halogen
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Dacron
I would like to synthesise dacron. I plan to oxidise xylene with potassium permanganate in alkaline conditions... somehow. Firstly, how would I
accomplish that? Xylene does not dissolve in water.
secondly, are there any modifications to the terphthalic acid before I polymerise it? If I use an FeCl3 catalyst, could I chlorinate the aromatic
ring. Lastly, I would think the polymerisation is instantaneous or nearly so, but does the reaction require special conditions?
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runlabrun
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Problems will be everywhere with this...
Commercial xylene is not pure, it has ethylbenzene, toluene amoungst many impurities, and it is a mixture of ortho, meta and para (ie xylenes) isomers
which under oxidation will produce phthalic, isophthalic and terephthalic acids, i dont know the % of each xylene isomer in commercial products but
unless you get specific p-xylene you wont get a pure product of terephthalic acid.
Dissolve permangenate and a carbonate in alcohol then mix with xylene.
As far as i see it, dacron being a dimer polymer of ethylene glycol and terephthalic acid shouldnt need any mods to either, but if your using
commercial ethylene glycol and xylene you will need to purify ur terephtlaic product from oxidation and the ethylene glycol from the dyes etc in the
bottle prior to polymerisation.
Why would you want to chlorinate the ring?
Also, isnt dacron one of the synthetic polymers that needs to be extruded through a spineret? otherwise your polymerisation reaction will glue itself
into the container and be relativly useless...
-rlr
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solo
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Here is an interesting read from a similar experiment performed at UC Berkeley by some students......solo
http://www.cchem.berkeley.edu/chem1b/spring04/labex9.htm
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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halogen
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Well it does seem that phthalic acid (anhydride) will react with ethylene glycol. 2/3 isn't too bad. Isophthalic acid can be extracted after the
oxidation and perhaps be used for something else. To chlorinate the ring would make the polymer more chemically resistant and have a higher m.p. would
it not?
F. de Lalande and M. Prud'homme showed that a mixture of boric oxide and sodium chloride is decomposed in a stream of dry air or oxygen at a red heat
with the evolution of chlorine.
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runlabrun
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Phthalic anhydride could be formed from the oxidation of o-xylene as the m and p isomers do not form anhydrides, this occurs at ~400oC doesnt it? so i
guess you could just heat it up until this occurs and seperate the anhydride from the rest of the mixture, hydrolyse it to phthalic acid and use it
for your dacron there, that could work well...
Chlorination of the ring would (using a similar thinking to PE and PVC) make the polymer more chemically resistant, the polymer would also probably be
more rigid due to the extra mass being carried into the polymer lattice, so care would probably need to be taken with the polymerisation reaction of
the chlorinated phthalic acid ring and ethylene glycol to make sure your polymer doesnt set in the container, i dont think there would be much room
for malleability once the reaction propogates.
My two cents...
-rlr
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