View source for Styrene

{{Short description|Chemical compound}}
{{Use dmy dates|date=July 2020}}

{{Chembox
|Verifiedfields = changed
|Watchedfields  = changed
|verifiedrevid  = 477173358
|Name = Styrene
|ImageFile = Styrene-2D.svg
|ImageClass = skin-invert 
|ImageSize = 150px
|ImageFile1 = Styrene-from-xtal-2001-3D-balls.png
|ImageClass1 = bg-transparent 
|ImageSize1 = 180px
|ImageFileL1 = Styrene-from-xtal-2001-3D-sf.png
|ImageClassL1 = bg-transparent 
|ImageFileR1 = Styrene-elpot-3D-vdW.png
|ImageClassR1 = bg-transparent 
|ImageName = Styrene
|IUPACName=Styrene<ref>[https://pubchem.ncbi.nlm.nih.gov/compound/7501 Styrene on PubChem] </ref>
|SystematicName = Ethenylbenzene<ref name=iupac2013>{{cite book |title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book) |publisher=[[Royal Society of Chemistry]] |location=Cambridge |date=2014 |chapter=Front Matter |pages=P001–P004 |doi=10.1039/9781849733069-FP001 |isbn=978-0-85404-182-4}}</ref>
|OtherNames = Styrene<ref name=iupac2013 /><br />Vinylbenzene<br />Phenylethene<br />Phenylethylene<br />Cinnamene<br />Styrol<br />Diarex HF 77<br />Styrolene<br />Styropol
|Section1 = {{Chembox Identifiers
|CASNo_Ref = {{cascite|correct|CAS}}
|CASNo = 100-42-5
|Beilstein = 1071236
|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|ChemSpiderID = 7220
|ChEBI_Ref = {{ebicite|correct|EBI}}
|ChEBI = 27452
|ChEMBL_Ref = {{ebicite|correct|EBI}}
|ChEMBL = 285235
|EC_number = 202-851-5
|Gmelin = 2991
|RTECS = WL3675000
|PubChem = 7501
|KEGG_Ref = {{keggcite|correct|kegg}}
|KEGG = C07083
|UNII_Ref = {{fdacite|correct|FDA}}
|UNII = 44LJ2U959V
|UNNumber = 2055
|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
|StdInChI = 1S/C8H8/c1-2-8-6-4-3-5-7-8/h2-7H,1H2
|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
|StdInChIKey = PPBRXRYQALVLMV-UHFFFAOYSA-N
|SMILES = c1ccccc1C=C
}}
|Section2 = {{Chembox Properties
|Formula = C<sub>8</sub>H<sub>8</sub>
|MolarMass = 104.15&nbsp;g/mol
|Appearance = colorless oily liquid
|Odor = sweet and floral<ref name=PGCH/>
|Density = 0.909&nbsp;g/cm<sup>3</sup>
|Solubility = 0.03% (20&nbsp;°C)<ref name=PGCH/>
|MeltingPtC = -30
|BoilingPtC = 145
|Viscosity = 0.762 [[Poise (unit)|cP]] at 20&nbsp;°C
|RefractIndex = 1.5469
|VaporPressure = 5 mmHg (20&nbsp;°C)<ref name=PGCH/>
|MagSus = {{val|-6.82e-5|u=cm<sup>3</sup>/mol}}
|LogP =2.70<ref name="chemsrc">{{Cite web|url=https://www.chemsrc.com/en/cas/100-42-5_28937.html|title=Styrene|website=www.chemsrc.com}}</ref>
}}
|Section3 = {{Chembox Structure
|Dipole = 0.13 [[Debye|D]]
}}
|Section7 = {{Chembox Hazards
|ExternalSDS = [https://www.sigmaaldrich.com/US/en/sds/sial/s4972?srsltid=AfmBOoqC4gnp2hBmP--rrKKfV5nSnCJxjoWx_cfFDel8mCnDQR53IbZM SDS]
|MainHazards = flammable, toxic, [[probable carcinogen|probably carcinogenic]]
|FlashPtC = 31
|NFPA-F = 3
|NFPA-H = 2
|NFPA-R = 2
|GHSPictograms = {{GHS02}}{{GHS07}}{{GHS08}}
|GHSSignalWord = Danger
|HPhrases = {{H-phrases|226|315|319|332|361|372}}
|PPhrases = {{P-phrases|201|202|210|233|240|241|242|243|260|261|264|270|271|280|281|302+352|303+361+353|304+312|304+340|305+351+338|308+313|312|314|321|332+313|337+313|362|370+378|403+235|405|501}}
|PEL = TWA 100 ppm C 200&nbsp;ppm 600&nbsp;ppm (5-minute maximum peak in any 3&nbsp;hours)<ref name=PGCH>{{PGCH|0571}}</ref>
|ExploLimits = 0.9–6.8%<ref name=PGCH/>
|IDLH = 700 ppm<ref name=PGCH/>
|LC50 = 2194 ppm (mouse, 4&nbsp;[[hour|h]])<br/>5543 ppm (rat, 4&nbsp;h)<ref name=IDLH>{{IDLH|100425|Styrene}}</ref>
|REL = TWA 50 ppm (215&nbsp;mg/m<sup>3</sup>)<br/> ST 100 ppm (425&nbsp;mg/m<sup>3</sup>)<ref name=PGCH/> 
|LCLo = 10,000 ppm (human, 30&nbsp;min)<br/>2771 ppm (rat, 4&nbsp;h)<ref name=IDLH/>
}}
|Section8 = {{Chembox Related
|OtherFunction_label = styrenes;<br/>related [[aromatic]] compounds
|OtherFunction = [[polystyrene]], [[stilbene]];<br/>[[ethylbenzene]]
}}
}}

