Sciencemadness Discussion Board - Red phosphorus to Phosphorus trichloride?

Red phosphorus to Phosphorus trichloride?

Agent MadHatter - 26-7-2009 at 14:15

I was curious as to how one would chlorinate phosphorus (red) into phosphorus trichloride?

I read up on wikipedia (This is why I'm asking, it is not a reliable source) that all you need to do is chlorinate water (I figured everything would be a 1:1 mole ratio)

From wikipedia:
Phosphorus trichloride is prepared industrially by the reaction of chlorine with a refluxing solution of white phosphorus in phosphorus trichloride, with continuous removal of PCl3 as it is formed.
P4 + 6 Cl2 → 4 PCl3

Refluxing the mixture is no problem, my only problem is in the equation

P4 + 6 Cl2 → 4 PCl3

Its been quite some time since balancing and working with equations and I need a quick freshen up on the P4. How would I get P4? Thats four P's...obviously, but how would I know I have 4, and not say, 5 Ps?

S.C. Wack - 26-7-2009 at 14:27

Since you apparently don't know that this is inorganic chemistry, not organic chemistry, you're going to have problems whether this works or not.

http://www.sciencemadness.org/talk/viewthread.php?tid=11803#...

ammonium isocyanate - 26-7-2009 at 14:37

Because that is the molecular structure of the white phosphorus allotrope. It exists as 4 phosphorus atoms bound together in a tetrahedral structure. White phosphorus is the most reactive allotrope of phosphorus because the acute bond angles place alot of stain on the bonds in the molecule.

Quote:

I read up on wikipedia (This is why I'm asking, it is not a reliable source) that all you need to do is chlorinate water (I figured everything would be a 1:1 mole ratio)

Huh? You what do you mean by chlorinating water?

You can't perform this reaction underwater, if that's what you're asking, because the phosphorus trichloride would undergo hydrolysis.

As for a 1:1 molar ratio, the equation shows that 1 mole of P4 reacts with six moles of Cl2.

White phosphorus is a little less stable than I like, so I would probably use red phosphorus (less due to handling concerns and more due to storage difficulties).

Depending on the quantities you need, different methods may be employed. For very small amounts, one could simply fill a test tube with chlorine gas and drop in little bits of red phosphorus.

What do you plan on using this for anyway? It may be that another chemical could be substituted, such as PBr3, which is synthesized by the reaction between phosphorus and bromine, which is convenient because bromine is a liquid at STP.

A couple notes on your thread though:

1. This is not organic chemistry, and as such does not belong in the organic chemistry forum.
2. Any thread about a synthesis like this that does not cite references belongs either as a post in the short questions thread in the misc. forum or in the beginnings forum.

DJF90 - 26-7-2009 at 14:51

As far as I know chlorinating red phosphorus will only yield the pentachloride. It seems apparent that only the white allotrope will stop at the trichloride, stoichiometry permitting.

ammonium isocyanate - 26-7-2009 at 14:57

I thought that phosphorus pentachloride would only result from an excess of chlorine, which could be avoided. Even if this is not the case, phosphorus pentachloride vapour could be heated to free it of chlorine and then recondensed.

DJF90 - 26-7-2009 at 15:03

That would be more hassle than necessary. It would be much easier to sublime the red phosphorus into white phosphorus, and use that in the preparation. Woelen performed the experiment (sublimation of red phosphorus) and took some wonderful pictrures - you can find the detailed procedure on his website.

Agent MadHatter - 26-7-2009 at 18:07

Well if I can't get ahold of any white phosphorus I'll have to use red.

Sorry for posting in the wrong section. I don't know why I thought this was organic. Brain burp.

Also, if I have powder chlorine, say from a pool supply store, how could one turn that into pure gas chlorine?

User - 27-7-2009 at 03:52

Ill do my best to translate this as good as possible:
It's translated from "leerboek der organische chemie"
Page 270

Phosphortrichloride PCl3
Meltingpoint : -111.8 C
Boilingpoint: 73.5 C

This substance can be made by direct contact of the elements.
For it's preparation one leads a stream of dry chlorine gas over white phosphorous.
This will burn with a hot flame and a distillate of PCl3 will come over.
Then more white phosphorous is added so that the PCl5 will go over in PCl3.
And one runs another distillation.
PCl3 is a colourless substance with a pungent smell.
Trough contact with water it rapidly decomposes to hydrochloric acid and Phosphorous acid.
PCl3 + 3H2O -- H3PO3 + 3 HCl

It's and old book, but who knows it might work quite well.

User1

Globey - 27-7-2009 at 10:54

PCL5 from exhaustive. PCL3 from quantitative and while controlling conditions. you can err and get a little penta or get all tri and not use up 100% of the p.

shouldn't there be a section just for urea/amonium cyanate (other than organic/inorganic)? lol;

slyder - 2-9-2011 at 09:13

can someone confirm if this reaction works for synthesis phosphorus trichloride :

Ca3P2 + Cl2 = PCl3 + CaCl2

calcium phosphide dissolvent in anhydrous solvent for example : methylene chloride and then bubbling chlorine gas throught calcium phosphide/methylene chloride mixture ?

can someone confirm if this works ??

I think this is the best method because Ca3P2 can be readily available if you roast calcium phosphate with charocal to around 1000 C to obtain Ca3P2 with some impurties.

[Edited on 2-9-2011 by slyder]

[Edited on 2-9-2011 by slyder]

slyder - 4-9-2011 at 01:23

anyone can confirm this please ?

Retard-3000 - 4-9-2011 at 09:42

P4 + 6Br2 > 4PBr3
4PBr3 + 6Cl2 > 4PCl3 + 6Br2

Would this work ?

This would be an easier method as bromine is liquid at STP.

Picric-A - 4-9-2011 at 12:22

Quote: Originally posted by Retard-3000

P4 + 6Br2 > 4PBr3
4PBr3 + 6Cl2 > 4PCl3 + 6Br2

Would this work ?

This would be an easier method as bromine is liquid at STP.

Who on earth would you go to the trouble of forming the tribromide just to turn it to the trichloride again?

Surly it would be easier to go straight to the trichloride as either way you will have to use Cl2 gas....

Dont forget the tribromide can be used in practically all the reactions the trichloride can be used for (save if you want to add a -Cl group not a -Br group)

The WiZard is In - 4-9-2011 at 15:25

Quote: Originally posted by Agent MadHatter

I was curious as to how one would chlorinate phosphorus (red) into phosphorus trichloride?

I was going to scan this, however, you (and I mean the
the word collectively) are to lazy/lame to use
a library or you would have found this
obvious/classic/standard inorganic chem reference.
I'll just note it here. Those of you interested
enough can put one foot in front of the other .....

Phosphorus (III) Chloride

P4 + 6Cl2 ---> 4PCl2

Inorganic Synthesis
Volume II
P. 145-147
Krieger Publishing Company 1978

djh
-----
If you give a woman
a fish ... you feed her
for one meal. If you
teach her to give good
---- you will both be
happy for life.

Ancient Chinese Proverb

slyder - 5-9-2011 at 08:47

can someone confirm please if this would work :

dissoliving Calcium phosphide in anhydrous methylene chloride and then bubbling into calcium phosphide/methylene chloride mixture chlorine gas?

and second:

If you would dissolve red phoshorus in anhydrous methylene chloride and bubbling chlorine gas into this mixture ?

does this work or works only with white phosphorus ?

[Edited on 5-9-2011 by slyder]

The WiZard is In - 5-9-2011 at 09:23

Quote: Originally posted by slyder

If you would dissolve red phoshorus in anhydrous methylene chloride and bubbling chlorine gas into this mixture ?

does this work or works only with white phosphorus ?

Ahhh someone else who only wants answers and is unwilling
to do their own work. So... I will answer your question with a
question. What is red phosphorus soluble in? I'll make it
easier for you — what organic solvent is red phosphorus soluble in?

I would be remiss if I didn't ask ... are you aware of
phosphorous trichloride's properties? Hazards?

slyder - 5-9-2011 at 09:49

Yes I am aware with hazardous with PCl3.

Yellow or white phosphorus is soluble in chloroform 1g/40ml

Yes I have find out that red phosphorus is insoluble in organic solvent. I didnt know lol

thanx !

but i do not find nowhere if calcium phosphide is soluble in organic solvent methylene chloride ?

Thanks !

The WiZard is In - 5-9-2011 at 11:37

Quote: Originally posted by Agent MadHatter

I was curious as to how one would chlorinate
phosphorus (red) into phosphorus trichloride?

I have taken timeout from sniffing the exhaust of the GC
to OCR this :—

I have OCR’d this from one of my favorite books.

Lowenheim and Moran
Faith, Keyes, & Clark’s 4th ed.
Industrial Chemicals
Wiley-Interscience 1975

Material Requirements
Basis- 1 metric ton phosphorus trichloride
Phosphorus 238 kg
Chlorine 815 kg

Process
Phosphorus trichloride is made by direct union of the elements
in an exothermic and spontaneous reaction. To moderate the
reaction, the chlorine and phosphorus are combined in the
presence of a continuously refluxing precharge of phosphorus
trichloride; the heat of reaction is removed by the refluxing.
Liquid phosphorus and chlorine gas are fed continuously to the
reaction vessel, so arranged that a sig-nificant proportion of the
phosphorus trichloride contained is refluxed. The remaining
phosphorus trichloride is distilled into a pot and analyzed for
elemental phosphorus. Additional chlorine, based on this
analysis, is introduced to remove these traces of unreacted
phosphorus. Yields are about 95% based on both the chlorine
and the phosphorus.

