1,2-Dioxin

1,2-Dioxin

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Names
Preferred IUPAC name 1,2-Dioxine
Systematic IUPAC name 1,2-Dioxacyclohexa-3,5-diene
Identifiers
CAS Number	289-87-2 ☒N
3D model (JSmol)	Interactive image
ChemSpider	10606250 checkY
ECHA InfoCard
E number
PubChem CID	15559065
UNII	R8H79L3J69 checkY
CompTox Dashboard (EPA)	{{#property:P3117}}
InChI InChI=1S/C4H4O2/c1-2-4-6-5-3-1/h1-4H checkY Key: VCZQYTJRWNRPHF-UHFFFAOYSA-N checkY 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). ☒N verify (what is checkY☒N ?) Infobox references

For other dioxin compounds, see dioxin.

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

File:Dioxin isomers.svg

1,2-Dioxin (left) and 1,4-dioxin (right)

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. Even substituted derivatives, such as 1,4-diphenyl-2,3-benzodioxin, are very labile.

File:1,4-diphenyl-2,3-benzodioxin.svg

Structure of the transient 1,4-diphenyl-2,3-benzodioxin

In 1990, 3,6-bis(p-tolyl)-1,2-dioxin (1) was incorrectly reported as the first stable derivative. It was subsequently shown that the initial compound was not a derivative of 1,2-dioxin, but a thermodynamically more stable dione (2).

File:Revised structure 1,2-Dioxin.svg

Dioxin (1) and dione form (2)