Enantiomer
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Phosphorus Pentachloride?
Hi all,
I've been wondering if there is a route to Phosphorus Pentachloride starting with Phosphorus Pentoxide. Since the pentoxide can be harvested from old
black and white television sets it seems like it may be a very economical way to get the desired end product. The real hope though is for a total
synthesis (all OTC). I'm not very brave when it comes to purchasing chemicals. If I did it would have to be something extremely safe with regard to
legislation/ laws.
Anyone have some advice on this?
Thanks in advance.
Enantiomer
Please don't eat the roses . . .
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not_important
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Yes, convert the "pentoxide" (P4O10) to elemental phosphorus then react that with chlorine.
I'm not sure why you think there is P4O10 in televisions. The only thing I can think of is phosphate glasses, but these are glasses - mixtures of the
oxides (typically) pf P, Al, Si, and other elements; there's no free P4O10.
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Enantiomer
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Thanks not_important,
Well, from what I've read, b&w televisions use powdered white phosphorus in thier picture tube. Since the picture tube is under a vacuum the phos
remains as such. In powder form, white phosphorus is highly reactive and when exposed to air oxidizes to the pentoxide rapidly (almost explosively).
So if one were to drill a hole in a b&w picture tube, thus introducing oxygen, he would have a vessel containing P4O10 which could be washed out
with something/ and then dried.
Am I correct so far??
Question is whether there is any point in going through the trouble if what is desired is PCl5. So far the only route to PCl5 I have seen is the
traditional one that chlorinates white phosphorus to the trichloride using chlorine gas and then a mixture of the trichloride with more white p to
arive at the pentachloride.
Assuming what was relayed in the first paragraph of this reply is correct - can the pentoxide really be reacted with chlorine gas? I wonder what the
rxn rate is and how long it takes to complete, how one would know when the rxn is complete, and whether there would be any contaminants in the final
product and how to purify. Would this be done at room temp? Is it exothermic? Would cooling thus be needed? Would heat be needed? Etc . . .
Thanks again.
Enantiomer
Please don't eat the roses . . .
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not_important
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No, I said - convert the oxide to phosphorous, react that with chlorine.
I seriously doubt that there is either phosphorous or its oxide in picture tubes. The vapour pressure of elemental phosphorous at ordinary pressures
is high enough that it would interfere with the electron beam. I think that you are confusing phosphorous the element with
phosphor - a substance that emits light when excited b light of a different wavelength, or energetic electrons or other particles.
B&W picture tubes used a bluish-white phosphor, colour tubes use 3 phosphors of different colours, oscilloscope and radar CRTs use/used a variety
of phosphors chosen for a number of attributes such as persistence of the light emission and so on.
[Edited on 31-10-2010 by not_important]
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Enantiomer
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My bad not_important. It seems I missed something on my first read of your reply. You mention converting the pentoxied to elemental phos first. This
strikes me as something that would be difficult and dangerous. The only information I have seen on phosphorus production is the way it is done in
industry where minerals containing phosphates are heated to an extreme temperature (usually in something like an electric ark oven) and the vapors
condensed to obtain the white P. I was truly hoping there was some way to convert the pentoxide directly to the penachloried.
However, since you raise the topic of elemental phos, I have considered a way of using bone meal in the past to perform a similar operation as what is
done in industry. One could do it on a modified bbg (I think). Just have a hole in the lid with a sort of nipple on it and connect a hose leading to
an aspirator (a very large one) that is recycling cold water using a pump (that moves a high vol of water - for your "large" aspirator) and a resoivor
for cold water/ ice water (say a 5 gal insulated thermos). Crush up charcoal briquettes and mix 50/50 by vol with the bone meal and use a torch to
burn. As time passes the concentration of white P in the water would increase. Use a large enough volume of water in the resoivor to ensure the
concentration doesn't reach a dangerous level. Filter to remove final product and store in an inert atmosphere. (Or just store under water).
Now you want to talk about dangerous . . . there it is!
Only thing I can't seem to get past is the fact that is is being done with good results every-day in industry. Granted they have a little more
sophisticated equipment than a bbq and an aspirator - but it does show that phos can be obtained without killing youself and burning up everyone
around you.
