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Sauron
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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]
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chloric1
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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.
Fellow molecular manipulator
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Sauron
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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]
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Fleaker
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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?
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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Sauron
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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.
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Sauron
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Yet ANOTHER Thing to Do with Your Red P
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)
This file has been downloaded 785 times
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S.C. Wack
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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.
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Sauron
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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]
Attachment: qj8510300005.pdf (643kB)
This file has been downloaded 524 times
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Polverone
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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]
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not_important
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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.
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Sauron
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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.
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not_important
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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 :-(
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Sauron
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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]
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not_important
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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.
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len2
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| 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.
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Sauron
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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]
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S.C. Wack
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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.
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Sauron
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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.
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