1,4-Dioxin (also referred as dioxin or ''p''-dioxin) is a heterocyclic,

organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ Chemistry * Organic matter, matter that has come from a once-living organism, is capable of decay or is the product ...

, non-aromatic compound with the chemical formula CHO. There is an

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

ic form of 1,4-dioxin,

1,2-dioxin 1,2-Dioxin is a heterocyclic, organic, antiaromatic compound with the chemical formula CHO. It is an isomeric form of 1,4-dioxin (or ''p''-dioxin). Due to its peroxide In chemistry, peroxides are a group of compounds with the structure ...

(or ''o''-dioxin). 1,2-Dioxin is very unstable due to its peroxide-like characteristics. The term "dioxin" is most commonly used for a family of derivatives of dioxin, known as

polychlorinated dibenzodioxins Polychlorinated dibenzodioxins (PCDDs), or simply dioxins, are a group of long-lived polyhalogenated compound, polyhalogenated organic compounds that are primarily anthropogenic, and contribute toxic, Persistent organic pollutant, persistent org ...

(PCDDs).

Preparation

1,4-Dioxin can be prepared by cycloaddition, namely by the

Diels–Alder reaction In organic chemistry, the Diels–Alder reaction is a chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene derivative. It is the prototypical example of a peric ...

furan Furan is a heterocyclic organic compound, consisting of a five-membered aromatic ring with four carbon atoms and one oxygen atom. Chemical compounds containing such rings are also referred to as furans. Furan is a colorless, flammable, highly ...

and maleic anhydride. The adduct formed has a carbon-carbon double bond, which is Epoxide#Olefin peroxidation, converted to an epoxide. The epoxide then undergoes a retro-Diels–Alder reaction, forming 1,4-dioxin and regenerating maleic anhydride. Synthesis-of-1,4-dioxin-1994-2D-skeletal

Synthesis-of-1,4-dioxin-1994-2D-skeletal

Derivatives

The word "dioxin" can refer in a general way to compounds which have a dioxin core skeletal structure with substituent molecular groups attached to it. For example, dibenzo-1,4-dioxin is a compound whose structure consists of two benzo- groups fused onto a 1,4-dioxin ring.

Polychlorinated dibenzodioxins

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-1,4-dioxin, more precisely the

(PCDDs), among which 2,3,7,8-Tetrachlorodibenzodioxin, 2,3,7,8-tetrachlorodibenzodioxin (TCDD), a derivative, is the best known. The polychlorinated dibenzodioxins, which can also be classified in the family of Halocarbon, halogenated organic compounds, have been shown to bioaccumulate in humans and wildlife due to their lipophilic properties, and are known teratogens, mutagens, and carcinogens. PCDDs are formed through combustion, chlorine bleaching and manufacturing processes. The combination of heat and chlorine creates dioxin. Since chlorine is often a part of the Earth's natural environment, environment, natural ecological activity such as volcanic activity and forest fires can lead to the formation of PCDDs. Nevertheless, PCDDs are mostly produced by human activity. Famous PCDD exposure cases include Agent Orange sprayed over vegetation by the British military in Malaya during the Malayan Emergency and the U.S. military in Vietnam during the Vietnam War, the Seveso disaster, and the poisoning of Viktor Yushchenko. Polychlorinated dibenzofurans are a related class compounds to PCDDs which are often included within the general term "dioxins".

References

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