Sciencemadness Discussion Board - Something Else to Do with Your Red P

Something Else to Do with Your Red P

Sauron - 10-2-2009 at 06:12

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]

Sauron - 11-2-2009 at 02:34

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!

Pomzazed - 11-2-2009 at 02:57

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]

Sauron - 11-2-2009 at 05:50

At least you are in a country where you can buy it when you want.

not_important - 11-2-2009 at 06:35

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).

panziandi - 11-2-2009 at 07:39

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.

PHILOU Zrealone - 11-2-2009 at 07:53

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 :cool:

Pomzazed - 11-2-2009 at 09:36

A phosphate acid rain wont be too bad? (P fertilizer) stick in bicarb in the field for more pressure (CO2, H2O) and acid neutralization

Sauron - 11-2-2009 at 10:42

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]

stoichiometric_steve - 11-2-2009 at 11:20

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.

woelen - 11-2-2009 at 12:20

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.

Sauron - 11-2-2009 at 13:01

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?

DJF90 - 11-2-2009 at 13:11

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.

woelen - 11-2-2009 at 13:15

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.

Sauron - 11-2-2009 at 13:40

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.

woelen - 11-2-2009 at 13:46

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]

Sauron - 11-2-2009 at 13:55

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.

S.C. Wack - 11-2-2009 at 19:00

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.

Sauron - 12-2-2009 at 00:36

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.

not_important - 12-2-2009 at 01:37

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]

not_important - 12-2-2009 at 03:22

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]

S.C. Wack - 12-2-2009 at 04:10

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]

Sauron - 12-2-2009 at 08:39

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)
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S.C. Wack - 12-2-2009 at 15:29

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]

Sauron - 12-2-2009 at 16:04

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]

Sauron - 15-2-2009 at 05:04

I cleaned up the Goldscmidt pages a little in Photoshop, so they are more readable. Attached below.

Also I found a nice old "Textbook of Inorganic Chemistry" by E.B.R.Prideaux, Vol VI Part II, Phosphorus. In the chapter on P-X compounds, there is the now familiar equation

2 S + PCl5 -> S2Cl2 + PCl3

and a citation of the Goldschmidt article in Chem.Zentralblatt.

So this reaction is not so obscure.

http://www.4shared.com/dir/2245331/5a78115f/sharing.html

[Edited on 15-2-2009 by Sauron]

chloric1 - 15-2-2009 at 07:20

A vapor phase reaction might be in order here. Just heat PCl5 in a flask to vaporization and drive the vapors over melted sulfur. If that doesn't do it, try mixing iron powder with the sulfur or even iron sulfide. Maybe the sulfur just needs a little "shove" in right direction.

Sauron - 15-2-2009 at 10:02

If you read Goldschmidt you will see the reaction did not requite temperatures outside of 100-200 C.

PCl5 sublimes at 101 C at normal pressure and boils at 160 C. At higher temperatures it dissociates. Accordingly a vapor phase experiment sound troublesome.

Goldschmidt described two sets of reactions, those of metals and metalloids with POCl3, and those of the same with PCl5.

It is apparent that the POCl3 was used in excess based on the mix of products obtaines. Goldschmidt detailed a series of reactions to explain the product mix, and looking at the stoichiometries, it is clear that nothing but the first reaction would take place unless POCl3 were in large excess. Let's illustrate for the case of silver metal (powder.

2 Ag + POCl3 -> Ag2O + PCl3 note that 2 mols Ag weighs more than 1 mol POCl3!

3 Ag2O + POCl3 -> Ag3PO4 + 3 AgCl

5 Ag2O + 2 POCl3 -> Ag4P2O7 + 6 AgCl

Ag3PO4 + POCl3 -> P2O5 + 3 AgCl

P2O5 + 4 POCl3 -> 3 P2O3Cl4

These were to explain a mix of PCl3, P2)5, P2O3Cl4, Ag3PO4 and AgCl obtained.

So it is clear that POCl3 must have been in large excess of the Ag to begin with. Goldschmidt was trying to determine the valence of P, not trying to prepare PCl3 from POCl3.

