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Author: Subject: Tetrachloroethylene as a solvent
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[*] posted on 23-9-2013 at 11:19
Tetrachloroethylene as a solvent


Has anybody used or considered using tetrachloroethylene (TCE) as a solvent? Particularly Acid/Base, organic extractions? Its non-polar and has a logp of 2.62.

-Its cheap at $4/l
-Its OTC as brake parts cleaner (Sorry california!)
-Relatively non-hazardous (besides the probable cancer and phosgene if heated beyone 500f)
-Somewhat volatile
-It smells nice
-Heavier than water (1.622 g/cm3)

Sounds pretty good. except the MSDS states "Incompatible with strong oxidizing agents, alkali metals,aluminium, strong bases." Does anybody know what will happen if it is used with a basic pH ~12 water layer? Will it decompose?




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[*] posted on 23-9-2013 at 11:53


"Relatively non-hazardous "

compared to what?

"The International Agency for Research on Cancer has classified tetrachloroethene as a Group 2A carcinogen, which means that it is probably carcinogenic to humans"
from
http://en.wikipedia.org/wiki/Tetrachloroethylene#Health_and_...
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[*] posted on 23-9-2013 at 12:05


Quote: Originally posted by I Like Dots  
Does anybody know what will happen if it is used with a basic pH ~12 water layer? Will it decompose?


It will be slowly attacked, gradually producing a witch's brew of various compounds. The more alkaline the water based layer, the quicker the degradation will proceed.




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[*] posted on 23-9-2013 at 12:12


Quote: Originally posted by unionised  
"Relatively non-hazardous "

compared to what?


Extremely flammable, peroxide forming, intoxicating, toxic, and cancerous solvents routinely encountered. Do you want a list?



@Blogfast That may not be a problem after all according to this






[Edited on 23-9-2013 by I Like Dots]




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[*] posted on 23-9-2013 at 12:49


If you're trying to extract phenols or acids from a TCE solution, it should work fine. You don't need anything terribly basic to extract an organic acid (pKa about 5) or a phenol (pKa about 9-10). Rather than using 1 mol/L NaOH (pH = 14) to extract a phenol, you could probably use sodium carbonate (pK2 for carbonic acid is 10.3).



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[*] posted on 23-9-2013 at 18:29


Warning about Handling: Animal studies and a study of 99 twins showed there is a "lot of circumstantial evidence" that exposure to tetrachloroethene increases the risk of developing Parkinson's disease ninefold. Certainly there is numerous evidence showing a link between trichloroethylene and Parkinson's-like symptoms:

http://thepoliticsforums.com/threads/7476-chemical-dumping-c...

[Edited on 24-9-2013 by AndersHoveland]
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[*] posted on 23-9-2013 at 23:06


I think that you can use this solvent without too much risk. I indeed would try to minimize exposure to the vapors, but a single whiff does not give you cancer, nor does it give you Parkinsons disease. I see it like smoking cigarettes. A single cigarette is not a problem, daily smoking for a long period of time is. If you are a home chemist, doing experiments with tetrachloroethylene occasionally, then I think that the risk is nearly non-existent (provided you do not live in the same room as where you store it). If you work with the chemical on a daily basis, then you have to be much more careful.



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[*] posted on 24-9-2013 at 09:28


Quote: Originally posted by I Like Dots  
[@Blogfast That may not be a problem after all according to this






[Edited on 23-9-2013 by I Like Dots]


What does this have to do with the hydrolysis of halo carbons?




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[*] posted on 24-9-2013 at 11:39


Does anyone know if tetrachloroethylene behaves like other unsaturated hydrocarbons? Will it spontaneously react with halogens? Can it be polymerized?
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[*] posted on 24-9-2013 at 16:30


Quote: Originally posted by blogfast25  
What does this have to do with the hydrolysis of halo carbons?


Well the alkaloid I am trying to extract has a pka of 7.8 so im trying to push the pH more alkaline in hopes of it going into the organic layer better.

@woelen,AndersHoveland,DracoincAcid
Thank you for your insight. I do uses this chemical more than I should... nothing else is as good as getting road grime off my motorcycle!




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[*] posted on 25-9-2013 at 08:16


Quote: Originally posted by AndersHoveland  
Does anyone know if tetrachloroethylene behaves like other unsaturated hydrocarbons? Will it spontaneously react with halogens? Can it be polymerized?


Because of the electron-withdrawing chlorines on it already, it will be less reactive towards halogen addition than ordinary alkenes. I couldn't say how much less.




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[*] posted on 25-9-2013 at 20:09


Today I tested the solvent properties of this on a few chemicals.
First I dissolved 20gm of instant coffee in 100ml water. extracted with two 15ml portions of TCE. I then evaporated the TCE and I got no caffeine, only a slight yellow residue, probably fats.

Next I tried to dissolve 100mg Aspirin crystals in 20ml. I observed no changes :/

So two strikes for TCE, maybe it will find a way to redeem itself.




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