PS: Didn't realize you where online. I was writing this reply at the same time you were writing yours.
Please don't eat the roses . . .
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Enantiomer
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Phosphorus in picture tubes
Here are a couple links in which it is implied that white phosphorus is used in television picture tubes. I hope I am not mistaken; but, even thought
the word "phosphor" (which can refer to other elemets, I guess) is used - I am sure I have read about it more explicitly in the past.
http://www.ehow.com/how-does_5064298_tvs-made.html
" . . .at a phosphor-coated sheet of thin glass . . ."
http://en.wikipedia.org/wiki/Cathode_ray_tube
"Various phosphors are available depending upon the needs of the measurement or display application. The brightness, color, and persistence of the
illumination depends upon the type of phosphor used on the CRT screen. Phosphors are available with persistences ranging from less than one
microsecond to several seconds.[7] For visual observation of brief transient events, a long persistence phosphor may be desirable. For events which
are fast and repetitive, or high frequency, a short-persistence phosphor is generally preferable."
Perhaps I am mistaken about this word "phosphor"?? Still, it seems I have read it very explicitly before that white phosphorus is used. It is
precisely because of this that if a television screen is broken all the white powder is explosively expelled. This, not because the glass was broken
and whatever was in there happened to 'spill' out, this white powder is phosphorus pentoxide (phosphorus that has reacted with air upon being exposed
to the atmosphere when the tv was broke and being expelled with force from the broken tube).
Pleaase, please - do correct me if this is wrong. Accuracy is very important in this game.
Please don't eat the roses . . .
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Enantiomer
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Well now I feel like an ass . . .
http://en.wikipedia.org/wiki/Phosphor
Didn't realize "phosphor" was different than "phosphorus". I don't understand how I got it in my head in the first place.
So . . . in the end, maybe 'phosphorus on the barbie' is about the only way one could obtain this element (at least without outright marching down to
the police station and begging to be put in prison). Friggin' laws in this sick, twisted country!!
Enantiomer
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Enantiomer
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Ahhh Fuck It! What's the use!!!
Please don't eat the roses . . .
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zed
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There is a specific thread on Phosphorus production.
Otherwise, I am inclined to believe that P2O5 itself cannot be easily converted to PCl5.
Though there is some possibility of converting it to POCl3, or PCl3.
Use the search engine. Examine some of Sauron's posts.
Don't expect to find a really easy procedure.
The problems with purchasing Phosphorus and Phosphorus Chlorides, are international.
Phosphorus is handy for making meth. Phosphorus Chlorides are handy for manufacturing chemical weapons.
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12AX7
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Phosphors are made of rare earths...
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madscientist
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P2O5 --(NaCl)--> POCl3
POCl3 --(red hot C)--> PCl3
PCl3 --(Cl2)--> PCl5
Not what I'd call easy, but it's possible. Dig around with the search engine... information on these reactions has previously been posted.
| Quote: | The problems with purchasing Phosphorus and Phosphorus Chlorides, are international.
Phosphorus is handy for making meth. Phosphorus Chlorides are handy for manufacturing chemical weapons. |
And essential for making many catalysts, preparing Wittig reagents, etc... sigh.
[Edited on 2-11-2010 by madscientist]
I weep at the sight of flaming acetic anhydride.
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Enantiomer
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Neat stuff fellas
Neat art 12AX7. That expresses exactly how I feel sometimes. madscientist, thanks for the input. It's interesting but looks time consuming (not easy -
like
you said). I'll have to look for that thread zed.
Does anyone have any thoughts on my phosphorus on the barbie idea? Probably extremely dangerous for one thing huh?
I have also considered the possibility of constructing a very small elecric ark oven/ furnace. Say something that could process maybe 10 lbs or so of
bone meal per run. Might be expensive though.
Enantiomer
Edit was deletion of a duplicate word.
[Edited on 3-11-2010 by Enantiomer]
Please don't eat the roses . . .
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zed
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It isn't impossible. Some of the guys have made elemental phosphorus. Some, no doubt, have insight into procedures that might produce sizable
amounts.
What do you need PCl5 for? Is there no way you can buy some outright?
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