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For other uses, see Pyrene (disambiguation).
Structural formula of pyrene
Ball-and-stick model of the pyrene molecule
IUPAC name
Other names
129-00-0 YesY
ChEBI CHEBI:39106 YesY
ChEMBL ChEMBL279564 YesY
ChemSpider 29153 YesY
Jmol interactive 3D Image
KEGG C14335 YesY
PubChem 31423
RTECS number UR2450000
Molar mass 202.25 g/mol
Appearance colorless solid

(yellow impurities are often found at trace levels in many samples).

Density 1.271 g/mL
Melting point 145 to 148 °C (293 to 298 °F; 418 to 421 K)
Boiling point 404 °C (759 °F; 677 K)
0.135 mg/L
Main hazards irritant
R-phrases 36/37/38-45-53
S-phrases 24/25-26-36
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point non-flammable
Related compounds
Related PAHs
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY verify (what is YesYN ?)
Infobox references

Pyrene is a polycyclic aromatic hydrocarbon (PAH) consisting of four fused benzene rings, resulting in a flat aromatic system. The chemical formula is C
. This colorless solid is the smallest peri-fused PAH (one where the rings are fused through more than one face). Pyrene forms during incomplete combustion of organic compounds.

Occurrence and reactivity[edit]

Pyrene was first isolated from coal tar, where it occurs up to 2% by weight. As a peri-fused PAH, pyrene is much more resonance-stabilized than its five-member-ring containing isomer fluoranthene. Therefore, it is produced in a wide range of combustion conditions. For example, automobiles produce about 1 μg/km.[1] More than 20% of the carbon in the universe may be associated with PAHs, including pyrene.[2]

Oxidation with chromate affords perinaphthenone and then naphthalene-1,4,5,8-tetracarboxylic acid. It undergoes a series of hydrogenation reactions, and it is susceptible to halogenation, Diels-Alder additions, and nitration, all with varying degrees of selectivity.[1] Bromination occurs at one of the 3-positions.[3]


STM image of self-assembled Br4Py molecules on Au(111) surface (top) and its model (bottom; pink spheres are Br atoms).[4]

Pyrene and its derivatives are used commercially to make dyes and dye precursors, for example pyranine and naphthalene-1,4,5,8-tetracarboxylic acid. Its derivatives are also valuable molecular probes via fluorescence spectroscopy, having a high quantum yield and lifetime (0.65 and 410 nanoseconds, respectively, in ethanol at 293 K). Its fluorescence emission spectrum is very sensitive to solvent polarity, so pyrene has been used as a probe to determine solvent environments. This is due to its excited state having a different, non-planar structure than the ground state. Certain emission bands are unaffected, but others vary in intensity due to the strength of interaction with a solvent.


Diagram showing the numbering and ring fusion locations of pyrene according to IUPAC nomenclature of organic chemistry.

Although it is not as problematic as benzopyrene, animal studies have shown pyrene is toxic to the kidneys and the liver.

Experiments in pig show that urinary 1-hydroxypyrene is a metabolite of pyrene, when given orally.[5]

See also[edit]


  1. ^ a b Senkan, Selim and Castaldi, Marco (2003) "Combustion" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim.
  2. ^ Hoover, Rachel (February 21, 2014). "Need to Track Organic Nano-Particles Across the Universe? NASA's Got an App for That". NASA. Retrieved February 22, 2014. 
  3. ^ Gumprecht, W. H. (1968) "3-Bromopyrene" Org. Synth., vol. 48, p. 30. doi:10.15227/orgsyn.048.0030
  4. ^ Pham, Tuan Anh; Song, Fei; Nguyen, Manh-Thuong; Stöhr, Meike (2014). "Self-assembly of pyrene derivatives on Au(111): Substituent effects on intermolecular interactions". Chem. Commun 50 (91): 14089. doi:10.1039/C4CC02753A. 
  5. ^ Keimig, S. D.; Kirby, K. W.; Morgan, D. P.; Keiser, J. E.; Hubert, T. D. (1983). "Identification of 1-hydroxypyrene as a major metabolite of pyrene in pig urine". Xenobiotica 13 (7): 415. doi:10.3109/00498258309052279. PMID 6659544. 

Further reading[edit]

  • Birks, J. B. (1969). Photophysics of Aromatic Molecules. London: Wiley. 
  • Valeur, B. (2002). Molecular Fluorescence: Principles and Applications. New York: Wiley-VCH. 
  • Birks, J.B. (1975). Eximers. london: Reports on Progress in Physics. 
  • Fetzer, J. C. (2000). The Chemistry and Analysis of the Large Polycyclic Aromatic Hydrocarbons. New York: Wiley. 

External links[edit]