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Sauron
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Something Else to Do with Your Red P
In the course of studying the chemistry of S2Cl2 I stumbled across an interesting reacton that for some of you (unfortunatelt not me) may be very
accesible.
I have unearthed a lot of ways to make POCl3 but unfortunately not PCl3. That one is quite elusive, requiring white phosphorus. Red P gives only PCl5.
However, in Mellor on Sulfur is mentioned
2 S + PCl5 -> S2Cl2 + PCl3
So if you can obtain red P as some of you can, and prepare PCl5, you can employ sulfur to obtain PCl3 and sulfur monochloride.
The products ought to be readily fractionated.
H.Goldschmidt, Chem.Centr., (3), 12, 489,1881
I think that is the German version of Chem Abstracts and so the full text may be unobtainable.
[Edited on 10-2-2009 by Sauron]
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Sauron
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Huh. No takers? I rather like this prep. Starting with only two elements, plus the third element Cl2, and in two operations you can have three useful
and interesting compounds:
PCl5 (keep some)
PCl3
S2Cl2
Nothing wrong with that!
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Pomzazed
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Well the reaction looks very interesting, especially when you can make another substance with sulfur monochloride! (add ammonia to obtain S4N4)
Unfortunately I have no P on hand atm.
[Edited on 11-2-2009 by Pomzazed]
Don't stare at me making fumes... I'm just experimenting with some gas...
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Sauron
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At least you are in a country where you can buy it when you want.
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not_important
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I suspect that elemental phosphorous is the deal breaker for many folks. Even if all you can get ised, making yellow isn't that difficult.
So what happens if you react chlorine with P4S10 ? Or Fe2P with Cl2 or Br2? I ask because in the past I've had opportunity to buy drums of crude
Fe2P, and I believe that P4S10 is more available than elemental phosphorous although several months go I saw a yellow phosphorous tank truck (and me
without some empty bottles).
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panziandi
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That is an interesting set of reactions Sauron!
In addition, another sulphur-phosphorus chloride reaction is:
PCl3 + S => PSCl3, thiophosphoryl chloride, analogus to the oxidation of PCl3 to POCl3.
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PHILOU Zrealone
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Red P with H2O2 (50%) is hypergolic ...smoke and then fire within a few seconds...
I mention this because I thought red P is less troubles than white P, but I found out that it can be dangerous aswel!
2P(red) + 5H2O2 --> 2H2O(g) + 2H3PO4 (+ a lot of heat and smoke)
But I have only used 3g of my valuable 100g red P to perform the experiment (twice).
A friend of mine proposed me to use that mix to make a rocket fuel...but it would cost too much to make a large test and I don't want to contribute to
acid rains 
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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Pomzazed
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A phosphate acid rain wont be too bad? (P fertilizer) stick in bicarb in the field for more pressure (CO2, H2O) and acid neutralization 
Don't stare at me making fumes... I'm just experimenting with some gas...
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Sauron
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not_important, I posed that question about chlorination of P4S10 a couple years ago and never got any answers, nor have I seen any lit. on it.
I have lit. on a number of interesting reactions of P4S10, of which I have about 250 g Merck in small metal cans.
One of the best uses is to make Lawesson's reagent for thiations, which is a lot better than using P4S10 directly.
P4S10 might do something rude like explode if chlorinated, and if it doesn't, most likely produces a mixture of P and S chlorides and PS-chlorides
that may be awkward to separate. S2Cl2, SCl2, PCl3, PCl5, PSCl3 are all possibilities and that is assuming anhydrous and inert atmosphere conditions.
Otherwise add POCl3 to the list. So I deem it unlikely that any single product can be produced and isolated in a preparatively useful yield.
Mellor talks about S2Cl2 and "a phosphorus sulfide" giving PSCl3 but as is often the case dealing with Mellor citations is like trying to pick up Hg
with a fork. Are they referring to P4S10 or P2S3? What is the yield and what are other products? Inorg Syn mentions about 5-6 methods for making PSCl3
but this is not one of them. I take that as a hint.
[Edited on 12-2-2009 by Sauron]
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stoichiometric_steve
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| Quote: | Originally posted by Sauron
One of the best uses is to make Lawesson's reagent for yhiations |
That sounds like the Mickey Mouse reagent for yodelations.
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woelen
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I tried the reaction between PCl5 and S. The chemicals were mixed very well and heated in a test tube (appr. 300 mg PCl5 and a small quantity of S,
excess PCl5 is used). The reaction does not proceed very well. I heated for a few minutes. The sulphur melts and the PCl5 largely sublimes. After
cooling down, most of the sulphur still is unreacted and the mix completely solidified again.
