Sciencemadness Discussion Board

Preparation of elemental phosphorus

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Magpie - 6-4-2006 at 15:20

Do you have an idea of how high a temperature you are going to have to heat this? I'm presuming it will have to form a melt before you can expect any significant reaction.

jimmyboy - 6-4-2006 at 15:45

something pretty powerful will be needed - hot enough to melt steel - ive seen four possibilities so far - thermite reaction - acetylene - gas/blower furnace - and the carbon arc

Agamemnon82 - 6-4-2006 at 16:00

oxy-acetylene torch, plenty hot enough to melt steel :) I'm going to be using a ceramic reaction vessel and tubing leading into water. Still a couple of weeks untill i'll be ready.

Magpie - 6-4-2006 at 17:28

I'm in no way trying to discourage you testing this route but if you need that kind of temperature (1600-1700C) why not use the standard industrial mix:

(Ca)3(PO4)2 + SiO2 + C ---> P + etc ?

Is there some particular advantage to using the reactants you have chosen?

Cyrus - 7-4-2006 at 10:45

Well, if all we need is 1340 degrees C, to melt the NaPO3, that's not too hard to get.

That is quite refractory for a sodium compound... but 1340 deg. C is 2444 degrees F, and I know for a fact that one can get to that temperature easily w/ 3" of kaowool insulation and a waste oil burner. A venturi propane burner will also get that hot. There's simply no need for exotic arc furnaces, however sweet they may be. :)

(How do I know? I was firing some ceramics to cone 10 (about 2381 degrees F, but it depends on how fast you heat the kiln) and the cone, which is supposed to bend over at 2381 degrees, had turned into a puddle by the time I was done with it. )

High temperatures are pretty easy to reach with kaowool. Mine was only rated to 2300 degrees, so I would recommend 3" of 2300 kaowool and perhaps an inch of 2800 degree F castable refractory on the inside to build a furnace. Heat with a Reil EZ burner using propane. If you're careful, the whole thing should cost less than $100, and it will be a sweet furnace.

Cy

PS- what I'm worried about is what you're going to use to contain the mix. Clay w/ a lot of alumina? Sintered alumina? These are pretty porous, so gasses will escape. Perhaps a high alumina layer to resist evil fluxing action by the sodium, surrounded by a glassy porcelain layer, which will seal in gasses. Quartz ? :D

Rabidwolf - 8-4-2006 at 13:09

hmmm,
how hot would a meeker burner running off a 20pounder(BBQ size) tank of propane get?
mebbie adding a shiteload of insulation around a stainless steel pipe stub that's aboot 3in dia and 6in tall, capped at one end and a 4in-to-1/2in reducer going to some stainless steel tubing that's led under water would work...

ah.....the wonderful thing about TIG, is that TIG is such a clean and precise thing

Gruson - 16-4-2006 at 10:13

Hello there. For a school project in Holland I chose to do some research on the preparation of White Phosphorous. There was some practical stuff, too. ;) A couple of weeks ago I prepared white Phosphorous from the following reaction:

12NaPO3 + 20Al + 6SiO2 = 6Na2SiO3 + 10Al2O3 + 3P4

The products reacting were 40 grams in total. NaPO3 was obtained from heating NaNH4HPO4. The remaining glassy stuff was crushed (damn hard it was) and dried in a drier at 80°C. SiO2 were not especially small particles, just made it with HCl and NaSiO3. Al was 100 um.

The reaction vessel looks a lot like BromicAcids's second one. But where he goes for a 'gass ball valve' (or something like that) I used a overpressure of nitrogen of 1.1-1.2 bar.
The reaction vessel is 20 cm long, throughcut 5cm. The steel is 5mm thick. A small pipe for the nitrogenflow is welded on the reaction vessel. That pipe is 6mm through, and 10 cm long. The bottom of the reaction vessel is welded airtight. (It's just closed, don't know how tot say that in english.)
The drainpipe for the gasses and P4 was screwed on the top of the reaction vessel. The drain is 20mm through. It is has a 90° bow. From the end of the vessel to the bow is the drain 15 cm, after that 40 cm long. Less heat was transferred to the water then we expected.

Picture of it in use (quite big, sorry for that)



I used a acetlylene burner for the heating. It melted the outside of the reaction vessel, so you had tot be careful not to burn a hole in your reaction vessel.

Closeup:



We put the end of the drain under boiled destilled water. In patent 2,050,796 it stated that dissolved oxygen in the water would oxidise the P4, so I boiled it and put in a PE bottle for usage.

The drainpipe while P4 came over, P2O5 'smoke' is formed.



The vessel was first heated 15 mins to 400°C to get rid of the H2O which would form PH3/P2H4. (Comprehensive Treatise on Inorganic and Theoretical Chemistry, vol 8) We also added some carbon (tip from Gmelins' to prevent phosfine forming)

After we heated it for about 2 hours the P4 started to came over. The water was becoming a bit whitey, what was supposed to be colloidal white P. After a while some solids were formed on the bottom. The heat was turned off after 3 1/2 hour.

This pic is after the reaction, it shows the white P on the bottom, seen from above.




If you stirred it up some P2O5 smoke was formed above the surface.
A day after the reaction I performed the 'Mitscherlich test' to positively identify white P. Is shows some greenish lighting, and that proofs the whitey-yellow stuff is white/yellow phosphorous.

Some of the solution was shaken with some CS2, and then placed under an UV lightsource. After a day or so, it started to look a bit reddish. Red P was formed.
This picture is after a week. Red P is like a film layer on the CS2. The upper layer is water.



Well, to conclude: I managed to make White P out of the NaPO3/Al/SiO2 method, relatively easy. If you can get hold of a acetylene torch, there should be no problem at all. You don't have to insulate your reaction vessel, seems to me. If you are using another heating source, you probably should.

Mainly with the help of this thread, and the use of some old standardworks this project came to an good end. Thanks for every bit of information posted here, maybe you can get something usefull out this post. If something is not clear, just ask. Thanks!

Magpie - 16-4-2006 at 14:30

Nice work Gruson. ;)

I have a question about the nitrogen purge. My understanding is that this is a continuous flow at a regulator pressure of 0.1 - 0.2 bar above atmospheric pressure. Is this correct?

You are fortunate that your school would let you tackle such a project. Somehow I can't envision that happening in the US. I'm sure you learned quite a bit.

Gruson - 17-4-2006 at 00:32

Thanks :)
Yes, that's correct. The nitrogen flow was ideal for the P4 not being oxidized (much cheaper then welding argon), and it also prevented, when the reaction was done and the vessel was cooling down, suckback of water what may have lead to a possible steam explosion. (although the drain had a not so small diameter and was quite long.) The N2 bubbles came out of the drain at a rate of 1 per 2 seconds or so. IIRC we used 15-20 bar of nitrogen during the experiment.

Indeed, I was quite lucky to do such a project at school. I had to talk quite a lot to get permission though.. But after exstensive research I succeeded to talk over my teacher. (he liked the idea a lot, it only had to be done 'safely'). I had quite a lot of fun with this project, and indeed, I learned a lot. Safety measures, technical solutions to problems, researching, etc, etc.

jimmyboy - 17-4-2006 at 14:38

very nice work - dang -- 3 hours of acetylene/o2? how many tanks of gas did you go through? and what was the yield?
thats what - a 300 dollar investment for some phosphorus - but grats on the success - nice pics as well :D

Rabidwolf - 17-4-2006 at 17:17

Quote:
Originally posted by Gruson
Thanks :)
Yes, that's correct. The nitrogen flow was ideal for the P4 not being oxidized (much cheaper then welding argon), and it also prevented, when the reaction was done and the vessel was cooling down, suckback of water what may have lead to a possible steam explosion. (although the drain had a not so small diameter and was quite long.) The N2 bubbles came out of the drain at a rate of 1 per 2 seconds or so. IIRC we used 15-20 bar of nitrogen during the experiment.

Indeed, I was quite lucky to do such a project at school. I had to talk quite a lot to get permission though.. But after exstensive research I succeeded to talk over my teacher. (he liked the idea a lot, it only had to be done 'safely'). I had quite a lot of fun with this project, and indeed, I learned a lot. Safety measures, technical solutions to problems, researching, etc, etc.


kudos scientific brotha'
:cool:
what kinda mark did you end up getting on your project?

Gruson - 18-4-2006 at 05:37

Well, we performed the project in a smithy (construction company) and they had pillars where you could plug your C2H2/O2 connection in. So I don't know exactly how much was used, but I can imagine it was quite a lot.. About the costs: That's the good thing when doing this kinds of project for school: School pays everything.. Although that was not that much, the men at the workshop were extremely kind and just asked some crates of beer, and that was all..:D

The maximum yield of a reaction mixture of 40 grams was 8 grams White Phosphorous. We were able to isolate some 5 grams of white P (measured under water, volume is x ml, should weigh x grams but weighs x+y grams, so y could be white P), and also 1.6 grams of Red P (from whiteP+UV -> RedP)
So the yield was.. 82,5%, :P Or should be somewhere around that number.

My mark.. 7.3 out of 10 (7 for practical part, 7 for presentation, 8 for theory & research). Not all that high, but hey, the highest mark was a 7.6 and that was for a lot less spectacular experiment about polarisation.. But I'm happy with my little project that succeeded against all odds, and I'm also happy that I'm still alive and kicking.

Magpie - 18-4-2006 at 09:17

Working for "crates of beer." This sounds like a simpler and better time in the US.

I'm very happy to see that your school has not succumbed to the "grade inflation" that is so rampant in the US. I do, however, think that you should have been given at least a "9" for project management and perseverance. :D

Madandcrazy - 3-5-2006 at 07:53

Can phosphorus not isolated by a isomer of phosphoric acid (hydrolysis) to the oxide ;) ?
Maybe natrium dihydrogenphosphat form per elctrolysis some dilute (HPO3)n and takes up phosphorus to a elektrode.

Gruson - 3-5-2006 at 10:49

In the scan of BromicAcid Gmelin's its stated that molten NaPO3 can be electrolyzed with a Ni kathode. Just that. NaPO3 can be obtained quite easily from heating NH4NaHPO4. Maybe sodiumdihydrogenphosphat will do it as well. Didn't do much research on the elektrolysis path, heating seemed easier to me..

jimwig - 14-5-2006 at 08:43

pardon if this has been cited ;;;


Method of Preparing Phosphorus

US6207024

http://v3.espacenet.com/results?sf=n&FIRST=1&F=0&...

Abstract - A method of producing phosphorus in which a mixture of phosphoric acid and carbon reductant is exposed to microwaves at a power level sufficient to heat the mixture to a temperature at which phosphorous is produced. This method can be carried out at lower temperatures than conventional phosphorous production and does not give rise to the solid waste normally formed in conventional phosphorous production. The phosphorus thus formed can be converted back to phosphoric acid, thus effecting purification of the phosphoric acid.

__this lower temp referal seems to get around the stumbling block of non lab type prep apparatus.

__also excepting the inert atmosphere (possibly avoidable) this seems to posses workable attributes

__the refs contained within the text are IMHO great.

Mason_Grand_ANNdrews - 19-6-2006 at 09:23

I`ve read Phosphorus exists in three different isomers.

Phosphorus red
Phosphorus white
Phosphorus black :D

I belive, all isomers can isolated by a other of the isomers. I found two methods obtaining Phosphorus red by Phosphorus white.

Careful put some quickly dryed Phosphorus white in a test tube and close this with a cotton-wool. The Phosphorus is heated itself and reacts with the oxygen in the test tube. Some fumes of Phosphorus red is deposited on the side of the test tube and the reaction is finished. Convert the rest of the Phosphorus white to red, the test tube is heated to 270 - 275 gegree celsius until the converting is ending.

I guessing the better way is converting Phosphorus white to Phosphorus red at lower temperatures when the white P is added to a mixture of carbon disulphide/iodine in a ratio of 95/5 and this is careful heated with a burner.