So I would keep Ag2O in large excess by the expedient of pumping the POCl3 through a column of Ag at the rxn temp, and monitoring the liquid for presence of PCl3/decline of POCl3. Flow rate will control residence time and ratio of mobile to fixed phases.

Similar results were obtained for most metals and metalloids tried, including Fe, Cu, Hg, Al, Zn, Pb etc.

For PCl5 the reaction was generally reduction of PCl5 to PCl3 with formation of the metal chloride. Anomalies included Cu where a phosphide formed along with Cu2Cl2. See text for details.

Reaction times and temperatures are sometimes mentioned.

[Edited on 16-2-2009 by Sauron]

Fleaker - 16-2-2009 at 12:53

It would be most convenient if you can avoid making silver phosphate or silver chloride.

Ag2O is easily made back into elemental silver just by heating. This would afford a very reusable catalyst.

Sauron, you planning to give this a try?

Sauron - 16-2-2009 at 17:49

True. But two considerations:

1. If POCl3 is not in excess, or better, if Ag is in excess, those subordinate reactions can't get off the ground.

2. I merely used Ag as an example, as Goldscmift did. Fe powder works as well, and who cares about recovery of that?

Strategically, this is one of my Oblique Ways to PCl3 threads. Now that I am onto a promising DIRECT Way (from PBr3) these roundabout ways diminish in importance at least for me. For those who need PCl3 but can't get PBr3, it is a different story.

Yet ANOTHER Thing to Do with Your Red P

Sauron - 16-2-2009 at 19:01

Here is another gem from Mellor vol 8 and also from Prideaux:

According to Kochlin and Heumann in Ber., pyrosulfuryl chloride reacts with red P to produce PCl3, SO2 and SO3.

But they proposed to employ sulfuryl chloride instead, in which case the only byproduct is SO2.

2 P + 3 SO2Cl2 -> 2 PCl3 + 3 SO2

An example of the use of sulfuyl chloride as a chlorinating agent.

Needless to say SO2Cl2 is easier to make than pyrosulfuryl chloride, ugh.

Pyrosulfuryl chloride is made from SO3 and CCl4, byproduct being lots of phosgene. Oh joy! See Brauer for details.

Sulfuryl chloride is nasty but not that nasty, it is easily made by union of dry SO2 with dry Cl2 over camphor or granular activated carbon catalysts.

Full text from Ber. attached.

[Edited on 17-2-2009 by Sauron]

Attachment: Heumann.pdf (294kB)
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S.C. Wack - 16-2-2009 at 20:29

It was suggested to me that I read this thread again, and I guess I have just a little more that I can add to it.

So...Sauron...deleting multiple posts now, after people respond to them...slick...no doubt to preserve the integrity of the thread...we need more of this. I thought that the Goldschmidt article was the subject of this thread. Personally I don't see how posting a link to it and then trying to explain how to view it, with Sauron saying that he cannot see it (for reasons unknown), with no mention of a lack of interest in doing so in the deleted posts, requires vitriolic response, but what do I know.

BTW Sauron, as you may know you do not own this site nor does it revolve around you (although it does seem that way sometimes, and he has a way of making that happen as you see in this post); other people view this as well, and not everything that people post is solely for your benefit, even in response to your posts.

It is interesting that Sauron's Dr. Gladstone, (who I looked up in a separate article on other reactions) failed in this reaction, which he mentioned in passing in this.

Sauron - 16-2-2009 at 21:36

No, I do not own this site. Neither do you. Your repeated attempts to derail this thread remain unappreciated. Your so called help re Goldscmidt availed me nothing at all. Others helped me get it. Not you. All you did was your usual niggardly pretense of assistance without the slightest substance. Don't you think people can see you for what you are? You can go to hell and take google books along with you.

Maybe this is the Gladstone paper you said you were posting then didn't. I had it already.

[Edited on 17-2-2009 by Sauron]

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Polverone - 16-2-2009 at 22:03

S.C. Wack was actually very helpful, as he often is. You just have an amazing ability to give and take offense to and from even the best members. I normally try to keep these spats to U2U but I'm afraid the public silence might be giving the wrong impression. Offering reference material related to the thread's topic is not derailing it. Arguing and venting and insulting other members in this thread is derailing it, and in the most destructive way possible. And now I've contributed further to the derail because handling things quietly and discreetly, as I have tried to do since you joined, apparently makes no lasting impression.

