1,2-Dioxin

1,2-Dioxin
Names
	Preferred IUPAC name 1,2-Dioxine
	Systematic IUPAC name 1,2-Dioxacyclohexa-3,5-diene
Identifiers
CAS Number	289-87-2 ;
3D model (JSmol)	Interactive image;
ChemSpider	10606250 ;
PubChem CID	15559065;
UNII	R8H79L3J69 ;
CompTox Dashboard (EPA)	DTXSID90574144 ;
	InChI InChI=1S/C4H4O2/c1-2-4-6-5-3-1/h1-4H Key: VCZQYTJRWNRPHF-UHFFFAOYSA-N ; InChI=1/C4H4O2/c1-2-4-6-5-3-1/h1-4H Key: VCZQYTJRWNRPHF-UHFFFAOYAH;
	SMILES O1OC=CC=C1;
Properties
Chemical formula	C4H4O2
Molar mass	84.074 g·mol−1
Related compounds
Related compounds	Dibenzodioxin; 1,4-Dioxin
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

1,2-Dioxin is a heterocyclic, organic, antiaromatic^[1] compound with the chemical formula C₄H₄O₂. It is an isomeric form of 1,4-dioxin (or p-dioxin).

Due to its peroxide-like characteristics, 1,2-dioxin is very unstable and has not been isolated. Calculations suggest that it would isomerize rapidly into but-2-enedial.^[2] Even substituted derivatives are very labile, e.g. 1,4-diphenyl-2,3-benzodioxin.^[3] Indeed, in 1990, 3,6-bis(p-tolyl)-1,2-dioxin was wrongly accounted as the first stable derivative.^[4] It was subsequently shown that the initial compound was not a derivative of 1,2-dioxin, but a thermodynamically more stable dione.^[5]

The isomers 1,2-dioxin (left) and 1,4-dioxin (right)
Structure of the transient 1,4-diphenyl- 2,3-benzodioxin
Dioxin (1) and dione form (2)

^ Pelloni, Stefano; Faglioni, Francesco; Lazzeretti, Paolo (2013-09-01). "Parity violation energies of C4H4X2 molecules for X = O, S, Se, Te and Po". Molecular Physics. 111 (16–17): 2387–2391. doi:10.1080/00268976.2013.794396. ISSN 0026-8976. S2CID 100861633.
^ Matsumoto, M. (2014). "Product Class 1: 1,2-Dioxins and Benzo- and Dibenzo- Fused Derivatives". Science of Synthesis: Houben-Weyl Methods of Molecular Transformations Vol. 16: Six-Membered Hetarenes with Two Identical Heteroatoms. Georg Thieme Verlag. p. 13. ISBN 9783131718815. Retrieved 2020-06-12.
^ Smith, Jimmie P.; Schrock, Alan K.; Schuster, Gary B. (1982). "Chemiluminescence of organic peroxides. Thermal generation of an o-xylylene peroxide". Journal of the American Chemical Society. 104 (4): 1041. doi:10.1021/ja00368a021..
^ Shine, Henry J.; Zhao, Da Chuan (1990). "Electron transfer to excited doublet states. Photoirradiation of 10-methylphenothiazine cation radical perchlorate in solutions of phenylacetylene and p-tolylacetylene in acetonitrile". The Journal of Organic Chemistry. 55 (13): 4086. doi:10.1021/jo00300a026..
^ Block, Eric; Shan, Zhixing; Glass, Richard S.; Fabian, Jürgen (2003). "Revised Structure of a Purported 1,2-Dioxin: A Combined Experimental and Theoretical Study". The Journal of Organic Chemistry. 68 (10): 4108–11. doi:10.1021/jo034305i. PMID 12737603.

[1] Pelloni, Stefano; Faglioni, Francesco; Lazzeretti, Paolo (2013-09-01). "Parity violation energies of C4H4X2 molecules for X = O, S, Se, Te and Po". Molecular Physics. 111 (16–17): 2387–2391. doi:10.1080/00268976.2013.794396. ISSN 0026-8976. S2CID 100861633.

[2] Matsumoto, M. (2014). "Product Class 1: 1,2-Dioxins and Benzo- and Dibenzo- Fused Derivatives". Science of Synthesis: Houben-Weyl Methods of Molecular Transformations Vol. 16: Six-Membered Hetarenes with Two Identical Heteroatoms. Georg Thieme Verlag. p. 13. ISBN 9783131718815. Retrieved 2020-06-12.

[3] Smith, Jimmie P.; Schrock, Alan K.; Schuster, Gary B. (1982). "Chemiluminescence of organic peroxides. Thermal generation of an o-xylylene peroxide". Journal of the American Chemical Society. 104 (4): 1041. doi:10.1021/ja00368a021..

[4] Shine, Henry J.; Zhao, Da Chuan (1990). "Electron transfer to excited doublet states. Photoirradiation of 10-methylphenothiazine cation radical perchlorate in solutions of phenylacetylene and p-tolylacetylene in acetonitrile". The Journal of Organic Chemistry. 55 (13): 4086. doi:10.1021/jo00300a026..

[5] Block, Eric; Shan, Zhixing; Glass, Richard S.; Fabian, Jürgen (2003). "Revised Structure of a Purported 1,2-Dioxin: A Combined Experimental and Theoretical Study". The Journal of Organic Chemistry. 68 (10): 4108–11. doi:10.1021/jo034305i. PMID 12737603.

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