Thats quite easy but i assume the special interest of the treath is obtaining white P by red P. Perhaps, i found a simple method later. :P

Do someone have any more information to black P ?

[Edited on 19-6-2006 by Mason_Grand_ANNdrews]

[Edited on 19-6-2006 by Mason_Grand_ANNdrews]

Gruson - 19-6-2006 at 09:57

Carefully heating CS2 with a burner? You rather then me..

Red P is made by putting white P in pipes, closing them and heating for 50 hours at 240-250 °C. Reaction product is treated with CS2, to remove unreacted white P.

This is not a method you choose to do at home, especially when there is a much easier way to make red P out of White P.

(as mentioned somewhere in the thread)
If you have CS2, dissolve white P in it. Place it in the sun / under an UV lamp. White P reacts under UV radiation to Red P, which will precipitate out of the CS2. (After a couple of days the reaction is complete, recording to my experiments [no change was observed after 4 days])

If you don't have CS2, just put the white P in a airtight container, and place it in the sun / under an UV lamp. White P will convert to Red P (the smaller the size of your White P, the faster).

I suggest you read some literature on this subject, all the answers you seek are in it.

Well, on black P.. (in Comprehensive Treatise on Inorganic and Theoretical Chemistry, vol 8 it is called violet / metallic P)

Quote:

W. Hittorf prepared metallic or violet phosphorus by heating phosphorus
in contact with lead for I0 hrs. at a temp. near 500 °. The phosphorus dissolves in
the lead at the high temp., and on cooling separates from the lead in the form of
small, dark, reddish-violet, rhombohedral crystals. The crystals can be separated
from the lead by treatment with dil. nitric acid, which dissolves only the lead.
The crystals are further purified by boiling them with hydrochloric acid. A. Stock
and F. Gomolka recommended the following procedure :

W. Hittorf's phosphdrus is best prepared by heating 3 grms. of pure phosphorus wRh
200 grins, of lead in a sealed hard glass tube, packed in sand, to 800 ° for 48 hrs. The
glass is broken and removed in a freezing mixture, and the lead cleaned by [,rushing
by washing with hydrofluoric acid. As nitric acid attacks the phosphorus, the lead is best
removed by electrolysis in acetic acid containing lead. The cathode is placed at the bottom
of the vessel, a clock-glass being fixed below the rod. The residue thus obtained contains
some lead, mechanically dislodged from the anode, and is purified by boiling with hydro-
chloric acid in an arm. of carbon dioxide, followed by treatment with hydrofluoric acid.
The purest product still co.ntains 1.5 per cent. of lead.

[Comprehensive Treatise on Inorganic and Theoretical Chemistry, vol 8, pg. 747]


Black P has about the same structure as graphite, hexagonal plates. It conducts electricity.
It is the hardest to make allotrope of P for a amateur scientist..

Mason_Grand_ANNdrews - 22-6-2006 at 09:35

White P is obtained by quickly cooling the vapours of red P, but it shouldn't ignite with the oxygen in the air. Can white P safe stored in H2O, in airtight and lightproof flasks always. Some nasty green highly toxic substances will form with the H2O on the surfaces of the white P.
Also, i guessing it will walk when the converted vapours of the white P are quickly and cool transfered to the storing liquid and less oxygen is present.

Rabidwolf - 15-10-2006 at 17:30

Quote:
Originally posted by jimwig
pardon if this has been cited ;;;


Method of Preparing Phosphorus

US6207024

http://v3.espacenet.com/results?sf=n&FIRST=1&F=0&...

Abstract - A method of producing phosphorus in which a mixture of phosphoric acid and carbon reductant is exposed to microwaves at a power level sufficient to heat the mixture to a temperature at which phosphorous is produced. This method can be carried out at lower temperatures than conventional phosphorous production and does not give rise to the solid waste normally formed in conventional phosphorous production. The phosphorus thus formed can be converted back to phosphoric acid, thus effecting purification of the phosphoric acid.

__this lower temp referal seems to get around the stumbling block of non lab type prep apparatus.

__also excepting the inert atmosphere (possibly avoidable) this seems to posses workable attributes

__the refs contained within the text are IMHO great.

hmmmm, this seems like an intresting microwave expariment....
and my friend has 2 microwaves for exparimental purposes
:cool:
that he also wants to get rid of....

so i'm theorizing ground up charcoal mixed with hydroponic store grade phosphoric acid in a glass dish.
put in a microwave,
in the middle of the yard,
powered by an extension cord.
would both confirm this patent,
and provide an entertaining show of white phosphourus Vs. a household microwave
(via the white phosphourus being allowed to form in an "open pot" type rxn in the sacrificial microwave)

thoughts anyone?

not_important - 15-10-2006 at 22:41

Still have to get it up above 500 C, which may be difficult in a home microwave without susceptors to absorb enough energy and insulation to keep the loses down.


Here is a discussion on using a microwave for metals casting. While they are going up to the 800 to 1000 C range, there are some general guidlines there.

http://home.c2i.net/metaphor/mvpage.html

jimmyboy - 15-11-2006 at 22:43

i was thinking maybe if you had the pipe insulated or placed inside an improvised kiln - alot of acetylene would have been saved (alot of heat saved) - or maybe a small tank of propane could have been used instead .. since its been done maybe some tweaking could be had :)

Sauron - 22-12-2006 at 22:13

The cleanest form of the reductive preparation of WP is carbon (graphite powder) and P4O10 which gives only P4 vapor and CO. You still need red and white heat though. And superheated phosphorus vapor IS a hugely hazardous affair, don't kid yourself.

Red phosphrus when heated always recondenses in the white form. That is, P4 vapor is white phosphorus. You convert WP to the red form by pressure and seperate the two by taking advantage of the difference in solubility in CS2. White dissolves in CS2, red does not. Red is relatively nontoxic but the caveat is that is must be totally free of the carcinogenic and otherwise toxic white form to achieve that state of grace.

My tube furnace only goes to 1100C to if I need red P I recover it tediously from match boxes. I don't mess with white at all. Moatly I don't need elemental phosphrus for anything as I can easily buy PBr3 PBr5 POBr3 and PI3 and I know how to make my own POCl3 from P4O10. The hassle is PCl3 for which red P is needed to make.

Sauron - 23-12-2006 at 18:35

I have some legitimate uses for trialkyl phospites but the lower ones at least are verboten per CWC. Therefore I look to prepare my own, which means PCl3 also verboten. PBr3 however is not restricted at least where I am. I have succeeded in buying this from Merck. The question mark is this: it is clear from the lit. that the reaction between alcohols and PCl3 depends on efficient stirring and efficient scavenging of the hydrogen chloride produced in order to minimize the cleavage of the P-ester formed to hydrogen. That is the formation of dialkyl hydrogen phospite instead of trialkyl phospite. See the Org.Syn. prep of tri-isopropyl phosphite, authored by chemists who worked with B.C>Saunders at Porton Down.

My point is that this side reaction is supposed to be worse with PBr3 and much worse with PI3. Which is why PCl3 is the preferred reagent and perhaps why PBr3 and PI3 were not proscribed by CWC (or even the Aust.Grp.) Do any of you have references or experience regarding this issue?

So where does that leave one? Back to the problem of obtaining elemental P. I am not attracted as a matter of aesthetics to tearing up 100,000 matchbook boxes to laboriously recover 50-100 g of red P. But I can't buy it here without a permit from the MOD permanent secretary. Not impossible I am told, but onerous.

I noted with interest in Brauer's book a prep of "bright red P" from PBr3 and Hg. Anyone ever try this? It looks laborious but at least these are chemical labors and not tearing up matchboxes.

As an alternative I think one might purchase higher alkyl phospites that are unrestricted (say in the C4-C8 range) and cleave them back to PCl3 with chlorine or appropriate chlorinating reagent (classically PCl5 but if I had that I'd have PCl3.)

As to the prep of PCl3 I dount that direct chlorination of red P "always" produces only PCl5. PCl3 has to be formed first. The member must have been running in Cl2 too rapidly. The procedure described in Merck calls for a SLOW stream of chlorine. The inorg reference books indicate cooling is advised, which contradicts Merck's recommendation of warming the red P in absence of air prior to introduction of the chlorine. Anyway the PCl3 formed will contain some PCl5 but that can be left behind by distillation. And yes absolutely, PCl5 admixed with red P will disproportionate slowly to PCl3. If you heat PCl5 enough it disproportionates to PCl3 and Cl2 but this isn't very useful preparatively because they will just recombine. Maybe under reduced pressure one could seperate them in cold traps efficiently.

It might be advantageous to suspent red P in a solvent in which Cl2 is highly soluble and control the rate of reaction that way, dissipating heat of reaction by reflux. Run in the chloring slowly, the red P will react and disappear, and only then will PCl5 start to form assuming efficient stirring. Pick a solvent (hopefully) in which PCl5 is soluble but PCl5 is not and in that case, stop adding Cl2 as soon as PCl5 starts to fall out of the rxn mixture. Seperate the PCl3 from the medium and purify. Seems more controllable than reacting a solid with a gas to make a liquid anyway.

Comments?

[Edited on 25-12-2006 by Sauron]

Sauron - 23-12-2006 at 18:57

By the way my application for trimethyl or triethyl phosphite is the prepn of BEDT-TTF. The final coupling to the tetrathiafulvalene system employs TMP per Org.Syn. Supposed to be really nice dark red crystals, which are charge transfer complexes -- all those conjugated nonbonded electron pairs on the 8 S atoms in the two pairs of rings. The materials-science lads have determined that certain complexes of this system are "organic superconductors" at relatively high temperature, and thus they are theoretically and technologically of great interest.

The other route to this system calls for reducing CS2 with a large quantity of sodium shavings (as usual potassium works better but sometimes blow up instead.) The notion of scraping sodium ingots over a cheese grater over a pool of pet.ether just does not float my boat. Although getting that polycyclic to form that way is very neat.

The better IMO route is to start by reacting ethanedithiol amd chloroacetyl chloride. This is straightforward enough. Ethanedithiol can be purchased. It reeks and gives one a nasty headache so a good hood is advised. Chloroacetyl chloride where I am, is a bit of a bother as only one company (Merck) has an import license for it and Merck advises it would have to be shipped by ocean in a refrigerated container, so sorry. Therefore, I will have to make my own from the readily available chloroacetic acid. Not a big deal though it is unplesant stuff to work with. The next step is chlorination with N-chlorosuccinimide in CCl4. Must find an alt. solvent (maybe DCM) or make my own CCl4. Lovely. Then a neat rex with a xanthate amd a cyclization. It's really a very elegant procedure well worth one's attention. The final step is the phosphite-mediated coupling.

Sauron - 24-12-2006 at 06:31

Brauer p.522, "bright red" (vermillion) P from Hg and PBr3.

55 g Hg
51 g PBr3

Heated two days at 100 C in a sealed combustion tube with constant shaking, one additional day at 130 C then one more day at 170 C. Worked up rather elaborately to free it from Hg (I) bromide and Hg (II) bromide. I have to calculate the working pressure but assuming it is not more than 60 psig then this could be done in a 500 ml Parr shaker with an Ace-threaded bottle (not neoprene stopper) and a heating mantle. The scale 6-7X the above without filling the bottle more than half. If the P is for chlorinating to PCl3 I'd omit the workup and use the crude product; the PBr3 if any and the mercury bromides will be removed in the purification of the PCl3. As a guess this ought to fetch about 100 g red P per run and that's a reasonable return for the labor. Where I am PBr3 is obtainable while the red P and esp the P-chlorides are verboten.

If you don't have a Parr shaker type hydrogenator, you can use a mag stirrer, and put a shield around the assembly as you should with any pressure operation.

Anyone want to guestimate the working pressure inside this 500 ml vessel with c.330 g Hg and 306 g PBr3 @ 100-170 C?

If it is too much for the glass (which can really take about 150 psig) then a steel autoclave is the way to go, but I bet a Parr bottle will take anything that a sealed glass combustion tube would.