'''Styrene''' is an [[organic compound]] with the [[chemical formula]] C<sub>6</sub>H<sub>5</sub>CH=CH<sub>2</sub>. Its structure consists of a [[vinyl group]] as [[substituent]] on [[benzene]]. Styrene is a colorless, oily [[liquid]], although aged samples can appear yellowish. The compound evaporates easily and has a sweet smell, although high concentrations have a less pleasant odor.{{Vague|date=August 2023}} Styrene is the precursor to [[polystyrene]] and several copolymers, and is typically made from benzene for this purpose. Approximately 25&nbsp;million tonnes of styrene were produced in 2010,<ref name="DOE2010">{{cite web |url=http://www1.eere.energy.gov/office_eere/pdfs/exelus_case_study.pdf |title=New Process for Producing Styrene Cuts Costs, Saves Energy, and Reduces Greenhouse Gas Emissions |archive-url=https://web.archive.org/web/20130421082549/http://www1.eere.energy.gov/office_eere/pdfs/exelus_case_study.pdf |archive-date=21 April 2013 |publisher=US Department of Energy}}</ref> increasing to around 35 million tonnes by 2018.
{{TOC limit|3}}

==Natural occurrence==
Styrene is named after [[storax balsam]] (often commercially sold as ''styrax''), the resin of [[Liquidambar]] trees of the [[Altingiaceae]] plant family. Styrene occurs naturally in small quantities in some plants and foods ([[cinnamon]], [[coffee bean]]s, [[balsam tree (disambiguation)|balsam tree]]s and [[peanut]]s)<ref>{{cite journal |last1=Steele |first1=D.H. |last2=M.J. |first2=Thornburg |last3=J.S. |first3=Stanley |last4=R.R. |first4=Miller |last5=R. |first5=Brooke |last6=J.R. |first6=Cushman |last7=G. |first7=Cruzan |date=1994 |title=Determination of styrene in selected foods |url=http://agris.fao.org/agris-search/search.do?recordID=US9561217 |journal=Journal of Agricultural and Food Chemistry |volume=42 |issue=8 |pages=1661–1665 |issn=0021-8561 |url-status=live |archive-url=https://web.archive.org/web/20180214073543/http://agris.fao.org/agris-search/search.do?recordID=US9561217 |archive-date=14 February 2018|doi=10.1021/jf00044a015|bibcode=1994JAFC...42.1661S |url-access=subscription }}</ref> and is also found in [[coal tar]].

==History==
In 1839, the German apothecary [[Eduard Simon]] isolated a fragrant volatile liquid from the resin (called ''storax'' or ''styrax'' (Latin)) of the American sweetgum tree (''[[Liquidambar styraciflua]]''). He called the liquid "styrol" (now called styrene).<ref>Simon, E. (1839) [https://babel.hathitrust.org/cgi/pt?id=uva.x002457910;view=1up;seq=277 "Ueber den flüssigen Storax (Styrax liquidus)"] (On liquid storax (Styrax liquidus), ''Annalen der Chemie'', '''31''' : 265–277. From p. 268: ''"Das flüchtige Oel, für welches ich den Namen ''Styrol'' vorschlage, … "'' (The volatile oil, for which I suggest the name "styrol", … )</ref><ref>For further details of the history of styrene, see: F. W. Semmler, ''Die ätherischen Öle nach ihren chemischen Bestandteilen unter Berücksichtigung der geschichtlichen Entwicklung'' [The volatile liquids according to their chemical components with regard to historical development], vol. 4 (Leipzig, Germany, Veit & Co., 1907), § 327. Styrol, [https://books.google.com/books?id=nA9aAAAAYAAJ&pg=PA24 pp. 24–28.] {{webarchive |url=https://web.archive.org/web/20180501152357/https://books.google.com/books?id=nA9aAAAAYAAJ&pg=PA24 |date=1 May 2018}}</ref> He also noticed that when styrol was exposed to air, light, or heat, it gradually transformed into a hard, rubber-like substance, which he called "styrol oxide".<ref>(Simon, 1839), p. 268. From p. 268: ''"Für den festen Rückstand würde der Name Styroloxyd passen."'' (For the solid residue, the name "styrol oxide" would fit.)</ref>

By 1845, the German chemist [[August Wilhelm von Hofmann]] and his student [[John Buddle Blyth]] had determined styrene's [[empirical formula]]: C<sub>8</sub>H<sub>8</sub>.<ref>
See:
* {{cite journal |last1=Blyth |first1=John |last2=Hofmann |first2=Aug. Wilhelm |title=On styrole, and some of the products of its decomposition |journal=Memoirs and Proceedings of the Chemical Society of London |date=1845a |volume=2 |pages=334–358 |url=https://books.google.com/books?id=7yFbAAAAYAAJ&pg=PA334 |url-status=live |archive-url=https://web.archive.org/web/20180501152357/https://books.google.com/books?id=7yFbAAAAYAAJ&lpg=PA334&pg=PA334 |archive-date=1 May 2018|doi=10.1039/mp8430200334}}; see p. 339.
* Reprinted in: {{cite journal |last1=Blyth |first1=John |last2=Hofmann |first2=Aug. Wilhelm |title=On styrole, and some of the products of its decomposition |journal=Philosophical Magazine |date=August 1845b |volume=27 |issue=178 |pages=97–121 |url=https://babel.hathitrust.org/cgi/pt?id=umn.319510006140796;view=1up;seq=117 |series=3rd series |doi=10.1080/14786444508645234}}; see p. 102.
* German translation: {{cite journal |last1=Blyth |first1=John |last2=Hofmann |first2=Aug. Wilh. |title=Ueber das Styrol und einige seiner Zersetzungsproducte |journal=Annalen der Chemie und Pharmacie |date=1845c |volume=53 |issue=3 |pages=289–329 |url=https://books.google.com/books?id=A8MwAAAAYAAJ&pg=PA289 |trans-title=On styrol and some of its decomposition products |language=de |doi=10.1002/jlac.18450530302}}; see p. 297.
* Note that Blyth and Hofmann state the empirical formula of styrene as C<sub>16</sub>H<sub>8</sub> because at that time, some chemists used the wrong atomic mass for carbon (6 instead of 12).</ref> They had also determined that Simon's "styrol oxide"—which they renamed "metastyrol"—had the same [[empirical formula]] as styrene.<ref>(Blyth and Hofmann, 1845a), p. 348. From p. 348: "Analysis as well as synthesis has equally proved that styrol and the vitreous mass (for which we propose the name of metastyrol) possess the same constitution per cent."</ref> Furthermore, they could obtain styrene by [[Dry distillation|dry-distilling]] "metastyrol".<ref>(Blyth and Hofmann, 1845a), p. 350</ref> 

