Anthracene

Anthracene

Names
IUPAC names Anthracene; Tricyclo[8.4.0.03,8]tetradeca-1,3,5,7,9,11,13-heptaene
Identifiers
CAS Number	120-12-7 Y
ChEBI	CHEBI:35298 Y
ChEMBL	ChEMBL333179 Y
ChemSpider	8111 Y
DrugBank	DB07372 Y
EC Number	217-004-5
Jmol 3D model	Interactive image Interactive image
KEGG	C14315 Y
PubChem	8418
RTECS number	CA9350000
UNII	EH46A1TLD7 Y
InChI InChI=1S/C14H10/c1-2-6-12-10-14-8-4-3-7-13(14)9-11(12)5-1/h1-10H Y Key: MWPLVEDNUUSJAV-UHFFFAOYSA-N Y InChI=1/C14H10/c1-2-6-12-10-14-8-4-3-7-13(14)9-11(12)5-1/h1-10H Key: MWPLVEDNUUSJAV-UHFFFAOYAK
SMILES c3ccc2cc1ccccc1cc2c3 c1ccc2cc3ccccc3cc2c1
Properties
Chemical formula	C14H10
Molar mass	178.23 g·mol−1
Appearance	Colorless
Odor	Weak aromatic
Density	1.28 g/cm3 (25 °C) 0.969 g/cm3 (220 °C)
Melting point	215.76 °C (420.37 °F; 488.91 K) at 760 mmHg
Boiling point	339.9 °C (643.8 °F; 613.0 K) at 760 mmHg
Solubility in water	0.022 mg/L (0 °C) 0.044 mg/L (25 °C) 0.287 mg/L (50 °C) 0.00045% w/w (100 °C, 3.9 MPa)
Solubility	Soluble in alcohol, (C2H5)2O, acetone, C6H6, CHCl3, CS2
Solubility in ethanol	0.076 g/100 g (16 °C) 1.9 g/100 g (19.5 °C) 0.328 g/100 g (25 °C)
Solubility in methanol	1.8 g/100 g (19.5 °C)
Solubility in hexane	0.37 g/100 g
Solubility in toluene	0.92 g/100 g (16.5 °C) 12.94 g/100 g (100 °C)
Solubility in carbon tetrachloride	0.732 g/100 g
log P	4.56
Vapor pressure	0.01 kPa (125.9 °C) 0.1 kPa (151.5 °C) 13.4 kPa (250 °C)
Henry's law constant (kH)	0.039 L·atm/mol
UV-vis (λmax)	345.6 nm, 363.2 nm
Thermal conductivity	0.1416 W/m·K (240 °C) 0.1334 W/m·K (270 °C) 0.1259 W/m·K (300 °C)
Viscosity	0.602 cP (240 °C) 0.498 cP (270 °C) 0.429 cP (300 °C)
Structure
Crystal structure	Monoclinic (290 K)
Space group	P21/b
Point group	C5 2h
Lattice constant	a = 8.562 Å, b = 6.038 Å, c = 11.184 Å α = 90°, β = 124.7°, γ = 90°
Thermochemistry
Specific heat capacity (C)	210.5 J/mol·K
Std molar entropy (So298)	207.5 J/mol·K
Std enthalpy of formation (ΔfHo298)	129.2 kJ/mol
Std enthalpy of combustion (ΔcHo298)	7061 kJ/mol
Vapor pressure	{{{value}}}
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

Anthracene is a solid polycyclic aromatic hydrocarbon (PAH) of formula C₁₄H₁₀, consisting of three fused benzene rings. It is a component of coal tar. Anthracene is used in the production of the red dye alizarin and other dyes. Anthracene is colorless but exhibits a blue (400-500 nm peak) fluorescence under ultraviolet light.

Occurrence and production

Coal tar, which contains around 1.5% anthracene, remains a major source of this material. Common impurities are phenanthrene and carbazole. A classic laboratory method for the preparation of anthracene is by cyclodehydration of o-methyl- or o-methylene-substituted diarylketones in the so-called Elbs reaction.

It may also occur in the interstellar medium. More than 20% of the carbon in the universe may be associated with PAHs, including anthracene.

Reactions

Anthracene photodimerizes by the action of UV light:

The dimer, called dianthracene (or sometimes paranthracene), is connected by a pair of new carbon-carbon bonds, the result of the [4+4] cycloaddition. It reverts to anthracene thermally or with UV irradiation below 300 nm. Substituted anthracene derivatives behave similarly. The reaction is affected by the presence of oxygen.

Reduction of anthracene with alkali metals yields the deeply colored radical anion salts M⁺[anthracene]^- (M = Li, Na, K). Hydrogenation gives 9,10-dihydroanthracene, preserving the aromaticity of the two flanking rings.

Chemical oxidation occurs readily, giving anthraquinone, C₁₄H₈O₂ (below), for example using hydrogen peroxide and vanadyl acetylacetonate.

Anthracene also reacts with dienophile singlet oxygen in a [4+2]-cycloaddition (Diels–Alder reaction):

Uses

Anthracene is converted mainly to anthroquinone, a precursor to dyes.

Niche

Anthracene, a wide band-gap organic semiconductor 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.

It is also used in wood preservatives, insecticides, and coating materials.

Anthracene is one of the three components (the other two being potassium perchlorate and sulfur) which are used to produce the black smoke released during a Papal Conclave.

Derivatives

A variety of anthracene derivatives find specialized uses. Derivatives having a hydroxyl group are 1-hydroxyanthracene and 2-hydroxyanthracene, homologous to phenol and naphthols, and hydroxyanthracene (also called anthrol, and anthracenol) are pharmacologically active. Anthracene may also be found with multiple hydroxyl groups, as in 9,10-dihydroxyanthracene.

Toxicology

Unlike many other polycyclic aromatic hydrocarbons (PAH), anthracene is not classified as carcinogenic as listed by the U.S. agency OSHA. Anthracene, as many other PAHs, is generated during combustion processes: Exposure to humans happens mainly through tobacco smoke and ingestion of food contaminated with combustion products.

See also

• 9,10-Dithioanthracene, "walks" in a straight line.
• Phenanthrene
• Tetracene

External links

• Image of anthracene crystals
• International Chemical Safety Card 0825
• IARC - Monograph 32
• National Pollutant Inventory - Polycyclic Aromatic Hydrocarbon Fact Sheet
• European Chemicals Agency - ECHA
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