1,4-Naphthoquinone

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Naphthoquinone[1]
Naphthoquinone.png
Ball-and-stick model
Identifiers
CAS number 130-15-4 YesY
PubChem 8530
ChemSpider 8215
ChEMBL CHEMBL55934 N
Jmol-3D images Image 1
Properties
Molecular formula C10H6O2
Molar mass 158.15 g/mol
Density 1.422 g/cm3
Melting point 126 °C (259 °F; 399 K)
Boiling point Begins to sublime at 100 °C
Solubility in water 0.09 g/L
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

1,4-Naphthoquinone or para-naphthoquinone is an organic compound derived from naphthalene. Several isomeric naphthoquinones are known, notably 1,2-naphthoquinone. 1,4-Naphthoquinone forms volatile yellow triclinic crystals and has a sharp odor similar to benzoquinone. It is almost insoluble in cold water, slightly soluble in petroleum ether, and more soluble in polar organic solvents. In alkaline solutions it produces a reddish-brown color. Vitamin K is a derivative of 1,4-naphthoquinone. It is a planar molecule with one aromatic ring fused to a quinone subunit.[2]

Preparation[edit]

The industrial synthesis involves aerobic oxidation of naphthalene over a vanadium oxide catalyst:[3]

C10H8 + 3/2 O2 → C10H6O2 + H2O

In the laboratory, naphthoquinone can be produced by the oxidation of a variety of naphthalene compounds. An inexpensive route involves oxidation of naphthalene with chromium trioxide.[4]

Reactions[edit]

1,4-Naphthoquinone acts as strong dienophile in Diels-Alder reaction. Its adduct with 1,3-butadiene can be prepared by two methods: 1) long (45 days) exposure of naphthoquinone in neat liquid butadiene taken in huge excess at room temperature in a thick-wall glass tube or 2) fast catalyzed cycloaddition at low temperature in the presence of 1 equivalent of tin(IV) chloride:[5]

Diels-Alder reaction of 1,4-naphthoquinone with 1,3-butadiene

Uses[edit]

1,4-Naphthoquinone is mainly used as a precursor to anthroquinone by reaction with butadiene followed by oxidation. Nitration gives 5-nitro-1,4-naphthalenedione, precursor to an aminoanthroquinone that is used as a dye precursor.[3]

Derivatives[edit]

Naphthoquinone forms the central chemical structure of many natural compounds, most notably the K vitamins. 2-Methylnaphthoquinone is a more effective coagulant than vitamin K.

Other natural naphtoquinones include juglone, plumbagin, droserone.

Naphthoquinone derivatives have significant pharmacological properties. They are cytotoxic, they have significant antibacterial, antifungal, antiviral, insecticidal, anti-inflammatory, and antipyretic properties. Plants with naphthoquinone content are widely used in China and the countries of South America, where they are used to treat malignant and parasitic diseases.[6]

Naphthoquinone functions as a ligand (through the electrophilic C=C).[7]

See also[edit]

References[edit]

  1. ^ Merck Index, 11th Edition, 6315.
  2. ^ Gaultier, J.; Hauw, C. (1965). "Structure de l'α-Naphtoquinone". Acta Crystallographica 18 (2): 179–183. doi:10.1107/S0365110X65000439. 
  3. ^ a b Grolig, J.; Wagner, R. (2005), "Naphthoquinones", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a17_067 
  4. ^ Braude, E. A.; Fawcett, J. S. (1953), "1,4-Naphthoquinone", Org. Synth. 33: 50 ; Coll. Vol. 4: 698 
  5. ^ M.A. Filatov, S. Baluschev, I.Z. Ilieva, V. Enkelmann, T. Miteva, K. Landfester, S.E. Aleshchenkov, A.V. Cheprakov (2012). "Tetraaryltetraanthra[2,3]porphyrins: Synthesis, Structure, and Optical Properties". J. Org. Chem. 77 (24): 11119–11131. doi:10.1021/jo302135q. 
  6. ^ Babula, P.; Adam, V.; Havel, L.; Kizek, R. (2007). "Naphthoquinones and their Pharmacological Properties". Ceská a Slovenská Farmacie (in Czech) 56 (3): 114–120. PMID 17867522. 
  7. ^ Kündig, E. P.; Lomberget, T.; Bragg, R.; Poulard, C.; Bernardinelli, G. (2004). "Desymmetrization of a meso-Diol Complex Derived from [Cr(CO)36-5,8-Naphthoquinone)]: Use of New Diamine Acylation Catalysts". Chemical Communications 2004 (13): 1548–1549. doi:10.1039/b404006f.