Coronene

Coronene
Names
Preferred IUPAC name
Coronene[1]
Other names
[6]circulene
X1001757-9, superbenzene
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.005.348
KEGG
Properties
C24H12
Molar mass 300.36 g·mol−1
Appearance white or pale yellow powder[2]
Density 1.371 g/cm3[3]
Melting point 437.3 °C (819.1 °F; 710.5 K) [3]
Boiling point 525 °C (977 °F; 798 K) [3]
0.14 μg/L[4]
Solubility Very soluble: benzene, toluene, hexane,[5]
Chloroform (1 mmol·L−1)[6] and ethers, sparingly soluble in ethanol.
-243.3·10−6 cm3/mol
Hazards
Main hazards flammable[2]
F[2]
R-phrases (outdated) R10 R20/21/22 [2]
S-phrases (outdated) S45
Structure
Monoclinic
P21/n[7]
D6h
a = 10.02 Å, b = 4.67 Å, c = 15.60 Å
α = 90°, β = 106.7°, γ = 90°
2
0 D
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Coronene (also known as superbenzene) is a polycyclic aromatic hydrocarbon (PAH) comprising six peri-fused benzene rings.[8] Its chemical formula is C
24H
12. It is a yellow material that dissolves in common solvents including benzene, toluene, and dichloromethane. Its solutions emit blue light fluorescence under UV light. It has been used as a solvent probe, similar to pyrene.

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 Clar sextet 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.

Occurrence and synthesis

Carpathite

Coronene occurs naturally as the very rare mineral carpathite, which is characterized by flakes of pure coronene embedded in sedimentary rock. This mineral may be created from ancient hydrothermal vent activity.[9] In earlier times this mineral was also called karpatite or pendletonite.[10]

Coronene is produced in the petroleum-refining process of hydrocracking, where it can dimerize to a fifteen ring PAH, trivially named "dicoronylene" (formally named benzo[10,11]phenanthro[2',3',4',5',6':4,5,6,7]chryseno[1,2,3-bc]coronene or benzo[1,2,3-bc:4,5,6-b'c']dicoronene). Centimeter-long crystals can be grown from a supersaturated solution of the molecules in toluene (ca. 2.5 mg/ml), which is slowly cooled (ca. 0.04  K/min) from 328  K to 298  K over a period of 12 hours.[7]

Structure

Crystals of β and γ coronene under daylight (left) and UV light (right).[7]

Coronene is a planar circulene. It forms needle-like crystals with a monoclinic, herringbone-like structure. The most common polymorph is γ, but β form can also be produced in an applied magnetic field (ca. 1 Tesla).[7]

See also

References

  1. ↑ Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 206. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
  2. 1 2 3 4 Coronene (EINECS NO. 205-881-7). guidechem.com
  3. 1 2 3 Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 3.128. ISBN 1439855110.
  4. ↑ Mackay, D.; Shiu, W. Y. (1977). "Aqueous solubility of polynuclear aromatic hydrocarbons". Journal of Chemical & Engineering Data. 22 (4): 399. doi:10.1021/je60075a012.
  5. ↑ Bertarelli, Chiara. Molecules for organic electronics: intermolecular interactions vs properties. Dipartimento di Chimica, Politecnico di Milano
  6. ↑ Wang, Chen; Wang, Jianlin; Wu, Na; Xu, Miao; Yang, Xiaomei; Lu, Yalin; Zang, Ling (2017). "Donor–acceptor single cocrystal of coronene and perylene diimide: molecular self-assembly and charge-transfer photoluminescence". RSC Adv. 7 (4): 2382–2387. doi:10.1039/C6RA25447K.
  7. 1 2 3 4 Potticary, Jason; Terry, Lui R.; Bell, Christopher; Papanikolopoulos, Alexandros N.; Christianen, Peter C. M.; Engelkamp, Hans; Collins, Andrew M.; Fontanesi, Claudio; Kociok-Köhn, Gabriele; Crampin, Simon; Da Como, Enrico; Hall, Simon R. (2016). "An unforeseen polymorph of coronene by the application of magnetic fields during crystal growth". Nature Communications. 7: 11555. doi:10.1038/ncomms11555. PMC 4866376. PMID 27161600.
  8. ↑ Fetzer, J. C. (2000). The Chemistry and Analysis of the Large Polycyclic Aromatic Hydrocarbons. New York: Wiley.
  9. ↑ Karpatite. luminousminerals.com
  10. ↑ Carpathite. mindat.org
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