dioxin

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Dioxin may refer to a number of different substances. Most notably:

• 1,2-Dioxin or 1,4-dioxin, two unsaturated heterocyclic 6-membered rings in which two carbon atoms have been replaced by oxygen atoms, which gives the molecular formula C₄H₄O₂. They are unstable.
• Dibenzo-1,4-dioxin, also known as dibenzodioxin or dibenzo-p-dioxin (molecular formula C₁₂H₈O₂), in which two benzene rings are connected through two oxygen atoms. That is the parent compound of the dioxins (see next in which the dioxins comprise a key part of the class).
• Dioxins and dioxin-like compounds, a diverse class of polychlorinated chemical compounds, including polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDFs), that are persistent organic pollutants and known to exhibit "dioxin-like" toxicity.
• 2,3,7,8-Tetrachlorodibenzodioxin (TCDD), the prototypical and most toxic example of the above class, often referred to simply as "dioxin".