Coronene
From Wikipedia, the free encyclopedia
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General |
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| Name | Coronene |
| Chemical formula | C24H12 |
| CAS-number | [191-07-1] [1] |
| ACX number | X1001757-9 |
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Physical |
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| Formula weight | 300.3588 amu |
| Melting point | 438 °C |
| Boiling point | 525 °C |
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SI units were used where possible. Unless otherwise stated, standard conditions were used. |
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Coronene is a polycyclic aromatic hydrocarbon consisting of seven peri-fused benzene rings. It is a yellow material, which dissolves in solvents such as benzene, toluene, and dichloromethane. Its solutions give blue light fluorescence under UV light. It occurs naturally as the mineral karpatite, which is characterized by flakes of pure coronene embedded in sedimentary rock. This mineral may result from ancient hydrothermal vent activity. [2] [3].
Coronene is produced in the petroleum refining process of hydrocracking, where it can domerize to a twenty-five ring PAH Coronene has been seen on the surface of Titan (Saturn's moon). It can cause DNA damage in mammals.
The compound is of theoretical interest to organic chemists because of its aromaticity. It can be described by 20 resonance structures or by a set of three mobile Clar sextets. In the latter case the most stable structure for coronene has only the three isolated outer sextets as fully aromatic although superaromaticity would still be possible when these sextets are able to migrate into the next ring.
According to in silico calculations on the following hypothetical isodesmic reactions coronene has a somewhat higher resonance energy per pi electron (REPE) than benzene [4]:
- coronene + 24 * ethylene -> 18 * butadiene REPE 4.2 kcal/mol (17.6 kJ/mol)
- benzene + 3 * ethylene -> 3 * butadiene REPE 3.6 kcal/mol (15 kJ/mol)
On the other hand the perimeter C–C bond length alternations are larger than in benzene.
[edit] See also
- A related compound lacking the central core: cyclooctadecanonaene
[edit] References
- ^ Information from Chemfinder Link
- ^ www.luminousminerals.com Link
- ^ www.mindat.org Link
- ^ Super-Delocalized Valence Isomer of Coronene Arkadiusz Ciesielski, Micha K. Cyraski, Tadeusz M. Krygowski, Patrick W. Fowler, and Mark Lillington J. Org. Chem.; 2006; 71(18) pp 6840 - 6845; (Article) DOI:0.1021/jo060898w
- Fetzer, J. C. (2000). The Chemistry and Analysis of the Large Polycyclic Aromatic Hydrocarbons. New York: Wiley.