In 1865, the German chemist [[Emil Erlenmeyer]] found that styrene could form a [[Dimer (chemistry)|dimer]],<ref>Erlenmeyer, Emil (1865) [https://babel.hathitrust.org/cgi/pt?id=uva.x002457969;view=1up;seq=134 "Ueber Distyrol, ein neues Polymere des Styrols"] (On distyrol, a new polymer of styrol), ''Annalen der Chemie'', '''135''' : 122–123.</ref> and in 1866 the French chemist [[Marcelin Berthelot]] stated that "metastyrol" was a [[polymer]] of styrene (i.e. [[polystyrene]]).<ref>Berthelot, M. (1866) [https://archive.org/stream/bulletin27frangoog#page/n295/mode/2up "Sur les caractères de la benzine et du styrolène, comparés avec ceux des autres carbures d'hydrogène"] (On the characters of [[benzene]] and styrene, compared with those of other hydrocarbons), ''Bulletin de la Société Chimique de Paris'', 2nd series, '''6''' : 289–298. From p. 294: ''"On sait que le styrolène chauffé en vase scellé à 200°, pendant quelques heures, se change en un polymère résineux (métastyrol), et que ce polymère, distillé brusquement, reproduit le styrolène."'' (One knows that styrene [when] heated in a sealed vessel at 200&nbsp;°C, for several hours, is changed into a resinous polymer (metastyrol), and that this polymer, [when] distilled abruptly, reproduces styrene.)</ref> Meanwhile, other chemists had been investigating another component of storax, namely, [[cinnamic acid]]. They had found that cinnamic acid could be [[decarboxylated]] to form "cinnamene" (or "cinnamol"), which appeared to be styrene. 

In 1845, French chemist [[Emil Kopp]] suggested that the two compounds were identical,<ref>Kopp, E. (1845), [http://gallica.bnf.fr/ark:/12148/bpt6k6449135m/f38.item.zoom "Recherches sur l'acide cinnamique et sur le cinnamène"] {{webarchive |url=https://web.archive.org/web/20161108062615/http://gallica.bnf.fr/ark:/12148/bpt6k6449135m/f38.item.zoom |date=8 November 2016}} (Investigations of cinnamic acid and cinnamen), ''Comptes rendus'', '''21''' : 1376–1380. From p. 1380: ''"Je pense qu'il faudra désormais remplacer le mot de styrol par celui de cinnamène, et le métastyrol par le métacinnamène."'' (I think that henceforth one will have to replace the word "styrol" with that of "cinnamène", and "metastyrol" with "metacinnamène".)</ref> and in 1866, Erlenmeyer suggested that both "cinnamol" and styrene might be vinylbenzene.<ref>Erlenmeyer, Emil (1866) [https://babel.hathitrust.org/cgi/pt?id=uva.x002457970;view=1up;seq=339 "Studien über die s.g. aromatischen Säuren"] (Studies of the so-called aromatic acids), ''Annalen der Chemie'', '''137''' : 327–359; [https://babel.hathitrust.org/cgi/pt?id=uva.x002457970;view=1up;seq=365 see p. 353.]</ref> However, the styrene that was obtained from cinnamic acid seemed different from the styrene that was obtained by distilling storax resin:  the latter was [[Optical rotation|optically active]].<ref>{{cite journal |last1=Berthelot |first1=Marcellin |title=Sur les états isomériques du styrolène |journal=Annales de Chimie et de Physique |date=1867 |volume=12 |pages=159–161 |url=https://babel.hathitrust.org/cgi/pt?id=uva.x002489147;view=1up;seq=165 |series=4th series |trans-title=On the isomeric states of styrene |language=fr}} From p. 160: ''"1° Le carbure des cinnamates est privé de pouvoir rotatoire, tandis que le carbure du styrax dévie de 3 degrés la teinte de passage (l = 100 mm)."'' (1. The carbon [atom] of cinnamates is bereft of rotary power [i.e., the ability to rotate polarized light], whereas the carbon of styrax deflects by 3 degrees the neutral tint [i.e., the relative orientation of the polarized quartz plates at which the light through the polarimeter appears colorless] (length = 100 mm). [For further details about 19th century polarimeters, see: {{cite book |last1=Spottiswode |first1=William |title=Polarisation of Light |date=1883 |publisher=[[Macmillan and Co.]] |location=London |pages=51–52 |edition=4th |url=https://archive.org/stream/polarisationofli00spotrich |access-date=15 September 2016 |archive-url=https://web.archive.org/web/20100910214825/http://www.archive.org/stream/polarisationofli00spotrich#page/52/mode/2up/ |archive-date=10 September 2010 |url-status=dead}}])</ref> Eventually, in 1876, the Dutch chemist [[Jacobus Henricus van 't Hoff|van 't Hoff]] resolved the ambiguity:  the optical activity of the styrene that was obtained by distilling storax resin was due to a contaminant.<ref>van 't Hoff, J. H. (1876) [https://babel.hathitrust.org/cgi/pt?id=uiug.30112025695146;view=1up;seq=13 "Die Identität von Styrol und Cinnamol, ein neuer Körper aus Styrax"] (The identity of styrol and cinnamol, a new substance from styrax), ''Berichte der deutschen chemischen Gesellschaft'', '''9''' :  5-6.</ref>

