1,4-Naphthoquinone
Chemical compound
From Wikipedia, the free encyclopedia
1,4-Naphthoquinone or para-naphthoquinone is a quinone derived from naphthalene. It 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.
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| Names | |
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| Preferred IUPAC name
Naphthalene-1,4-dione | |
| Other names
1,4-Naphthoquinone Naphthoquinone α-Naphthoquinone | |
| Identifiers | |
3D model (JSmol) |
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| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.004.526 |
PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| 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 |
| 0.09 g/L | |
| â73.5·10â6 cm3/mol | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Natural vitamin K is a derivative of 1,4-naphthoquinone. It is a planar molecule with one aromatic ring fused to a quinone subunit.[2] 1,4-naphathoquinone itself has some vitamin K activity.[3]
It is an isomer of 1,2-naphthoquinone.
Preparation
The industrial synthesis involves aerobic oxidation of naphthalene over a vanadium oxide catalyst:[4]
- C10H8 + 3/2 O2 â C10H6O2 + H2O
However, naphthoquinone rapidly oxidizes to phthalic anhydride under these conditions, and the latter is the major product.[5]
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.[6]
Reactions
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:[7]
Reduction of 1,4-naphthoquinone with dithionite gives 1,4-dihydroxynaphthalene. The reaction is reversible: oxidation of the diol give back the quinone.[8]
Uses
1,4-Naphthoquinone is mainly used as a precursor to anthraquinone 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.[4]
Naphthoquinone functions as a ligand through its electrophilic carbon-carbon double bonds.[9]
Derivatives
Naphthoquinone forms the central chemical structure of many natural compounds, most notably the K vitamins. 2-Methyl-1,4-naphthoquinone, called menadione, is a more effective coagulant than vitamin K. Some naphthoquinone derivatives 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.[10]
Natural 1,4-naphthoquinones
- Alkannin, commercial red-brown dye from Alkanna tinctoria
- Dichlone, a chlorinated derivative of 1,4-naphthoquinone, a fungicide.
- Droserone, found in plants of the genus Plumbago
- Hexahydroxy-1,4-naphthalenedione
- Juglone, growth-stunting exudate of black walnut trees
- Lapachol, yellow irritant from lapacho tree
- Lawsone, dye in henna
- Menatetrenone, a polyhydroxylated 1,4-naphthoquinone found in some sea urchins
- 2-Methoxy-1,4-naphthoquinone, a compound found in Impatiens species
- Nigrosporin B, lightly studied compound found in the fungus Nigrospora sp
- Plumbagin, yellow toxin found in plants of the genus Plumbago
- Spinochrome B, a marine pigment
- Spinochrome D, a marine pigment
- Vitamin K and related compounds
- Phylloquinone
- Vitamin K2
- Menadione (2-Methyl-1,4-naphthoquinone)
- Naphthazarin, red solid that occurs naturally and is earily prepared
Synthetic 1,4-naphthoquinones
- Atovaquone, a drug
- Buparvaquone, an antiprotozoal drug used in veterinary medicine