1,2-Dioxin

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).

Quick facts Names, Identifiers ...

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 N
3D model (JSmol)	Interactive image
ChemSpider	10606250 Y
PubChem CID	15559065
UNII	R8H79L3J69 Y
CompTox Dashboard (EPA)	DTXSID90574144
InChI InChI=1S/C4H4O2/c1-2-4-6-5-3-1/h1-4H Y Key: VCZQYTJRWNRPHF-UHFFFAOYSA-N Y 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 Â°C [77 Â°F], 100 kPa). N verify (what is YN ?) Infobox references

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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, such as 1,4-diphenyl-2,3-benzodioxin, are very labile.^[3]

In 1990, 3,6-bis(p-tolyl)-1,2-dioxin (1) was incorrectly reported 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 (2).^[5]