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bluamine
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[*] posted on 22-5-2016 at 09:07
Phosphorous pentoxide from phosphate?


Hi everyone!!
I want to make some P2O5 but i don't have any source for white phosphorous (unfortunately i can only get small amounts of red phosphorous) So i must use calcium phosphate (or any other phosphate salts as an intermediate)
Need your help!!
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Aqua-regia
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[*] posted on 22-5-2016 at 09:32


you can get pure and usable P2O5 from dry red phospor burning with dry oxygen /aer. Other methode don't exist, unless you want wasting your time.

Preparation of red phosphorous is hard job. Before you something ask please using the google! look this topic:

http://www.sciencemadness.org/talk/viewthread.php?tid=65
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bluamine
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[*] posted on 22-5-2016 at 13:18


Quote: Originally posted by Aqua-regia  
you can get pure and usable P2O5 from dry red phospor burning with dry oxygen /aer. Other methode don't exist, unless you want wasting your time.

Preparation of red phosphorous is hard job. Before you something ask please using the google! look this topic:

http://www.sciencemadness.org/talk/viewthread.php?tid=65

Unfortunately i don't have any source for white phosphorous rather than phosphate fertilizer (i have read some documents about extracting phosphorous from urine!! but that seems incredible & unpractical).. I just mentioned red phosphorous as an alternative for white one, i am not planning to get it though
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bluamine
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[*] posted on 22-5-2016 at 13:20


Unfortunately it sounds that it can not be prepared by phosphate salts pyrolysis.. & even their reduction is quite hard to do
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[*] posted on 22-5-2016 at 14:12


Why do you mean phosphorus pentoxide? Many transformations can be accomplished using metaphosphoric or pyrophosphoric acid. There is a thread around here somewhere on the subject. Conversion of calcium phosphate to phosphoric acid via sulfuric acid in the 'wet process' is well established and converting the formed phosphoric acid to something more aggressively dehydrating is covered on this forum.



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bluamine
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[*] posted on 22-5-2016 at 14:31


Quote: Originally posted by BromicAcid  
Why do you mean phosphorus pentoxide? Many transformations can be accomplished using metaphosphoric or pyrophosphoric acid. There is a thread around here somewhere on the subject. Conversion of calcium phosphate to phosphoric acid via sulfuric acid in the 'wet process' is well established and converting the formed phosphoric acid to something more aggressively dehydrating is covered on this forum.

First thanks for the informations. I have already thought about using phosphoric acid istead, but i am not sure if that would work. Honestly i am planning to produce acetic anhydride through sodium acetate/acetyl chloride reaction. Both chemicals can be prodeuced from available chemicals (especially the first one, the second one can be prepared more hardly)
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[*] posted on 22-5-2016 at 15:15


Here is one of the relevant threads:

http://www.sciencemadness.org/talk/viewthread.php?tid=4409

What helps set metaphosphoric acid apart is that it will dehydrate sulfuric acid to sulfur trioxide. It is definitely worth a look as it is much easier to make than phosphorus pentoxide (which would require phosphorus as an intermediate step).




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[*] posted on 27-5-2016 at 03:29


How about a reaction like:
Ca3(PO4)2+3SiO2->3CaSiO3+P2O5?
Sure, P2O5 is a stronger acid than SiO2. But P2O5 boils under 800 degrees, while SiO2 boils above 2200 degrees.
So, would it be feasible to distil off P2O5 by heating the reagents to, say, 1000 or 1500 degrees, and collect the condensed P2O5 vapours, perhaps as solids under 400 degrees?
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[*] posted on 27-5-2016 at 06:20


Heat H3PO4 to 316C to create HPO3:

H2PO4 → HPO3 + H2O

and, at that temperature, neutralize with MgCO3 forming Mg(PO3)2:

MgCO3 + 2 HPO3 → Mg(PO3)2 + H2O + CO2(g)

Source: http://magnesium.atomistry.com/magnesium_metaphosphate.html

Heat the dry Mg(PO3)2 to form the pyrosulfate and P2O5:

2 Mg(PO3)2 → Mg2P2O7 + P2O5

Source: https://books.google.com/books?id=lxlKAQAAMAAJ&pg=PA20&a...

Unfortunately, I suspect the decomposition of Mg(PO3)2 occurs way above 550 C!

Also, avoid reducing agents including carbon as phosphorous could form.

[Edited on 27-5-2016 by AJKOER]
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bluamine
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[*] posted on 31-5-2016 at 04:15


Quote: Originally posted by AJKOER  
Heat H3PO4 to 316C to create HPO3:

H2PO4 → HPO3 + H2O

and, at that temperature, neutralize with MgCO3 forming Mg(PO3)2:

MgCO3 + 2 HPO3 → Mg(PO3)2 + H2O + CO2(g)

Source: http://magnesium.atomistry.com/magnesium_metaphosphate.html

Heat the dry Mg(PO3)2 to form the pyrosulfate and P2O5:

2 Mg(PO3)2 → Mg2P2O7 + P2O5

Source: https://books.google.com/books?id=lxlKAQAAMAAJ&pg=PA20&a...

