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|ImageSizeR1 = 130px
|ImageNameR1 = 1,4-dioxane
|ImageFile2 = 1,4-dioxane.png
|ImageSize2 = 150px
|PIN = 1,4-Dioxane
|SystematicName= 1,4-Dioxacyclohexane
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|ExploLimits = 2.0–22%<ref name=PGCH />
|IDLH = Ca [500 ppm]<ref name=PGCH />
|REL = Ca C 1 ppm (3.6 mg/m
|MainHazards = Suspected human carcinogen<ref name=PGCH />
|LC50 = {{Unbulleted list
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'''1,4-Dioxane''' ({{IPAc-en|d|aɪ|ˈ|ɒ|k|s|eɪ|n}}) is a [[Heterocyclic compound|heterocyclic]] [[organic compound]], classified as an [[ether]]. It is a colorless liquid with a faint sweet [[odor]] similar to that of [[diethyl ether]]. The compound is often called simply '''dioxane''' because the other dioxane [[isomer]]s ([[1,2-Dioxane|1,2-]] and [[1,3-Dioxane|1,3-]]) are rarely encountered.
Dioxane is used as a solvent for a variety of practical applications as well as in the laboratory, and also as a stabilizer for the transport of [[chlorinated hydrocarbons]] in
== Synthesis ==
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=== Trichloroethane transport ===
In the 1980s, most of the dioxane produced was used as a stabilizer for [[1,1,1-Trichloroethane|1,1,1-trichloroethane]] for storage and transport in [[aluminium]] containers. Normally aluminium is protected by a passivating oxide layer, but when these layers are disturbed, the metallic aluminium reacts with trichloroethane to give [[aluminium trichloride]], which in turn catalyses the [[dehydrohalogenation]] of the remaining trichloroethane to [[vinylidene chloride]] and [[hydrogen chloride]]. Dioxane "poisons" this catalysis reaction by forming an [[adduct]] with
=== As a solvent ===
[[File:Binary phase diagram dioxane-water.svg|left|thumb|200px|Binary [[phase diagram]] for the system 1,4-dioxane/water]]
Dioxane is used in a variety of applications as a versatile [[aprotic solvent]], e.
While diethyl ether is rather insoluble in water, dioxane is [[miscible]] and in fact is [[hygroscopic]]. At standard pressure, the mixture of water and dioxane in the ratio 17.9:82.1 by mass is a positive [[azeotrope]] that boils at 87.6 °C.<ref>Schneider, C. H.; Lynch, C. C.: ''The Ternary System: Dioxane-Ethanol-Water'' in [[J. Am. Chem. Soc.]], 1943, vol. 65, pp 1063–1066. {{doi|10.1021/ja01246a015}}.</ref>
The oxygen atoms are weakly [[Lewis base|Lewis-basic]]. It forms adducts with a variety of Lewis acids. It is classified as a [[HSAB theory|hard base]] and its base parameters in the [[ECW model]] are E<sub>B</sub>
Dioxane produces [[coordination polymer]]s by linking metal centers.<ref>{{cite journal |doi=10.1002/chem.201903120|title=Structure–Solubility Relationship of 1,
:2 CH{{sub|3}}MgBr + (C{{sub|2}}H{{sub|4}}O){{sub|2}} → MgBr{{sub|2}}(C{{sub|2}}H{{sub|4}}O){{sub|2}} + (CH{{sub|3}}){{sub|2}}Mg
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|archive-url = https://web.archive.org/web/20050429004946/http://www.cdc.gov/niosh/ipcsneng/neng0041.html
|archive-date = 29 April 2005
|url-status = dead}}</ref> In a 1978 mortality study conducted on workers exposed to 1,4-dioxane, the observed number of deaths from cancer was not significantly different from the expected number.<ref>{{cite journal
|title= Mortality Follow-up of Workers Exposed to 1,4-Dioxane.
