Sciencemadness Discussion Board - phosphorus oxychloride (POCl3)

phosphorus oxychloride (POCl3)

Slimz - 9-10-2007 at 09:00

I have searched thru and researched some. This Chemical is scheduel 3 so i should be able to get my hands on this correct?

I UTFSE and found info about SOCl2 (Thionyl chloride), but not so much about POCl3. Is this used in high quantities in any consumer products. Is it possible to synthesize this at "home".

If there are threads already that I have missed, just post em here and ill check em out, I never have much luck with that search engine.

**Bonus**
in my searching i found an interesting link
http://www.roguesci.org/megalomania/synthesis.html

[Edited on 9-10-2007 by Slimz]

Phosphor-ing - 9-10-2007 at 09:33

Search through Google. The search string should include "site:sciencemadness.org" without quotes.

Slimz - 9-10-2007 at 09:46

I did that and came up blank.

Polverone - 9-10-2007 at 12:58

Google returns hundreds of hits from this site containing "phosphorus oxychloride" or "pocl3." No consumer product contains it and I'm not aware of any really "easy" synthesis. All lab procedures that I've seen start from PCl3 or PCl5. Those materials are not markedly more available than POCl3 itself. The chlorides are prepared in the lab from elemental phosphorus, which can be produced in a home lab but not easily.

Slimz - 9-10-2007 at 14:03

ok so i could obtain POCl3 thru hydrolysis of PCl5
PCl5 + H2O → POCl3(phosphorus oxychloride ) + 2 HCl(dichlorobenzidine)

You mentioned that PCl5 was more available?

[Edited on 9-10-2007 by Slimz]

Sauron - 9-10-2007 at 15:43

Kindly elucidate why you want POCl3 and/or SOCl2.

Whose "schedule 3" are you referring to?

If you want to make acid chlorides, there are better reagents that are not politically incorrect.

But I doubt that you even know what an acid chloride is, so what is your game?

Slimz - 9-10-2007 at 17:30

Souron

#1 Im interested in dehydration of primary amides
#2 Schedule 3 substances, in the sense of the Chemical Weapons Convention
#3 I was not asking about any specific reactaions
#4 Acyl chloride is more proper and i do know what one is.

FYI i have spent alot of time reading and cross refrencing this past week and hav e come here with a very specific question/request. My motives are intelectual. I am not experienced enough to atemt any of the complex (or in some case simple) reactions, nor handle the toxic and dangerous chemicals, that would be needed to atempt the specific synthesises that you seem to be implying that im iterested in. I can understand your concern, but im not stupid enough to actualy try to manufacture a drug. It would be cheaper and easier to buy it anyway.

Sauron - 10-10-2007 at 05:31

It's a forum. All members are free to post in any thread. It's not "your" thread. It's Polverone's thread.

As to your personal attacks, I will let the moderators deal with them and you.

Polverone - 10-10-2007 at 11:01

All members are free to post on-topic information in every thread. I had to prune a lot of trash from this thread because that rule was somehow forgotten.

Slimz, I was saying earlier that PCl5 is not easy to get. There is no easy way to get POCl3 in a home lab without purchasing some pretty restricted materials*. Any route from OTC materials is going to be very difficult and involved.

*Sauron said this in an earlier post that I had to delete because of much unrelated off-topic content. You might not have believed him. He was right.

S.C. Wack - 25-10-2007 at 15:58

There's usually ways around something if you want there to be. If someone really wanted POCl3, they could make it in the usual way from PCl3 (i.e. from the less restricted dichlorophenylphosphine + AlCl3), for instance. You just have to look.

JohnWW - 25-10-2007 at 16:47

I think that compound is also called "phosphoryl chloride", or "phosphoryl trichloride" or "phorsphoryl(V) trichloride", or similar. Look for it under these names.

chemrox - 25-10-2007 at 19:40

It all depends on where you live and what your status is with the suppliers. I can get SOCl2, POCl3 and a lot of other "restricted" things. I have a long standing status as a business that uses these things from time to time. I had as much trouble with CCl4. I favor TCT since Sauron acquainted me with it. Do a search for those threads where its use is illucidated. Hint- username-Sauron; subject line - TCT. BTW a few typos are one thing but we all might undertand you better if you ran your posts through a spell-check. Just a suggestion.