[Edited on 25-12-2006 by Sauron]

Sauron - 24-12-2006 at 06:56

Footnote to above

Hg d 13.5 g/ml, b.p. c.350 C

PBr3 d 2.88 b.p. 175 C

I reckon that the scale can be 10X Brauser's, 550 g Hg and 510 g PBr3 won't take up even 40% of that 500 ml vessel. The yld of red P ought to be on the order of 125-150 g -- I haven't calculated the mass percent of P in the PBr3 but it ought to be something not too far off 25%.

Looks like the entire reaction is conducted at well below the b.p. of both reactants and all the PBr3 is long gone before the temp gets raised to just under the b.p. of that reactant on the fourth day.

Eclectic - 24-12-2006 at 08:02

If all you want is PCl3, wouldn't it be a lot simpler just to chlorinate Ca3P2 or Mg3P2 from carbon reduction of the phosphate?
Also white P will transform to red P with a few days heating under CO2 when held right at its boiling point.

Sauron - 24-12-2006 at 10:08

Dun me for a coward but I'd rather not have to work with WP "willie peter" unless given no choice. In my case I have several kg of Degussa Hg and several Kg of Merck PBr3 and a Parr 500ml shaker so, this procedure represents the path of least resistance. And I can buy more Hg and PBr3 if I need them.

I have a 2" x 12" tube furnace but it only goes to 1100 C. Even that is somewhat above the capabilities of Vycor tubing, but inadequate for the white P preps. But even if that were not the case I'd sooner dance across Cambodia wearing snoshoes, if you see what I mean.

However don't let me rain on your parade. I will observe with interest from 10,000 miles away. :)

12AX7 - 24-12-2006 at 11:55

OT:

Hey Sauron, did you go through the turstiles sideways? :P

Don't know if you know that joke...

Tim

Eclectic - 24-12-2006 at 14:42

I wasn't suggesting you make red P from white P, only pointing out that you don't need pressure. I don't see how hot PBr3 and mercury in a Parr shaker is much safer.

Also, did you miss the Ca3P2 or Mg3P2 with Cl2 bit? You don't NEED elemental P. A metal phosphide will do.

[Edited on 24-12-2006 by Eclectic]

Sauron - 24-12-2006 at 18:12

No, I missed that, it's a long thread. I read the first few pages, then found that procedure in Brauer and as it only involved materials and apparatus I have on hand, decided to post it. I will happily study the rest of the thread.

Aren't phosphides commercially available? Or are you just cost-cutting? Also Mg powder is I think restricted here. I recall when I bought a few Kg of Mg turnings for Grignard there was some issue about this because the sales person was a bit sensitized about Mg powder. Al powder is probably OK as long as it's not the microfine stuff used for aluminizing HE.

The mercury-PBr3 does not look to be spectacular. There's no offgassing (no HNr product) so only pressure is vapor pressure of the Hg and that of the PBr3. At 100 C this won't be (I think...must look it up) anything like the rated 4 atm or the actual limit of the vessel which is about 9 atm. As the rxn proceeds the mix goes into solid phase and the partial pressure of red P and of the Hg(I)Br are calculable at 100, 130, and 170 C where this finishes up. So unless there's a huge exotherm involved in the formation of the mercury bromides (seems unlikely and can be looked up) this rxn does not seem very dramatic.

HOWEVER I will keep an open mind and study the thread much more fully. Thanks for your comments.

Sauron - 24-12-2006 at 20:30

I peeked at Alfa's catalog. Calcium phosphide (tech grade) is an off the shelf item, 250 g is well under $100. It is the preferred reagent for PH4 generation.

I do not know what transportation difficulties there might be but the cost does not seem to me to be a serious barrier I also don't know what govt formalities (if any) there are for export or import.

Brauer documents the aluminothermic preparation of this material as well as the preparation directly from the elements.

Sauron - 24-12-2006 at 20:35

Quote:
Originally posted by 12AX7
OT:

Hey Sauron, did you go through the turstiles sideways? :P

Don't know if you know that joke...



Tim


Sorry, Tim, I missed that. Don't know the joke. These days I have trouble fitting through turnstiles in any orientation.

Eclectic - 24-12-2006 at 20:59

If you chlorinate a metal phosphide you should get the metal chloride and PCl3. Reduction of phosphates to phosphides does not need as much heat as freeing elemental P?

I'd think a big slug of mercury banging back and forth in a glass container would have a similar effect as hitting it with a hammer...

Sauron - 24-12-2006 at 21:39

The shaking can be replaced with a spinbar and a mag stirrer, if the stress of the Hg in a shaker is too much for the glass. I am sure the object of the exercise is just to keep the reactants in contact, obviously they will initially be in two layers and unless mixed products forming at the intrerface could effectively isolate the reactants from each other.

Did anyone actually find a reference or procedure for chlorinating an alkali, alkali-earth or other metal phosphide? Or is this an educated guess only? Sometimes these things just don't go the way they "should" don't they? See my thread regarding speculative chlorination of P2S5 (P4S10).

Brauer's entry for technical Ca phosphide suitable for making phosphine is aluminum powder ground from shot and calcium phosphate ground and mixed. An ignition mixture is used, set off with Mg ribbon, ignition mixture unspecified but I'd guess anyoen familiar with thermite reactions will know it. I seem to recall sodium peroxide and barium oxide maybe? Anyway all this in an iron crucible with a cover. The scale was in hundreds of g so we are talking a large iron crucible. The phosphide produced cannot, according to Brauer, be freed from alumina slag, they are simply broken up and ground together after cooling. Given the reactivity of the phosphide with atmospheric moisture I'd think a dry (glove) box would be indicated, the air inside should be dessicated but an inert atmosphere isn't required.

I have a large glovebox, never thought I'd be doing an aluminothermic rxn in it. But I would think that something needs to be done to minimize or eliminate PH4 formation. Apart from the toxicity, stench and pyrophoricity issues it represents a waste of P product.

Given all of that I'd sooner buy the phosphide if I don't run into a headache over shipping or importation.

Let me know if the chlorination of a phosphide is a known rxn.

Sauron - 25-12-2006 at 03:24

I checked some numbers and it appears I overestimated the % P content of PBr3. It's only c.11%. Therefore the theoretical recovery assuming a perfect process and perfect technique is only about 110 g of P from a Kg of PBr3. In real world terms maybe 50-75 g.

Therefore, I no longer think the Hg-PBr3 route is very economically appealing.

Looking at the aluminothermic process the same way well, Al is cheap, and so is calcium phosphate. I do note that the technical calcium phosphide is rated as having 8% active P. Going by the formula that would be 20% P if the stuff were pure. One source claims an assay of only 23.7% calcium phosphide in their product.

Besides Alfa, calcium phosphide (tech.) is also sold by Aldrich, Fluke and Riedel-Haas.

If the actual P content by weight is 8% then this is similar to the 11% above for PBr3. If it is 20% then it is substantially better The latter is unlikely. A Kg of the phosphide costs about the same as a Kg of PBr3. A toss-up.

Of course is one is making his own phosphide from cheap phosphate that is a different story. Al is cheap. In my location though as I mentioned Mg is not an option at least not as powder. I do seem to recall a procedure in Org.Syn. for making a finely divided highly reactive form of Mg from ordinary turnings. I will have to review that. Maybe that can be modified to produce Mg powder in a dry form. Worth a look-see.

Sauron - 25-12-2006 at 05:51

This might help those who can't obtain Mg powder but note that the product is highly pyrophoric (!) if exposed to air when dry. I would therefore advise working up (to dryness) in a glove box with an atmosphere of dry Argon. Note that sodium metal and NaI work in place of K/KI if the quality of the reagents is adequate, and that while activity for the Grignard rxn is reduced, pyrophoricity may also be reduced, which is desirable, and would not be a hindrance to the use of this Mg in the reduction of calcium phosphate. I see no reason why this procedure should not scale up well.

Org.Syn. Coll. Vol. 6, p.845 (1988); Vol. 59, p.85 (1979).

Active magnesium. A 200-ml., three-necked, round-bottomed flask equipped with a Teflon-coated magnetic stirring bar, stopper, rubber septum, and condenser connected to an argon inlet (Note 6) is charged with 1.5 g. (0.038 g.-atom) of freshly cut potassium (Note 7), (Note 8), and (Note 19), 2.01 g. (0.0211 mole) of anhydrous magnesium chloride (Note 9), 3.55 g. (0.0214 mole) of anhydrous potassium iodide (Note 10), and 50 ml. of tetrahydrofuran (Note 11). The mixture is stirred vigorously (Note 12) and heated to reflux with an electric heating mantle (Note 13). A black precipitate starts to form within a few minutes. After 3 hours at reflux temperature, the reduction should be complete (Note 14), producing active magnesium as a black powder that settles very slowly when the stirring is stopped (Note 15).

Notes:

7. Purified grade potassium from J. T. Baker Chemical Company has been found by the submitters to give the most consistent results. The checkers used potassium metal from Allied Chemical Corporation. Very impure potassium or sodium generally gives magnesium powder with much reduced reactivity. Sodium may be used in place of potassium provided that the boiling point of the solvent chosen (Note 11) is higher than the melting point of the metal.
8. The potassium is usually cut into two or three pieces under hexane or heptane and placed wet in a tared flask that has been purged with argon. The flask is evacuated, removing the hydrocarbon, filled again with argon, and weighed to determine the exact amount of potassium. The amount of potassium used by the checkers varied from 1.4 to 1.6 g., the weights of the other reagents being adjusted proportionately. With this procedure the pieces of potassium are shiny and relatively free from oxide coating. Alternatively, the potassium cuttings may be wiped free of solvent, quickly weighed in air, and placed in the flask. The submitters recommend that the first procedure be used.
9. Anhydrous magnesium chloride from Alfa Division, Ventron Corporation, was used as supplied by both the submitters and checkers. The submitters have subsequently had success with anhydrous magnesium chloride and bromide purchased from Cerac, Inc., P.O. Box 1178, Milwaukee, Wisconsin 53201. The checkers were unsuccessful in several attempts to prepare suitably active magnesium from analytical grade anhydrous magnesium chloride, purchased from Research Organic/Inorganic Chemical Corporation. The submitters stress that the reagent must be anhydrous. It may be stored in a desiccator containing anhydrous calcium sulfate and, if required, dried overnight in an oven at 120°. Anhydrous magnesium chloride cannot, however, be prepared by heating the hexahydrate under vacuum, since hydrogen chloride is released before dehydration is complete. The submitters have prepared active magnesium from anhydrous magnesium bromide and iodide; however, highly insoluble magnesium salts such as the fluoride or sulfate are not reduced. A small excess of magnesium chloride is used in this procedure to ensure that the potassium is completely consumed. The submitters have also provided the following unchecked procedure, which is suitable for preparing both anhydrous magnesium chloride and bromide. The magnesium turnings and 1,2-dibromoethane used were purchased from J. T. Baker Chemical Company and Aldrich Chemical Company, Inc., respectively. A 200-ml., three-necked, round-bottomed flask equipped with a magnetic stirring bar, two stoppers, and a condenser connected to an argon inlet (Note 6) is charged with 0.35 g. (0.014 g.-atom) of magnesium turnings, 50 ml. of tetrahydrofuran (Note 11), and 3.0 g. (0.016 mole) of 1,2-dibromoethane. The suspension is warmed gently, initiating the reaction. After the initially exothermic reaction subsides, the mixture is heated at reflux for 50 minutes. The solvent is evaporated under a reduced pressure of argon or nitrogen, leaving a white solid. The flask is then evacuated and heated in an oil bath at 150° for 1 hour. The dry magnesium bromide is ready for preparing active magnesium in the same flask.
10. Potassium iodide (>99% purity) from Allied Chemical Corporation or Mallinckrodt Chemical Works is finely ground with a mortar and pestle, dried overnight in an oven at 120°, and stored in a desiccator. The molar ratio of potassium iodide to magnesium chloride is not highly critical and may vary from 0.05 to 2.0. However, the optimum ratio is 1:1, as specified in the procedure. If the potassium iodide is omitted, the black magnesium powder produced reacts with bromobenzene at −78°. However, since the magnesium prepared in this way does not react with fluorobenzene in refluxing tetrahydrofuran, it is evidently less reactive than that produced in the presence of potassium iodide.
11. The submitters purified the tetrahydrofuran prior to use by distillation from lithium aluminum hydride. For a warning concerning potential hazards of this procedure, see Org. Synth., Coll. Vol. 5, 976 (1973). The checkers distilled the solvent from the sodium ketyl of benzophenone. The submitters have found that diglyme and 1,2-dimethoxyethane are also effective solvents. The reactivity of the magnesium obtained with 1,2-dimethoxyethane as solvent is slightly reduced. Hydrocarbons, amines, and dioxane proved to be ineffective solvents, owing to the insolubility of the magnesium salts and consequent incomplete reduction.
12. Efficient stirring is essential for the generation of highly reactive magnesium. If the stirring is not effective, the reduction may not be complete after the 3-hour reaction time. The remaining unreacted potassium is a fire hazard during the isolation of the product. If the scale of the reaction is increased, measures should be taken to ensure that effective stirring can be maintained throughout the reaction period. The submitters recommend that, as a precaution, the scale be increased gradually.
13. The mildly exothermic reduction may result in excessive foaming which carries potassium particles up into the condenser. This problem is avoided by using a relatively large flask (in this case, 200 ml. instead of 100 ml.) and by carefully controlling the temperature at the beginning of the reduction.
14. The reduction appears to be essentially complete in 30–45 minutes. However, a reaction time of 3 hours is recommended to ensure complete consumption of the potassium (Note 12).
15. Although the submitters have found that the active magnesium may be stored under argon for several days, they advise that the preparation be used within a few hours to obtain the maximum reactivity. Most of the reactions carried out by the submitters with the active magnesium were performed in the same flask and solvent used for the reduction. Attempts to evaporate the tetrahydrofuran and replace it with different solvents resulted in magnesium suspensions of reduced reactivity. The active magnesium may be conveniently transferred to another reaction vessel, if desired, as a slurry under an atmosphere of argon.

