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Author: Subject: Preparation of elemental phosphorus
Magpie
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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?

The single most important condition for a successful synthesis is good mixing - Nicodem
Strepta
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 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
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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.

PGP Key and corresponding e-mail address
Magpie
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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?

The single most important condition for a successful synthesis is good mixing - Nicodem
evil_lurker
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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
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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]

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evil_lurker
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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 1342 times

garage chemist
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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.

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

Looks really healthy.

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obsessed_chemist
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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
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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

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obsessed_chemist
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^^^ 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
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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
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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.

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]

evil_lurker
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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.

Not all chemicals are bad. Without chemicals such as hydrogen and oxygen, for example, there would be no way to make water, a vital ingredient in beer.
Misanthropy
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$110,000.00 USD to buy it now!?!? Surely, lindarow is mad. alancj Hazard to Self Posts: 76 Registered: 16-6-2006 Member Is Offline Mood: No Mood You don't think big old hunks of refractory clay are worth 110,000 big ones? But they're OLD! I wonder what it's like to be so stinking rich you actually waste money on crap like that... -Alan DeAdFX National Hazard Posts: 339 Registered: 1-7-2005 Location: Brothel Member Is Offline Mood: @%&$ing hardcore baby

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
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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.

Fellow molecular manipulator
jimmyboy
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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

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
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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]

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

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jimmyboy
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Can you translate the first paragraph as well? They speak about sodium metaphosphate/silica with aluminum powder -- thanks GC
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 Sciencemadness Discussion Board » Fundamentals » Chemistry in General » Preparation of elemental phosphorus Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues