nicksdnas
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POCL3-Phosphorus Oxychloride Synthesis
Hello Sirs,
I am interested in synthesizing this chemical for research related phosphate esters. I do not have a high pressure steel autoclave at my disposal, so
NaCl+ P2O5 at specified moralities are not in the scope. Does anyone have pure stoichiometry or access. I am willing to pad your pocket for your
professional advice in regards to this research chemical. IM me
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chemrox
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Sign me on too.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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careysub
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Are you acquainted with the Tarbutton paper?
See the paper included in the post by Sauron on this thread:
http://www.sciencemadness.org/whisper/viewthread.php?tid=9&a...
They perform this reaction at temperatures from 350 to 600 C, but there is no need to high pressure. They were doing something a bit more complex,
heating chlorides and fluorides together, and the mixed volatile compounds then needed to be separated. If you are just doing NaCl for produce POCL3
this can be run at atmospheric.
Regarding the problem of where to get stainless steel reaction vessels, I have been pointed to this site:
http://deepwoodbrew.com/15-stainless-steel-bottles
which has reasonably priced stainless bottles from 360 mL to 2000 mL.
The apparatus I envision is to use 360 mL bottle, that can be capped with steel caps, and punching/drilling a hole through the cap for a stainless
steel delivery tube (using a press fit). The steel bottle cap is disposable, replaced with a new one for each run.
A Mecker burner, with an insulated chimney sleeve should probably suffice as the heat source on this scale.
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Chemosynthesis
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There is also the chlorate oxidation of phosphorus trichloride (among others) in this thread complete with pdf files: https://www.sciencemadness.org/whisper/viewthread.php?tid=92...
I thought I remembered a method proposed utilizing sodium metaphosphate chlorination as well, but don't see it.
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nicksdnas
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nicksdnas
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So I guess there is no recent information to be processed related to this subject.
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Bert
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Threads Merged
25-11-2014 at 17:37 |
nicksdnas
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[Edited on 2-12-2014 by nicksdnas]
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paphiopedilum
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I have a good book that contains a chapter dealing with two preparations of POCl3. POCl3 from P2O5 & NaCl, and POCl3 from Ca3(PO4)2, Cl2, & C.
Is anyone familiar with "Small-Scale Synthesis of Laboratory Reagents with Reaction Modeling" by Leonid Lerner?
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gdflp
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Yes, he was a user here for a while, though that book is quite expensive. Could you post the method involving Ca3(PO4)2, Cl2, and C, as all of those
are reasonably well available to the amateur?
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careysub
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Here we go:
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.
"Small-Scale Synthesis of Laboratory Reagents with Reaction Modeling", by Leonid Lerner
p. 173-174
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careysub
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And here is the prep from Calcium Phosphate:
Preparation of Sugar Charcoal
This form of carbon is particularly suitable for gaseous thermal reduction due to
its porosity, purity, and low ash content. Marvin et al. [10] describes a small-scale
synthesis (12 g) in a 1-L container, while here we describe a preparation of 300 g in
a slightly larger reactor volume.
Begin by placing 1500 g (4.4 mol) of food-grade sugar, C12H22O11, in a highform,
3-L beaker and heated inside an air oven at 200°C for several hours. When
the sucrose has melted, substantially dehydrated, and charred, the temperature is
raised to 350°C in the course of several hours, during which the volume of the
contents increases severalfold and a matrix of black, low-density carbon is formed.
If the mixture ignites during this period, a lid is placed on top of the beaker until
it is extinguished. The carbon is finally allowed to cool, ground in a mortar, and
calcined at 600°C for 1 h. The yield of black porous charcoal is 300 g, or 47% of
the theoretical yield.
Preparation from Ca3(PO4)2
This reaction must be carried out in a quartz tube or U-tube heated in either a tube
oven or a box oven, respectively. Because the calcium chloride product attacks quartz
in depth and also expands substantially on cooling, the reagents are best contained in
a sacrificial inner glass tube, which can be either quartz or ceramic. Borosilicate glass
also can be used provided the maximum temperature is not raised above 720°C.
First, 65.5 g (0.2 mol) of 96% Ca3(PO4)2 is ground to a fine powder mixed
with 22 g of sugar charcoal and placed inside a glass tube about 250 mm long
and 22 mm in diameter. The ends of the tube are lightly blocked with glass wool,
and the tube is centered inside a quartz reactor tube using tightly wedged glass
wool padding at both ends to minimize gas leakage outside the inner tube. If a
borosilicate glass tube is used, the inner tube also must be supported by ceramic
wool padding underneath.