Eclectic - 25-12-2006 at 07:39

PCl3 from a metal phosphide is a procedure in Kings Survival Chemistry. Many of the procedures in Kings look suicidal, but this one seems reasonable. I think they use charcoal reduction of calcium phosphate to get the phosphide.

Metal phosphides are used as an agricultural pesticide for gassing burrowing creatures with phosphine. A license is required to purchase in USA.

If your government does not allow you to purchase PCl3, is it legal for you to make and use it? Not that government rules have to be rational...

chromium - 25-12-2006 at 08:12

Quote:
Originally posted by Eclectic
PCl3 from a metal phosphide is a procedure in Kings Survival Chemistry. Many of the procedures in Kings look suicidal, but this one seems reasonable.


It, indeed, seems reasonable but Kings chemistry survival guide should not be used as realiable source (but rather as idea book) because, apart of dangerous, it contains also lot of synths that will give very low yield although they are described as proper high-yield procedures.

Other more reliable sources are needed or someone should try this synth to see what actually happens.

[Edited on 25-12-2006 by chromium]

Sauron - 25-12-2006 at 08:38

A license is required from the Ministry of Defense to import or manufacture chemicals on a certain list. That includes PCl3 PCl5 POCl3 and elemental P (white and red). It does not include the corresponding Br compounds or PI3 for that matter. This country (Thailand) is a signatoree of the CWC and so has definite treaty obligations regarding CWC scheduled chemicals. It is not a member of the Australian Group which seeks to expand the coverage of the CWC but so far is just advisory. The Thai MOD list is lengthier than either, but a lot of what is on there is obsolete (obscure WWI arsenicals, no not the Lewisites, I mean things like cacodyl chloride.) Anyway, if I make and use a small qty of PCl3 to make TMP (also on the list) and use it to make the totally unregulated BEDT-TTF who's going to give a damn? I'm not going to stockpile the naughty precursors and I'm not engaged in anything nefarious (no drugs, no energetics, and no chemical weapons.) The trouble these days is that you can't perform a great many procedures that are really routine any more without requiring something verboten.

Banned solvents

CCl4
CHCl3
1,2-dichloroethane
1,2-dibromoethane

banned chlorinating reagents

SOCl2
POCl3
PCl3
PCl5
SO2Cl2
SCl2
S2Cl2

Other banned basic reagents

Acetyl chloride and acetyl bromide
Acetic anhydride
bromoacetic acid and ethyl bromoacetate
ethyl chloroacetate
ethyl iodoacetate

and so on.

Bromine and dimethyl sulfate are on the list but for some reason are still being sold. I am told that the govt does not care as long as the quantities purchased are not excessive (maybe 1 or 2Kg/month).

Chlorine and sulfur dioxide are proscribed. Fluorine and anhydrous HF are proscribed. Chlorosulfonic acid is proscribed.

Dimethylamine is on the list.

Chloroacetyl chloride is not prohibited, but is effectively impossible to ship any more.

It certainly could have been on the list because of its use in Friedel-Crafts acylation of benzene to make CN (phenacyl chloride tear gas, Mace, chloroacetophenone.) Bromoaacetyl bromide IS on the list for that reason, phenacyl bromide is more potent.

So the list is (as usual) rather arbitrary.

Examples of the obscure and irrelevant on the list:

Selenium mustard
Tellurium mustard -- which turned out not to be vessicant at all
sym-dichlorodimethyl ether

Anyway any practicing synthesist has got to spend his/her time dodging all these "unobtainiums" -- here's an example from peptide synthesis. Standard reagent for global deprotection of peoptides in Fmoc strategy is a 5% soln of piperidine. And now almost everywhere in the world, even university labs need to waste administrator time filling out bureaucratic forms to attest that the piperidine is not to be diverted to making PCP. This is even true in countries where there is no abuse of PCP and no clandestine (or other) production. What good is this? Piperidine is not hard to make.

This is all a huge nuisance. And I doubt that it's in aid of anything. Example: acetic anhydride. Because of Thailand's proximity to Burma and Laos heroin production Ac2) is a huge no no here. So even school labs can't have small quantities.

But that hasn't slowed down heroin manufacture one little bit. So what is it in aid of? What good does it so?

No one should feel guilty about bending such a rule.

If I need it I make it and I use it. I don't keep it around and I don't sell it on the black market. I wouldn't know how to make contact with the black market. If I did I wouldn't have any trouble getting red P would I?

Surely these are sentiments shared by most of the people on this board, yourself included?

Sauron - 25-12-2006 at 08:47

I never heard of Kings Survival Chemistry. It sounds like a contemporary descendant in spirit of The Anarchist's Cookbook from the 60s (I am an old fart). I used to read that and laugh at the idea that anyone would be foolish enough to take those instructions seriously. We used to joke that the govt must have put it out to kill off clueless radical wannabe bomb makers.

Sauron - 25-12-2006 at 09:06

Calcium phosphide as a rodenticide: yes that was clear from Googling it. It also has been employed at some point in the past as an incendiary in aerial bombs. Also in signal flares.

Apart from the technical issues and the cost and the questions unsnaswered on shipping and importation here, I see no reason not to try this.

Same goes for chlorination of P2S5. I started a thread on that, but so far it's gone unnoticed, maybe due to the holidays. I have the stuff on hand, top quality from Merck. When chlorinated will it fall apart to PClx and SxCly? Or will it give a more complex product SxClyPz. I dunno. Anyway it's OT here.

Eclectic - 25-12-2006 at 09:57

You could try carbon reduction of calcium phosphate in your tube furnace, followed by chlorination in situ. I'd be interested to know if the procedure actually works.

A potential problem might be the formation of a stable adduct of PCl3 with the metal chloride.

This is the ONLY prep in Kings that actually seemed reasonable to me. There is a copy on the FTP site I think...

Sauron - 25-12-2006 at 10:21

I seem to recall that there are certain phosphrus compounds that upon hydrolysis fall apart to red P among other products. I will look for th source and see if any of them are accessible by purchase or preparation.

I can also hire local people cheap to cut up vast numbers of matchbook covers like 100,000 of them. If I retrieve 1 mg red P per cover, there's 100 g for the cost of that labor plus some technical acetone (sold here in 22 L tins.) I realize this is footling but, anything else is looking like becoming a magnum opus.

CD-ROM-LAUFWERK - 25-12-2006 at 11:45

red P is not souble in aceton, in fact, i dont know any solvent
afaik the P only is on the striking surface, not on the match itself

Sauron - 25-12-2006 at 12:44

Yes I am well aware. I toss the matches. The match boxes have two striking surfaces and that's where the red P is. The acetone is to dissolve the glue and liberate the P from the adhesive. Time and agitation help. The fine suspension of P gets filtered and the P is ready for cleanup. It is not a high tech procedure.

But thanks for your advice.

What to do with about 5-10 million leftover matches? Laboriously recover a few hundred g antimony trisulfide? Not worth the effort.

12AX7 - 25-12-2006 at 14:45

Ain't there P4S3 (or P3S4?) in there too? Oughta be something that can be done with it, maybe does it decompose i.e. "dry" distill to P4 + liquid S?

Tim

[Edited on 12-25-2006 by 12AX7]

S.C. Wack - 25-12-2006 at 15:38

I already posted on this in the phosphorus chlorides (inexplicably in Organic Chemistry). I think there is a Russian reference somewhere with Zn reduction.

"I seem to recall that there are certain phosphrus compounds that upon hydrolysis fall apart to red P among other products" - I wouldn't think so. But thanks for posting the long preparation for Rieke magnesium. I'm sure we're all going to be rushing to use potassium to make magnesium with your help, or buying his inexpensive products from his company. And thanks to everyone for adding yet another valuable page to this thread.

The [_rl=]words[/_rl] is not working. It used to.

Review http://ep.espacenet.com/advancedSearch?locale=en_ep , typing in C01B25/01, C01B25/02, or C01B25/10 in the European Classification field, if you really want to know P chemistry.

[Edited on 25-12-2006 by S.C. Wack]

Sauron - 25-12-2006 at 18:35

Why the apparent sarcasm, S.C.Wack?

I pointed out the note in that procedure that says that Na works in place of K. I doubt I am the only one who has been stymied in buying Mg powder. I am not a shill for any supplier. I'm just another chemist trying to make little ones into bigger one like the rst of us.

Potassium is too expensive and too much of a pain to handle. I have 250 g of it sitting under parafin oil and it cost me dearly. On the other hand I have about 6 Kg Na on hand. Which metal am I more likely to use?

Thanks for the pointer to your post on Zn, which I will go see.

I did find the ref I was after, there are simple P compounds that fall apart to red P and other products but so far none of them appear to be of practical preparative value. If you are interested I can write them up but, it sounds like you would prefer I keep my insights to myself.

I do not fathom the hostility you are putting out.

But, I do appreciate all your work on the Library. So have a happy New Year.

Sauron - 25-12-2006 at 18:44

The phosphorus sulfide in match tips is admixed with SbS3 and other things, seems like a lot of work to recover a modest qty. I already have commercial P2S5 on my shelf and know what it is for. I have yet to see a synthetic use for the trisulfide which seems to have only this one technological niche. Maybe it has other uses in pyrotechnics, but that is off my beat.

If I needed it that would be different.

S.C. Wack - 25-12-2006 at 22:48

Both Kirk-Othmer and Ullmann's do not mention antimony in modern matches, so you might want a reference to their presence.

The Russian ref using Zn and P4S3 is Zhurnal Prikladnoi Khimii 44(2) 429-33 (1971). It seems quite impractical as apparently done and the yields are unknown to me, but it illustrates the question of reduction, which seems not tackled elsewhere. Not having Crossfire available to me, I can't say for sure if there is more modern research. They used quartz tubes, 1100C, 10.5 torr, and 10 minutes in: P4S3 + 3 Zn -> 3 ZnS + P4.
However,
P4S3 + 9 Zn -> 3 ZnS + 2 Zn3P2. also,
2 Zn3P2 + 6 S -> 6 ZnS + P4 and
2 Zn3P2 + 9 S -> 6 ZnS + P4S3

The patent searching part was not sarcasm. It is quite interesting.

