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Anthracene



Anthracene[1]
IUPAC name Anthracene
Identifiers
CAS number 120-12-7
SMILES C12=CC=CC=C1C=C3C(C=CC=C3)=C2
Properties
Molecular formula C14H10
Molar mass 178.23 g/mol
Appearance Light Brown
Density 1.25 g/cm³ at 19.85 °C, Solid
0.969 g/cm³ at 220 °C, liquid
Melting point

218 °C, 491 K, 424 °F

Boiling point

340 °C, 613 K, 644 °F

Solubility in other solvents Water: none
Methanol: 0.908g per liter
Hexane: 1.64g per liter
Hazards
EU classification Irritant
Dangerous for the Environment
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Anthracene is a solid polycyclic aromatic hydrocarbon consisting of three fused benzene rings derived from coal-tar. Anthracene is used in the artificial production of the red dye alizarin. It is also used in wood preservatives, insecticides, and coating materials. Anthracene is colorless but exhibits a blue (400-500 nm peak) fluorescence under ultraviolet light.

Additional recommended knowledge

Contents

Synthesis

A classic method for the preparation of anthracene in the laboratory is by cyclodehydration of o-methyl- or o-methylene-substituted diarylketones in the so-called Elbs reaction (named for the German chemist Karl Elbs).[citation needed]

Reactions

Anthracene has the ability to photodimerize with irradiation by UV light. This results in considerable changes in the physical properties of the material.


The dimer is connected by two covalent bonds resulting from the [4+4] cycloaddition. The dimer reverts to anthracene thermally or with UV irradiation below 300 nm. The reversible bonding and photochromic properties of anthracenes is the basis of many potential applications using poly and monosubstituted anthracene derivatives. The reaction is sensitive to oxygen.

In most other reactions of anthracene, the central ring is also targeted, as it is the most highly reactive. Electrophilic substitution occurs at the "9" and "10" positions of the center ring, and oxidation of anthracene occurs readily, giving anthraquinone, C14H8O2 (below).

Uses

Anthracene can also have a hydroxyl group to form 1-hydroxyanthracene and 2-hydroxyanthracene, homologous to phenol and napthol, and hydroxyanthracene is also called anthrol, and anthracenol.[2][3] Hydroxyanthracene derivatives are pharmacologically active, and are contained in aloe for example.[4][5]

Anthracene is an organic semiconductor. It is used as a scintillator for detectors of high energy photons, electrons and alpha particles. Plastics such as polyvinyltoluene can be doped with anthracene to produce a plastic scintillator that is approximately water equivalent for use in radiation therapy dosimetry. Anthracene's emission spectrum peaks at between 400 nm and 440 nm.

Bipedal derivative

In 2005, chemists at the University of California, Riverside developed the first bipedal molecule, 9,10-Dithioanthracene, which propels itself in a straight line when heated on a flat copper surface. Researchers believe the molecule has potential for use in molecular computers.

See also

  • Phenanthrene
  • Tetracene

References

  1. ^ NIST Chemistry WebBook Anthracene
  2. ^ 1-Hydroxyanthracene NIST datapage
  3. ^ 2-Hydroxyanthracene NIST datapage
  4. ^ TGA News
  5. ^ Herbals and Breastfeeding
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Anthracene". A list of authors is available in Wikipedia.
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