==Industrial production==
===From ethylbenzene===
The vast majority of styrene is produced from [[ethylbenzene]],<ref name="ullstyrene">{{Ullmann |first1=Denis H. |last1=James |first2=William M. |last2=Castor |title=Styrene |year=2007 |doi=10.1002/14356007.a25_329.pub2}}</ref> and almost all ethylbenzene produced worldwide is intended for styrene production. As such, the two production processes are often highly integrated. Ethylbenzene is produced via a [[Friedel–Crafts reaction]] between benzene and [[ethene]]; originally this used [[aluminum chloride]] as a [[catalyst]], but in modern production this has been replaced by [[zeolite]]s.

====By dehydrogenation====
Around 80% of styrene is produced by the [[dehydrogenation]] of [[ethylbenzene]]. This is achieved using superheated steam (up to 600&nbsp;°C) over an [[iron(III) oxide]] catalyst.<ref>{{cite journal |last1=Lee |first1=Emerson H. |title=Iron Oxide Catalysts for Dehydrogenation of Ethylbenzene in the Presence of Steam |journal=Catalysis Reviews |date=13 December 2006 |volume=8 |issue=1 |pages=285–305 |doi=10.1080/01614947408071864}}</ref> The reaction is highly [[endothermic]] and reversible, with a typical yield of 88–94%.

:[[File:StyreneProduction.svg|500px|class=skin-invert]]

The crude ethylbenzene/styrene product is then purified by distillation. As the difference in boiling points between the two compounds is only 9&nbsp;°C at ambient pressure this necessitates the use of a series of distillation columns. This is energy intensive and is further complicated by the tendency of styrene to undergo thermally induced polymerisation into polystyrene,<ref name=autopoly1>{{cite journal |last1=Khuong |first1=Kelli S. |last2=Jones |first2=Walter H. |last3=Pryor |first3=William A. |last4=Houk |first4=K.N. |title=The Mechanism of the Self-Initiated Thermal Polymerization of Styrene. Theoretical Solution of a Classic Problem |journal=[[Journal of the American Chemical Society]] |date=February 2005 |volume=127 |issue=4 |pages=1265–1277 |doi=10.1021/ja0448667 |pmid=15669866|bibcode=2005JAChS.127.1265K }}</ref> requiring the continuous addition of [[polymerization inhibitor]] to the system.

====Via ethylbenzene hydroperoxide====
Styrene is also co-produced commercially in a process known as POSM ([[Lyondell Chemical Company]]) or SM/PO ([[Royal Dutch Shell|Shell]]) for styrene monomer / [[propylene oxide]]. In this process, ethylbenzene is treated with oxygen to form the [[ethylbenzene hydroperoxide]]. This hydroperoxide is then used to oxidize [[propylene]] to propylene oxide, which is also recovered as a co-product. The remaining 1-phenylethanol is dehydrated to give styrene:

: [[File:Styrol synthesis.svg|450px|Synthesis of styrene|class=skin-invert]]

===Other industrial routes===
==== Pyrolysis gasoline extraction ====
Extraction from [[pyrolysis gasoline]] is performed on a limited scale.<ref name="ullstyrene"/>

==== From toluene and methanol ====
Styrene can be produced from [[toluene]] and [[methanol]], which are cheaper raw materials than those in the conventional process. This process has suffered from low selectivity associated with the competing decomposition of methanol.<ref>{{cite journal |last1=Yashima |first1=Tatsuaki |last2=Sato |first2=Keiichi |last3=Hayasaka |first3=Tomoki |last4=Hara |first4=Nobuyoshi |year=1972 |title=Alkylation on synthetic zeolites: III. Alkylation of toluene with methanol and formaldehyde on alkali cation exchanged zeolites |journal=Journal of Catalysis |volume=26 |issue=3 |pages=303–312 |doi=10.1016/0021-9517(72)90088-7}}</ref> Exelus Inc. claims to have developed this process with commercially viable selectivities, at 400–425&nbsp;°C and atmospheric pressure, by forcing these components through a proprietary [[zeolitic]] catalyst. It is reported<ref>{{cite web |url=http://www.icis.com/Articles/2008/01/21/9093889/new-process-may-rescue-styrenics-industry.html |title=Welcome to ICIS |website=www.icis.com |access-date=1 May 2018}}</ref> that an approximately 9:1 mixture of styrene and ethylbenzene is obtained, with a total styrene yield of over 60%.<ref>Stephen K. Ritter, Chemical & Engineering News, 19 March 2007, p.46.</ref>

====From benzene and ethane====
Another route to styrene involves the reaction of benzene and [[ethane]]. This process is being developed by Snamprogetti and Dow. Ethane, along with ethylbenzene, is fed to a dehydrogenation reactor with a catalyst capable of simultaneously producing styrene and ethylene. The dehydrogenation effluent is cooled and separated and the ethylene stream is recycled to the alkylation unit. The process attempts to overcome previous shortcomings in earlier attempts to develop production of styrene from ethane and benzene, such as inefficient recovery of aromatics, production of high levels of heavies and tars, and inefficient separation of [[hydrogen]] and ethane. Development of the process is ongoing.<ref>{{cite web |url=http://www.chemsystems.com/reports/search/docs/toc/0708_4_toc.pdf |title=CHEMSYSTEMS.COM |website=www.chemsystems.com |access-date=1 May 2018 |url-status=dead |archive-url=https://web.archive.org/web/20110708142010/http://www.chemsystems.com/reports/search/docs/toc/0708_4_toc.pdf |archive-date=8 July 2011}}</ref>

