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Melgar
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Quote: Originally posted by symboom  | Now the question if you have white phosphorous homemade from phosphate how can that be converted to red phosphorus
To make it safer to handle
[Edited on 17-10-2017 by symboom] |
I think rapid heating under pressure is all that's needed. I don't think the temperature necessary is even that high, and the pressure would just be
to keep it from boiling. Obviously, an inert atmosphere would be required.
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Chemateur80
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Greetings.
I decided to clean some of my red phosphorus a little.
It's been standing for a few years in a plastic jar inside a metal can with an airtight lid.
When I opened the metal can there was a faint, weird smell. Hard to describe, but kind of like onion and garlic.
The phosphorus was not clumped, but quite free flowing, like sand.
I put three scoops of P in some water. The pH was around 1-2, so I suppose there was some phosphoric acid present.
The heavier particles sank, but there was also a very fine, orange suspension of fine particles.
I then added a solution of Na2CO3 and let it simmer for a while with stirring. The pH was basic.
I then filtered the P through filter paper and rinsed until the pH was neutral. A lot of very fine particles made it through the filter, and the
filtering was quite slow.
The P is now dried with gentle heat on the filter paper. There is a faint smell of garlic, though.
What could this be? Tiny amounts of phosphine? Seems weird.
Shouldn't clean phosphorus be odourless?
Is my red phosphorus reasonably pure after this cleaning?
Any improvements I could make, or anything I should do differently?
Has anyone else experienced that the phosphorus consists of a lot of very fine particles that are hard to recover?
I've seen here on SM that people suggest boiling the phosphorus with NaOH, but since my P seemed quite free flowing and pure, I just went with this
method.
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LearnedAmateur
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Phosphorus is apparently described to have the odour of garlic, I’d put these down to impurities formed. Wikipedia says that pure phosphine is
odourless, and substituted phosphines and/or P2H4 are responsible for the disagreeable odour, and are likely only present in trace quantities.
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woelen
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Red phosphorus is odorless, but in practice, samples of red phosphorus contain trace amounts of white phosphorus. Even the purest samples contain
some. It is this contamination which gives it the particular smell. I never had red phosphorus, which is completely odorless. I purchased 20 grams of
99.99% red phosphorus for my element collection and even this had a faint smell.
If your red phosphorus is free flowing, then it is quite pure and contains hardly any white phosphorus. The white phosphorus makes it somewhat sticky.
[Edited on 3-2-18 by woelen]
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Chemateur80
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| Quote: Originally posted by LearnedAmateur | | Phosphorus is apparently described to have the odour of garlic, I’d put these down to impurities formed. Wikipedia says that pure phosphine is
odourless, and substituted phosphines and/or P2H4 are responsible for the disagreeable odour, and are likely only present in trace quantities.
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Yes, it's probably traces of diphosphane and substituted phospines.
Can white phosphorus form spontaneously from red phosphorus, or why are there traces of the white allotrope?
It's strange that the wet phosphorus still smelled of garlic after cleaning.
It is now a dry, sand-like, free flowing powder, almost without any smell..
I've put it in a dry bottle with parafilm over and then a lid with a PTFE liner.
Will cleaned red phosphorus oxidize over time?
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woelen
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Clean and dry red phosphorus will remain so if stored tightly sealed. When it is not properly stored, then over the years it becomes wet and sticky.
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Chemateur80
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| Quote: Originally posted by woelen | Red phosphorus is odorless, but in practice, samples of red phosphorus contain trace amounts of white phosphorus. Even the purest samples contain
some. It is this contamination which gives it the particular smell. I never had red phosphorus, which is completely odorless. I purchased 20 grams of
99.99% red phosphorus for my element collection and even this had a faint smell.
If your red phosphorus is free flowing, then it is quite pure and contains hardly any white phosphorus. The white phosphorus makes it somewhat sticky.
[Edited on 3-2-18 by woelen] |
My red phosphorus is somewhat sticky, but not that much. After cleaning and drying it is free flowing and practically odourless.
I was under the impression that red phosphorus is very unreactive. When stored, what exactly does it react with? Or are small amounts spontaneously
converted into white phosphorus, which then reacts to form the smelly phosphine-compunds?
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Bert
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It will oxidize slowly in air. For purposes such as match book covers or other ignition strips where it must remain reactive in long term, non sealed
storage, it is available in microencapsulated forms.
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BackyardScience2000
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Red phosphorus is not illegal to sell in the US as long as you can guarantee that it is not being used with the intentions to make methamphetamine.
That's why companies like sigma have stopped selling it to average people. They can't guarantee that. Smaller companies that deal with far fewer
customers can. I've been selling it for years and the feds have absolutely no problem with me selling it as long as I report any suspicious activity.
Like large orders (I limit orders to no more than 100g per year per customer, any request for larger amounts gets reported), suspicious inquiries,
when they ask if my product can be used for such things (making it obvious) and just any general suspicious activity. I normally only deal with
people that I trust with it as well. New customers are few and far between. They have to be able to prove to me that they have no intentions
whatsoever to use it in that manner. Which is hard for people to do. Every single purchase is recorded and kept on file forever as well. The feds
want suppliers to keep detailed lists of the buyers name, address, how much they buy, what they want to use it for, etc. That stipulation usually
drives away any wrong doers. I am required to tell customers of that fact and that the feds could show up anytime wanting to make a copy of said
lists. So unless you want to put in all that work and have to deal with the federal government in a regular basis, I would stray away from attempts
to sell it.
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