Unfortunately, I suspect the decomposition of Mg(PO3)2 occurs way above 550 C!

Also, avoid reducing agents including carbon as phosphorous could form.

[Edited on 27-5-2016 by AJKOER]

You mean magnesium pyrophosphate!!
The amazing about that reaction is the fact we can (at least theorically) use pyrophosphate to recover our phopsphpric acid to gain more phosphorus pentoxide..
Anyway how can we seperate the two products (phosphorus pentoxide & magnesium pyrophosphate)??!!

[Edited on 1-6-2016 by bluamine]
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[*] posted on 6-1-2018 at 15:03


Very interesting also maybe copper phosphate could be turned into phosphorous pentoxide by decomposition such as copper sulfate heating leads to formation of sulfur trioxide

And also silver phosphate may form phosphorous pentoxide on heating




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[*] posted on 7-1-2018 at 12:12


Does anyone have an experience of losing glassware to hot metaphosphoric acid? I've heard that it's a glass eater.



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[*] posted on 7-1-2018 at 12:21


Quote: Originally posted by ave369  
Does anyone have an experience of losing glassware to hot metaphosphoric acid? I've heard that it's a glass eater.


I am pretty sure I have seen it on a msds for a glass etching gel, so i think your right.
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[*] posted on 7-1-2018 at 18:05


Quote: Originally posted by ave369  
Does anyone have an experience of losing glassware to hot metaphosphoric acid? I've heard that it's a glass eater.


Please see the preparation of oleum by use of phosphoric acid:

https://www.sciencemadness.org/whisper/viewthread.php?tid=78...




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[*] posted on 7-1-2018 at 21:15


Copper phosphate decomposes to copper oxide and phosphorus pentoxide?



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[*] posted on 7-1-2018 at 21:49


bluamine I think you missed something pointed out by Aqua-regia, both red phosphorous and white phosphorous will burn in air producing phosphorous pentoxide.
Its just red phosphorous requires a little energy to get it started e.g. a flame.

You say you have access to red phosphorous in small quantities, how much is a small quantity?
Remember that P2O5 has a considerably larger molecular mass than phosphorous, thus burning 31g of red phosphorous would leave you with about 284g of P2O5.
I think the best way to burn it would be to get a steel drum with a seal-able lid and then put the phosphorous inside and light it, followed by quickly sealing the steel container, A pressure cooker should work fine.
If you do this in open air your product will likely contain a bit of phosphoric acid however you could rig up an oxygen generator with a calcium chloride drying tube and enrich the oxygen inside the steel container, this will also ensure all of the phosphorous is oxidized, provided you didn't burn to much.
............MnO2
2H2O2 -------> 2H2O + O2
https://www.youtube.com/watch?v=eI-HMUCEJsI

A pressure equalized addition funnel won't be required as the gas will only be led into the chamber which is at atmospheric pressure and will not encounter any resistance.

Once the container has cooled to room temp you could then scrape the P2O5 off the walls of the steel container.

http://www.sciencemadness.org/smwiki/index.php/Phosphorus_pe...

I do like the idea of preparing P2O5 by decomposing copper or magnesium pyrophosphate however this would likely require some serious investment into a steal retort.
If your are going to go that far then i just see no reason why you wouldn't go all the way and prepare white phosphorous via reduction of sodium hexametaphosphate.
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[*] posted on 7-1-2018 at 23:03


Quote: Originally posted by Assured Fish  
bluamine I think you missed something pointed out by Aqua-regia, both red phosphorous and white phosphorous will burn in air producing phosphorous pentoxide.
Its just red phosphorous requires a little energy to get it started e.g. a flame.

You say you have access to red phosphorous in small quantities, how much is a small quantity?
Remember that P2O5 has a considerably larger molecular mass than phosphorous, thus burning 31g of red phosphorous would leave you with about 284g of P2O5.
I think the best way to burn it would be to get a steel drum with a seal-able lid and then put the phosphorous inside and light it, followed by quickly sealing the steel container, A pressure cooker should work fine.
If you do this in open air your product will likely contain a bit of phosphoric acid however you could rig up an oxygen generator with a calcium chloride drying tube and enrich the oxygen inside the steel container, this will also ensure all of the phosphorous is oxidized, provided you didn't burn to much.
............MnO2
2H2O2 -------> 2H2O + O2
https://www.youtube.com/watch?v=eI-HMUCEJsI

A pressure equalized addition funnel won't be required as the gas will only be led into the chamber which is at atmospheric pressure and will not encounter any resistance.