P4S3 matches are sadly too expensive to try 16 KClO3 + 3 P4S3 -> 16 KCl + 6 P2O5 + 9 SO2, and the kitchen matches do seem to be getting replaced with the non-P4S3 matches on the shelves here.

*waits for* "What's the problem getting P4O10, I have kilos of it on my desk. Why don't you just buy some from Mallinckrodt?"

Sauron - 26-12-2006 at 00:46

No problem getting P4O10 here, at all. Thanks for the Russian ref. Given the cost of the P4S10 I have not to mention the quartz tube I don't have I think I will just find another employement for my tube furnace. It does have an 1100 C top end and it's a pretty good size (5 cm diameter x 30 cm longth) and 5.5A # 220 V. I got it for $100 on LabX. I know the seller well, we have done business before so I am happy.

If you see the Chlorination of P4S10 thread (in which I am still sole poster) I posted a number of interesting uses for the pentasulfide in organic synthesis. Some I already knew and some fell out of a Google. So in the end if I hang onto this pentasulfide rather than just trying to pull the red P out of it that may be just as well.

If I can't make or buy red P I can still fall back on the matchbooks gambit and failing that I have plenty of other projects to absorb my attention. This phosphorus thing has been puzzling and frustrating me for several years and I keep picking away at the problem in hope of a practical solution.

garage chemist - 26-12-2006 at 08:43

I think that the microwave heating of a charcoal/phosphoric acid mix to produce white phosphorus is the most promising home method for phosphorus production.
Charcoal absorbs microwave energy very efficiently. In the german board a user has documented how he successfully melted silver (1000°C!) using charcoal granules in a microave oven.

Sauron - 26-12-2006 at 13:18

Any sentence containing the concatonation "prparing white P in the home" seems to me to be epistomologically invalid. Dental caries and "phosphrus jaw" anyone?

My own goal is to obtain red P not white or to proceed directly to PCl3 without passing "Go" or collecting any loathsome illness.

Seriously though - I was being jocular - on a preperative scale that does sound like rather a lot of microwave energy to expect. Or to control. Or to generate. Anyway wouldn't it be better to start with C/P2O5 rather than forcing your MW system to drive off the water from the PA first?

The process needs a lot higher temp than 1000 C, 50-100% higher.

The advantage of the calcium phosphate reduction to Ca phosphide is lower heat required to initiate. If you use the aluminothermic variation, external heat is not employed (after ignition of a Mg ribbon).

And dealing with white P is avoided.

garage chemist - 26-12-2006 at 14:57

Well, I am able to buy red phosphorus, and I have prepared quite a bit of the white modification from it.
The reason: Red phosphorus can not be chlorinated to PCl3.
I have done countless experiments on it. Adding chlorine to red phosphorus always results in PCl5, no matter if you do it in an inert solvent or just in protective atmosphere or with any else method.
PCl3 can only be prepared from white phosphorus, which I have done and which works nicely (in protective atmosphere of course).
Here is my documented synthesis of PCl3 from white phosphorus:
http://www.versuchschemie.de/topic,5775,-Phosphortrichlorid....

And here is my documented synthesis of PCl5 from red phosphorus in dried Chloroform:
http://www.versuchschemie.de/topic,8040,-Herstellung+von+Pho...

Here is my conversion method of red P into white P (well, "yellow" P, but commercial white P is always yellow, the term "white" comes from the white crust that forms on it after months under water):
http://www.versuchschemie.de/topic,5774,-Wei%DFer+Phosphor.h...

I would be very happy to find a method that allows the generation of PCl3 directly from red P without having to deal with the white form. I have experience with white P and know how to handle it safely (though I encountered several bad surprises of it violently catching fire and splattering burning drops everywhere) but it is just plain nasty.

You see, having access to red P does not solve the problems. PCl3 remains a rare substance even if you can get red P.
However, if you can get white P instead, your problems are solved.

The closest I have come to making PCl3 from red P is the discovery that PCl5 heated with red P makes PCl3 which can be distilled off. The reason I am not doing this is a) the PCl5 preparation is lengthy and b) the resulting PCl3 is strongly contaminated by POCl3 because PCl5 is incredibly hygroscopic.

Sauron - 26-12-2006 at 15:50

Lucky for you, you can buy red P.

If, as your experience indicates red P can't be chlorinated to PCl3 but always proceeds to PCl5, that is not much of a problem as PCl5 also reverts to PCl3 when red P is added (although it takes some time).

6 PCl5 + P4 = 10 PCl3

So for each mol of PCl5 add about 20 g red P and let it sit at rt till it is liquified and then distill.


My problems would disappear if I could prepare trialkyl phosphites from PBr3 which I can buy. (and have already done.)

Another possibility is to procure an available alkyl phosphite and cleave off the alkoxy groups with chlorine. It is only the C1 and C2 trialkyl phosphites that are proscribed. n-Propyl is not. n.Butyl is not. Triphenyl phosphite is not. If the Cl2 concentration is kept high then the liberated alcohols will be disfavored from recombining with the PCl3. This might need to be done in several steps and worked up in between.

I can't dispute your experience but see Inorg.Syn. 2, p 145 (1946) for prep of PCl3 from red P. That's the ref from Merck Index 12th. Maybe it's a matter of technique?

[Edited on 26-12-2006 by Sauron]

[Edited on 27-12-2006 by Sauron]

[Edited on 27-12-2006 by Sauron]

garage chemist - 26-12-2006 at 16:04

I have already written in my previous post that PCl5 can be converted to PCl3 by heating with red P. And I have also written why this technique is not good at all.

Can you tell me some details about the preparation of PCl3 from red P? I can't access this reference. I would be most interested in this.
Or do they cheat by using premade PCl3 as reaction medium as I have already seen?

Sauron - 26-12-2006 at 16:53

I don't have the full text of the Inorg.Syn Vol.2 p.145 prep of PCl3. I only have the citation from Merck Index.

I'd like to request this article from the forum, but have not the password for the References forum as yet.

I emailed a Moderator and requested this password a few days ago but no answer.

Brauser does not have a PCl3 prep, nor PCl5.

Gattermann prepared this from white P.

Somewhere else I recall reading that red P is placed in a combustion tube, warmed, and a SLOW stream of dry Cl2 is passed over it, the tube being angled downward toward the receiver so that the PCl3 flows to the receiver. I think it is done under nitrogen too. But I can't recall where I saw this and might be confusing it with some other prep entirely.

All sources say that PCl5 forms if chlorine is in excess so I's say keep P in excess, distill off from the unreacted red P. Most sources also say some PCl5 usually forms but being solid is left behind upon distillation. Several sources point out that strong heating breaks PCl5 into PCl3 and Cl2. Although that may be of questionable preparative value as they would rapidly recombine.

S.C. Wack - 26-12-2006 at 17:56

If only someone would scan good parts of Inorg Syn and post it as djvu somewhere.

That article uses PCl3 to obtain PCl3.

Are we trying to make this like the DPPP thread? I didn't get the memo.

On topic, "I seem to recall that there are certain phosphrus compounds that upon hydrolysis fall apart to red P among other products"..."I did find the ref I was after, there are simple P compounds that fall apart to red P and other products "

Which ones are these, exactly?

Sauron - 26-12-2006 at 20:12

Are the early years of Inorg.Syn. in the public domain yet? I think it was originally a McGraw-Hill property before Wiley got their mitts on it. Too bad Wiley hasn't donw with it like they have with Org.Syn. and made it freely available in searchable form on the net.

Yes, if someone would pdf or DjVu these I'd shake their hand or buy them a Havana cigar.

Here's what I found in an early 20th century encyclopedia online:

http://www.1911encyclopedia.org/Phosphorus

There's actually some thought provoking info there.

I will go find the particular paragraphs now.

"Phosphine (phosphoretted hydrogen), PH 3 a gas formed in the putrefaction of organic matter containing phosphorus, was obtained by Gengembre (Crell's Ann., 1789, i. 450) by the action of potash upon phosphorus, the gas so prepared being spontaneously inflammable. Some time later Davy, by heating phosphorous acid, obtained a phosphoretted hydrogen which was not spontaneously inflammable. These gases were considered to be distinct until Le Verrier (Ann. chim. phys., 1835 [2], 60, p. 174) showed that the inflammability of Gengembre's phosphine was due to small quantities of liquid phosphoretted hydrogen, P 2 H 4. Phosphine may be prepared by the decomposition of calcium phosphide with water (P 2 H 4 being formed simultaneously); by the decomposition of phosphorous and hypophosphorous acids when strongly heated; and by the action of solutions of the caustic alkalis on phosphorus: P4+3NaOH+3H20= PH3+3NaH2P02; hydrogen and P 2 H 4 are produced at the same time, and the gas may be freed from the latter substance by passing into a hydrochloric acid solution of cuprous chloride, and heating the solution, when pure phosphine is liberated (Riban, Comptes rendus, 58, p. 581). The pure gas may also be obtained by heating phosphonium iodide with caustic potash (A. W. Hofmann, Ber., 1871, 4, p. 200); by the decomposition of crystalline calcium phosphide or of aluminium phosphide with water (H. Moissan, Bull. soc. chim., 99 (3), 21, p. 926; Matignon, Comptes rendus , 1900, 130, p. 1391); and by the reduction of phosphorous acid with nascent hydrogen.

It is a colourless, extremely poisonous gas, possessing a characteristic offensive smell, resembling that of rotting fish. It becomes liquid at-90° C., and solid at -133° C. (K. Olszewski, Monats., 1866, 7, 37) It is only slightly soluble in water, but is readily soluble in solutions of copper sulphate, hypochlorous acid, and acid solutions of cuprous chloride. It burns with a brightly luminous flame, and is spontaneously inflammable at about too° C. When mixed with oxygen it combines explosively if the mixture be under diminished pressure, and is violently decomposed by the halogens. It is also decomposed when heated with sulphur or with most metals, in the latter case with the liberation of hydrogen and formation of phosphide of the metal. It combines with the halide derivatives of boron and silicon to form, e.g. PH3.2BF31 2PH 3 =S1C1 4 (Besson, Comptes rendus, 1890, Ito, 80, pp. 240, 516; 1891, 113, p. 78), with the halogen acids to form phosphonium salts, PH 4 X (X=C1,Br,I), and with sodammonium and potassammonium to form PH 2 Na, PH 2 K (Joannis, Comptes rendus, 189x, 9, 557). It oxidizes slowly in air, and is a reducing agent. It decomposes when heated, hydrogen and red phosphorus being formed."


That's one example. I am NOT proposing this as a preparative method, but PH3 can be prepared from materials other than elemental P, some of them commercially available, and decomposed by strong heating into H2 and RED P. True enough that the toxicity of PH3 makes this too hazardous to actually contemplate IMO but there it is. Whether it is or is not more hazardous than an aluminothermic rxn liberating a phosphide (which would liberate PH3 and P2H4 anyway if exposed to moisture) or various processes at 1500-1800 C, liberating white P in vapor phase, is a matter of opinion.

Again, NOT my idea of a project except as an elaborate former of suicide. But, there it is.

Calcium phosphide is commercial.
Phosphonium iodide may be commercial; it is solid and stable.
Phosphorous acid is most definitely commercial, Merck sells it and AFAIK it is not restricted.

All of those are PH3 precursors, the first suffers from the collateral liberation of diphosphine, from which it has to be seperated.

I will look for more examples.

[Edited on 27-12-2006 by Sauron]

[Edited on 27-12-2006 by Sauron]

[Edited on 27-12-2006 by Sauron]

Sauron - 26-12-2006 at 21:52

NB: that encyclopedia appears to have been OCR'd without editing so there are occasional errors, particularly in equations but they are generally easy to spot like P257 in a section on P-S compounds is clearly meant to be P2S7, Make allowances.