If it is desired to produce phosphorus pentachloride (PC15), the
plant shown in the flow diagram may be extended so that the
trichloride is fed into another vessel along with additional
chlorine from the main chlorine supply. In making either the tri
- or pentachloride, it is necessary to meter the chlorine flow
carefully.

The Devil is in the Chemical Engineering. Details of lab CE
can be found in Inorganic Synthesis. Loc. cit.

For the obvious reasons white P is used by industry
red P in la Lab.

At no extra charge, this of historical interest ....

Melor VIII : 999

H. Davy ca. 1810

I introduced phosphorus into a receiver having a stopcock,
which had been exhausted, and admitted oxymuriatic acid gas.
As soon as the retort was full the phosphorus entered into
combustion, throwing forth pale white flames. A white
sublimate collected in the top of the retort, and a fluid as limpid
as water trickled down the sides of the neck. The gas seemed
to be entirely absorbed, for, when the stopcock was opened, a
fresh quantity of oxymuriatic acid gas, nearly as much as could
have filled the retort, entered. The same phenomenon of
inflammation again took place, with similar results.
Oxyrnuriatie acid gas was admitted until the whole of the
phosphorus was consumed.

djh
----
[The] growing good of the world is partly dependent on
unhistoric acts; and that things are not so ill with you and
me as they might be is half owing to the number who
lived faithfully a hidden life, and rest in unvisited graves.

"George Elliot" Middlemarch

Retard-3000 - 5-9-2011 at 14:06

Quote: Originally posted by Picric-A

Quote: Originally posted by Retard-3000

P4 + 6Br2 > 4PBr3
4PBr3 + 6Cl2 > 4PCl3 + 6Br2

Would this work ?

This would be an easier method as bromine is liquid at STP.

I never mentioned forming the trichloride then turning it into the tribromide and back to the trichloride?

I'm just saying using this method would be easier and probably safer seeing as bromine is liquid whereas chlorine is a gas.

careysub - 24-6-2016 at 06:26

What is "oxymuriatic acid gas" in today's terminology? I am assuming a chlorine-oxygen compound of which there are several possible ones.

aga - 24-6-2016 at 07:27

Quote: Originally posted by careysub

What is "oxymuriatic acid gas" in today's terminology?

A reference in Encyclopaedia Britannica 1824 says it was prepared with "common salt, black oxide of manganese and sulphuric acid"

So HCl then ?

chemplayer... - 24-6-2016 at 08:17

We've played around with a bit of PCl3 and done a lot of research on it.

DJF is correct - red phosphorus forms PCl5 when chlorinated, which is why the industrial processes for creating PCl3 use white phosphorus as the starting material. Of course, the reaction between white phosphorus and gaseous chlorine is somewhat rampant and sexually charged. So the safest way to do it is to use a large excess of PCl3 and use this as the solvent/medium for the reaction - which is the industrial process for manufacture today.

In theory you can get phosphoryl chloride (almost as exciting) by heating sodium chloride and phosphorus pentoxide, but you need a high temperature (above glass capability) to do it.

Note that attempting to just reflux PCl3 (forget the phosphorus and chlorine bit) in even a lab environment is a BIG deal. The amount of drying precautions you need are crazy. The amount of HCl gas that is going to be produced (even with your drying precautions) is immense.

To think that H.Davy played around with this in what was effectively no more than a garage 200 years ago and managed to come up with scientifically accurate observations is just lovely. Feel shame or inspiration!

Magpie - 24-6-2016 at 08:56

Quote: Originally posted by chemplayer...

Of course, the reaction between white phosphorus and gaseous chlorine is somewhat rampant and sexually charged. So the safest way to do it is to use a large excess of PCl3 and use this as the solvent/medium for the reaction - which is the industrial process for manufacture today.

IIRC garage chemist tried this and concluded it wasn't viable. If this skilled experimentalist can't make it work, well I would think long and hard before trying it.

You can find his post on this forum by use of the SE.

Quote: Originally posted by chemplayer...

To think that H.Davy played around with this in what was effectively no more than a garage 200 years ago and managed to come up with scientifically accurate observations is just lovely. Feel shame or inspiration!

...reminiscent of Julius Caesar weeping at the statue of Alexander the Great.