I've slightly cleaned up the thread before this point again on the off chance that people want to discuss chemistry in it.

[Edited on 2-16-2009 by Polverone]

not_important - 16-2-2009 at 22:51

Looking at those POCl3 reactions the most interesting IMHO is that with tin, provided the rather terse description isn't omotting anything

2 POCl3 + Sn => 2 PCl3 + SnO2

Less expensive than silver, no loss of chlorine to metal-halide as with iron, not too bad to recover tine from the oxide.

-------

A bit of drift now, looking at some of the references given here and elsewhere, I noticed these:

SO2 + Cl2 + SCl2 => 2 SOCl2
SO3 + Cl2 + 2 SCl2 => 3 SOCl2

If those reactions do go fairly well without some bothersome conditions it would seem to be a useful route to SOCl2. Chlorinate sulfur to a definite excess, burn sulfur in dry air giving mostly SO2 with some SO3, pass that through the SCl2 while also adding chlorine. When it seems to be complete bring to a gentle reflux while continuing to bubble SOx through it to decompose any remaining SCl2 - either combining or decomposing to S2Cl2 + Cl2 which the SOx would carry off. S2Cl2 boils ~137 C while SOCl2 is ~76 C so cleanup shouldn't be too bad.

Sauron - 16-2-2009 at 23:18

One at a time:

Yes the tin reduction is interesting, I will have another look, thanks.

SO2 + Cl2 + SCl2 amounts to SO2Cl2 + SCl2 which then disproportionates to 2 SOCl2 - if in fact that is what happens

SO3 + S2Cl2 + Cl2 is hardly novel, that is the industrial process for thionyl chloride. As I recall from the Stauffer Chemical patent, the Cl2 is added to suppress the formation of pyrosulfuryl chloride which otherwise decreases the yield. Len1 performed this process in an Illustrated Guide. Great if you have SO3. While it is not my personal fave, there is no margin for doubting that it works.

As long as we are drifting, SOCl2 reacts with P4S10 to give S2Cl2 and P4O10. Not that doing this makes any sense at all!

More interestingly 4 PBr3 + 6 H2S -> P4S6 + 12 HBr(g)

P4S6 also known as P2S3 or phosphorus trisulfide is used in the match and pyrotechnics biz. I can buy P4S10 but have not found a supplier for the lower sulfide. This is a convenient prep.

not_important - 16-2-2009 at 23:47

It was that either sulfur oxide would work, meaning the mixed oxides from burning sulfur would be a convenient feedstock. However it was mentioned in older texts that don't give references, so any catalyst needed and reaction conditions were not mentioned :-(

Sauron - 17-2-2009 at 00:12

Well the disproportionation reaction looks good on paper.

And there are similar disproportionations that are pertinent

PCl3 + SO2Cl2 -> SOCl2 + POCl3

That one works in a CSLR pumped through a fixed bed of heated GAC. In fact it works equally well with inpot of Cl2 and SO2 as long as they are dry and in correct proportions maintained by mass flow controllers. Monitored by UV-Vis spec inline and with fine tuning by a syringe pump to add PCl3 as needed. A similar setup might work for SO2Cl2 and SCl2. Peristaltic and PTFE disphragm pumps are used. PTFE tubing is best as most polymers will not resist SO2Cl2 for long. Service life of Viton peristaltic tubing 6 hours. But only short length is needed, then you connect it to PTFE. Also PTFE peristaltic tubing is available but requires a special pump head.

The fly in the ointment is that POCl3 and SOCl2 are damned near impossible to fractionate, ask garage cgemist if you don't believe me.

That is not pertinent to your proposed disproportionation if it works.

Compare to the established industrial methods in Ullmann and Lirk-Othmer to get a good idea if it ever got off the ground.