Sauron - 26-12-2006 at 22:37

From the same article another imptactically hazardous route to P (but it does not say red or white) or tantalizingly, this could just be a route to PCl3 without combining P and Cl.

P4O6 described in text below is the anhydride of phosphorous acid.

As I have already posted elsewhere, P2O5 (P4O10) is converted to POCl3 by the action of oxalyl chloride.

The only other products are CO and CO2.

Therefore, it is perfectly reasonable to conclude that P4O6 will react with oxalyl chloride in like fashion to give PCl3.

The fly in the ointment is that P4O6 is toxic. It may not be commercially available. If not then preparing it would be hazardous.

"Phosphorus oxide, P 4 0 6, discovered by Sage in 1777, is a product of the limited combustion of phosphorus in air. It may be conveniently prepared by passing a rapid current of air over burning phosphorus contained in a combustion tube, and condensing the product in a metal condenser, from which it may be removed by heating the condenser to 50 0 -60° (Thorpe and Tutton, Jour. Chem. Soc., 1890, pp. 545, 632; 1891, p. 1019). Jungfleisch has obtained it by carrying out the combustion with oxygen under reduced pressure, or diluted with an inert gas. It forms crystals, apparently monoclinic, which melt at 22.5° to a clear, colourless, mobile liquid of boiling-point 173-i°. Its specific gravity is 2.135 at 21°. Vapour density and cryoscopic determinations point to the double formula, P406. It is comparatively stable up to 200°, but when heated in a sealed tube to 440° it gives phosphorus and the tetroxide P204. It is unaffected by light when pure, but if phosphorus be present, even in minute quantity, it turns yellow and ultimately dark red. It oxidizes on exposure to air to the pentoxide, and with a brilliant inflammation when thrown into oxygen at 50 0 _60°. It slowly reacts with cold water to form phosphorous acid; but with hot water it is energetically decomposed, giving much red phosphorus or the suboxide being formed with an explosive evolution of spontaneously inflammable phosphoretted hydrogen; phosphoric acid is also formed. With dilute alkalis phosphites are slowly formed, but with concentrated solutions the decomposition follows the same course as with hot water. With chlorine it gives phosphoryl and " metaphosphoryl " chlorides, the action being accompanied with a greenish flame; bromine gives phosphorus pentabromide and pentoxide which interact to give phosphoryl and " metaphosphoryl " bromides; iodine gives phosphorus di-iodide, P 2 I 4, and pentoxide, P 2 0 5; whilst hydrochloric acid gives phosphorus trichloride and phosphorous acid, which interact to form free phosphorus, phosphoric acid and hydrochloric acid. It combines violently with sulphur at 160° to form phosphorus sulphoxide, P406S4, which forms highly lustrous tetragonal plates (after sublimation), melting at 102° and boiling at 295°; it is decomposed by water .into sulphuretted hydrogen and metaphosphoric acid, the latter changing on standing into orthophosphoric acid. Sulphur trioxide and sulphuric acid oxidize phosphorus oxide, giving the pentoxide and sulphur dioxide, whilst sulphur chloride, S 2 C1 2, gives phosphoryl and thiophosphoryl chlorides, free sulphur and sulphur dioxide. Ammonia also reacts immediately, giving phosphorus diamide, P(OH)(NH2)2, and the corresponding ammonium salt. Phosphorous oxide is very poisonous, and is responsible for the caries set up in the jaws of those employed in the phosphorus industries (see below). It is probable, however, that pure phosphorous oxide vapour is odourless, and the odour of phosphorus as ordinarily perceived is that of a mixture of the oxide with ozone."

Sauron - 26-12-2006 at 23:06

Alfa does not show P4O6 but they do sell phosphorous acid, 97%, 98% and 98+%.

[Edited on 27-12-2006 by Sauron]

Sauron - 27-12-2006 at 00:08

Merck Index 12th edition has this stuff listed as phosphorus trioxide P2O3 monograph 7517 on p. 1267

A useless circular prep from PCl3 with tetramethylammonium sulfite in liq SO2: Jander et al. Ber., 77, 689 (1944)

Preparation from P and O

Thorpe, Tutton, J.Chem.Soc 57, 545 (1890)
Miller, ibid. 1928, p 1847 and 1929, p. 1823
Wolf, Schumager, Ber., 62, p 779 (1929)

Review: van Wazer, Inorg.Chem. 5, 178 (1966)

Dissasocates to RED P abd P2O4 when heated above 210 C

That is now two simple phosphorus compounds that proceed to red P, as I remembered, although unfortunately neither is likely to be useful. I would like to see those areticles though and I would like to know if their is a commercial source for P2O3/P4O6.

Maybe one of the specialist phosphorus-chemical companies.

SPECULATION

H3PO3 + excess Oxalyl Chloride (might dehydrate the acid to the "anhydride" then clorinate the P4O6 to PCl3 the "acid chloride"

H3PO3 + CC slight excess - dry distillation
Sodium phosphite + CC same process

(CC is TCT cyanuric chloride, trichloro-s-triazine)

Those are safe and cheap and well worth a try! Well CC is cheap, oxalyl chloride not quite so cheap unless you make your own from CC and anhydrous oxalic acid or anhydrous sodium oxalate.

(Getting crazed Gene Wilder expression on face) This...could...WORK!!
(Thunrclap and lighning flash)

Sauron - 27-12-2006 at 01:23

in A Treatise on Inorganic Chemistry Volume 1 (from this site's Library) the author gives on page 488-89 a procedure for preparation of P2O3 (P4O6) simply by burning white P in a combustion tube with a limited flow of air. The apparatus is illustrated.

On the following page in section on Phosphorous acid he states that equimolar amounts of H3PO3 and PCl5 give equimolar amounts of PCl3 and POCl3 plus 3 mols of HCl.

Thus there are not one but two ways to convert PCl5 (from chlorine combustion of red P) to PCl3:

1. 6 PCl5 + P4 (red) = 10 PCl3 rather slowly

2. PCl5 + H3PO3 = PCl3 + POCl3 + 3HCl

(2) has drawback that half of one's hard-won PCl5 is converted not to PCl3 but to a different but still useful reagent.

I would still like to hear why our esteemed colleague garage mechanicdoes not favor (1).

[Edited on 27-12-2006 by Sauron]

Sauron - 27-12-2006 at 01:37

PS I am sure red P will also burn in limited air to phosphorus (III) oxide just will require a higher ignition temperature, right?

This would obviate the need to convert red P to white P or otherwise prepare or procure white P.

roamingnome - 17-1-2007 at 16:01

Quote:

think that the microwave heating of a charcoal/phosphoric acid mix to produce white phosphorus is the most promising home method for phosphorus production.


garage chemist


so do you have any updates or tips about this process....

all i know is a SHARP model 1200 watt microwave that i used the other day works soooo good I was quite amazed that my pizza burnt in like 25 secounds! now i want one of my own.... SHARP models i think are better....

i just know that it can really work for gold refining or the like...

garage chemist - 17-1-2007 at 16:58

I have not done research into this, but I have heard of patents here that specify the microwave heating of a charcoal/phosphoric acid mix as a method to produce elemental phosphorus.

It would be a simple experiment to see if this is promising: wet some activated charcoal with 85% phosphoric acid, heat in an oven to drive off the water, fill the mix into a loosely stoppered test tube (glass wool or the like) and microwave it for several minutes at full power. See if the mix absorbs the microwaves and heats up to red or even yellow heat. Phosphorus production would be evident if the vapors catch fire upon meeting the air or the green glow is visible, or maybe even yellow drops of P condense on the glass wall.

I do not have my "research microwave" ready, I have dismantled it to make use of the transformer inside. But I still have all the parts needed to drive the magnetron, so I can put it together again when I have time (in spring or summer).

[Edited on 18-1-2007 by garage chemist]

Per - 27-1-2007 at 05:37

I´m very interested in the preparation of white phosphorus by electrolysis.

But I don´t even found a solvent which solve any matal phosphide and doesn´t react with white phosphorus.

The elektrodes could prevent from deposite phosphorus while heating the solvent of about 45°C so the P wuold melt and the electrolyse could go on, otherwise the P would isolate the electrode.

Does anybody knows a solvent which solves any phosphide?

garage chemist - 29-1-2007 at 05:52

In the german forum a member reported that heating sodium hypophosphite in a test tube yielded substantial amounts of white phosphorus (condensate on the walls) and also some PH3.

If somebody here has sodium or another hypophosphite salt I definately recommend trying this out (only under a fume hood of course) to confirm this (I do not have any hypophosphite- I could make it myself from white P, but my white P is too precious for that).

Per - 31-1-2007 at 08:18

Couldn´t Na3P prepared by heating Na3PO4 with Al or Mg powder?

Or by mixing melting Na with Na3PO4?
8Na + Na3PO4 > 8Na2O + Na3P
Sodium isn´t so expensive, soon I will buy 1kg for just 50,90€.

S.C. Wack - 3-2-2007 at 21:59

Since the supposed lack of hydrogen reduction power came up in another thread, here is the article related to the Pb3(PO4)2 reduction/chlorination patent that was brought up and that I linked to earlier in this thread. Not that the patent doesn't cover it all, this is just because I can scan my photocopies and I'd like to see a site where this sort of thing is done a little more often. As opposed to people authoritatively talking out of their ass or writing throwaway post after throwaway post on science issues, like so much of the internet.

An Annales de chimie et de physique (Annales de Physique) article mentioned in the paper and patent as a good experimental look at reduction by hydrogen looks interesting, but the holdings of the local library don't go back to 1953; and of course Gallica stops short.

Now if only I knew at what temperature sugar charcoal reduces this salt. I don't have any 1700's journals. It would be an interesting experiment.

Journal of Labelled Compounds and Radiopharmaceuticals 15, 117 (1978)

Attachment: jlc_15_117_1978.djvu (244kB)
This file has been downloaded 1039 times


Polverone - 22-2-2007 at 23:24

Quote:
Originally posted by S.C. Wack
An Annales de chimie et de physique (Annales de Physique) article mentioned in the paper and patent as a good experimental look at reduction by hydrogen looks interesting, but the holdings of the local library don't go back to 1953; and of course Gallica stops short.

Turns out my local library did have it, though this isn't the nicest scanning work I've ever done:

CONTRIBUTION A L'ÉTUDE DE L'ACTION DE L'HYDROGÈNE SUR LES PHOSPHATES

For the low-temperature production of phosphorus, the most interesting candidates appear to be phosphates of lead, bismuth, and antimony. The case of silver phosphate is rather interesting too, as its reduction first yields finely divided metallic silver plus phosphoric acid, which appears to be catalytically reduced in the presence of the silver to give free phosphorus.

Other metals may be reduced at even lower temperatures, but they give phosphides or phosphites, depending on metal and conditions, never free phosphorus. I daren't wonder how much harder the reductions would be with hydrocarbon gases in place of hydrogen... yet I do wonder, given the difficulties of preparing pure dry hydrogen from metal and acid as opposed to cracking the valve on a gas line or cylinder.

Strepta - 3-3-2007 at 17:46

Note: See attachment for pictures.

I attempted the reduction of Pb3(PO4)2 according to the method (H2 reduction of Pb3(PO4)2 @ 700C) in the patent by Rupp, et al. I made a quartz tube furnace from a section of .8” i.d. quartz tubing overwound with nichrome wire from a toaster oven. It is shown in the first photo, with 115v volts applied.



The actual color of the energized nichrome was orange, the violet effect apparently a combination of the photo flash and the emitted light. A firebrick has been drilled lengthwise (1 inch dia) through which the quartz tube is fitted and acts as insulation. The temperature in the tube is monitored with a Fluke P 80 inconel immersion type probe embedded in the Pb3(PO4)2 and connected to an ExTech temp meter. The input and output ends of the tube are fitted with natural cork stoppers which stand up to the heat far better than rubber. The cork to glass tube joint is sealed with silicon rubber. To further ensure that the system remains sealed, the ouput tube is run into a beaker of water and produces visible/audible bubbles when everything is working correctly.

