Sciencemadness Discussion Board - Preparation of elemental phosphorus

Preparation of elemental phosphorus

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JScott - 1-9-2018 at 11:40

Quote: Originally posted by Hunterman2244

@Hunterman2244,

Thanks, when I scale up, it is my intention to work in a metal apparatus. However, I am a ways from there at this point. As mentioned, I really just wanted to recreate what I had seen in that video. Though it only appeared to be partially successful, I thought for me, it would make a good first step.

Partial successes can be instructional, and a bit more fun than absolute failure ;-) Further, I have been stymied by not having any inert gases on hand. I was sent down this path when I found that wine connoisseurs used Ar to replace the air in opened bottles. Though I'm sure 15$ for that much gas is a gouging, it's a lot cheaper than buying even the smallest refillable canister of Argon.

Any experience I can gain using these small, easily located cans of Argon will be helpful until I can afford more substantial supplies.

Still, your advise is right on point and very much inline with what I hope to do as I move further along in my studies. Thank you very much for getting back to me.

[Edited on 9-1-2018 by JScott]

Thanks. My intention was to eliminate the need for inert gasses due to the production of CO2. It also reduces the potential for accidents due to the fact it's not an energetic redox. I hope to try it out myself.

Ah, so you did, and I clearly missed your assist. My apologies, I should have read your advice more carefully. Clearly I had thought my use of the balloon was so clever I stopped listening <LOL>, avoiding the use of the gas would be even better.

But, fascinated by the idea of that particular video I have already purchased the materials. Still, saving that expensive gas would be key.

Also, this was one phosphorus experiment that looked doable in the fume hood. It is sometimes difficult for me to use the yard.

Hunterman2244 - 1-9-2018 at 13:13

Quote: Originally posted by JScott

Quote: Originally posted by Hunterman2244

Quote: Originally posted by JScott

Cool, get back with your results, would love to see how it turns out.

Doped-Al2O3-fusion - 13-9-2018 at 13:01

Quote: Originally posted by Magpie

yes, I believe the intimate contact provided by molten aluminum/SHMP greatly augments the reaction rate. I don't understand how Monsanto and FMC get such good production using Apatite, sand, and coke at 1200°C. Perhaps the apatite is molten at that temperature.

I wish I could find a simple way to make briquettes about 1/4" in diameter.

I recently roasted apatite crystals from an igneous rock I crushed up into a fine powder. There was plenty of silicon based mineral as part of the composition. I had noted the previous day, I was observing the apatite crystals to melt into a black glassy substance. At hot temperatures it seemed to be a bit tar like but quickly cools into a glassy like condensate. I used a stainless steel crucible with a narrow tube exhaust port, which condensed a hot black tar like substance on the collection vessel ceiling. I then took this black substance and broke it off into my agate mortise and pulverized it into a fine powder.

I figured I would try to reduce it if I could thinking that would help identify the mystery end result compound. I mixed this with carbon and heated until it was red hot. The inside of the test tube became coated in white substance and the thought occurred to me that this could possible be phosphorus and I assumed it was at first out of pure excitement. The white substance glows brightly under UV light and it appeared to still emit a soft glow with the lights out.

I don't have a sense of smell, so I can't reference that observation. The little bit of exposed white material did seem to react energetically with water, but since my knowledge level and experience are still limited, I can't say for certain "I made phosphorus!" Not when I see all you other guys that have been working so hard over years to produce this element.

The two other test tube pictures that are obviously different than the first two were experiments with ammonium phosphate I created after isolating the phosphoric acid from Naval Jelly. Removing the xanthum gum is a gooey mess, but coagulated fairly well with ethanol and can be twisted around a glass stir rod into a globular mass. I neutralized the phosphoric acid with ammonium hydroxide to form ammonium phosphate, then heated the salt mixed with carbon dust. I don't know if any of the residue that formed in those last two test tubes were anything buy recrystallized salt. It didn't seem to glow under UV light like the first test tube did.

Doped-Al2O3-fusion - 26-9-2018 at 12:53

I've learned quite a bit more since my last post just a couple weeks ago on this thread. I've successfully created white P and have been having fun despite the incredibly small amount.--I don't feel safe with my hands on any volume greater than what I made.

BromicAcid - 26-9-2018 at 19:19

In your previous post you mention an energetic reaction with water, do you figure this could be aluminum phosphide? Very cool stuff, thanks for sharing.

Herr Haber - 27-9-2018 at 04:16

Has anyone during these experiments gotten white P that stayed liquid no matter the temperature ?
I have a drop sitting in water in the fridge that wont harden. Could this be impurities ?

It smokes like WP when exposed to air, burns when small globules reached the surface in boiling water so I figured it should be WP.
Interested in your opinions.

