Volitox Ignis
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Phosphorus from phosphoric acid?
Content ahead involves speculation [at the very least,I couldn't find publications describing parts of the following process, just a single patent]
(Which is why I am making this separately from the "Preparation of elemental phosphorus" megathread).
I am wondering whether it would be possible to isolate phosphorus from phosphoric acid by heating Iron Trichloride with phosphoric acid in order to
dehydrate it to hydrogen chloride and ferric phosphate, with removal of the HCl. After the phosphoric acid is converted to iron phosphate, would some
heating be enough to convert the iron phosphate to iron oxide and phosphorus pentoxide? If so, would introducing heated oxalic acid reduce the
phosphorus pentoxide to elemental phosphorus, carbon dioxide (From oxalic acid), and water with some phosphoric acid due to hydrolysis? I am thinking
that the reaction sequence would be as follows:
4 FeCl3 + 4 H3PO4 --> 12 HCl + 4 FePO4
4 FePO4 -Heat-> 2 Fe2O3 + P4O10
10 C2H2O4 + P4O10 --> 20CO2 + 10H2O + P4
The water in the final reaction would react with unreacted P4O10, leading to some phosphoric acid forming.
Is this viable?
Minor edit done; also found two publications which may be relevant:
https://www.google.com/patents/US20110068295
http://www.theodora.com/encyclopedia/o/oxalic_acid.html <--- Mentions that a related compound,oxamide, will react with phosphorus pentoxide. I
believe that oxalic acid will as well.
[Edited on 2-12-2016 by Volitox Ignis]
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Marvin
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You've not given conditions. The first step is workable, but probably not the easiest way, it may need driving. Beyond that I don't think the rest
of the plan can be made to work at all. You could do with reading the phosphorous thread and trying to understand why the materials and conditions
work.
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Melgar
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Carbon monoxide will form before elemental phosphorus does. That's what happens with oxalic acid. You can mix it with elemental carbon and silica
and heat that to extremely high temperatures, but that's just the classic phosphorus synthesis route.
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BromicAcid
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They may be specifically using oxamide for the purpose of creating a finely dispersed carbon, oxamide breaks down to cyanogen on heating and although
I could not find a specific temperature involved, searching for Cyanogen Decomposition shows it ends up as carbon/graphite. So if that was the
intention the oxalic acid would instead go to CO as Melgar said. Actually, just mixing phosphorus pentoxide with oxalic acid will probably start to
dehydrate the acid which will take you a step back starting from polyphosphoric acids instead.
It would be an interesting route, starting from ferric chloride, but patents are notoriously unreliable.
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fluorescence
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I remember in the very old books of Römpp and Raaf I think there was a quite common experiment where you took bones from chicken for example and
converted them into Phosphorus which distilled off. I remember some of my older German colleagues talking about headaches when they experimented with
this stuff in their childhood.
So you could form the Calciumphosphate and then convert it into white Phosphorus by heating it with Magnesium powder not sure how dangerous this will
be though.
Edit:
Look at the way how Scheele extracted it from boneash.
[Edited on 3-12-2016 by fluorescence]
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macckone
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There is a whole thread on doing this with aluminum and various phosphates.
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