Oxirene
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| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 416814959
| ImageFileL1=oxiren.png
| ImageSizeL1=80px
| ImageFileR1=oxirene structure.png
| ImageSizeR1=120px
| ImageFile2=Oxirene-3D-vdW.png
| ImageSize2=150px
| PIN=Oxirene{{cite book | title = Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = The Royal Society of Chemistry | date = 2014 | location = Cambridge | page = 146 | doi = 10.1039/9781849733069-FP001 | isbn = 978-0-85404-182-4| chapter = Front Matter }}
| SystematicName=Oxacyclopropene
| OtherNames=Epoxyethene
Ethyne oxide
Acetylene oxide
|Section1={{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|??}}
| CASNo=157-18-6
| PubChem=160438
| SMILES=C1=CO1
| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}
| ChemSpiderID = 140985
| InChI = 1/C2H2O/c1-2-3-1/h1-2H
| InChIKey = BJEYNNFDAPPGST-UHFFFAOYAU
| StdInChI_Ref = {{stdinchicite|changed|chemspider}}
| StdInChI = 1S/C2H2O/c1-2-3-1/h1-2H
| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}
| StdInChIKey = BJEYNNFDAPPGST-UHFFFAOYSA-N
| RTECS =
| MeSHName = C012469
| ChEBI_Ref = {{ebicite|changed|EBI}}
| ChEBI = 30973
}}
|Section2={{Chembox Properties
| Formula=C2H2O
| MolarMass=42.04 g/mol
| Appearance=
| Density=
| MeltingPt=
| BoilingPt=
| Solubility=
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|Section3={{Chembox Hazards
| MainHazards=
| FlashPt=
| AutoignitionPt =
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|Section8={{Chembox Related
| OtherFunction = Ethylene oxide cyclopropane cyclopropene aziridine thiirane thiirene
| OtherFunction_label = molecules with 3-membered rings
| OtherCompounds =
}}
}}
Oxirene is a heterocyclic chemical compound which contains an unsaturated three-membered ring containing two carbon atoms and one oxygen atom. The molecule was synthesized in low temperature ices and detected upon sublimation by isomer selective photoionization reflectron time-of-flight mass spectrometry.{{Cite journal|last1=Wang|first1=Jia|last2=Marks|first2=Joshua|last3=Turner|first3=Andrew|last4=Mebel|first4=Alexander|last5=Eckhardt|first5=Andre|last6=Kaiser|first6=Ralf|date=March 2023|title=Gas-phase detection of oxirene|journal=Science Advances|language=en|volume=9|issue=10 |pages=eadg1134|doi=10.1126/sciadv.adg1134 |pmid=36897943 |pmc=10005165 |bibcode=2023SciA....9G1134W }}
Quantum chemical computational techniques found the configuration to be extremely strained and proposed an antiaromatic 4π electron system, as such oxirene is expected to be very high energy.{{cite journal | doi = 10.1016/S0166-1280(03)00198-2 | title = Assessment of density functional theory for the prediction of the nature of the oxirene stationary point | year = 2003 | last1 = Mawhinney | first1 = Robert C | last2 = Goddard | first2 = John D | journal = Journal of Molecular Structure: THEOCHEM | volume = 629 | issue = 1–3 | pages = 263–270}}{{Cite book|title=Computational Chemistry - Introduction to the Theory and Applications of Molecular and Quantum Mechanics|first=Errol G.|last=Lewars|publisher=Springer|year=2011|edition=2nd|isbn=978-90-481-3862-3|doi=10.1007/978-90-481-3862-3|language=en}}
Experimental indications exist that substituted oxirenes (as intermediates or transition states) may be involved in carbonylcarbene rearrangements observed in the Wolff rearrangement.{{Cite journal|title=100 Years of the Wolff Rearrangement|journal=European Journal of Organic Chemistry|volume=2002|issue=14|year=2002|pages=2193–2256|first=Wolfgang|last=Kirmse|doi=10.1002/1099-0690(200207)2002:14<2193::AID-EJOC2193>3.0.CO;2-D}} Computational evidence also point to the intermediacy of oxirenes in the ozonolysis of alkynes.{{Cite journal|last1=Cremer|first1=Dieter|last2=Crehuet|first2=Ramon|last3=Anglada|first3=Josep|date=June 2001|title=The Ozonolysis of AcetyleneA Quantum Chemical Investigation|journal=Journal of the American Chemical Society|language=en|volume=123|issue=25|pages=6127–6141|doi=10.1021/ja010166f|pmid=11414847|issn=0002-7863}}