradigm for organic reactivity", Advances in Physical Organic Chemistry, Elsevier, pp. 193–318, doi:10.1016/s0065-3160(00)35014-6, ISBN 9780120335350
10. Brown, W.; Turner, A. B. (1971). "Application of High-potential Quinones. 7. Synthesis of Steroidal Phenanthrenes by Double Methyl Migration". Journal of the Chemical Society C: Organic. 1971: 2566–2572. doi:10.1039/J39710002566. PMID 5167256.
11. Zhang, Y.; Li, C. J. (2006). "DDQ-Mediated Direct Cross-Dehydrogenative-Coupling (CDC) between Benzyl Ethers and Simple Ketones". Journal of the American Chemical Society. 128 (13): 4242–4243. doi:10.1021/ja060050p. PMID 16568995.

External links

• "Like Neurons in the Brain": A Molecular Computer that Evolves