Chemical Structure of Dibenzo-p-dioxins
The structure of dibenzo-p-dioxin comprises two benzene rings joined by two oxygen bridges. This makes the compound an aromatic diether. The name dioxin formally refers to the central dioxygenated ring, which is stabilized by the two flanking benzene rings.
In PCDDs, chlorine atoms are attached to this structure at any of 8 different places on the molecule, at positions 1–4 and 6–9. There are 75 different PCDD congeners (that is: related dioxin compounds).
The toxicity of PCDDs depends on the number and positions of the chlorine atoms. Congeners that have chlorines in the 2, 3, 7, and 8 positions have been found to be significantly toxic. In fact, 7 congeners have chlorine atoms in the relevant positions which were considered toxic by the World Health Organization toxic equivalent (WHO-TEQ) scheme.
Read more about this topic: Polychlorinated Dibenzodioxins
Famous quotes containing the words chemical and/or structure:
“We are close to dead. There are faces and bodies like gorged maggots on the dance floor, on the highway, in the city, in the stadium; they are a host of chemical machines who swallow the product of chemical factories, aspirin, preservatives, stimulant, relaxant, and breathe out their chemical wastes into a polluted air. The sense of a long last night over civilization is back again.”
—Norman Mailer (b. 1923)
“Why does philosophy use concepts and why does faith use symbols if both try to express the same ultimate? The answer, of course, is that the relation to the ultimate is not the same in each case. The philosophical relation is in principle a detached description of the basic structure in which the ultimate manifests itself. The relation of faith is in principle an involved expression of concern about the meaning of the ultimate for the faithful.”
—Paul Tillich (1886–1965)