The preparation can be carried out as well in a standard box oven using a quartz
U-tube with quickfit joints. In this case, two inner tubes packed with
reagent and lightly blocked at the lower end with ceramic wool are inserted into
both straight legs of the U-tube and supported by ceramic wool. A gas inlet tube
is attached to one end of the quartz reactor, while the other end is connected to a
receiver flask as in the previous preparation. Chlorine gas is generated as described
in the PCl5 preparation procedure.
Initially, the reactor is disconnected from the receiver, while a slow current of dry
nitrogen is introduced through the chlorine generator head, and the oven temperature
is raised to 760°C. This arrangement dehydrates tricalcium phosphate over several
hours. When water vapor is no longer evolved, which can be checked by attaching a
short length of cold glass tube to the reactor outlet and observing that no condensation
forms over a period of several minutes, the receiver is reattached to the reactor
and a flow of chlorine commenced at a rate corresponding to about 1 drop HCl per
sec. The flow of chlorine is accompanied by vigorous bubbling of outlet gases containing
no chlorine (color), while the last remnants of water (<0.1 g) exit the tube as
a fine mist depositing in the distillation bend.
After the chlorine generator has consumed about 80 mL of HCl, a transparent
liquid begins collecting in the receiver at a rate of about 1 drop/sec. The experiment
is continued until a total of 420 mL HCl has been consumed in the chlorine
generator (5–6 h), at which point there should appear the first signs of chlorine gas
exiting the reactor in the form of a fine PCl5 mist on the receiver flask walls. Gas
generation is then stopped, the reactor cooled, and flushed with nitrogen. The 51.2 g
of liquid product was fractionated, yielding two fractions, one boiling at 76°C (PCl3),
the other at 107°C (POCl3). Higher boiling products (PCl5) amounted to less than
1%. The yield of phosphorus chlorides to the point where Cl2 appears in the reaction
products is thus 83%, based on tricalcium phosphate in Reaction 19.3 (100% yield
from 63 g Ca3(PO4)2 is 62 g POCl3, or 56 g PCl3).
10. Marvin, G. G., Booth, H. S., and Dolance, A., Sugar charcoal. Inorg. Synth. 2: 74–75,
1946.
"Small-Scale Synthesis of Laboratory Reagents with Reaction Modeling", by Leonid Lerner
p. 174-176
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careysub
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Should ordinary table salt suffice for doing the P2O5/NaCl?
As we know, table salt contains anti-caking agents even it it contains no iodide, but the quantities are very small.
Anti-caking additives are YPS (for Yellow Prussiate of Soda) or ferric ferrocyanide (Prussian blue), which are added in amounts of 20 to 100 ppm, and
calcium silicate added at a level of less than 0.5%.
Iodized salt contains KI at the level of 0.006 to 0.010%, dextrose is then usually added to stabilize the KI (typically at about 0.04%).
So adding these up even iodized table salt looks like it is 99.5% sodium chloride (assuming that the original salt source itself was pure), basically
reagent grade (Sigma-Aldrich lists their reagent grade sodium chloride as >99.0%).
It seems like ordinary table salt would be fine for this reaction.
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mnick12
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Table salt is probably fine, but if you want kosher salt does not have any additives.
Also I would advise against stainless steel for this reaction. Basically all grades of common stainless are subject to stress corrosion cracking and
sever pitting in the presence of chloride ions, especially in acidic conditions. Using something like 316l or any common stainless grades poses a
serious risk of failing in this reaction.
Stick to glass
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careysub
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Quote: Originally posted by mnick12  | Table salt is probably fine, but if you want kosher salt does not have any additives.
Also I would advise against stainless steel for this reaction. Basically all grades of common stainless are subject to stress corrosion cracking and
sever pitting in the presence of chloride ions, especially in acidic conditions. Using something like 316l or any common stainless grades poses a
serious risk of failing in this reaction.
Stick to glass |
Are you sure this applies to the completely dry reaction involved?
If you fail to desiccate everything in this system the reaction will produce dismal results.
A little Googling suggests that dry HCl is much less reactive toward steel than hydrochloric acid, such that ordinary carbon steel can handle it.
