Pyrene

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For other uses, see Pyrene (disambiguation).
Pyrene
Pyrene.svg
Pyrene-3D-balls.png
Identifiers
CAS number 129-00-0 YesY
PubChem 31423
ChemSpider 29153 YesY
KEGG C14335 YesY
ChEBI CHEBI:39106 YesY
ChEMBL CHEMBL279564 YesY
RTECS number UR2450000
Jmol-3D images Image 1
Properties
Molecular formula C16H10
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)
Solubility in water 0.135 mg/l
Hazards
R-phrases 36/37/38-45-53
S-phrases 24/25-26-36
Main hazards irritant
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 (yellow): no hazard code Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point non-flammable
Related compounds
Related PAHs benzopyrene
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references
Diagram showing the numbering and ring fusion locations of pyrene according to IUPAC nomenclature of organic chemistry.

Pyrene is a polycyclic aromatic hydrocarbon (PAH) consisting of four fused benzene rings, resulting in a flat aromatic system. The chemical formula is C
16
H
10
. 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]

Applications[edit]

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.

Safety[edit]

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

See also[edit]

References[edit]

  1. ^ a b Selim Senkan and Marco Castaldi "Combustion" in Ullmann's Encyclopedia of Industrial Chemistry, 2003 Wiley-VCH, Weinheim. Article Online Posting Date: March 15, 2003.
  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. ^ W. H. Gumprecht "3-Bromopyrene" Org. Synth. 1968, vol. 48, p. 30.

Additional 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]