== Laboratory synthesis ==
A laboratory synthesis of styrene entails the [[decarboxylation]] of [[cinnamic acid]] with catalytic [[hydroquinone]]:<ref>{{OrgSynth |last1=Abbott |first1=T.W. |last2=Johnson |first2=J.R. |title=Phenylethylene (Styrene) |collvol=1 |collvolpages=440 |year=1941 |prep=CV1P0440}}</ref>  
:{{chem2|C6H5CH\dCHCO2H → C6H5CH\dCH2 + CO2}}

Styrene was first prepared by this method.<ref>R. Fittig und F. Binder "Ueber die Additionsproducte der Zimmtssaure" in "Untersuchungen über die ungesättigten Säuren. I. Weitere Beiträge zur Kenntniß der Fumarsäure und Maleïnsäure" Rudolph Fittig, Camille Petri, Justus Liebigs ''Annalen der Chemie'' 1879, volume 195, pp. 56–179. {{doi|10.1002/jlac.18791950103}}</ref>

==Polymerization==
The presence of the vinyl group allows styrene to [[polymerize]]. Commercially significant products include [[polystyrene]], [[acrylonitrile butadiene styrene]] (ABS), [[styrene-butadiene]] [[rubber]] (SBR), styrene-butadiene latex, SIS (styrene-isoprene-styrene), [[Styrene ethylene butylene styrene|S-EB-S]] (styrene-ethylene/butylene-styrene), styrene-[[divinylbenzene]] (S-DVB), [[styrene-acrylonitrile resin]] (SAN), and [[Polyester resin|unsaturated polyesters used in resins and thermosetting compounds]].  These materials are used in rubber, plastic, insulation, [[fiberglass]], pipes, [[automobile]] and boat parts, food containers, and carpet backing.

==Hazards==
=== Autopolymerisation ===
As a liquid or a gas, pure styrene will polymerise spontaneously to polystyrene, without the need of external [[Radical initiator|initiators]].<ref>{{cite journal |last1=Miller |first1=A.A. |last2=Mayo |first2=F.R. |title=Oxidation of Unsaturated Compounds. I. The Oxidation of Styrene |journal=Journal of the American Chemical Society |date=March 1956 |volume=78 |issue=5 |pages=1017–1023 |doi=10.1021/ja01586a042|bibcode=1956JAChS..78.1017M }}</ref> This is known as ''autopolymerisation''. At 100&nbsp;°C it will autopolymerise at a rate of ~2% per hour, and more rapidly than this at higher temperatures.<ref name=autopoly1 /> As the autopolymerisation reaction is [[exothermic]] it can be self-accelerating, with a real risk of a [[thermal runaway]], potentially leading to an explosion. Examples include the 2019 explosion of the tanker ''Stolt Groenland'',<ref>{{cite web |title=Report on the investigation of the cargo tank explosion and fire on board the chemical tanker Stolt Groenland |url=https://assets.publishing.service.gov.uk/media/60f93e2cd3bf7f044c51590b/2021-09-StoltGroenland-Report.pdf |publisher=e UK Marine Accident Investigation Branch}}</ref> explosions at the [[Phillips Petroleum Company]] in [[Phillips explosion of 1999|1999]] and [[2000 Phillips explosion|2000]] and overheating styrene tanks leading to the 2020 [[Visakhapatnam gas leak]], which killed several people.<ref>{{cite web |url=https://economictimes.indiatimes.com/news/politics-and-nation/live-updates-eight-dead-several-fall-sick-after-gas-leak-at-lg-poymers-plant-in-visakhapatnam/articleshow/75592838.cms |title=Vizag Gas Leak Live News: Eleven dead, several hospitalised after toxic gas leak from LG Polymers plant |access-date=2020-05-07 |date=2020-05-07 |work=The Economic Times}}</ref><ref>{{cite web |url=https://www.theguardian.com/world/2020/may/07/gas-leak-at-chemical-factory-in-india-kills-hospitalises-lg-polymers |title=Hundreds in hospital after leak at Indian chemical factory closed by lockdown |access-date=2020-05-07 |date=2020-05-07 |newspaper=The Guardian}}</ref> The autopolymerisation reaction can only be kept in check by the continuous addition of [[polymerisation inhibitor]]s such as [[butylated hydroxytoluene]].