But get some water in there, look out.
The Lerner procedure does indicate that glass is successful, which I had doubted given the high temperature (very close to Corning's extreme service
limit for Pyrex).
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mnick12
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Dry HCl may be less active against stainless at rt, but at 450C HCl will wreck just about any metal in a matter of minutes. At those tempuratures I
don't even think common nickel superalloys would resist corrosion.
As far as perfectly dry NaCl and stainless, im not sure. Although I wouldn't take any chances, most compatability charts strongly advise against the
use of anything chloride with your common austentitc stainless steels.
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careysub
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| Quote: Originally posted by mnick12 | | As far as perfectly dry NaCl and stainless, im not sure. Although I wouldn't take any chances, most compatability charts strongly advise against the
use of anything chloride with your common austentitc stainless steels. |
A point of reference is the original Tarbutton paper, where they specify: "the reactions were carried out in a three-inch iron or stainless steel
closed-end tube" and were carried out under several bar of pressure, at temperatures up to 1000 C, producing both phosphoryl chloride and fluoride.
The stainless steel beer bottle reactor OTOH would be treated as semi-disposable, would be operating at a max temp of about 450 C, and would be at
atmospheric pressure, though it no doubt has a thinner wall.
Both Tarbutton and Lerner use tube reactors, rather tall and slender, as a thick layer of reactant seems to help the P2O5 react rather than escape.
The beer bottle does rather well in this respect, in comparison to standard round flasks.
Not sure where to source a 100 mL ground glass test tube like Lerner used. Checking various sources I can only find small test tubes with joints. I
would probably try a pear shaped flask if using glass.
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Chemosynthesis
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| Quote: Originally posted by careysub |
Not sure where to source a 100 mL ground glass test tube like Lerner used. Checking various sources I can only find small test tubes with joints. I
would probably try a pear shaped flask if using glass.
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You may consider asking this user if you would prefer a more authentic replication. They offer discount glassblowing, and so have lots of odds and
ends that might be shippable for postage or a pittance.
https://www.sciencemadness.org/whisper/viewthread.php?tid=37...
aka
http://www.sciencemadness.org/talk/viewthread.php?tid=37974
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careysub
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Then there is always the plain old iron pipe. Tarbutton cites an iron tube as being used also, so this maybe even more authentic to the original.
The worst that could happen here with respect to reactor corrosion is loss of product.
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Technito
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I found this interesting pdf, but I'm not exactly sure how I would upload it since it's almost 20 MB, though I do have a link to it. http://avaxhm.com/ebooks/science_books/chemistry/1439813124....
Edit: I guess I just skipped right over this post, but my link directs to this book.
| Quote: Originally posted by paphiopedilum | I have a good book that contains a chapter dealing with two preparations of POCl3. POCl3 from P2O5 & NaCl, and POCl3 from Ca3(PO4)2, Cl2, & C.
Is anyone familiar with "Small-Scale Synthesis of Laboratory Reagents with Reaction Modeling" by Leonid Lerner? |
[Edited on 23-12-2014 by Technito]
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Dr.Bob
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Quote: Originally posted by careysub
Not sure where to source a 100 mL ground glass test tube like Lerner used. Checking various sources I can only find small test tubes with joints. I
would probably try a pear shaped flask if using glass.
I have some simple 24/40 jointed closed tubes, they were likely used for drying samples in vials, but might hold up to 50-100 ml, depending on the
exact one. They would be $10 each, as I have a few to get rid of.
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nicksdnas
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Dr. Bob
Thank you for your response. I seem to be on the correct road at the moment and have located some great, which seems to be of the correct dimensions.
At the moment I am still looking for a 20/ Liebig condensor. Would that Lab which recently went out of business have one. Could you help?
Thx in advance
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nicksdnas
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24/40 lieberg, typing on small screen thx
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chemrox
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Whoa! I have NOT been able to find salt labeled as "Kosher" that does not have anticaking crap in it; usually Ca-silicate
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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careysub
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| Quote: Originally posted by chemrox | | Whoa! I have NOT been able to find salt labeled as "Kosher" that does not have anticaking crap in it; usually Ca-silicate |
Considering that calcium phosphate is one of the reactant choices, and that you are performing the reaction in a silica containing tube, I very much
doubt that calcium silicate at the <0.5% level is going to interfere with the reaction.
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