Pyrene

Structural formula
General
Surname	Pyrene
other names	Benzo [ def ] phenanthrene
Molecular formula	C 16 H 10
Brief description	Colorless crystals in the pure state
External identifiers / databases
EC number	204-927-3
ECHA InfoCard	100.004.481
PubChem	31423
Wikidata	Q415723
properties
Molar mass	202.26 g mol −1
Physical state	firmly
density	1.21 g cm −3 (20 ° C)
Melting point	156 ° C
boiling point	404 ° C
Vapor pressure	0.2-4.9 m Pa
solubility	almost insoluble in water (0.134 mg l −1 at 25 ° C); soluble in diethyl ether and aromatic solvents;
safety instructions
GHS labeling of hazardous substances Caution
H and P phrases	H: 410
	P: 202-273-280-391-501
Authorization procedure under REACH	of particular concern : persistent, bioaccumulative and toxic ( PBT ), very persistent and very bioaccumulative ( vPvB )
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Pyrene is a whitish yellow solid that is obtained as a powder or flake. It belongs to the polycyclic aromatic hydrocarbons . The French chemist Auguste Laurent (1807-1853) synthesized pyrene for the first time.

Occurrence

Pyrene occurs in coal tar .

Extraction and presentation

Pyrene can be made from ethyne and hydrogen by passing a mixture through porcelain tubes at 650 ° C.

properties

As is typical for many PAHs, the absorption spectrum has a three-fold comb-like structure (compare perylene , diindenoperylene ). The longest-wave main absorption band is at 335 nm. The main fluorescence band is at approx. 388 nm.

In concentrated solution ( hexane , cyclohexane , decalin or similar hydrocarbons), pyrene forms so-called excimers ( excited dimers ) with itself when excited with UV light . In solutions, unlike dilute solutions of pyrene, these excimers have a fluorescence band at approx. 466 nm. The formation of excimers depends largely on the viscosity of the solvent used, which in turn depends on the temperature. In the presence of quenchers ( fluorescence quenchers ) such as oxygen , the fluorescence quantum yield of the excimer drops significantly. This is related to the fact that an excimer is created from an excited and a non-excited pyrene and the excited pyrene changes back to the ground state due to the presence of oxygen as a quencher. In contrast to anthracene , for example , pyrene does not enter into a [4 + 4] cycloaddition with itself upon UV excitation , so that the excimers only have the option of either dissociating again or changing to the ground state to be radiating or non-radiating.

use

It is used as a probe molecule in fluorescence spectroscopy .

safety instructions

It is classified as irritant, it reddens the skin and eyes, but a MAK value has not been specified.

Individual evidence

↑ ^a ^b entry on pyrene. In: Römpp Online . Georg Thieme Verlag, accessed on December 28, 2014.
↑ ^a ^b ^c ^d ^e ^f Entry on pyrene in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
↑ LAWA expert group for substances: Material data sheet: Pyrene, status March 17, 2010 , accessed on September 12, 2016.
↑ Entry in the SVHC list of the European Chemicals Agency , accessed on January 21, 2019.
^ Brockhaus ABC Chemie , VEB FA Brockhaus Verlag Leipzig 1965, p. 1145.

[roempp-1] try on pyrene. In: Römpp Online . Georg Thieme Verlag, accessed on December 28, 2014.

[GESTIS-2] ↑ ^a ^b ^c ^d ^e ^f Entry on pyrene in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .

[LAWA_Expertenkreis_Stoffe-3] LAWA expert group for substances: Material data sheet: Pyrene, status March 17, 2010 , accessed on September 12, 2016.

[SVHC-4] Entry in the SVHC list of the European Chemicals Agency , accessed on January 21, 2019.

[ABC_Chemie-5] Brockhaus ABC Chemie , VEB FA Brockhaus Verlag Leipzig 1965, p. 1145.