Anthracene

Anthracene

Names
IUPAC name Anthracene
Identifiers
CAS Number	120-12-7 Y
3D model (JSmol)	Interactive image
Beilstein Reference	1905429
ChEBI	CHEBI:35298 Y
ChEMBL	ChEMBL333179 Y
ChemSpider	8111 Y
DrugBank	DB07372 Y
ECHA InfoCard	100.003.974
EC Number	217-004-5
Gmelin Reference	67837
KEGG	C14315 Y
PubChem CID	8418
RTECS number	CA9350000
UNII	EH46A1TLD7 Y
CompTox Dashboard (EPA)	DTXSID0023878
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 c1ccc2cc3ccccc3cc2c1
Properties
Chemical formula	C14H10
Molar mass	178.234 g·mol−1
Appearance	Colorless
Odor	Weak aromatic
Density	1.28 g/cm3 (25 °C)[1] 0.969 g/cm3 (220 °C)
Melting point	216 °C (421 °F; 489 K)[1] at 760 mmHg
Boiling point	341.3 °C (646.3 °F; 614.5 K)[1] at 760 mmHg
Solubility in water	0.022 mg/L (0 °C) 0.044 mg/L (25 °C) 0.29 mg/L (50 °C) 0.00045% w/w (100 °C, 3.9 MPa)[2]
Solubility	Soluble in alcohol, (C2H5)2O, acetone, C6H6, CHCl3,[1] CS2[3]
Solubility in ethanol	0.76 g/kg (16 °C) 19 g/kg (19.5 °C) 3.28 g/kg (25 °C)[3]
Solubility in methanol	18 g/kg (19.5 °C)[3]
Solubility in hexane	3.7 g/kg[3]
Solubility in toluene	9.2 g/kg (16.5 °C) 129.4 g/kg (100 °C)[3]
Solubility in carbon tetrachloride	7.32 g/kg[3]
log P	4.56
Vapor pressure	0.01 kPa (125.9 °C) 0.1 kPa (151.5 °C)[4] 13.4 kPa (250 °C)[5]
Henry's law constant (kH)	0.0396 L·atm/mol[6]
UV-vis (λmax)	345.6 nm, 363.2 nm[5]
Magnetic susceptibility (χ)	−129.8×10−6 cm3/mol[7]
Thermal conductivity	0.1416 W/(m·K) (240 °C) 0.1334 W/(m·K) (270 °C) 0.1259 W/(m·K) (300 °C)[8]
Viscosity	0.602 cP (240 °C) 0.498 cP (270 °C) 0.429 cP (300 °C)[8]
Structure
Crystal structure	Monoclinic (290 K)[9]
Space group	P21/b[9]
Point group	D5 2h[9]
Lattice constant	a = 8.562 Å, b = 6.038 Å, c = 11.184 Å[9] α = 90°, β = 124.7°, γ = 90°
Thermochemistry[10]
Heat capacity (C)	210.5 J/(mol·K)
Std molar entropy (S⦵298)	207.5 J/(mol·K)
Std enthalpy of formation (ΔfH⦵298)	129.2 kJ/mol
Std enthalpy of combustion (ΔcH⦵298)	7061 kJ/mol[5]
Hazards
GHS labelling:
Pictograms	[11]
Signal word	Warning
Hazard statements	H302, H305, H315, H319, H335, H410[11]
Precautionary statements	P261, P273, P305+P351+P338, P501[11]
NFPA 704 (fire diamond)	[12] 1 1 0
Flash point	121 °C (250 °F; 394 K)[11]
Autoignition temperature	540 °C (1,004 °F; 813 K)[11]
Lethal dose or concentration (LD, LC):
LD50 (median dose)	100-149 mg/kg (rats, oral)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) 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 radiation.^[13]

Occurrence and production

Coal tar, which contains around 1.5% anthracene, remains a major source of this material. Common impurities are phenanthrene and carbazole. The mineral form of anthracene is called freitalite and is related to a coal deposit.^[14] 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, for example from o-tolyl phenyl ketone.^[15]

Reactions

Reduction

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.^[16]

Cycloadditions

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.^[17][18]

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

With electrophiles

Chemical oxidation occurs readily, giving anthraquinone, C₁₄H₈O₂ (below), for example using hydrogen peroxide and vanadyl acetylacetonate.^[19]

Electrophilic substitution of anthracene occurs at the 9 position. For example, formylation affords 9-anthracenecarboxaldehyde. Substitution at other positions is effected indirectly, for example starting with anthroquinone.^[20] Bromination of anthracene gives 9,10-dibromoanthracene.^[21]

Uses

Anthracene is converted mainly to anthraquinone, a precursor to dyes.^[22]

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.^{[citation needed]}

Anthracene is commonly used as a UV tracer in conformal coatings applied to printed wiring boards. The anthracene tracer allows the conformal coating to be inspected under UV light.^[23]

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)^[24][25] are pharmacologically active. Anthracene may also be found with multiple hydroxyl groups, as in 9,10-dihydroxyanthracene.

Some anthracene derivatives are used as pharmaceutical drugs, including bisantrene, trazitiline, and benzoctamine.

Occurrence

Anthracene, as many other polycyclic aromatic hydrocarbons, is generated during combustion processes. Exposure to humans happens mainly through tobacco smoke and ingestion of food contaminated with combustion products.

Toxicology

Many investigations indicate that anthracene is noncarcinogenic: "consistently negative findings in numerous in vitro and in vivo genotoxicity tests". Early experiments suggested otherwise because crude samples were contaminated with other polycyclic aromatic hydrocarbons. Furthermore, it is readily biodegraded in soil. It is especially susceptible to degradation in the presence of light.^[22]

See also

• 9,10-Dithioanthracene, derivative with two thiol groups added to the central ring
• Phenanthrene
• Tetracene

References

Cited sources

• Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). CRC Press. ISBN 978-1439855119.

External links

Wikimedia Commons has media related to Anthracenes.

Wikisource has the text of the 1879 American Cyclopædia article Anthracene.

• International Chemical Safety Card 0825
• IARC – Monograph 32
• National Pollutant Inventory – Polycyclic Aromatic Hydrocarbon Fact Sheet
• European Chemicals Agency – ECHA
• "Anthracene" . Encyclopædia Britannica (11th ed.). 1911.