{{Distinguish|1,4-Dioxane|Dioxygen}} {{For|other dioxin compounds|dioxin}} {{chembox | Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 477206346 | Name = 1,4-Dioxin | ImageFile = 1,4-Dioxin.svg | ImageClass = skin-invert | ImageSize = 120px | ImageFileL1 = 1,4-Dioxin-3D-balls 2.png | ImageClassL1 = bg-transparent | ImageFileR1 = 1,4-Dioxin-3D-spacefill.png | ImageClassR1 = bg-transparent | PIN = 1,4-Dioxine<ref name=iupac2013>{{cite book | title = Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = [[Royal Society of Chemistry|The Royal Society of Chemistry]] | date = 2014 | location = Cambridge | page = 147 | doi = 10.1039/9781849733069-FP001 | isbn = 978-0-85404-182-4| chapter = Front Matter }}</ref> | SystematicName = 1,4-Dioxacyclohexa-2,5-diene | OtherNames = 1,4-Dioxin<br />Dioxin<br />''p''-Dioxin<br />1,4-Dioxa[6]annulene |Section1={{Chembox Identifiers | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 71301 | InChI = 1/C4H4O2/c1-2-6-4-3-5-1/h1-4H | InChIKey = KVGZZAHHUNAVKZ-UHFFFAOYAD | SMILES = O\1/C=C\O/C=C/1 | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C4H4O2/c1-2-6-4-3-5-1/h1-4H | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = KVGZZAHHUNAVKZ-UHFFFAOYSA-N | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 290-67-5 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = ZD32358XMG | PubChem = 78968 | ChEBI = 134044 }} |Section2={{Chembox Properties | Formula = C{{sub|4}}H{{sub|4}}O{{sub|2}} | MolarMass = 84.07 g/mol | Appearance = Colorless liquid | Density = | Solubility = | MeltingPt = | BoilingPtC = 75 <!-- CRC Handbook of Data on Organic Compounds, 2nd Edition, Weast, R.C and Grasselli, J.G., ed(s)., CRC Press, Inc., Boca Raton, FL, 1989, 1. --> }} |Section7={{Chembox Hazards | MainHazards = highly flammable | NFPA-H = | NFPA-F = | NFPA-R = }} |Section8={{Chembox Related | OtherCompounds = [[1,2-dioxin]], [[dibenzodioxin]]<br> [[dithiin]]}} }}
'''1,4-Dioxin''' (also referred as '''dioxin''' or '''''p''-dioxin''') is a [[heterocyclic compound|heterocyclic]], [[organic compound|organic]], non-[[aromatic]] [[chemical compound|compound]] with the [[chemical formula]] C{{sub|4}}H{{sub|4}}O{{sub|2}}.<ref>Science of Synthesis: Houben-Weyl Methods of Molecular Transformations Vol. 16: Six-Membered Hetarenes with Two Identical Heteroatoms</ref>{{Rp|date=May 2026|needed=y}} It is colorless and very flammable, and has a boiling point of {{Convert|75|C|K}}.<ref>{{Cite book |last= |title=CRC handbook of chemistry and physics: a ready-reference book of chemical and physical data |date= |publisher=Chemical Rubber Company (CRC Press) |year=2004 |isbn=978-0-8493-0485-9 |editor-last=Lide |editor-first=David R. |edition=85th |location=Boca Raton |page=3-145 <!--This is a single page, do not move to pp. -->}}</ref>
There is an [[isomer]]ic form of 1,4-dioxin, [[1,2-Dioxin|1,2-dioxin]] (or ''o''-dioxin). 1,2-Dioxin is very unstable due to its [[peroxide]]-like characteristics.
The term "dioxin" is most commonly used for a family of derivatives of 1,4-dioxin, known as [[polychlorinated dibenzodioxins]] (PCDDs).