Doped-Al2O3-fusion - 27-9-2018 at 11:21

Quote: Originally posted by BromicAcid

In your previous post you mention an energetic reaction with water, do you figure this could be aluminum phosphide? Very cool stuff, thanks for sharing.

I'm not sure. I wish I could go back and record everything in detail so that I could be more accurate / have others duplicate my results. I have a bunch of that unknown substance still in solution from the igneous rocks I dissolved. I'm not sure what to do with it other than neutralize it and store it as a solid.

Doped-Al2O3-fusion - 27-9-2018 at 11:25

Quote: Originally posted by Herr Haber

Has anyone during these experiments gotten white P that stayed liquid no matter the temperature ?
I have a drop sitting in water in the fridge that wont harden. Could this be impurities ?

It smokes like WP when exposed to air, burns when small globules reached the surface in boiling water so I figured it should be WP.
Interested in your opinions.

What is your ambient room temperature? That could be a huge factor in determining this one property of the substance you have. The micro quantity I have/had was still solid in storage this morning, but the ambient room temperature was 10 degrees Celsius in my home office / lab.

[Edited on 27-9-2018 by Doped-Al2O3-fusion]

Herr Haber - 28-9-2018 at 02:51

Quote: Originally posted by Doped-Al2O3-fusion

4 degrees in the fridge, 20 in the room. It should be solid at that temperature.
That's why I'm thinking of impurities but... except for a thin "skin" on the droplet it's transparent. I has no resemblance to the white / yellow waxy substance one would expect. But when exposed to air it's behaviour is exactly what one would expect.

simple-guest-7125 - 21-11-2018 at 19:15

Home Made Electric Arc Furnace on the Cheap!
https://www.youtube.com/watch?v=VTzKIs19eZE

halogenstruck1 - 21-12-2018 at 18:13

main reasons for failure in P4 preparations:
1-you can not reach needed temperature. for example you need minimum 700'C for C+H3PO4 mixed powder

2-you can not provide air free environment. no need to fill/purge the container with nitrogen or any inert gas as

air inside container will be consumed very soon and P4 vapour will release but slightest crack/opening even if

you can not see it, is enough to prevent any P4 from formation.

easiest mixture used as raw material: C like granulated C used in fish tank as filter+H3PO4 85% mixed in a

stainless steel bowl(>100% extra C based on molecular ratio: 4H3PO4+4C==>P4+4CO+6H2) and heat on

electric or gas stove with constant mixing up to 400'C till all extra water removes. use granulated powder to

release P4 at higher T by one of following methods:

notes: granulated charcoal should be used[like 1x1x2 mm particles(like activated charcoal used in fish tank filter packs)] not fine powder as otherwise powder will be

going out under released gas and also other problems will arise.

halogenstruck1 - 21-12-2018 at 18:18

easiest method to make on small amounts up to 0.2g: microwave method[consider H2 release that may lead

to possible explosion although I never encounter when used MW oven with good ventilation in the unit]
method: best as using fused silica test tube but can be done also by pyrex although will melt soon.
put some 4H3PO4+4C as granulated powder at the bottom of test tube. push a small piece of rock wool or

aluminosilicate ceramic blanket mat or even glasswool on the H3PO4/C mix but not pressing and leave it a bit

loose. piece of wool should not be thick to prevent P4 vapour and released gasses to pass through.
for best results, end of test tube should be wrapped in glasswool or rockwool or ... externally. this helps as

thermal insulation as MW waves pass it and make the charcoal mix inside hot but heat insulation prevents heat

to go out and this lead to easily increasing T.
then put this test tube upside down inside a metallic bowl(bottom) filled with little water[test tube end should be

at water and no air can go inside but just little bit more than needed] and microwave it[system should be

placed on a piece of refractory brick to avoid MW oven bottom metal contact. metallic bowl should let test tube

stand straigth or at least slant to avoid air entering at bottom. can place a piece of rockwool at contact point of

test tube and metallic container to avoid sparking if tst tube glass melt ]. the top closed heat gets red[should be

well above the small metal containet to absorb waves] then will release P4 and gas will bubble through water

and fire and smoke can be seen over water level at less than 2-4 mins. some P4 will collect underneath the

water layer and some inside test tube at the bottom close to water level.
do not use this method for making more.

