Anthraquinone
Yellow chemical compound: building block of many dyes
From Wikipedia, the free encyclopedia
Anthraquinone, also called anthracenedione or dioxoanthracene, is an aromatic organic compound with formula C
14H
8O
2. Several isomers exist but these terms usually refer to 9,10-anthraquinone (IUPAC: 9,10-dioxoanthracene) wherein the keto groups are located on the central ring. It is used as a digester additive to wood pulp for papermaking. Many anthraquinone derivatives are generated by organisms or synthesised industrially for use as dyes, pharmaceuticals, and catalysts. Anthraquinone is a yellow, highly crystalline solid, poorly soluble in water but soluble in hot organic solvents. It is almost completely insoluble in ethanol near room temperature but 2.25 g will dissolve in 100 g of boiling ethanol. It is found in nature as the rare mineral hoelite.
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| Names | |
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| Preferred IUPAC name
Anthracene-9,10-dione[2] | |
Other names
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| Identifiers | |
3D model (JSmol) |
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| 390030 | |
| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.001.408 |
| EC Number |
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| 102870 | |
| KEGG | |
PubChem CID |
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| RTECS number |
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| UNII | |
| UN number | 3143 |
CompTox Dashboard (EPA) |
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| Properties | |
| C14H8O2 | |
| Molar mass | 208.216 g·mol−1 |
| Appearance | Yellow solid |
| Density | 1.438 g/cm3[1] |
| Melting point | 284.8 °C (544.6 °F; 558.0 K)[1] |
| Boiling point | 377 °C (711 °F; 650 K)[1] |
| Insoluble | |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards |
possible carcinogen |
| GHS labelling: | |
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| Danger | |
| H350 | |
| P201, P202, P281, P308+P313, P405, P501 | |
| Flash point | 185 °C (365 °F; 458 K) |
| Related compounds | |
Related compounds |
quinone, anthracene |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Synthesis
There are several current industrial methods to produce 9,10-anthraquinone:
- The oxidation of anthracene. Chromium(VI) is the typical oxidant.
- The Friedel–Crafts reaction of benzene and phthalic anhydride in presence of AlCl3. o-Benzoylbenzoic acid is an intermediate. This reaction is useful for producing substituted anthraquinones.
- The Diels-Alder reaction of naphthoquinone and butadiene followed by oxidative dehydrogenation.
- The acid-catalyzed dimerization of styrene to give a 1,3-diphenylbutene, which then can be transformed to the anthraquinone.[3] This process was pioneered by BASF.
It also arises via the Rickert–Alder reaction, a retro-Diels–Alder reaction.
Reactions
Hydrogenation gives dihydroanthraquinone (anthrahydroquinone). Reduction with copper gives anthrone.[4] Sulfonation with oleum gives anthroquinone-1-sulfonic acid,[5] which reacts with sodium chlorate to give 1-chloroanthraquinone.[6]
Applications
Anthraquinone itself has few direct applications except as a precursor to some dyes. It has been used as a bird repellant on seeds, and as a gas generator in satellite balloons.[7] It has also been mixed with lanolin and used as a wool spray to protect sheep flocks against kea attacks in New Zealand.[8] Anthraquinone is utilized in the production of hydrogen peroxide via the Riedl–Pfleiderer process.[9] Anthraquinone derivatives are considered more useful.
Other isomers
Several other isomers of anthraquinone exist, including the 1,2-, 1,4-, and 2,6-anthraquinones. They are of minor importance compared to 9,10-anthraquinone.