Skeletal formula of 1,2-dioxin
Preferred IUPAC name
Systematic IUPAC name
3D model (JSmol)
  • InChI=1S/C4H4O2/c1-2-4-6-5-3-1/h1-4H checkY
  • InChI=1/C4H4O2/c1-2-4-6-5-3-1/h1-4H
  • O1OC=CC=C1
Molar mass 84.074 g·mol−1
Related compounds
Related compounds


Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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]


  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.