It is not true that no reaction occurs at all. A horrible smell comes from the test tube, quite different from the smell of PCl5 (which is not bad, it
stings, but the smell is not too bad if concentration is low, it resembles the smell of SO2Cl2). When water is added, then there is the well-known
hissing noise of PCl5, reacting with water. Besides the smell of HCl, there also is a smell of H2S.
So, from this I conclude that a small amount of sulphur reacted, but indeed only a small part. If this reaction is carried out, then probably it must
be carried out in a closed vessel, where the chemicals are kept in contact at high temperature for a prolonged time.
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Sauron
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You did not exclude moisture. HCl would only form from hydrolysis. Dry the S, run this under N2 or Ar, you ought to get no HCl, no POCl3, no PSCl3
(which forms from PCl3 and D) and no H2S (after all, if only S and PCl5 are present, where is the hydrogen coming from?)
It would really be nice to have the original publication rather than one line in Mellor, wouldn't it?
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DJF90
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I think you missed this sauron...
| Quote: |
When water is added, then there is the well-known hissing noise of PCl5, reacting with water. Besides the smell of HCl, there also is a smell of H2S.
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woelen
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In the first part of the experiment I did not obtain HCl, but a mix of PCl5, S and a small mount of reacted chemicals. The second part of the
experiment, where I added water, was just to confirm that some of the sulphur reacted. If no sulphur had reacted, there would not have been H2S.
Indeed, it would be great if the original paper could be obtained. Unfortunately I have no equipment for working under N2 or Ar, but I can dry the
sulphur (e.g. by heating it at 70 C for a longer time) and repeat the experiment, but I do not really expect a different outcome.
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Sauron
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Maybe you are right and it is a waste of time.
But even without N2 or Ar, you could evacuate and seal a tube. You could make use of a vacuum dessicator and a pump to dry the S over H2SO4 or P2O5.
Maybe the reaction requires more time than you gave. I would expect the temp to be lower as well. Maybe the S should be added more slowly to the PCl5.
Lots of maybes, I know, but they all come down to absence of original procedural details.
So all I am saying is, if you want this reaction to suceed, maybe it is worth trying a few such gambits.
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woelen
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Sauron, what I can do is mix some PCl5 and carefully dried S and put these in a small glass ampoule, which is sealed. Then I'll put this ampoule aside
for a longer time and see how it changes over time. I am confident that this can be done safely, I do not expect any gaseous products, which may lead
to rupture of the ampoule due to pressure buildup. Maybe the ampoule should be heated, but too strong heating may cause cracking of the ampoule.
I am willing to experiment a little with this reaction. It sounds quite interesting and there may be nice and interesting results. But as you stated,
without the original documents, it remains a thing of trial and error.
[Edited on 12-2-09 by woelen]
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Sauron
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If you are going to heat it, keep it below the bp of PCl3, or use a Carius tube (thick walled.)
It may all come to noting, but you never know till you try.
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S.C. Wack
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| Quote: | Originally posted by Sauron
I have unearthed a lot of ways to make POCl3 but unfortunately not PCl3. That one is quite elusive, requiring white phosphorus. Red P gives only PCl5.
|
Maybe you should be looking in the PCl3 section of Mellor instead of the S volume?
Dumas managed to pull it off in 1859.
http://visualiseur.bnf.fr/CadresFenetre?O=30000000347967&...
T.E. Thorpe's experience with RP and Cl (Proc. Roy. Soc. 24, 283 (1876): "The reaction is very regular, and large quantities of the liquid may be thus
obtained with great ease and rapidity." The apparatus used probably looked like the one in the first preparation in Vanino using white P. Obviously
you either stop the chlorine before it adds to all the PCl3, distill off the PCl3 as it is formed, or add white P to the PCl3 containing PCl5. Likely
all three.
And if desired one can then use the PCl3 as solvent for the second preparation in Vanino, which uses either form of P.
So I'm not sure what the problem is.
The abstract of Goldschmidt is quite long but not great reading, and the original paper is indeed very obscure. Chemisches C[Z]entralblatt is not so
obscure at present, many volumes being available at Google Books including this one.
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Sauron
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S.C., the old lit. notwithstanding, as well as the Inorg Syn prep and Vanino, we have the contrary experience of our own very talented garace Chemist
who insists most vehemently that in his hands, RP gives only PCl5, and that attempts to prepare PCl3 by adding the stoichiometric amount of RP to PCl5
do not succeed.
Accordingly I am always looking for procedures such as this one.
garage chemist asserts that PCl3 can only be prepared by the chlorination of WP, preferably in CS2 soln.