[Edited on 17-2-2009 by Sauron]

not_important - 17-2-2009 at 07:26

Well, it's not exactly my proposed reaction so much as one reported to happen that I found intriguing. I'm a bit skeptical and hope to find a report with a little detail in it. You would think that if it went at a reasonable rate with decent yields it would be used, so perhaps it's a sealed tube reaction or other similar inconvenient nonsense. Even so it still might be practical if all one needed were a few 10s of ml of SOCl2.

len2 - 18-2-2009 at 02:48

Quote:

A bit of drift now, looking at some of the references given here and elsewhere, I noticed these:

SO2 + Cl2 + SCl2 => 2 SOCl2
SO3 + Cl2 + 2 SCl2 => 3 SOCl2

If those reactions do go fairly well without some bothersome conditions it would seem to be a useful route to SOCl2. Chlorinate sulfur to a definite excess, burn sulfur in dry air giving mostly SO2 with some SO3, pass that through the SCl2 while also adding chlorine. When it seems to be complete bring to a gentle reflux while continuing to bubble SOx through it to decompose any remaining SCl2 - either combining or decomposing to S2Cl2 + Cl2 which the SOx would carry off. S2Cl2 boils ~137 C while SOCl2 is ~76 C so cleanup shouldn't be too bad.

I had observed the oxidation of sulphur dichloride in my practical guide

SO3 + SCl2 -> SOCl2 + SO2

with the evolved SO2 driving the equilibrium, and giving a good yield. The delG is -100kJ/mol or so, meaning equilibrium is well to right, as observed.

Now the reactions quoted reduce really to Cl2 doing the oxidation

SO2 + Cl2 + SCl2 -> 2SOCl2

with the second reaction quoted being just the first with my observed reaction added.

Now if Cl2 could do the work of SO3 the latter is superfluous .. but I dont believe it!

At least not in good yield!

That is because SOCl2 is indeed decomposed above 120C or so by the very same reaction. So the equilibrium is not favourable, gas evolution drives it in the opposite dircetion, its delG is substantially lower than in my reaction, and it reduces to sulphuryl chloride essentially oxidizing SCl2, which I dont believe will happen. To demonstrate me wrong someone will have to quote good yield for this reaction.

Sauron - 18-2-2009 at 03:13

The above reaction, the disproportionation of SO2Cl2 and SCl2, is taken from the old literature. I don't know if it works. What I do know is that the disproportionation of PCl3 and SO2Cl2 does work and works quantitatively with GAC as catalyst in a loop reactor. I have posted the John Hill US patent previously. The reactions are quite similar, one component oxidized, one reduced. This suggests that the old lit. dug up by not_important may well work.

not_important has a good point.

One mol SO2Cl2 is reduced to SOCl2, one mol SCl2 is oxidized, not by Cl2, but by the SO2Cl2. If you don't like this as redox, regard it as dispropotionation.

My surmise is that a catalyst such as granular activated carbon is probably needed.

S(II) and S(VI) reorganizing to 2 S(IV)

in the parallel reaction, P(III) goes to P(V) and S(VI) goes to S(IV). That one certainly works. Half of that reaction is identical to the other.

I deem it to be credible.

[Edited on 18-2-2009 by Sauron]

[Edited on 2-18-2009 by Polverone]

S.C. Wack - 23-2-2009 at 18:00

BTW Gmelin's (up to 1960) quite unsurprisingly says nothing more about the reaction of PX3 with Cl, (which it mentioned in the general preface to P and halogens) and PCl5 and S (in the S volume on the page cited in the pdf in the phosphorus chlorides thread), than the already cited Gladstone, Baudrimont, and Goldschmidt.

Sauron - 23-2-2009 at 21:05

With regard to PBr3 or PI3 and elemental Cl2, I guess we will just have to experiment to decide whether Dr Gladstone can be relied upon.

He is quite explicit about it though.

If it fails there is always the Hg2Cl2.

And the Sn metal reduction of POCl3.

The matter of PCl5 and S is a muddle - as recounted by Glastone and reviewed by Baudrimont. Most likely this is useless even at a 1:1 molar basis, but it is worth noting that Gladstone used 4 parts of S to one of PCl5.

Thanks again.