Cheers,
CRX

Easy synthesis of POCl3

jarynth - 12-8-2008 at 13:01

I've been devouring the phosphorus chapter in J. W. Mellor's "Comprehensive treatise on inorganic and theoretical chemistry" (Vol. VIII), which provided me with the following procedure for synthesizing phosphoryl chloride:

"When P2O5 is saturated with dry HCl, it becomes liquid, and the liquid, on distillation, gives off POCl3, and leaves a residue of HPO3." (p. 944)

and

"(...) when P2O5 is heated (...) with NaCl, POCl3 is formed (...)" (p. 945)

If you're not in the possession of any P2O5, the same reference says:

"When Ca3(PO4)2 is heated with finely divided SiO2, CaSiO3 and P2O5 are produced." (p. 742)

The latter procedure is similar to the industrial (and historical) synthesis of phosphorus (and a constituent part of that process), as described in the phosphorus thread:

http://www.sciencemadness.org/talk/viewthread.php?tid=65

Also:

"The composition of bone-ash may be taken to be P2O5 39.5%, CaO 52.5% (...)" (p. 735)

Now turn the calcium compounds to something that doesn't react with the POCl3 on formation, and use the mix in one of the first couple procedures.

[Edited on 12-8-2008 by jarynth]

Ritter - 12-8-2008 at 13:38

Quote:

Originally posted by Sauron

Whose "schedule 3" are you referring to?

This one: http://www.cbwinfo.com/Chemical/Precursors/p2.shtml

chloric1 - 12-8-2008 at 14:59

Quote:

"When P2O5 is saturated with dry HCl, it becomes liquid, and the liquid, on distillation, gives off POCl3, and leaves a residue of HPO3." (p. 944)

Yes that might be a neat trick but try heating calcium phosphate mixed with carbon in a combustion tube heated to 750 Celsius and run dry Chlorine throught the heated mix. A mixture of products should come over incuding POCl3. Just redistill to purify.

Another path would be converting calcium phosphate to phosphide with aluminum powder or carbon and heat the phosphide in dry chlorine at 100 Celsius to make PCl3. This can be oxidized to the oxychloride with potassium chlorate.

[Edited on 8/12/2008 by chloric1]

Sauron - 12-8-2008 at 17:13

Mellor is pretty useless preparatively, he is short on details, where the devil resides.

The calcium phosphate method is an old commercial one starting from rock phospahate. Lots of patents on it.

The reaction between NaCl and P2O5 works fine, if you happen to have an autoclave (pressure reactor.) You can't do it in glass. You can find the experimental details in a JACS article by a fellow named Tarbutton in 1940. Oh, the P2O5 and NaCl must be scrupulously dry because any moisture present ends up reducing the yield and turning into HCl.

The one about saturating P2O5 with dry HCl - well to try it you'd need a tank of anhydrous HCl, and an apparatus bone dry and charged with P2O5 and utterly isolated from atmospheric moisture. You could achieve that with dry Argon, but not N2 because N2 is not inert to P compounds, P-N bonds form. I guess if you go to all that trouble then you will find out if P2O5 liquifies under dry HCl. But I'd recommend you continue passing in HCl. That's because my recollection is that POCl3 (putatively forming and dissolving the rest of the P2O5) reacts with P2O5 and so you have a couple of competing reactions going on and you want to drive them toward POCl3 as primary product.

It would help to have some equations for those reactions.

I know of one other reaction of P2O5 that yields POCl3, the only other products being CO and CO2. But the reagent is not cheap. The same reagent will convert As2O3 to AsCl3. It'll convert antimony and bismuth oxides (corresponding to anhydrides) to the respective chlorides. If P2O3 were available it would convert that to PCl3. The reason why the use of this reagent to convert P2O5 to POCl3 is rarely mentioned is because the reagent is made from PCl5 and so is POCl3 so in that light there's little point. The reagent is oxalyl chloride. The reactions I am talking about were all detailed by Roger Adams in JACS prior to 1920.

So, one not so easy industrial route.

One easy but requiring an expensive steel autoclave.

One easy but requiring a costly reagent.($600 a liter and rising.)

You can still scrape red P off tens of thousands of striker strips and make PCl5, then hydrolyze that to POCl3. But I would not call that easy.

Klute - 12-8-2008 at 17:26

Hum, it's a pity the NaCl/P2O5 would haev been a very neat preparation, both easily obtained and can be easily dried (NaCl). large amoutns of HCl is somethign else, and if generated at home, would require very scrupulous drying, surely wasting alot of P2O5 in a inline drier...

I would think anyone that can get oxalyl chloride can get POCl3, no? It's way cheaper...

Sauron - 12-8-2008 at 18:37

POCl3 is way cheaper, but here, it's restricted while oxalyl chloride is not.

And in my case, I do have a heated and stirred autoclave, with a working capacity of 650 ml. So I can try the NaCl route as well. The pressure is autogenous. Temperature 300 C. so obviously the POCl3 is in vapor phase till the reactor cools. A minor ampount of PCl3 also forms, I'd like to figure out how to make that the major or only product. Tarbutton theorized catalytic action of Fe from the autoclave walls.

