What is the structure of Polychlorinated Biphenyls?

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Discussion Overview

The discussion centers on the structure of Polychlorinated Biphenyls (PCBs), exploring the various possible structures and their implications. Participants inquire about the existence of a "main" structure and discuss environmental effects associated with PCBs.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that there are numerous possible structures for PCBs, with at least 209 congeners identified.
  • One participant questions whether there is a "main" structure, referencing an image from a health agency.
  • Another participant clarifies that there is no singular "main" structure, as multiple substitution patterns exist for chlorine atoms on the biphenyl framework.
  • Environmental effects of PCBs are mentioned, including potential bioaccumulation in fatty tissues and observed health impacts in animal studies, though the causative factors remain unclear.

Areas of Agreement / Disagreement

Participants generally agree that there are many possible structures for PCBs, but there is no consensus on a singular "main" structure. The discussion remains unresolved regarding the specific environmental impacts and mechanisms of PCBs.

Contextual Notes

Participants express uncertainty regarding the implications of PCB structures on environmental health, and there are unresolved questions about the effects observed in animal studies.

devilkidjin
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does that have a specific structure ?

cause i saw like at least 2 different structure anyone help? =/
 
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There are tons of possible structures!
 
There are 209 congeners, 210 if you include biphenyl, 206 if you are a purist and exclude mono-substitution from the "poly-" prefix.
 
so there are many, is there like a "main" one?

like the one from http://www.atsdr.cdc.gov/HEC/CSEM/pcb/fig1.JPG

would that be the main ? or general one?

any effect on the environments? beside the poison in fishes..=/ that i know
 
No "main" one. You see ten possible positions at which Cl can be substituted for H; mono-, di-, tri-, ... , decachlorobiphenyl are all included in the term "polychlorobiphenyl." There are three monochloros, ortho-, meta-, and para-, or 2-, 3-, 4-, doesn't matter which phenyl group, since they are equivalent. Dichloro? 2,3-, 2,4-, 2,5-, 2,6-, 2,2'-, 2,3'-, 2,4'-, 3,3'-, 3,4'-, 4,4'-, where unprimed indicates one phenyl group, and the prime indicates substitution on the second phenyl group. The rest of the patterns "are left to the reader as an exercise."

Environmental effects? Rats on PCBs (by gavage) lived on an average 6 mos. longer than control animals; there was an increased incidence of liver tumors observed, but it was not clear whether this was caused by the physical abuse associated with gavage feeding, or the activity of PCBs on rat metabolism.

There is a bioaccumulation observed in fatty tissues as you move up the foodchain.
 
thank you bystander :D
 

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