Once the container has cooled to room temp you could then scrape the P2O5 off the walls of the steel container.

http://www.sciencemadness.org/smwiki/index.php/Phosphorus_pe...

I do like the idea of preparing P2O5 by decomposing copper or magnesium pyrophosphate however this would likely require some serious investment into a steal retort.
If your are going to go that far then i just see no reason why you wouldn't go all the way and prepare white phosphorous via reduction of sodium hexametaphosphate.


IDK how you came up with the 31g yeilding 284g? from my calculations I think it is 124g to get 284g of P4O10 or P2O5. The molecular weight of P is 31 and O is 16. So 160g of O + 124g of P = 284g of P4O10
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[*] posted on 7-1-2018 at 23:53


Assured Fish Quote: like the idea of preparing P2O5 by decomposing copper or magnesium pyrophosphate however this would likely require some serious investment into a steal retort.
If your are going to go that far then i just see no reason why you wouldn't go all the way and prepare white phosphorous via reduction of sodium hexametaphosphate.

Looks like a new project potential
Make phosphorous pentoxide from copper phosphate
So the same retort could be used to make white phosphorous
Just have to add aluminum or carbon the steel retort.

Also would decomposing ammonium phosphate
Yield phosphorous pentoxide and ammonia gas

[Edited on 8-1-2018 by symboom]




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[*] posted on 8-1-2018 at 00:37


RogueRose oh shit, yea i screwed that one up, i skimmed over the molecular weight of both, i forgot there were 2 phosphorous atoms present per 5 oxides.

Good thing im not the only one proof reading my scriblings.

symboom i dont think it would. As only NH3 would be lost, that 4th proton in the ammonium cation would stay behind.
(NH4)3PO4 ----> (NH4)2HPO4 ----> (NH4)H2PO4 ----> H3PO4

[Edited on 8-1-2018 by Assured Fish]
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[*] posted on 8-1-2018 at 03:01


How pure is P4O10, formed by burning red phosphorus? I have red phosphorus, and when I ignite this, then it burns with a lot of white smoke, which is (mostly) P4O10. I, however, always have some reddish or yellowish remains. I never took collected the white smoke of burning red phosphorus, but I can imagine that it contains quite a large amount of lower oxides and maybe even some of the red or yellow stuff (which are sub-oxides of phosphorus, like P4O).

For drying purposes the presence of lower oxides of phosphorus may not be that bad, but it makes the drying agent reducing, which may cause incompatibilities with some compounds.

Anyway, I am not really fond of using P4O10 for drying. I tends to form a thin sticky and glassy layer around clumps of solid and this glassy layer very effictively shields the lower lying P4O10 from reacting. P4O10 comes in the form of a very fine free flowing powder, but when used as drying agent, it quickly clumps and then only a small fraction of the material reacts. I frequently mix it with CaCl2 (e.g. 10% P4O10 on 90% CaCl2), such that the CaCl2 becomes covered with P4O10. This is a very nice method of drying certain gases which do not react with CaCl2 (e.g. Cl2, SO2, C2H2).




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[*] posted on 8-1-2018 at 10:23


The most important indrustially production of P2O5 is igniting of white phosphorus. This is the first step so called thermo process for producing H3PO4. (Not red one) It is burned in spec. furnace with relatively high temperature to avoid the composition low valency oxidationsproduct.
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[*] posted on 8-1-2018 at 11:59


The heat in these phosphate decomposition reactions is probably -very- high, silver metaphosphate is stable up to 600 C (at least) and based on the behavior of other salts I'd expect the silver salt to have the lowest decomposition temperature.

Salts of the H-phosphonic acid, H2PO3H, are available; by heating the monohydrogen salys you can produce salts of pyro-H-phosphonate (P2O5H2)2- eg Na2P2O5H2. If you treat the pyro-H-phosphonates with chlorine, POCl3 should be produced:

2Na2P2O5H2 + 4 Cl2 >> 3 NaPO3 + NaCl + POCl3 + 4 HCl

[Edited on 8-1-2018 by clearly_not_atara]




[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 8-1-2018 at 16:37


P2O5 may occasionally be purchased. It is not legally restricted.

Might not be possible to desiccate, other phosphates completely enough to form P2O5.

Phosphorus itself, unless you make your own, is quite hard to obtain.

Try the search engine. Perhaps there is a current P2O5 source listed.
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[*] posted on 8-1-2018 at 22:08


I have bought P2O5 from a supplier in Poland. Recently I ordered a lb from Firefox Enterprises in Pocatello. I haven't received it yet. Their search engine is currently down. I will call them tomorrow.

[Edited on 9-1-2018 by Magpie]




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[*] posted on 8-1-2018 at 22:32


I got some from them, several months ago. Seems pretty good, but I haven't used it yet.



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