WP is inconveniently unavailable.
If you wish to champion these old preps, please argue with garage chemist and not with me.
I have PBr3 and can get more easily so I can proced:
PBr3 -> RP -> PCl5 -> PCl3 by the present method. If it wI was looking in Mellor on S for other information entirely and simply ran across
this entry.
I do not have Mellor on P, mainly because you have not posted it. If you were to do so I would be most delifgted.
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not_important
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Download link is:
http://books.google.com/books/pdf/Chemisches_Zentralblatt.pd...
cut & paste it to get the PDF of the volume, linking into a book on Google is not always successful nor is extracting text from the OCRed book.
[Edited on 12-2-2009 by not_important]
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not_important
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I just tried the link using Firefox, and it popped up the download dialog.
Make sure you don't get the HTML 'break' string that is showing up at the end of the URL or try this:
http://tinyurl.com/b5yfe6
which worked for me. I'd chop the pages out, but I've not good PF editing tools and not enough disk space to process that file with the tools I have.
[Edited on 12-2-2009 by not_important]
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S.C. Wack
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I did not post a link because I already downloaded it some time ago and figured that anyone could find it as well as I could.
http://books.google.com/books?id=ExcAAAAAMAAJ&pg=PA489
Either images or text can be saved from there.
I most certainly have posted the N and P volume of Mellor.
[Edited on 12-2-2009 by S.C. Wack]
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Sauron
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The DjVu version is useless.
The pdf is nearly so but at least the pages that were blank in the DjVu are present sort of.
Most page numbers are cut off.
The logical pages are way off the actual by 20-30 pages.
I am trying to find p 489. This is on logical p 527 of the pdf.
The Goldschmidt paper is not an abstract. It is full text. Unfortunately the p 490 is mostly unreadable, but the reaction I am interested in is later
in the article.
No details unfortunately but Goldschmidt claims that indeed
2S + PCl5 -> S2Cl2 + PCl3
He also claims that Fe and Pb reduce PCl5 similarly while Cu gives a mix of CuCl2 and copper phosphide.
Fe + PCl5 -> FeCl2 + PCl3
You may recall that Tarbutton observed that the Fe or stainless steel walls of his autoclaves reduced part of the POCl3 he prepared from P2O5 and
NaCl, to PCl3 (10-25% as PCl3) JACS in 1940, I have posted it before.
These reactions may be slow. Tarbutton ran his experiments at 300-400 C for 20 hours if I recall.
According to Goldschmidt, Ag reduces POCl3 to PCl3
2 Ag + POCl3 -> Ag2O + PCl3
which is very interesting as the Ag is readily recovered in the metallic state with thiosulfate soln. (The Tarn-X reaction)
Al and Zn will reduce PCl5 to PCl3 and so will Hg.
[Edited on 13-2-2009 by Sauron]
Attachment: Pages f527-533.pdf (566kB)
This file has been downloaded 792 times
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S.C. Wack
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| Quote: | Originally posted by Sauron
I am trying to find p 489. |
My link doesn't go there for you?
Back to more Mellor off-topicness, realize that volumes 2 and 8 were posted long ago, and many posts dealing with my books are probably now hidden in
references section and the rapidshare links are dead anyways. I believe that at one time they were in the library, and thought they still were. In any
case it doesn't matter, because as I've said before, links to all of my books and many others are in every post I make, and have been for some time
now.
I've been meaning to scan some of Gmelin's on P halides, among other things, as part of a larger project. I suppose this gives me a good excuse to do
so unless someone knows of this being done already.
[Edited on 12-2-2009 by S.C. Wack]
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Sauron
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No, your link did not. I finally obtained the complete Bd 12 from archive.org with help from gsd, who showed me how to find a link to the pdf without
having to hassle with Google Books.
The DjVu was useless.
The PDF is pretty atrocious, page numbers are mostly trimmed off, so navigation is a matter of finding a page with its number and then counting down
to the target. The lofical pages are almost 40 out from the originals. I found 489 on logical 527.
And in the end there is no more detail than was present in Mellor' although some of the other reactions, presented just as sketchily, as interesting.
----------------
2 Ag + POCl3 -> Ag2O + PCl3
So 216 g silver powder ought to reduce a mol (153 g) POCl3 to PCl3 (137 g)
Goldschmidt describes a series of reactions that can follow, I would therefore keep Ag in excess by looping the POCl3 through a reservoir flask and
pumping relatively small volumes at a time through a bed of Ag (column) and remove aliquots to monitor progress.
Refractive index ought to do the trick.
[Edited on 13-2-2009 by Sauron]
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