The reason why glass is unusable is, molten P2O5 just like hot phosphoric acid will eat glass. The reaction takes the better part of 24 hours, plenty time to trash a flask.

See the Tarbutton paper, which was principally about POF3 but also illustrated POCl3.

Beats the hell out of matchbook striker strips.

Mush - 24-12-2011 at 12:22

Preparation of phosphorus oxychloride
(Phosphoryl chloride, Phosphoryl trichloride, Phosphorus trichloride oxide, Phosphoric trichloride, )

1,
3 PCl3 + KClO3 = 3 POCl3 + KCl
(Dervin, C. r. 97. 576)

2,
3 PCl5 + 3 P2O5 = 5 POCl3
(Kolbe und Lautemann, A. 113, 240)

3,
PCl5 + H2O = POCl3 + 2 HCl
(Wurtz, Ann. chim. [3] 20, 472, 1847)

4,
Ca2P2O8 + 2CO + 4Cl = CaP2O6 + 2 CO2 + 2 CaCl2
CaP2O6 + 4CO + 8Cl = 2 POCl3 + 4 CO2 + CaCl2
(Riban, C. r. 95, 1161, 1882)

5,
2 H3BO3 + 3PCl3 = B2O3 + 3 PClO3 + 6HCl
(C. Gerhardt, Ann. Chim. Phys. [3] 45, 90-107 (102 Fubnote 2), 1855)

Attachment: E. Dervin Compt. Rend. 97, 576 ,1884.pdf (144kB)
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Attachment: Kolbe u. Lautemann, Lieb. Ann. 113, 240, 1860.pdf (266kB)
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[Edited on 24-12-2011 by Mush]

Mush - 24-12-2011 at 13:26

1,
2CrO2Cl2 + 4PCl5 = 4POCl3 + 2CrCl3 + 3Cl2
(H. SCHIFF , Liebigs Ann. Chem. 102 [1857] 111/8, 118))

2,
3 PCl3 + NaClO3 = 3 POCl3 + NaCl
( Ber. 34, 650 [1901])

3,
3 PCl3 + KClO3 = 3 POCl3 + KCl
(Ber. 34 (1901) 2172)

Attachment: Ber. 34 (1901) 2172 Ueber die Herstellung des Phosphoroxychlorides .pdf (117kB)
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Mush - 13-3-2021 at 10:15

The preparation of organic compounds by
Barnett, E. de Barry 1912 , p65

PREPARATION OF BENZOYL CHLORIDE (PhCOCl).
Fifty grammes of dry benzoic acid are mixed with 90 grm. of
powdered phosphorus pentachloride. The reaction, which
commences at the ordinary temperature, is completed by heating
for a short time on the water-bath. The phosphorus oxychloride
(BP. 110° C) and the benzoyl chloride (BP, 200 °C
are then separated by fractional distillation. Colourless,
fuming oil with pungent odour. Yield 90 per cent.

[Edited on 13-3-2021 by Mush]

zed - 14-3-2021 at 13:03

Well, yes.... But, nowadays Phosphorus Pentachloride is in very short supply.

Even Phosphorus Pentoxide is hard to come by, and spendy if you can find it.

Now, if someone could come up with a procedure utilizing highly concentrated PolyPhosphoric Acid....

THAT would be a revelation. We can make PPA, and at it's most dehydrated, it kind-of approaches Phosphorus Pentoxide. Ummm...

I'm gonna go check on that.

Triflic Acid - 15-3-2021 at 12:06

I'm not too sure about this, but maybe reacting something like SOCl2, which has been prepared on the forum, with H3PO4 would give POCl3, since POCl3, is kind of like the acid chloride of H3PO4.

draculic acid69 - 15-3-2021 at 18:59

Can U not just buy p2o5 from China or something.they sell everything.

Where to get pentoxide

Elemental Phosphorus - 16-3-2021 at 05:22

Quote: Originally posted by draculic acid69

Can U not just buy p2o5 from China or something.they sell everything.

As far as I can tell, at least for Americans, it is available from various suppliers, even on ebay (but only as an ultra-pure analytical reagent), however it tends to be expensive:

https://www.ebay.com/itm/Phosphorus-Pentoxide-99-9999-Metals...

This is over a hundred bucks for 25 grams. However, if you make an account with firefox-fx.com (Firefox Fireworks) you can buy a pound of phosphorus pentoxide for $21.

Vosoryx - 16-3-2021 at 10:24

A few years ago I synthesized a small amount of POCl3, IIRC I planned on using it as a catalyst for something, clearly never got around to it and that experiment got lost.

