1,4-Benzoquinone
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| 1,4-Benzoquinone | |
|---|---|
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| IUPAC name | Cyclohexa-2,5-diene-1,4-dione |
| Other names | p-benzoquinone; p-quinone |
| Identifiers | |
| CAS number | [106-51-4] |
| RTECS number | DK2625000 |
| SMILES | C1=CC(=O)C=CC1=O |
| Properties | |
| Molecular formula | C6H4O2 |
| Molar mass | 108.095 g/mol |
| Appearance | Yellow solid |
| Density | 1.318 g/cm3 at 20 °C, solid |
| Melting point |
115 °C |
| Boiling point |
Sublimes |
| Solubility in water | Slightly soluble |
| Solubility | Slightly soluble in petroleum ether; soluble in acetone; very soluble in ethanol, benzene, diethyl ether |
| Hazards | |
| Main hazards | Toxic |
| R-phrases | R23/25 R36/37/38 R50 |
| S-phrases | S26 S28 S45 S61 |
| Related compounds | |
| Related compounds | 1,2-Benzoquinone |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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1,4-Benzoquinone is the chemical compound with the formula C6H4O2. In pure state, it forms bright yellow crystals with characteristic irritating odor, resembling that of chlorine; impure samples are often dark colored due to the presence of quinhydrone (1:1 complex of quinone with hydroquinone). This nonaromatic six-membered ring compound is the oxidized derivative of 1,4-hydroquinone.[1] The molecule is multifunctional: it exhibits properties of a ketone, forming an oxime; an oxidant, forming the dihydroxy derivative; and an alkene, undergoing addition reactions, especially those typical for α,β-unsaturated ketones. 1,4-Benzoquinone is sensitive towards both strong mineral acids and alkalies, which cause condensation and decomposition of the compound.
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[edit] Applications in organic synthesis
It is used as a hydrogen acceptor and oxidant in organic synthesis.[2] 1,4-Benzoquinone serves as a dehydrogenation reagent. It is also uses as a dienophile in Diels Alder reactions.[3]
Benzoquinone reacts with acetic anhydride and sulfuric acid to the triacetate of 1,3,4-trihydroxybenzene. This reaction is called the Thiele reaction [4] after Johannes Thiele who first described the reaction in 1898. An application is found in total synthesis [5]:
[edit] Related 1,4-benzoquinones
A variety of derivatives and analogues are known. Illustrative examples:
- 1,4-Naphthoquinone, derived by oxidation of naphthalene with chromium trioxide.[6]
- 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, a stronger oxidant and dehydrogenation agent than 1,4-benzoquinone.[7]
- Ubiquinone-1, a naturally occurring 1,4-benzoquinone.
- Chloro-p-benzoquinone, (CAS no. [695-99-8])[8]
- Chloranil, 1,4-C6Cl4O2, a stronger oxidant and dehydrogenation agent than 1,4-benzoquinone.
[edit] See also
[edit] References
- ^ H. W. Underwood, Jr. and W. L. Walsh (1943). "Quinone". Org. Synth.; Coll. Vol. 2: 553.
- ^ Yang, T.-K.; Shen, C.-Y. ”1,4-Benzoquinone” in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289.
- ^ Oda, M.; Kawase, T.; Okada, T.; Enomoto, T. (1998). "2-Cyclohexene-1,4-dione". Org. Synth.; Coll. Vol. 9: 186.
- ^ Ueber die Einwirkung von Essigsäure-anhydrid auf Chinon und auf Dibenzoylstyrol (p 1247-1249) Johannes Thiele Berichte der deutschen chemischen Gesellschaft Volume 31, Issue 1 , Pages 1247 - 1249 1898 doi:10.1002/cber.189803101226
- ^ Stereoselective Total Synthesis and Enantioselective Formal Synthesis of the Antineoplastic Sesquiterpene Quinone Metachromin A Wanda P. Almeida, and Carlos Roque D. Correia J. Braz. Chem. Soc., Vol. 10, No. 5, 401-414, 1999 doi:10.1590/S0103-50531999000500011.
- ^ E. A. Braude E. A.; Fawcett, J. S. (1963). "1,4-Naphthoquinone". Org. Synth.; Coll. Vol. 4: 698.
- ^ Vogel, E.; Klug, W.; Breuer, A. (1988). "1,6-Methano[10]annulene". Org. Synth.; Coll. Vol. 6: 731.
- ^ Harman, R. E. (1963). "Chloro-p-benzoquinone". Org. Synth.; Coll. Vol. 4: 148.