|journal= Journal of Occupational and Environmental Medicine
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|archive-url = https://web.archive.org/web/20140714132609/http://ntp.niehs.nih.gov/pubhealth/roc/roc12/index.html
|archive-date = 14 July 2014
|url-status = dead}}</ref> It is also classified by the [[International Agency for Research on Cancer|IARC]] as a [[List of IARC Group 2B carcinogens|Group 2B carcinogen]]: ''possibly carcinogenic to humans'' because it is a known carcinogen in other animals.<ref>{{cite book |title= IARC Monographs Volume 71 |publisher= International Agency for Research on Cancer |url= http://monographs.iarc.fr/ENG/Monographs/vol71/mono71-25.pdf|access-date =11 July 2014}}</ref> The [[United States Environmental Protection Agency]] classifies dioxane as a probable human [[carcinogen]] (having observed an increased incidence of cancer in controlled animal studies, but not in epidemiological studies of workers using the compound), and a known irritant (with a no-observed-adverse-effects level of 400 milligrams per cubic meter) at concentrations significantly higher than those found in commercial products.<ref name="U.S.EPA_Dioxane">1,4-Dioxane (1,4-Diethyleneoxide). Hazard Summary. ''U.S. Environmental Protection Agency''. Created in April 1992; Revised in January 2000. [http://www.epa.gov/ttn/atw/hlthef/dioxane.html Fact Sheet].
It tends to concentrate in the water and has little affinity for soil. It is resistant to abiotic degradation in the environment, and was formerly thought to also resist [[biodegradation]]. However, more recent studies since the 2000s have found that it can be biodegraded through a number of pathways, suggesting that [[bioremediation]] can be used to treat 1,4-dioxane contaminated water.<ref>{{cite journal |last1=Zenker |first1=Matthew J. |last2=Borden |first2=Robert C. |last3=Barlaz |first3=Morton A. |title=Occurrence and Treatment of 1,4-Dioxane in Aqueous Environments |journal=Environmental Engineering Science |date=September 2003 |volume=20 |issue=5 |pages=423–432 |doi=10.1089/109287503768335913}}</ref><ref>{{cite journal |last1=Zhang |first1=Shu |last2=Gedalanga |first2=Phillip B. |last3=Mahendra |first3=Shaily |title=Advances in bioremediation of 1,4-dioxane-contaminated waters |journal=Journal of Environmental Management |date=December 2017 |volume=204 |issue=Pt 2 |pages=765–774 |doi=10.1016/j.jenvman.2017.05.033|pmid=28625566 }}</ref>▼
=== Explosion hazard ===
Like some other ethers, dioxane combines with atmospheric oxygen upon prolonged exposure to air to form potentially explosive [[peroxide]]s. [[Distillation]] of these mixtures is dangerous. Storage
=== Environment ===
▲
Dioxane has affected groundwater supplies in several areas. Dioxane at the level of 1 μg/L (~1 ppb) has been detected in many locations in the US.<ref name="OPPT" /> In the U.S. state of New Hampshire, it had been found at 67 sites in 2010, ranging in concentration from 2 ppb to over 11,000 ppb. Thirty of these sites are solid waste landfills, most of which have been closed for years. In 2019, the Southern Environmental Law Center successfully sued Greensboro, North Carolina's Wastewater treatment after 1,4-Dioxane was found at 20 times above EPA safe levels in the Haw River.<ref>{{Cite web |date=2020-11-18 |title=1,4-dioxane in Greensboro {{!}} Haw River Assembly |url=https://hawriver.org/14-dioxane-in-greensboro/ |access-date=2022-05-13 |language=en-US}}</ref>
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== See also ==
[[File:Dioxane isomers named.PNG|
* [[Dioxolane]]
* [[9-crown-3]]
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* [[Oxalic anhydride]]
* [[Dioxanone]]
{{clear|right}}
== References ==
{{Reflist}}
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