==Preparation== 1,4-Dioxin can be prepared by [[cycloaddition]], namely by the [[Diels–Alder reaction]] of [[furan]] and [[maleic anhydride]]. The [[adduct]] formed has a carbon-carbon double bond, which is [[Epoxide#Olefin peroxidation using peroxycarboxylic acids|converted to an epoxide]]. The epoxide then undergoes a [[retro-Diels–Alder reaction]], forming 1,4-dioxin and regenerating maleic anhydride.<ref>{{cite journal | doi = 10.1039/p19940000927 | journal = J. Chem. Soc., Perkin Trans. |volume=1 |issue=8 | year = 1994 | pages = 927–931 | title = Effect of ring strain on the formation and pyrolysis of some Diels–Alder adducts of 2-sulfolene (2,3-dihydrothiophene 1,1-dioxide) and maleic anhydride with 1,3-dienes and products derived therefrom | first=R. Alan |last=Aitken |first2=J. I. G. |last2=Cadogan |name-list-style=amp |first3=Ian |last3=Gosneya }}</ref>
[[File:Synthesis-of-1,4-dioxin-1994-2D-skeletal.png|600px|Scheme describing the 1994 synthesis of 1,4-dioxin]]
==Derivatives== [[File:Dibenzo-p-dioxin-numbering-2D-skeletal.png|thumb|The [[skeletal formula]] and [[substituent]] numbering scheme of [[dibenzo-1,4-dioxin]], the parent compound of PCDDs]] The word "[[dioxin]]" can refer in a general way to compounds which have a dioxin core skeletal structure with [[substituent]] molecular groups attached to it. For example, [[dibenzo-1,4-dioxin]] is a compound whose structure consists of two benzo- groups fused onto a 1,4-dioxin ring.
===Polychlorinated dibenzodioxins=== {{Main|Polychlorinated dibenzodioxins}}
Because of their extreme importance as environmental pollutants, current scientific literature uses the name dioxins commonly for simplification to denote the chlorinated derivatives of dibenzo-1,4-dioxin, more precisely the [[polychlorinated dibenzodioxins]] (PCDDs), among which [[2,3,7,8-Tetrachlorodibenzodioxin|2,3,7,8-tetrachlorodibenzodioxin]] (TCDD), a {{Not a typo|tetrachlorinated}} derivative, is the best known. The polychlorinated dibenzodioxins, which can also be classified in the family of [[Halocarbon|halogenated organic compounds]], have been shown to [[bioaccumulate]] in humans and other organisms due to their [[lipophilic]] properties, and are known [[teratogens]], [[mutagens]], and [[carcinogens]].
PCDDs are formed through [[combustion]], [[chlorine]] bleaching and [[manufacturing]] processes.<ref name="mgov">{{Cite web |url=http://maine.gov/dep/dioxin/ |title=Dioxin Information |archiveurl=https://web.archive.org/web/20090615124630/http://maine.gov/dep/dioxin/ |archivedate=2009-06-15 |publisher=Department of Environmental Protection, State of Maine |year=2005 |url-status=dead |access-date=2008-08-10 }}</ref> The combination of heat and chlorine creates dioxin.<ref name="mgov"/> Since chlorine is often a part of the Earth's [[natural environment|environment]], natural ecological activity such as volcanic activity and forest fires can lead to the formation of PCDDs.<ref name="mgov"/> Nevertheless, PCDDs are mostly produced by human activity.<ref name="mgov"/>
Famous PCDD exposure cases include [[Agent Orange]] sprayed over vegetation by the [[British military]] in Malaya during the [[Malayan Emergency]] and the [[U.S. military]] in Vietnam during the [[Vietnam War]], the [[Seveso disaster]], and the poisoning of [[Viktor Yushchenko]].
[[Polychlorinated dibenzofurans]] are a related class compounds to PCDDs which are often included within the general term "dioxins".
==References== {{reflist}}
==External links== * {{Commons category-inline}}
{{DEFAULTSORT:Dioxin, 1, 4-}} [[Category:Dioxins]]