=== Health effects ===
Styrene is regarded as a "known [[carcinogen]]", especially in case of eye contact, but also in case of skin contact, of ingestion and of inhalation, according to several sources.<ref name="ullstyrene" /><ref>{{cite web |author=MSDS |date=1 November 2010 |title=Material Safety Data Sheet Styrene (monomer) MSDS |url=http://www.sciencelab.com/msds.php?msdsId=9925112 |publisher=[[MSDS]] |access-date=2011-06-11 |url-status=live |archive-url=https://web.archive.org/web/20110807203703/http://www.sciencelab.com/msds.php?msdsId=9925112 |archive-date=7 August 2011|author-link=MSDS }}</ref><ref>{{cite web |title=OPPT Chemical Fact Sheets (Styrene) Fact Sheet: Support Document (CAS No. 100-42-5) |date=December 1994 |url=http://www.epa.gov/chemfact/styre-sd.pdf |publisher=[[US EPA]] |access-date=2011-06-11 |url-status=dead |archive-url=https://web.archive.org/web/20101224191345/http://www.epa.gov/chemfact/styre-sd.pdf |archive-date=24 December 2010}}</ref><ref>{{cite web |url=http://www.atsdr.cdc.gov/tfacts53.pdf |title=Archived copy |access-date=2008-04-06 |url-status=live |archive-url=https://web.archive.org/web/20080602233207/http://www.atsdr.cdc.gov/tfacts53.pdf |archive-date=2 June 2008}}</ref> Styrene is largely metabolized into [[styrene oxide]] in humans, resulting from oxidation by [[cytochrome P450]]. [[Styrene oxide]] is considered [[toxic]], [[mutagenic]], and possibly [[carcinogenic]]. Styrene oxide is subsequently hydrolyzed ''in vivo'' to styrene glycol by the enzyme [[epoxide hydrolase]].<ref>{{cite journal | doi = 10.2307/3428333 | first = Kenneth C. | last = Liebman | journal = [[Environmental Health Perspectives]] | volume = 11 | pages = 115–119 | year = 1975 | url = http://ehis.niehs.nih.gov/members/1975/011/11018.PDF | archive-url = https://web.archive.org/web/20110806040622/http://ehp03.niehs.nih.gov/article/browseIssue.action?issue=info%3Adoi%2F10.1289%2Fissue.ehp.v11.i00 | url-status = dead | archive-date = 6 August 2011 | title = Metabolism and toxicity of styrene | jstor = 3428333 | pmid = 809262 | pmc = 1475194}}</ref> The [[US Environmental Protection Agency]] (EPA) has described styrene to be "a suspected toxin to the gastrointestinal tract, kidney, and respiratory system, among others".<ref name="epa2004">{{cite web | title=EPA settles case against Phoenix company for toxic chemical reporting violations | publisher=US Environmental Protection Agency | url=http://yosemite.epa.gov/opa/admpress.nsf/6427a6b7538955c585257359003f0230/09b1cf3cd5813928852570d8005e1603!OpenDocument | access-date=2008-02-11 | url-status=dead | archive-url=https://web.archive.org/web/20080925222611/http://yosemite.epa.gov/opa/admpress.nsf/6427a6b7538955c585257359003f0230/09b1cf3cd5813928852570d8005e1603!OpenDocument | archive-date=25 September 2008}}</ref><ref name="epa2003">{{cite web | title=EPA Fines California Hot Tub Manufacturer for Toxic Chemical Release Reporting Violations | publisher=US Environmental Protection Agency | url=http://yosemite.epa.gov/opa/admpress.nsf/6427a6b7538955c585257359003f0230/b3249e555c0ed02c852570d8005e1576!OpenDocument | access-date=2008-02-11 | url-status=dead | archive-url=https://web.archive.org/web/20080925224819/http://yosemite.epa.gov/opa/admpress.nsf/6427a6b7538955c585257359003f0230/b3249e555c0ed02c852570d8005e1576!OpenDocument | archive-date=25 September 2008}}</ref> 

On 10 June 2011, the [[National Toxicology Program|US National Toxicology Program]] has described styrene as "reasonably anticipated to be a human carcinogen".<ref name="Harris">{{cite news |last1=Harris |first1=Gardiner |title=Government Says 2 Common Materials Pose Risk of Cancer |date=10 June 2011 |url=https://www.nytimes.com/2011/06/11/health/11cancer.html |newspaper=[[The New York Times]]|access-date=2011-06-11 |url-status=live |archive-url=https://web.archive.org/web/20110613153643/http://www.nytimes.com/2011/06/11/health/11cancer.html |archive-date=13 June 2011}}</ref><ref name="12Report2011">{{cite web |author=National Toxicology Program |title=12th Report on Carcinogens |date=10 June 2011 |publisher=[[National Toxicology Program]] |url=https://ntp.niehs.nih.gov/go/roc12 |access-date=2011-06-11 |url-status=dead |archive-url=https://web.archive.org/web/20110612024850/http://ntp.niehs.nih.gov/index.cfm?objectid=72016262-BDB7-CEBA-FA60E922B18C2540 |archive-date=12 June 2011|author-link=National Toxicology Program}}</ref> However, a [[Statistical Assessment Service|STATS]] author describes<ref>{{cite web |url=http://stats.org/stories/2011/styrene_crosshairs_sept14_11.html |title=STATS: Styrene in the Crosshairs: Competing Standards Confuse Public, Regulators |access-date=2012-09-24 |url-status=dead |archive-url=https://web.archive.org/web/20120609233948/http://www.stats.org/stories/2011/styrene_crosshairs_sept14_11.html |archive-date=9 June 2012}}</ref> a review that was done on scientific literature and concluded that "The available epidemiologic evidence does not support a causal relationship between styrene exposure and any type of human cancer".<ref>Boffetta, P., et al., [http://journals.lww.com/joem/Abstract/2009/11000/Epidemiologic_Studies_of_Styrene_and_Cancer__A.5.aspx Epidemiologic Studies of Styrene and Cancer: A Review of the Literature] {{webarchive |url=https://web.archive.org/web/20121009081133/http://journals.lww.com/joem/Abstract/2009/11000/Epidemiologic_Studies_of_Styrene_and_Cancer__A.5.aspx |date=9 October 2012}}, ''J. Occupational and Environmental Medicine'', Nov.2009, V.51, N.11.</ref> Despite this claim, work has been done by Danish researchers to investigate the relationship between occupational exposure to styrene and cancer. They concluded, "The findings have to be interpreted with caution, due to the company based exposure assessment, but the possible association between exposures in the reinforced [[plastics industry]], mainly styrene, and degenerative disorders of the nervous system and pancreatic cancer, deserves attention".<ref>{{cite journal |last1=Kolstad |first1=HA |last2=Juel |first2=K |last3=Olsen |first3=J |last4=Lynge |first4=E. |title=Exposure to styrene and chronic health effects: mortality and incidence of solid cancers in the Danish reinforced plastics industry. |journal=Occupational and Environmental Medicine |date=May 1995 |volume=52 |pages=320–7 |pmc=1128224 |pmid=7795754 |issue=5 |doi=10.1136/oem.52.5.320}}</ref> In 2012, the [[EPA Network|Danish EPA]] concluded that the styrene data do not support a cancer concern for styrene.<ref>Danish EPA 2011 review {{cite web |url=http://www.compositesworld.com/cdn/cms/uploadedFiles/danish_epa_styrene_review(2).pdf |title=Archived copy |access-date=2012-02-15 |url-status=live |archive-url=https://web.archive.org/web/20140714125424/http://www.compositesworld.com/cdn/cms/uploadedFiles/danish_epa_styrene_review(2).pdf |archive-date=14 July 2014}}</ref> The US EPA does not have a cancer classification for styrene,<ref>{{cite web |url=http://www.epa.gov/iris/subst/0104.htm |title=Styrene (CASRN 100-42-5) &#124; Region &#124; US EPA |access-date=2009-10-18 |url-status=dead |archive-url=https://web.archive.org/web/20090512191949/http://www.epa.gov/iris/subst/0104.htm |archive-date=12 May 2009}} US environmental protection agency. Section I.B.4 relates to neurotoxicology.</ref> but it has been the subject of their Integrated Risk Information System (IRIS) program.<ref>{{cite web |url=http://cfpub.epa.gov/ncea/iristrac/index.cfm?fuseaction=viewChemical.showChemical&sw_id=1051 |title=EPA IRIS track styrene page |website=epa.gov |access-date=1 May 2018 |url-status=dead |archive-url=https://web.archive.org/web/20111222014519/http://cfpub.epa.gov/ncea/iristrac/index.cfm?fuseaction=viewChemical.showChemical&sw_id=1051 |archive-date=22 December 2011}}</ref> 

