anthracene

Crude anthracene (with a melting point of only 180°) was discovered in 1832 by Jean-Baptiste Dumas and Auguste Laurent{{Cite journal |last=Wisniak |first=Jaime |date=2009 |title=Auguste Laurent: Radical and radicals |url=https://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0187-893X2009000200010 |archive-url=https://web.archive.org/web/20241111201753/https://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0187-893X2009000200010 |url-status=dead |archive-date=November 11, 2024 |journal=Educación química |language=en |volume=20 |issue=2 |pages=166–175 |doi=10.1016/S0187-893X(18)30023-5 |issn=0187-893X|doi-access=free }} who crystalized it from a fraction of coal tar later known as "anthracene oil". Since their (inaccurate) measurements showed the proportions of carbon and hydrogen of it to be the same as in naphthalene, Laurent called it paranaphtaline in his 1835 publication of the discovery,{{Cite wikisource|title=fr:Comptes rendus de l'Académie des sciences/Tome 1, 1835/7 décembre}} which is translated to English as paranaphthalene. Two years later, however, he decided to rename the compound to its modern name derived from {{Langx|grc|ἄνθραξ|lit=coal|translit=anthrax}} because after discovering other polyaromatic hydrocarbons he decided it was only one of isomers of naphthalene.{{Cite book |url=https://books.google.com/books?id=wZg5AAAAcAAJ&pg=PA149 |title=Annales de chimie et de physique |date=1837 |language=fr}} This notion was disproved in 1850s and 1860s.{{Cite web |title=À propos de l'anthracène et de l'alizarine - p3 - N°467 - L'Actualité Chimique, le journal de la SCF |url=https://new.societechimiquedefrance.fr/numero/a-propos-de-lanthracene-et-de-lalizarine-p3-n467 |access-date=2024-11-11 |website=Société Chimique de France (SCF) |language=fr-FR}}{{Cite journal |last1=Jackson |first1=C. Loring |last2=White |first2=J. Fleming |date=1880 |title=Researches on the Substituted Benzyl Compounds. Ninth Paper. The Synthesis of Anthracene and Phenanthrene from Orthobrombenzylbromide |url=https://www.jstor.org/stable/25138602 |journal=Proceedings of the American Academy of Arts and Sciences |volume=16 |pages=63–77 |doi=10.2307/25138602 |jstor=25138602 |issn=0199-9818|url-access=subscription }}

Anthracene, as many other polycyclic aromatic hydrocarbons, is generated during combustion processes. Most human exposure is through tobacco smoke or ingestion of charred food.

The mineral form of anthracene is called freitalite and is related to a coal deposit.Freitalite, Mindat, https://www.mindat.org/min-54360.html Coal tar, which contains around 1.5% anthracene, remains a major industrial 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, for example from o-tolyl phenyl ketone.{{Cite web |title=Anthracene |url=https://www.acs.org/content/acs/en/molecule-of-the-week/archive/a/anthracene.html |access-date=2022-09-14 |website=American Chemical Society |language=en}}

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.{{OrgSynth|first = K. C.|last = Bass|title = 9,10-Dihydroanthracene|year = 1962|volume = 42|page = 48|doi = 10.15227/orgsyn.042.0048}}

In any solvent except water,{{Kirk-Othmer|title=Liquid salts for reactions|first1=Keith E.|last1=Johnson|first2=Richard M.|last2=Pagni|doi=10.1002/0471238961.liqupagn.a01|p=28}} anthracene photodimerizes by the action of UV light:

:Image:Anthracene Photodimerisation.svg

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.{{cite book|author=Rickborn, Bruce |chapter=The Retro– D iels– A lder Reaction Part I . C  C Dienophiles |title=Organic Reactions|pages=1–393|doi=10.1002/0471264180.or052.01|year=1998|isbn=978-0-471-26418-7}}{{cite journal |author=Bouas-Laurent, Henri |author2=Desvergne, Jean-Pierre |author3=Castellan, Alain |author4=Lapouyade, Rene |title=Photodimerization of anthracenes in fluid solution: Structural aspects|journal=Chemical Society Reviews|volume=29|pages=43–55|doi=10.1039/a801821i|year=2000}}

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

:Image:Anthracene singlet oxygen Diels-Alder reaction.svg

Chemical oxidation occurs readily, giving anthraquinone, C₁₄H₈O₂ (below), for example using hydrogen peroxide and vanadyl acetylacetonate.{{cite journal|doi=10.1021/ed100843a|title=Coordination Complexes as Catalysts: The Oxidation of Anthracene by Hydrogen Peroxide in the Presence of VO(acac)2|journal=Journal of Chemical Education|volume=88|issue=8|pages=1155–1157|year=2011|last1=Charleton|first1=Kimberly D. M.|last2=Prokopchuk|first2=Ernest M.|bibcode=2011JChEd..88.1155C}}