The tube is charged with Pb3(PO4)2 also made according to Rupp (except for the ultrasonic agitation). The Pb3(PO4)2 was dryed in an oven and ground to a flour –like consistency using a coffee grinder.

The hydrogen is generated by electrolysis using sulfuric acid-water at battery acid concentration, ie, sg =1.275. The anode and cathode are both made from sheet lead (from Home Depot). The cathode is a 3 inch high section spiraled inward for max surface area. A 3 inch wide funnel is mounted over the cathode to capture the H2 and funnel it into a 10 in. long tube which is terminated with a rubber stopper. A glass tube carries the hydrogen out and another hole in the stopper permits a piece of #10 Cu wire to complete the circuit to the cathode. The anode is also sheet Pb and sits immediately above the cathode.




Transformer & rectifier/fan

The 10 inch collection tube permits the generator to produce a sufficient “pressure head” to bubble the H2 through the subsequent H2SO4 and CaSO4 dryer sections.

The container is a tall glass flower vase. When operated (typically @ 6 amps) for an hour, the solution becomes too hot to handle. It also progressively darkens as it produces the brown precipitate, PbO2, as can be seen in the sequence of photos. A strong odor of ozone is apparent during operation.

In the experiment shown, about 12 g of the Pb3(PO4)2, prepared as described as above, was placed into the quartz tube against a wad of fiberglass insulation to hold it in place.

The hydrogen generator (6.6 amp) is started and run for about 10 minutes before the heating coil is energized. Heating is begun slowly, keeping the temperature below 400C for the first hour. You can see the moisture from the drying and later reduction condensing in the far section at the output of the quartz tube.


H2O Condensation




After the H2O no longer appears at the end of the tube, the temp is raised to 700 – 750C.
A red film deposit near the output of the tube appears first. Later and further away a yellow film appears. There was also a popping sound and some smoke from bubbles (PH3?) breaking the surface of the water in the beaker.






Last picture is apparatus being disassembled. Only a film of P was produced—no quantity of any significance. The viability of this as a practical technique for producing even laboratory amounts (a few grams) remains to be demonstrated.

[Edited on 4-3-2007 by Strepta]

[Edited on 4-3-2007 by Strepta]

Attachment: Reduction of Pb3(O4)2.doc (522kB)
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Magpie - 3-3-2007 at 20:37

Nice try, with several clever uses of OTC materials noted. Nice "chromatographic" separation of yellow and red phosphorus? ;)

What was your expected yield? Do you think too much P went off as PH3? What do you think needs to be changed?

Strepta - 7-3-2007 at 06:46

Quote:
What was your expected yield? Do you think too much P went off as PH3? What do you think needs to be changed?


8 H2 + Pb3(PO4)2 --> Pb +2P + 8H2O

It takes 8 moles of H2 to reduce 1 mole of Pb3(PO4)2 into 2 moles of P. I had used just 12 g of Pb3(PO4)2 or 12.0/811 = .015 mole.

(.015)(32)(2) ~ 1g P. This would be the max available P from 12 g of the phosphate.

It takes 2 moles of electrons to produce 1 mole of H2 from 1 mole of H20. (8)(.015)(2)(105coulombs/mole) = 24,000 Amp-seconds of charge. This is equiv. to 6.7 amp-hours for reduction of the 12g of phosphate assuming 100% efficiency.

I ran the generator for a couple of hours @ 6 amps. The first hour is the low heating portion to remove moisture and the second hour the active reduction at ~ 700C. After this time the glass container of the electrolysis cell is very hot to the touch. If I had achieved even 10% efficiency, I should have produced ~ .1 g of P. I’m sure that the film shown in the photos is considerably less than that.

I don’t believe that much P was lost to PH3, but that is very subjective.- I don’t have any evidence to back it up—just a gut feel.

I know little about the applied practice of gaseous reduction of solids, but suspect that the crystal size of the reductant is critical, smaller being better. Certainly a lot of the gaseous H2 went right over the powdered phosphate without ever contacting it, although this is the description of the technique given by Rupp. The use of ultrasonic agitation (Rupp) may help to produce ultrafine crystals.

I first used the H3PO4 + PbO synthesis for Pb3(PO4)2 described by Rupp, but after reading Hutter, I used his procedure. That method uses Na2HPO4 and Pb(C2H3O2)2 according to the technique developed by Alders and Stahler (1909). Dilute solutions of both reactants are kept near boiling and the biphosphate is added to the lead acetate dropwise to keep the concentration of H3PO4 to a minimum. Alders and Stahler show in their 1909 work that unless this is done, the secondary (PbHPO4) and primary, (Pb(H2PO4)2), phosphates of lead will dominate over the desired tertiary salt, Pb3(PO4)2. This work is at variance with that of Rupp, who states: “The acid
concentration is not critical to the reaction, with .1 M to 100% acid suitable for this step”—go figure. I have a .pdf of the Alders and Stahler paper (German) if anyone is interested, but the quality of the copy is poor—almost unreadable in sections.

I also prepared BiPO4 according to method II in Handbook of Preparative Inorganic Chemistry, 2nd ed, Schenk, p. 626. This method is similar to that given in Hutter except that it uses Na2HPO4 instead of (NH4)2HPO4. I had no success with that attempt, although Hutter says: ‘The reduction (of the Bi PO4) begins suddenly at 425C and is very rapid. There is a phosphorus deposit on the outlet side of the furnace and the gondola contains only bismuth. The reduction is thus complete and bismuth phosphide is not formed.’

I’m interested to hear if anyone else has tried any of these or related hydrogen reduction experiments and what they may have found.

[Edited on by Strepta]

Polverone - 7-3-2007 at 12:00

I agree that it seems unlikely that you lost much phosphorus as phosphine. Hutter did not find any phosphine produced in the reduction of lead phosphate, testing for PH3 in the waste gases with a mercuric chloride/potassium iodide strip. But if you look at Figure 3, curve 2 in the Hutter paper, it appears that you may need to go above 750 degrees to get full reduction. I don't know what temperature your apparatus is capable of.

The only other difference I would remark upon is that Hutter calcined his phosphates to remove water, then re-powdered them before the reduction, while you did not make that separate step. I don't know if that would make much difference, but it does seem at least possible that doing it in a separate step would yield a finer powder that is more readily reduced.

Magpie - 7-3-2007 at 12:16

I have no experience with gas-solid reactions. I did see on TV (of all places) a demonstration of the deoxygenation of an iron oxide using hydrogen. The oxide was placed in a boat and the boat was placed in a glass tube. H2 was passed through the tube as the tube was heated using a bunsen burner. Apparently this was successful as demonstrated by the magnetizability of the the iron product. % yield wasn't determined, however.

Did you weigh the residue remaining in the tube? If your stoichiometry is correct this could be a method to determine how much P was released. Can you do any quantitative analyses that would indicate the degree of reaction completion, such as a determination for phosphate?

evil_lurker - 31-3-2007 at 01:37

Thought I'd take a gander at what all progress has been made toward the goal of P... looks like strepta has definately made some progress in the right direction.

Just for shits and giggles I happend to do some digging on googles new patent seach. I found a reaction which is very very interesting... I'm in the process translating the patent DE929999.

In a nutshell, calcium phosphate and aluminum powder is finely intermixed and set off via magnesium ribbon and the reaction proceeds somewhat like thermite, with the resulting mass consisting of a decent portion being calcium phosphide. Of course the phosiphide can be reacted in water to form phosphine, which can be reduced at high temps... so far I've gotten translated:

The production of the mixtures takes place in simplest way via thorough, dry merging of the respective components in purify-distributed form. The adherence to the theoretical weight quantities determined after the decomposition equation is not always appropriately, since the maximum of the reactivity and the necessary Zuendlichkeitsgrad does not agree often with the theoretically guestigen mixing proportion. As example of a such mixture is aforementioned: Aluminum Pyroschliff 43% calcium phosphate tertiarily 57% Such mixtures are naturally completely innocuous and harmless and can step in no way with water in the sense into reaction that it can come to the development of phosphorus hydrogen. They are shelf stable unbegrentz and can be dispatched and stored without any danger. During suitable composition they are relatively easily inflammatory, so that the Reacktion can be already released by a match flame or a through-glowing salpeterpapier. The using reaction exists in a rapid Fortglimmen of the mass, similarly the burn-off Thermitgemi down. The compact cinder staying contains the Metallphosphid in even distribution with derm crystallized alumina formed at the same time. Due to this even dilution the Reacktion with water is not by any means as stormy as those of the pure phosphides, so that the gassing itself extended to a longer period and so that the continuous effect increases. Peculiar way is the developing phosphorwasserstoff not inflammatory; it is aslo freely of liquid phosphorwasserstoff and furnishes thereby an advantage, which is characteristic for this application. The phosphorus hydrogen development is considerably, since e.g. 1 g of the Schlackenrueclstandes out tertiary calcium of an existing mixture 72cc gas develops phosphate and aluminum. This mass of gas is sufficient, in order to lend 3 to 5 cbm air deadly concentration.

garage chemist - 31-3-2007 at 04:13

I can give a translation of the relevant passages german patent, if you cant translate it yourself.

I recently thought about using large fresnel lenses for focusing sun energy onto chemical mixtures in order to reach high temperatures for certain reactions. Phosphorus being one of them.
I searched a bit and thought something like this would be appropriate for the job:
http://www-personal.umich.edu/~bclee/lens.html
If it can melt pennies in the focus, highly absorptive substances, like mixtures consisting mainly of charcoal, could be heated to very high temperatures.
Sounds easy: focus sun energy onto a test tube containing phosphate/charcoal/silica mixture. Lots of other fun uses for such a solar furnace are also imaginable.

[Edited on 31-3-2007 by garage chemist]

evil_lurker - 31-3-2007 at 15:15

Sorry, it was late last night and I gave the wrong patent number.. the correct number is DE923999 (which I have attached to this post).

I have a hunch that the reason why noone has had very much success in producing phosphorus is the fact that most of the reduced P gets trapped within the reaction matrix.

From what I have gathered in the the german patent, aluminum is used to reduce calcium phosphate simply by mixing a finely powdered form of the two chemicals together and lighting with a match or other means, sort of like a low temperature thermite.

Such an exothermic reaction would solve the problem of trying to heat any significant quantity of reaction mixture to the 1500-1700ºC range normally required in industry.

After the reaction, the leftover mass is simply chunked in water where it produces phosphine, and is subsequently led into a reaction tube where it is reduced @700-1000ºC to P4.


The reaction can be shown as:

3Ca3(PO4)2 + 16Al = 8Al2O3 +3CaP2

So in theory for every 416 grams of aluminum powder used, one could theoretically get 6 moles of P.

Attachment: DE923999C1.pdf (237kB)
This file has been downloaded 1327 times


garage chemist - 7-4-2007 at 02:56

Yes, you got it right in your posting, evil_lurker.

The patent you attached is about the usage of phosphine as a poison against rodents, and about a mixture that creates calcium phosphide in-situ in order to avoid the strict legal regulations that alkali and earth-alkali phosphides are subject to due to their highly poisonous nature and ready hydrolysis to phosphine even with aerial moisture.
A mixture of an alkali or earth-alkali phosphate, like Ca3(PO4)2, and aluminium powder, burns similar to thermite when ignited and leaves a slag that consists of Ca3P2 and Al2O3.
With moisture of air, earth or by contact with liquid H2O, 1g of the slag that burning a mixture of 43% Al and 57% Ca3(PO4)2 gives produces 72ml of gas (PH3) that imparts a lethal phosphine concentration to 3 - 5 cubic meters of air.
Due to the admixture of Al2O3, the mixture hydrolyses much slower than pure calcium phosphide.

I remember that poison cartridges against rodents which are avilable in german home-stores utilize this very principle to generate PH3: they are ignited, produce a phosphide slag hat hydrolyzes with moisture of the earth and liberates PH3 which kills the rodents.

