Sciencemadness Discussion Board

how to deal with posphine fumes?

SHADYCHASE54 - 26-1-2011 at 12:57

Okay I have a quick problem that I would really appreciate some advice on. I am running a purification step that may or may not result in the evolution of phosphine gas. Is there anything I might load my wash bottles with that would clear this volatile before venting it outdoors? Thanks in advance for any advice.

SHADYCHASE54 - 26-1-2011 at 13:20

Okay I will clarify what I am doing, I intend on purifying some red P. "alarm bells ringing!" well chill out I want to purify the P as I am going to chlorinate P in glacial acetic acid in hopes of producing acetyl chloride. Its worth a shot.

UnintentionalChaos - 26-1-2011 at 13:34

Potentially talking out my ass...

[Edited on 1-26-11 by UnintentionalChaos]

SHADYCHASE54 - 26-1-2011 at 13:45

geat advice thanks a bunch

ScienceSquirrel - 26-1-2011 at 14:31

The best idea in my opinion is to do the experiment in a vented apparatus connected to a tube leading out to the open air.
Phosphine will quickly react in the atmosphere to form phosphoric acids that will then fall in the rain. Further reactions will result in the formation of phosphate salts and the phosphorous will then join the phoshorous cycle that has gone on for billions of years.

not_important - 26-1-2011 at 14:34

ou're talking the standard boiling with alkali purification? Before that stir the red P with warm benzene, toluene, tech xylene, dichloromethane, dichloroethane, or similar solvent; most of these dissolve 1 g or more of P4 per 100 cc when warm.

Boiling with concentrate HNO3 is also supposed to remove yellow from crude red phosphorus, and without PH3 production as the P4 is oxidised to H3PO4. I've not tried this or seen a detail description.

Or for your purposes just leave it unpurified, and be careful about the addition rate of the Cl2.

ThatchemistKid - 26-1-2011 at 14:59

I am not to familiar with this method of making acetyl chloride. I know that PCL3 reacts with glacial acetic to make acetyl chloride, but I am thinking that with the excess of glacial acetic that will be present in your set up that all of your acetyl chloride will react to form acetic anhydride and you will not really isolate acetyl chloride...just a thought.

SHADYCHASE54 - 26-1-2011 at 15:30

Thank you for the responces I appreciate it more than you know. So am I then right to assume that thereis not a viable to way wash out the phosphine how about bubbling it through an oxidant? maybe

Sedit - 26-1-2011 at 15:35

What method do you plan to use to purify it that will generate PH3?

SHADYCHASE54 - 26-1-2011 at 17:20

It's my intent to follow the procedure listed in, "Handbook of preparative inorganic chemistry," boil gently in dilute aqeous hydroxide for 24hr rinse excess hyroxide and boil in H2O for 24hr but i think i'll cut it to 12hr on both steps? then dry under vacuum.

not_important - 26-1-2011 at 18:28

Don't shorten the NaOH boiling. You may be able to half the rinse time if you give several stir-and-drain steps before the rinse boil.

SHADYCHASE54 - 26-1-2011 at 18:40

It really takes that long of a NaOH boil to do away with the adhearing impurities? have any of you done this? one last Q. why is it that in the book, "Purification of lab. chemicals," they merely suggest a H2O boil followed by hot filtration?

not_important - 26-1-2011 at 19:07

The alkali boil removes unconverted yellow phosphorus by converting it to PH3, NaH2PO2, and Na2HPO. You are doing a reaction between a solid - red phosphorous - and an liquid, diffusion in the solid takes time; there's yellow phosphorus in solid solution in the red.

If the purification reference starts with commercial red, then it's already undergone the alkaline boil; contaminates are likely oxyacids of phosphorus and their salts so a simple water boiling removes them.

SHADYCHASE54 - 26-1-2011 at 20:11

Thank you for the explanation, mine is supposed to be lab grade however it has one hell of a bad rotten egg stink to it? It may be old but aside from that I trust the supplier as trust worthy.

The WiZard is In - 27-1-2011 at 07:10

Eidted by The WiZard is In to correct errors noted by DJF90
Quote: Originally posted by SHADYCHASE54  
Okay I have a quick problem that I would really appreciate some advice on. I am running a purification step that may or may not result in the evolution of phosphine gas. Is there anything I might load my wash bottles with that would clear this volatile before venting it outdoors? Thanks in advance for any advice.



Granted — you can never be too good looking; rich; safe,
and phosphine is the chemical of choice by a large number
of people to end all suffering

My J.T.Baker chemical catalogue for technical grade red
phosphorus lists it yellow phosphorus content at Max. 0.015%
[0.075gms per 500]

Presumable you could burn it off.

The Curious method of production of phosphorous (III)
chloride in Inorganic Syntheses II:145-147 does not make mention
of any requirement to purify ones red P. Would think I, yes,
any yellow P would simply be chlorinated along with its red cousin.

As was previously mentioned years back the US Army spent a lot
of time/money on ways to purify red P for use in small arms primers.

If you run it through Google.com/patents you will find
a 'hole bunch of their patents. I believe they best method they
found was boiling in HNO3. That said they were interested in
removing more than white P and phosphoric acid.


djh
---
Carthago Deleta

An embassy hastened to Rome with authority to meet all demands.
The Senate promised that if Carthgage would turn over to the
Roman consuls in Sicily 300 children of the noblest families as
hostages, and would obey whatever orders the consuls would
give, the territorial integrity of Carthage would be preserved. The
Carthaginians gave up their children with forebodings and
laments; the relatives crowded the shores in a despondent
farewell; at the last moment the mothers tried by force to prevent
the ships from sailing; and some swam out to sea to
catch last glimpse of their children.

[D&D III:106]




[Edited on 27-1-2011 by The WiZard is In]

[Edited on 27-1-2011 by The WiZard is In]

DJF90 - 27-1-2011 at 07:32

Wizard you've made an error or two. Firstly, 0.015% of 500g is a measely 0.075g, not 7.5g as you say. Secondly, P4 is white phosphorus, which is not being purified, but being removed in the purification of the red allotrope (which, being an amorphous solid with no "molecular structure", is best described just as P).

The WiZard is In - 27-1-2011 at 07:57

Quote: Originally posted by DJF90  
Wizard you've made an error or two. Firstly, 0.015% of 500g is a measely 0.075g, not 7.5g as you say. Secondly, P4 is white phosphorus, which is not being purified, but being removed in the purification of the red allotrope (which, being an amorphous solid with no "molecular structure", is best described just as P).




Yes. I blame my errors on Global Warming.

mr.crow - 27-1-2011 at 08:15

You could use Bromine instead, reacts violently with red P and white P to make PBr3. One mol of PBr3 can make 3 mols of acetyl bromide. It also stinks and reacts with oxygen.

BUT you can't do it in situ, PBr3 catalyzes alpha-bromination with Br2 so you will get bromoacetic acid instead. Use a slight excess of P to get rid of all the free bromine then add your acetic acid.

ScienceSquirrel - 27-1-2011 at 09:38

The suggested method is by reaction with sodium hypochlorite or similar materials;

http://www.praxair.com/praxair.nsf/0/98a2939cec509dc785256a8...

SHADYCHASE54 - 27-1-2011 at 11:50

Thank you everyone for your posts some have been helpful. In particular I send a happy thanks to ScienceSquirrel for finally answering my original question, you rock!