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Dioxin is a name for either one of two organic chemical compounds which are isomers and whose chemical structures are shown at right. These isomers are called 1,2-dioxin (or o-dioxin) and 1,4-dioxin (or p-dioxin). Both dioxins are heterocyclic compounds which have the chemical formula C4H4O2.

The ortho isomer 1,2-dioxin is very unstable due to its peroxide-like characteristics.

The known properties of 1,4-dioxin are listed in the infobox to the right.

IUPAC name 1,4-dioxin
Other names p-dioxin, dioxin
CAS number 290-67-5
Molecular formula C4H4O2
Molar mass 87.07 g/mol
Appearance Colorless liquid
Boiling point

75°C (348°K)

EU classification Toxic (T)
Main hazards highly flammable
Related Compounds
Related compounds dibenzodioxin
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

1,4-dioxin can be prepared by cycloaddition, namely by the Diels-Alder reaction[1]

Other meanings of dioxin


The word dioxin can also in a general way refer to compounds whose molecules have a dioxin core skeletal structure with substituent molecular groups attached to it. For example, dibenzo-p-dioxin is a compound whose structure consists of two benzo- groups fused onto a p-dioxin ring as shown below (see also Dibenzodioxin).

Because of their extreme importance as environmental pollutants, current scientific literature uses the name dioxins commonly for simplification to denote the chlorinated derivatives of dibenzo-p-dioxin, more precisely the polychlorinated dibenzodioxins (PCDDs). The polychlorinated dibenzodioxins, which can also be classified in the family of halogenated organic compounds, have been shown to bioaccumulate in humans and wildlife due to their lipophilic properties, and are known teratogens, mutagens, and carcinogens.[citation needed]

Additionally, sometimes with dioxins a similar, but unrelated compound type the polychlorinated dibenzofurans of like importance are also implied.


  1. ^ R. Alan Aitken, J. I. G. Cadogan and Ian Gosneya (1994). "Effect of ring strain on the formation and pyrolysis of some Diels–Alder adducts of 2-sulfolene (2,3-dihydrothiophene 1,1-dioxide) and maleic anhydride with 1,3-dienes and products derived therefrom". J. Chem. Soc., Perkin Trans. 1: 927 - 931. doi:10.1039/p19940000927.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Dioxin". A list of authors is available in Wikipedia.
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