-cyan- - 22-4-2007 at 08:46

do u think it would be possible to decompose Ag3P under an inert atmosphere to get P4? maybe it wuold be red P because of the low decomposition temp (i think Ag3P will decompose at a lower temp), but red P to WP isnt a big problem

garage chemist - 2-5-2007 at 19:49

Heres how to make your fingers smoke using white phosphorus:
http://www.metacafe.com/watch/530151/smoking_fingers/

Looks really healthy.

obsessed_chemist - 4-5-2007 at 14:24

I once took some zero-silver phosphor-copper brazing rods, which are composed of 93% copper, 7% phosphorus. I then proceed to dissolve this in an appropriate amount of ferric chloride etching solution (after working-out stoichiometry), in an attempt to isolate the phosphorus. It took days to dissolve; the fact that I cut the rods up helped, but a reflux setup would have been quite ideal, and much quicker.

To my dismay, I later discovered that copper sulfate solution is used as an antidote for phoshorus burns, for it renders to phosphorus harmless by converting it to copper phosphide, an insoluble and relatively inactive compound. Since I was using a chloride, and the iron was consumed, leaving cupric chloride, I can only assume that the phosphorus was converted into copper phosphide in this case as well. It's a shame, really.

12AX7 - 4-5-2007 at 18:59

http://www.crct.polymtl.ca/fact/phase_diagram.php?file=Cu-P....

Actually, powdered copper phosphide was probably left as a powder as the hypoeutectic alpha copper matrix was dissolved. Assuming phosphide isn't affected anyway; wouldn't it be dissociated somewhat (especially in the acid solution) and then oxidized to phosphate by Fe(III)?

Tim

obsessed_chemist - 6-5-2007 at 18:25

^^^ I thought about this; when I performed the procedure, I noticed that there was a yellowish solid left-over. It would have been nice if I had created yellow phosphorous, but obviously quite doubtful. I ended up dumping the mixture because I was afraid of it's toxicity, not knowing what the product(s) were. My sources tell me that copper phosphide, or Cu3P is in fact a yellowish-grey, brittle and insoluble solid. This could obviously be confused with phosphorous to the untrained experimenter.

alancj - 16-5-2007 at 14:04

For what it's worth, I was testing a calcium phosphate containing Plaster/MgSO4/aluminum incendiary mixture that I've been working on as a gopher gasser. It included just enough plaster to make it cure into a block. After roasting it in a toaster oven for 30 minutes I tested it on an iron plate at night. When scraping off the slag left behind I noticed that every time I scratched the surface I would leave a trail of white light! So apparently one of the side reactions released white phosphorus which as you all know glows in air. If I rubbed the plate fast enough to uncover as much WP as possible I could see white smoke (yes, in the dark).

The main products would be calcium phosphide, aluminum oxide, CaO, MgO and SO2 gas. I confirmed the presence of calcium phosphide by grinding the slag into a powder (with a dust mask, out doors, and a fan to blow the dust away from me) and dumping the powder into a beaker filled with water. I used a propane torch to light the PH3 gasses that came off and they popped and exploded quite nicely. FYI, I did this outside with a fan blowing the crap away from me so I wouldn't drop dead.

-Alan

alancj - 16-5-2007 at 18:34

I just found something interesting on eBay. This person has an auction for rare phosphorus retorts and gives a very interesting history lesson about them. Phosphorus Retorts on eBay I'll repeat it here (without permission) since it will be gone in 90 days. Credit to eBay member "lindarow." If this is against the rules then let me know and I'll remove it.

Quote:
Making of the Vessels/Crucibles/Retorts

The crucibles or retorts used in the making of phosphorus were made at the Rancocas Chemical Works from highly refractory clay coming from Amboy, NJ. This clay was worked by means of threading with bare feet. Although some retorts were made with the aid of a pug mixing machine, it was found these retorts would not stand up under the terrific heat used in the furnances like those made by "treading". Treading made the clay more resilient and would neither check nor crack when the heat hit them.

Molds to make crucibles were wooden cores or plugs about 8" in diameter and 36" long, one end rounded, the other having an ear or tenon through which a 1" hole was drilled. This core was inverted on a bench and a dowell or wooden pin was driven through the 1" eye locking the core fast. Clay was applied and formed by hand with the aid of a paddle. After the core was covered with about an inch of clay and formed, they were left to dry.

When the clay was partly dried, the dowel was knocked out and the core was turned right side up. The core was then lifted out by means of block and fall hooked into the eye of the tenon. After the core was removed, the mouth or open end of the retort was formed and slightly closed. These retorts were placed on a heated flue and left for a few days to completely dry. When dry they were placed in a large beehive shape muffle and baked or burned which glazed the surface. They were then stored ready for use.

Next, the retorts were filled with a prepared mixture from a hopper like device that fitted into the open end of the retort, and the powder was rammed tight. A large 4" cast ell was inserted into the open end and sealed with fire clay. The furnaces were fired with soft coal on a return draft principle maintaining a temperature of 3500 to 4000 degrees. Then the gases from the phosphorus mix in the retorts were forced out through the cast ell into water, where it condensed into a soft mass.

Due to the excessive heat used for the extraction of the phosphorus, both the crucibles/retorts and the furnances had to be repaired or discarded frequently. It took about two weeks for a batch to complete its cycle from the raw to the finished product. Most furnances had to be relined and new retorts installed after one or two batches.


She also said that they are 4 foot long and about 100 lbs each.

-Alan

I guess this is from the "Journal of Chemical Education, Vol. 27,Page 269, May 1950" according to her webpage, here

[Edited on 16-5-2007 by alancj]

phosphorus retorts.jpg - 47kB

evil_lurker - 21-6-2007 at 02:25

This morning I made some phosphorus via reduction of sodium hexametaphosphate and magnesium in an old soup can.

This was a non-scientific-I'm-bored-lets-see-what-happens-reaction. First I took a mg ingot, and made turnings with a drill press and put them in a coffee grinder. Then I took about a 1/3rd of a volume of some hexametaphosphate and grinded it up, then put it in an old aluminum can, threw some more mg shavings on top, and set it off with a ribbon. Total volume was around about a handful or so.

It took about a minute for the mg to burn down. Once it hit the ground up portion, the color went from white to a nice orange throwing off quite a bit of light.

Upon the end of the reaction, I dumped out the can and broke up the lump, which immediately caught on fire with a green flame and there was a few small pops and there was a a definate smell of phosphine in the air so I quickly exhaled got the heck out of there.

Needless to say, the reaction works, and I hope I don't die later for breathing the phosphine. :P

Misanthropy - 22-6-2007 at 15:38

$110,000.00 USD to buy it now!?!?

Surely, lindarow is mad.

alancj - 24-6-2007 at 01:35

You don't think big old hunks of refractory clay are worth 110,000 big ones? But they're OLD!

I wonder what it's like to be so stinking rich you actually waste money on crap like that...

-Alan

DeAdFX - 12-11-2007 at 09:03

She is probably one of those people who watches antique roadshow on PBS and doesn't want to be the moron who ended up parting ways with a "valuable"artifact for $10....

chloric1 - 3-2-2008 at 07:24

Aha! Yes indeed! I strongly believe this would be an ideal microwave Phosphorus precurser. Only a tube extending maybe a half or three quarters of a meter outside the microwave would be needed to condense the WP vapors. THere should be enough carbon monoxide and H2O vapor to protect the WP. It may be advantagous to mix in a precentage of diammonium phosphate with said precurser. I say dibasic with the understanding that a metaphosphate then metaphosphoric acid will be formed in situo.

jimmyboy - 14-3-2008 at 10:21

I decided to roughly - VERY ROUGHLY translate a german passage on phosphorus production from an old manuscript
off google books ... more help is appreciated since german is definitely not my first language - i kind of got lost when they mention sulfur

http://books.google.com/books?id=uTEOAAAAYAAJ&pg=PA1015&...

Neue method zur Darstellung von Phosphor

Auf Calciumphosphate wirkt aluminumpulver bei der verhaltnismafsig niedrigen temperatur der hellen rotglut unter lebhafter gluberscheidung
und glanzender lichtausstrahlung aufserst energisch ein es destilliert dabei phosphor ab wahrend phosphorcalcium und phosphoraluminium um ruckstande bleiben diese rk bei welcher gebrannte knochenasche verwendet wurde vollzieht sich bei weit niedrigerer temperatur als die von wohler empfohlene reduktion mit kohle
Am leichtesten wirkt aluminium auf calciummetaphosphate ein doch darf letzteres nicht in der form von gegluhtem superphosphat angewendet werden da der gipagehalt desselben zu explosiv verlaufenden nebeurkk veranlassung giebt
Die Knochenashe mufs vielmehr von vornherein nicht mit schwefels sondern mit salzs aufgeschlossen u das erhaltene prod zu metaphosphat gegluht werden


New Method for Phosphorus

calcium phosphate works with aluminum powder the reaction is a low (lower) temperature with bright red heat under a lively brilliant glow and first starts to distill phosphorus from protecting calcium phosphide and aluminium phosphide which residually remain afterwards - burnt bone-ash was used in its place as well (with the aluminum powder) using a far lower temperature than from more probably recommended reduction with carbon
The easiest was aluminium with calciummetaphosphate, nevertheless may not latter in that form from glowing phosphate are applied there contents of the same too explosive running besides. veranlassung giebt.
Using boneash from the start with sulfur do not separate with salzs openly preserved prod to metaphosphat starts to glow


[Edited on 14-3-2008 by jimmyboy]

garage chemist - 14-3-2008 at 14:36

The rough translation is completely useless. Also, the german text itself is full of text acquisition errors.
Here's my translation.
Remember, if you need a german text translated, you can always ask me, german is my first language. But please do so via PM, I don't read all posts here.

"Aluminum powder vigorously acts upon calcium phosphate at the relatively low temperature of bright red heat, under strong glowing and bright light emission. Phosphorus distills off, and calcium phosphide and aluminum phosphide are left as residue.
This reaction, which is done with calcined bone ash, occurs at much lower a temperature than the reduction with charcoal recommended by Wöhler.
Aluminum powder most easily acts upon calcium metaphosphate, but this must not be used in the form of calcined superphosphate because its gypsum content gives rise to an explosive side reaction.
The bone ash must be pretreated with hydrochloric acid instead of sulfuric acid, and the obtained product calcined to calcium metaphosphate."

Explanations: The neutral calcium phosphate in bone ash (and phosphate rock) does not react with charcoal or aluminum powder.
It must first be pretreated with acid to convert it to calcium dihydrogen phosphate and this calcined to calcium metaphosphate. This can then be reduced with aluminum powder.
In modern phosphorus production in the electric arc furnace, SiO2 plays the role of the acid (producing CaSiO3 slag), but this requires 1500°C.
"Superphosphate" is a commercial fertilizer manufactured by treating phosphate rock with sulfuric acid and consisting of a mixture of calcium dihydrogen phosphate and gypsum.
Gypsum (CaSO4) reacts explosively with aluminum and therefore superphosphate is not suitable for phosphorus production.
With HCl pretreatment, the byproduct is CaCl2 instead of CaSO4 and this can simply be leached out with water, leaving calcium dihydrogen phosphate which, after calcination to metaphosphate, is the starting material for reduction with aluminum.

[Edited on 15-3-2008 by garage chemist]

Magpie - 14-3-2008 at 15:14

GC:
Quote:

"Superphosphate" is a commercial fertilizer manufactured by treating phosphate rock with sulfuric acid and consisting of a mixture of calcium dihydrogen sulfate and gypsum.


Do you have a typo here?

garage chemist - 14-3-2008 at 17:56

Yes, that's a typo of course, I meant calcium dihydrogen phosphate. I'll correct it.

jimmyboy - 15-3-2008 at 09:49

Can you translate the first paragraph as well? They speak about sodium metaphosphate/silica with aluminum powder -- thanks GC
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