I can't recall the exact procedure, but it involved passing chlorine gas over a mixture of Trisodium Phosphate and (I think?) activated carbon in a quartz tube heated to a few hundred degrees. The resulting mess of chemicals were condensed and then distilled, I had to do the reaction a few times to generate enough to distill as my quartz tubes are very small in diameter.

The exact procedure I got from here but all my chemistry books are on my old hard drive at home...

That reaction would only really work for small scale amounts, and I hate doing anything with chlorine gas.

draculic acid69 - 16-3-2021 at 18:09

Quote: Originally posted by Elemental Phosphorus

Quote: Originally posted by draculic acid69

Can U not just buy p2o5 from China or something.they sell everything.

A pound for $21, problem solved. U can make all the pocl3 or poly phosphoric acid you'd ever need.
This deal sounds like a logical choice.

draculic acid69 - 16-3-2021 at 18:13

Quote: Originally posted by Vosoryx

A few years ago I synthesized a small amount of POCl3, IIRC I planned on using it as a catalyst for something, clearly never got around to it and that experiment got lost.

I can't recall the exact procedure, but it involved passing chlorine gas over a mixture of Trisodium Phosphate and (I think?) activated carbon in a quartz tube heated to a few hundred degrees. The resulting mess of chemicals were condensed and then distilled, I had to do the reaction a few times to generate enough to distill as my quartz tubes are very small in diameter.

The exact procedure I got from here but all my chemistry books are on my old hard drive at home...

That reaction would only really work for small scale amounts, and I hate doing anything with chlorine gas.

This also sounds doable for the more adventurous members

zed - 17-3-2021 at 06:45

Ummm. Things get lost. This has been on the site for years. Once upon a time, a poster here wrote a book.

It's a good book. Not cheap... About 70-80 Bucks in Paperback. Gotta search for it too! POCl3 prep is included. Though Chemplayer's/Querty Querty's Acetyl Chloride prep, and The Benzoyl Chloride Chlorination are very useful, sometimes you gotta have the fancy stuff... PCl3, PCl5, POCl3, Oxalyl Chloride.

........................................................................................

See Lerner, Leonid (2011). Small-Scale Synthesis of Laboratory Reagents with Reaction Modeling. Boca Raton, Florida: CRC Press. pp. 169–177. ISBN 9781439813126. PDF available from libgen.

Quote:

19.3.1 Preparation from P2O5

The best reaction vessel for this preparation is a test tube with a quickfit joint, a capacity of at least 100 mL, and at least 22 mm in diameter. If this is not available, a 100-mL, single-neck flask can be used instead with a slight loss of yield. Scaling the reaction requires proportionally larger vessels.

First, 35.1 g (0.25 mol) of phosphorus pentoxide is rapidly introduced into the reaction vessel, ensuring that as little atmospheric moisture as possible reacts with the P2O5, as it subsequently generates HCl and HPO3, which attacks the glass. The transfer is best done by inverting a powder funnel inserted into the reaction vessel, over the mouth of the reagent bottle, and tilting until approximately the right amount of reagent is transferred into the flask. Next, 34 g (0.58 mol) of finely ground and thoroughly desiccated (1 h at 250°C) NaCl is added, and the reagents thoroughly mixed. The approximately twofold excess of NaCl improves the yield by about 10%. Finally, about 10 g NaCl is poured in a layer on top of the mixture, which serves to convert unreacted P2O5 subliming from the reaction zone (bp 360°C). The reaction vessel is placed in an air oven and connected to a bend leading through a Liebig condenser to a receiver flask immersed in cold water. The outlet from the flask is vented through a CaCl2 protection tube with a bubbler optionally attached for observation of reaction progress.

The oven is rapidly heated to 270°C, from where the temperature is raised more slowly to 450°C at about 65°C/h. A distillation conducted more rapidly than this will serve both to reduce yield by excessive sublimation of P2O5, and increase the possibility of the reagent vessel bursting due to excessive buildup of HCl and POCl3 pressure inside the reactor, as these do not have sufficient time to percolate through the viscous sodium metaphosphate medium (the reagents liquefy during the reaction). About 8.2 g (0.053 mol) POCl3 collects in the receiver at the end of the reaction while the reactor tube loses 9.3 g (the difference is due to losses in the distillation setup), corresponding to a yield of 76% (86% with respect to reactor weight loss) based on P2O5.

[Edited on 3-7-2020 by DavidJR]

[Edited on 17-3-2021 by zed]

FrenchChemist - 26-4-2021 at 23:19

Good preparation of POCl3, I did mine with PCl3 which made the process a bit easier.

It is known that having access to pcl3 - pocl3 synthesis may seem strange and wasteful but I did it on a very small scale purely experimental.