Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
 Pages:  1  ..  9    11    13  ..  60
Author: Subject: Preparation of elemental phosphorus
Sauron
International Hazard
*****




Posts: 5351
Registered: 22-12-2006
Location: Barad-Dur, Mordor
Member Is Offline

Mood: metastable

[*] posted on 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.
View user's profile View All Posts By User
S.C. Wack
bibliomaster
*****




Posts: 2419
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline

Mood: Enhanced

[*] posted on 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?"
View user's profile Visit user's homepage View All Posts By User
Sauron
International Hazard
*****




Posts: 5351
Registered: 22-12-2006
Location: Barad-Dur, Mordor
Member Is Offline

Mood: metastable

[*] posted on 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.
View user's profile View All Posts By User
garage chemist
chemical wizard
*****




Posts: 1803
Registered: 16-8-2004
Location: Germany
Member Is Offline

Mood: No Mood

[*] posted on 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.




www.versuchschemie.de
Das aktivste deutsche Chemieforum!
View user's profile View All Posts By User
Sauron
International Hazard
*****




Posts: 5351
Registered: 22-12-2006
Location: Barad-Dur, Mordor
Member Is Offline

Mood: metastable

[*] posted on 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.
View user's profile View All Posts By User
garage chemist
chemical wizard
*****




Posts: 1803
Registered: 16-8-2004
Location: Germany
Member Is Offline

Mood: No Mood

[*] posted on 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.




www.versuchschemie.de
Das aktivste deutsche Chemieforum!
View user's profile View All Posts By User
Sauron
International Hazard
*****




Posts: 5351
Registered: 22-12-2006
Location: Barad-Dur, Mordor
Member Is Offline

Mood: metastable

[*] posted on 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]
View user's profile View All Posts By User
garage chemist
chemical wizard
*****




Posts: 1803
Registered: 16-8-2004
Location: Germany
Member Is Offline

Mood: No Mood

[*] posted on 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?




www.versuchschemie.de
Das aktivste deutsche Chemieforum!
View user's profile View All Posts By User
Sauron
International Hazard
*****




Posts: 5351
Registered: 22-12-2006
Location: Barad-Dur, Mordor
Member Is Offline

Mood: metastable

[*] posted on 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.
View user's profile View All Posts By User
S.C. Wack
bibliomaster
*****




Posts: 2419
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline

Mood: Enhanced

[*] posted on 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?
View user's profile Visit user's homepage View All Posts By User
Sauron
International Hazard
*****




Posts: 5351
Registered: 22-12-2006
Location: Barad-Dur, Mordor
Member Is Offline

Mood: metastable

[*] posted on 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]
View user's profile View All Posts By User
Sauron
International Hazard
*****




Posts: 5351
Registered: 22-12-2006
Location: Barad-Dur, Mordor
Member Is Offline

Mood: metastable

[*] posted on 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.
View user's profile View All Posts By User
Sauron
International Hazard
*****




Posts: 5351
Registered: 22-12-2006
Location: Barad-Dur, Mordor
Member Is Offline

Mood: metastable

[*] posted on 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."
View user's profile View All Posts By User
Sauron
International Hazard
*****




Posts: 5351
Registered: 22-12-2006
Location: Barad-Dur, Mordor
Member Is Offline

Mood: metastable

[*] posted on 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]
View user's profile View All Posts By User
Sauron
International Hazard
*****




Posts: 5351
Registered: 22-12-2006
Location: Barad-Dur, Mordor
Member Is Offline

Mood: metastable

[*] posted on 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)
View user's profile View All Posts By User
Sauron
International Hazard
*****




Posts: 5351
Registered: 22-12-2006
Location: Barad-Dur, Mordor
Member Is Offline

Mood: metastable

[*] posted on 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]
View user's profile View All Posts By User
Sauron
International Hazard
*****




Posts: 5351
Registered: 22-12-2006
Location: Barad-Dur, Mordor
Member Is Offline

Mood: metastable

[*] posted on 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.
View user's profile View All Posts By User
roamingnome
National Hazard
****




Posts: 363
Registered: 9-9-2006
Member Is Offline

Mood: No Mood

[*] posted on 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...
View user's profile View All Posts By User
garage chemist
chemical wizard
*****




Posts: 1803
Registered: 16-8-2004
Location: Germany
Member Is Offline

Mood: No Mood

[*] posted on 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]




www.versuchschemie.de
Das aktivste deutsche Chemieforum!
View user's profile View All Posts By User
Per
Hazard to Others
***




Posts: 134
Registered: 26-1-2007
Location: Europe
Member Is Offline

Mood: No Mood

[*] posted on 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?
View user's profile View All Posts By User This user has MSN Messenger
garage chemist
chemical wizard
*****




Posts: 1803
Registered: 16-8-2004
Location: Germany
Member Is Offline

Mood: No Mood

[*] posted on 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).




www.versuchschemie.de
Das aktivste deutsche Chemieforum!
View user's profile View All Posts By User
Per
Hazard to Others
***




Posts: 134
Registered: 26-1-2007
Location: Europe
Member Is Offline

Mood: No Mood

[*] posted on 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€.
View user's profile View All Posts By User This user has MSN Messenger
S.C. Wack
bibliomaster
*****




Posts: 2419
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline

Mood: Enhanced

[*] posted on 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

View user's profile Visit user's homepage View All Posts By User
Polverone
Now celebrating 18 years of madness
*********




Posts: 3164
Registered: 19-5-2002
Location: The Sunny Pacific Northwest
Member Is Offline

Mood: Waiting for spring

[*] posted on 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.




PGP Key and corresponding e-mail address
View user's profile Visit user's homepage View All Posts By User
Strepta
Harmless
*




Posts: 44
Registered: 6-5-2004
Member Is Offline

Mood: No Mood

[*] posted on 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)
This file has been downloaded 1620 times

View user's profile View All Posts By User
 Pages:  1  ..  9    11    13  ..  60

  Go To Top