The [[National Toxicology Program]] of the [[US Department of Health and Human Services]] has determined that styrene is "reasonably anticipated to be a human carcinogen".<ref>{{cite web |url=https://ntp.niehs.nih.gov/sites/default/files/ntp/roc/content/profiles/styrene.pdf |title=Styrene entry in National Toxicology Program's Thirteenth Report on Carcinogens |website=nih.gov |access-date=1 May 2018 |url-status=live |archive-url=https://web.archive.org/web/20171022090346/https://ntp.niehs.nih.gov/ntp/roc/content/profiles/styrene.pdf |archive-date=22 October 2017}}</ref> Various regulatory bodies refer to styrene, in various contexts, as a possible or potential human carcinogen. The [[International Agency for Research on Cancer]] considers styrene to be "probably carcinogenic to humans".<ref>{{cite journal |last1=Kogevinas |first1=Manolis |last2=Gwinn |first2=William M. |last3=Kriebel |first3=David |last4=Phillips |first4=David H. |last5=Sim |first5=Malcolm |last6=Bertke |first6=Stephen J. |last7=Calaf |first7=Gloria M. |last8=Colosio |first8=Claudio |last9=Fritz |first9=Jason M. |last10=Fukushima |first10=Shoji |last11=Hemminki |first11=Kari |date=2018 |title=Carcinogenicity of quinoline, styrene, and styrene-7,8-oxide |journal=The Lancet Oncology |volume=19 |issue=6 |pages=728–729 |doi=10.1016/s1470-2045(18)30316-4 |pmid=29680246 |s2cid=48357020 |issn=1470-2045 }}</ref><ref>{{cite web |url=https://www.sciencedaily.com/releases/2018/05/180530113105.htm |title=After 40 years in limbo: Styrene is probably carcinogenic |website=ScienceDaily |access-date=2020-03-31}}</ref>

