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 Edit this at Wikidata
EC Number
  • 201-542-2
RTECS number
  • GU4825000
UNII
  • InChI=1S/C8Cl2N2O2/c9-5-6(10)8(14)4(2-12)3(1-11)7(5)13 checkY
    Key: HZNVUJQVZSTENZ-UHFFFAOYSA-N checkY
  • InChI=1/C8Cl2N2O2/c9-5-6(10)8(14)4(2-12)3(1-11)7(5)13
    Key: HZNVUJQVZSTENZ-UHFFFAOYAL
  • ClC=1C(=O)C(\C#N)=C(\C#N)C(=O)C=1Cl
Properties
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
reacts
Hazards
GHS labelling:
GHS06: Toxic
Danger
H301
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).
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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 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:

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 (HCN).

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. 1 2 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. Bibcode:2006JAChS.128.4242Z. doi:10.1021/ja060050p. PMID 16568995.