:Image:Anthraquinone acsv.svg

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.{{cite journal|doi=10.1016/j.tet.2017.08.038|title=Synthesis of asymmetrically disubstituted anthracenes|journal=Tetrahedron|volume=73|issue=40|pages=5892–5899|year=2017|last1=Škalamera|first1=Đani|last2=Veljković|first2=Jelena|last3=Ptiček|first3=Lucija|last4=Sambol|first4=Matija|last5=Mlinarić-Majerski|first5=Kata|last6=Basarić|first6=Nikola}} Bromination of anthracene gives 9,10-dibromoanthracene.{{cite journal |doi=10.15227/orgsyn.003.0041|first1=I. M.|last1=Heilbron|first2=J. S.|last2=Heaton|title=9,10-Dibromoanthracene|journal=Organic Syntheses|year=1923|volume=3|page=41}}

Anthracene proper has application as an organic semiconductor and chemical feedstock for various preservatives and dyes.

File:Fluorescence of Anthracene under UV light.jpg

Anthracene is a wide band-gap organic semiconductor, with an emission spectrum peaking between 400 nm and 440 nm. Organic field-effect transistors have been constructed from it. In particle physics, it is used as a scintillator to detect high-energy photons, electrons, or alpha particles.{{Cite web |title=Anthracene |url=https://www.acs.org/molecule-of-the-week/archive/a/anthracene.html |access-date=2025-01-18 |website=American Chemical Society |language=en}} Plastics, such as polyvinyltoluene, can be doped with anthracene to produce an approximately water-equivalent scintillator in radiation therapy dosimetry.

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.Zeitler, Alex (2012-06-27) [https://www.smta.org/chapters/files/UpperMidwest_BTW_Conformal_Coating_June_27th_2012.pdf Conformal Coating 101: General Overview, Process Development, and Control Methods]. BTW, Inc.

It is also used in wood preservatives, insecticides, and coating materials.{{Citation needed|date=September 2010}}

File:Antracene diradical AFM2.png image of anthracene diradical, where hydrogen atoms are removed at carbons 9 and 10]]

A variety of anthracene derivatives find specialized uses. Industrially, anthracene is converted mainly to anthraquinone, a precursor to dyes.Collin, Gerd; Höke, Hartmut and Talbiersky, Jörg (2006) "Anthracene" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a02_343.pub2}} Derivatives having a hydroxyl group are 1-hydroxyanthracene and 2-hydroxyanthracene, homologous to phenol and naphthols, and hydroxyanthracene (also called anthrol, and anthracenol)[http://webbook.nist.gov/cgi/cbook.cgi?Name=1-hydroxyanthracene&Units=SI 1-Hydroxyanthracene]. NIST datapage[http://webbook.nist.gov/cgi/cbook.cgi?Name=2-hydroxyanthracene&Units=SI 2-Hydroxyanthracene]. NIST datapage 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.

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. The International Agency for Research on Cancer (IARC) classifies anthracene as IARC group 2B, possibly carcinogenic to humans.{{Cite web |title=IARC Monographs evaluate the carcinogenicity of anthracene, 2-bromopropane, butyl methacrylate, and dimethyl hydrogen phosphite |url=https://www.iarc.who.int/faq/iarc-monographs-evaluate-the-carcinogenicity-of-anthracene-2-bromopropane-butyl-methacrylate-and-dimethyl-hydrogen-phosphite/#:~:text=Anthracene%20was%20classified%20as%20possibly,for%20cancer%20in%20experimental%20animals. |access-date=2025-01-17 |website=www.iarc.who.int |language=en-US}}

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

{{reflist}}

• {{cite book | editor= Haynes, William M. | year = 2011 | title = CRC Handbook of Chemistry and Physics | edition = 92nd | publisher = CRC Press | isbn = 978-1-4398-5511-9}}

{{Commons category|Anthracenes}}

{{AmCyc Poster}}

• {{ICSC|0825|08}}
• [https://web.archive.org/web/20091114145131/http://monographs.iarc.fr/ENG/Monographs/vol32/volume32.pdf IARC – Monograph 32]
• [https://web.archive.org/web/20060518002254/http://www.npi.gov.au/database/substance-info/profiles/74.html National Pollutant Inventory – Polycyclic Aromatic Hydrocarbon Fact Sheet]
• [https://web.archive.org/web/20110122105255/http://echa.europa.eu/home_en.asp European Chemicals Agency – ECHA]
• {{Cite EB1911|wstitle=Anthracene |short=x}}

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Category:Organic semiconductors

Category:Phosphors and scintillators

Category:IARC Group 2B carcinogens

Category:Ionising radiation detectors

Category:Acenes

Category:PBT substances

Category:Polycyclic aromatic hydrocarbons