The neurotoxic<ref>{{Cite journal|last1=Cherry|first1=N.|last2=Gautrin|first2=D.|date=January 1990|title=Neurotoxic effects of styrene: further evidence|journal=British Journal of Industrial Medicine|volume=47|issue=1|pages=29–37|issn=0007-1072|pmc=1035091|pmid=2155647|doi=10.1136/oem.47.1.29}}</ref> properties of styrene have also been studied and reported effects include effects on vision<ref>{{Cite journal|last1=Murata|first1=K.|last2=Araki|first2=S.|last3=Yokoyama|first3=K.|date=1991|title=Assessment of the peripheral, central, and autonomic nervous system function in styrene workers|journal=American Journal of Industrial Medicine|volume=20|issue=6|pages=775–784|issn=0271-3586|pmid=1666820|doi=10.1002/ajim.4700200609}}</ref> (although unable to reproduce in a subsequent study<ref>{{cite journal |last1=Seeber |first1=Andreas |last2=Bruckner |first2=Thomas |last3=Triebig |first3=Gerhard |date=2009-03-29 |title=Occupational styrene exposure, colour vision and contrast sensitivity: a cohort study with repeated measurements |journal=International Archives of Occupational and Environmental Health |volume=82 |issue=6 |pages=757–770 |doi=10.1007/s00420-009-0416-7|pmid=19330514|bibcode=2009IAOEH..82..757S |s2cid=7463900 |issn=0340-0131}}</ref>) and on hearing functions.<ref>{{cite journal |last1=Campo |first1=Pierre |last2=Venet |first2=Thomas |last3=Rumeau |first3=Cécile |last4=Thomas |first4=Aurélie |last5=Rieger |first5=Benoît |last6=Cour |first6=Chantal |last7=Cosnier |first7=Frédéric |last8=Parietti-Winkler |first8=Cécile |date=October 2011 |title=Impact of noise or styrene exposure on the kinetics of presbycusis |journal=Hearing Research |volume=280 |issue=1–2 |pages=122–132 |doi=10.1016/j.heares.2011.04.016 |issn=1878-5891 |pmid=21616132|s2cid=34799773 }}</ref><ref name=":0">{{cite journal |last1=Lataye |first1=R. |last2=Campo |first2=P. |last3=Loquet |first3=G. |last4=Morel |first4=G. |date=April 2005 |title=Combined effects of noise and styrene on hearing: comparison between active and sedentary rats |journal=Noise & Health |volume=7 |issue=27 |pages=49–64 |issn=1463-1741 |pmid=16105249 |doi=10.4103/1463-1741.31633 |doi-access= free}}</ref><ref name=":1">{{cite journal |last1=Campo |first1=Pierre |last2=Venet |first2=Thomas |last3=Thomas |first3=Aurélie |last4=Cour |first4=Chantal |last5=Brochard |first5=Céline |last6=Cosnier |first6=Frédéric |date=July 2014 |title=Neuropharmacological and cochleotoxic effects of styrene. Consequences on noise exposures |journal=Neurotoxicology and Teratology |volume=44 |pages=113–120 |doi=10.1016/j.ntt.2014.05.009 |issn=1872-9738 |pmid=24929234|bibcode=2014NTxT...44..113C }}</ref><ref>{{cite book |title=Occupational exposure to chemicals and hearing impairment |last=Johnson |first=Ann-Christin |date=2010 |orig-year=2009 |publisher=[[University of Gothenburg]] |others=Morata, Thais C., Nordic Expert Group for Criteria Documentation of Health Risks from Chemicals., Sahlgrenska akademin (Göteborgs universitet), Göteborgs universitet., Arbetsmiljöverket. |isbn=9789185971213 |location=Gotenburg |oclc=792746283}}</ref> Studies on rats have yielded contradictory results,<ref name=":0" /><ref name=":1" /> but epidemiologic studies have observed a [[synergistic]] interaction with noise in causing hearing difficulties.<ref>{{cite journal |last1=Sliwińska-Kowalska |first1=Mariola |last2=Zamyslowska-Szmytke |first2=Ewa |last3=Szymczak |first3=Wieslaw |last4=Kotylo |first4=Piotr |last5=Fiszer |first5=Marta |last6=Wesolowski |first6=Wiktor |last7=Pawlaczyk-Luszczynska |first7=Malgorzata |date=January 2003 |title=Ototoxic effects of occupational exposure to styrene and co-exposure to styrene and noise |journal=Journal of Occupational and Environmental Medicine |volume=45 |issue=1 |pages=15–24 |issn=1076-2752 |pmid=12553175 |doi=10.1097/00043764-200301000-00008|s2cid=7030810 }}</ref><ref>{{cite journal |last1=Morata |first1=Thais C. |last2=Sliwinska-Kowalska |first2=Mariola |last3=Johnson |first3=Ann-Christin |last4=Starck |first4=Jukka |last5=Pawlas |first5=Krystyna |last6=Zamyslowska-Szmytke |first6=Ewa |last7=Nylen |first7=Per |last8=Toppila |first8=Esko |last9=Krieg |first9=Edward |date=October 2011 |title=A multicenter study on the audiometric findings of styrene-exposed workers |journal=International Journal of Audiology |volume=50 |issue=10 |pages=652–660 |doi=10.3109/14992027.2011.588965 |issn=1708-8186 |pmid=21812635|s2cid=207571026 }}</ref><ref>{{cite journal |last1=Sisto |first1=R. |last2=Cerini |first2=L. |last3=Gatto |first3=M.P. |last4=Gherardi |first4=M. |last5=Gordiani |first5=A. |last6=Sanjust |first6=F. |last7=Paci |first7=E. |last8=Tranfo |first8=G. |last9=Moleti |first9=A. |date=November 2013 |title=Otoacoustic emission sensitivity to exposure to styrene and noise |journal=The Journal of the Acoustical Society of America |volume=134 |issue=5 |pages=3739–3748 |doi=10.1121/1.4824618 |issn=1520-8524 |pmid=24180784 |bibcode=2013ASAJ..134.3739S}}</ref><ref>{{Cite web |title=Preventing hearing loss caused by chemical (ototoxicity) and noise exposure. SHIB 03-08-2018: DHHS (NIOSH) Publication No. 2018-124 |url=https://www.cdc.gov/niosh/docs/2018-124/default.html |language=en-us |doi=10.26616/NIOSHPUB2018124|doi-access=free |publisher= Occupational Safety and Health Administration and the National Institute for Occupational Safety and Health |year= 2018}}</ref>

== References ==
{{Reflist}}

==External links==
*[[American Industrial Hygiene Association]], [https://synergist.aiha.org/201811-the-ear-poisons The Ear Poisons], The Synergist, November 2018. 
*[https://www.cdc.gov/niosh/topics/styrene/ CDC – Styrene – NIOSH Workplace Safety and Health Topic]
*[http://www.osha.gov/SLTC/styrene/index.html Safety and Health Topics | Styrene (OSHA)]
*[[Nordic Expert Group]], [https://gupea.ub.gu.se/bitstream/2077/23240/1/gupea_2077_23240_1.pdf Occupational Exposure to Chemicals and Hearing Impairment], 2010.

{{Authority control}}
{{Hydrocarbons}}

[[Category:Monomers]]
[[Category:Vinylbenzenes]]
[[Category:C2-Benzenes]]
[[Category:Commodity chemicals]]
[[Category:Phenyl compounds]]
[[Category:Chemical hazards]]
[[Category:IARC Group 2A carcinogens]]
[[Category:Sweet-smelling chemicals]]