halogenstruck1 - 21-12-2018 at 18:20

for larger amount like 10-15g in one run: ***do at your own risk***
use tube furnace with like 1000'C capability.
use the above mix filled inside like
1.25" diameter screw threaded: cap+iron nipple like 10" length and then reducer to 1" or 3/4" then 90 degree

bent 10" and 2" iron nipple[it inserted under water level[water level is just little bit under water or otherwise

upon cooling, it sucks water inside hot reactor and lead to sudden steam generation and explosion***]]
cover the iron nipple assembly with a thin layer of ceramic fiber math paper in places that has contact with

heating element coil to avoid metal contact with nichrome wire contact and spark/shortcut creation but let heat

pass through it.
use a cut piece of refractory brick to block one side of tube furnace entrance and seal the other side around the reducer with rockwool.
should put a metal sponge like kitchen stainless steel scrub piece(small piece only to cover the hole) just

before reducer inside to avoid carrying charcoal particles and blockage of smaller nipple and explosion***
If you calculate by Gib and delta H and delta G==>it needs miniumu 700'C and in practice also you can exactly

see the same T when P4 release and firing exiting gas can be seen.
distillation nipple(after reducer) should not be long. actually if you calculate heat transfer by iron tube

considering its thickness and length and its heat transfer constant, you will realise that just short distance after

inside tube furnace, T of iron tube falls under 340'C(boiling point of P4).therefore if it is long, P4 easily

condense just inside nipple and does not go into water.
other methods:
using thin iron tube blocked in one side by hammering and filled with granulated H3PO4/C powder and kept in

place by inserting a small piece of rockwool on charcoal level and and placed upside down inside water then

using a **induction coil heater[like >1KW or better 1.8KW], heating the area filled with charcoal.
I did not get good results although P4 released

using charcoal kiln with air blower will also work as heating source mentioned in old chemical literatures as well but

too much smoke

halogenstruck1 - 21-12-2018 at 18:29

***I do not recommend doing any of them. if do, do it at your own risk and if you have complete understanding of everything***

very promissing: using iron nipple system as mentioned above without end cap and instead using a reducer then using the mixture of

Kaolin+sodium silicate 40% solution+4% CaSO4 putty mixed with little bit of rock wool fibers and casting

graphite rod in the middle[you can put nipple end on ground and fill it with sand till like 2" under the top then insert graphite rod then fill 1" gap till top with putty and push and cover all end and going out covering even outside nipple on threads for best seal] and let it dry. after drying, with a brush, loose solution od sodium silicate mixed with

little kaolin powder was brushed on the dried putty for best seal. upon heating, most of the time, the mix will not

crack and is perfect for air exclusion and sticks very hard on threaded iron nipple.
for heating needs like 2 microwave oven transformer paralelled and controlled by minimum 4KW

semiconductor dimmer should work perfect. needs to use clamp meter[non contact] to monitor amper on wire

from electricity outlet 110v and avoiding more than 2.2KW total for 2 transformer[20A].
outside voltage is high voltage like 2kv***danger***
I did on 3/8" and then upgraded to 3/4" and electricity easily pass and upon like 10A, gas release starts right

away and should control amperage by dimmer to avoid getting very violent release of gas. I used brass ending

and flare fitting and used copper tube and iron nipple placed inside pot and filled with sand. released P4 and

most of P4 condensed inside copper tubing and stick to it.***looks like P4 gas reacts with copper***

in another test:
I used a terra cotta jar and made 2 holes by rotary tool(engraver) and inserted 2 graphite rod, sealing by above

putty[putty used also inside to create a 1cm layer at the bottom inside jar as well as a layer outside to seal

perfectly the holes and graphite rods] and brushed afterward and submerged system under sand==>it

released little bit P4 as later upon close observation, some cracks revealed in the jar.

fusso - 21-12-2018 at 18:36

PhD?

halogenstruck1 - 21-12-2018 at 18:49

note: terra cotta jar got cracks but not on the putty but at farther at its own clay. also its stainless steel distilling is very long and should be shorter and should also be wrapped by rockwook for thermal insulation. glass tube at end not necessary and should be omited

in metallic one: copper tubing is long and P4 can not come out easily.

**note: none of them creates real arc. for real arc version, graphite rod should be movable and touch at forst then move away

***Unfortunately I am unable to post more videos or fotos or answer any questions regarding my posts at this point.

also these tests need shield to cover the area when doing to protect person.

all given information in all posts I did are completely incomplete therefore should not be replicated other than at your own risk if you are already master in the field.

halogenstruck1 - 21-12-2018 at 19:02

heat transfer calc. on iron nipple:

https://en.wikipedia.org/wiki/List_of_thermal_conductivities
Fe: using T at between 1000&60=1000+60/2=530'C==>at 500'C
61.3

thickness: 2mm
OD: 1.72cm ID: 1.3cm
12.5cm length

delta T=1000-60=940'C or 'K

A=2pR*h=3.14*(1.3+1.72)/2x0.2 cm^2=0.942 cm^2=10^-4 m^2

https://en.wikipedia.org/wiki/Thermal_conduction
W=k*delta T*.A/d
wat= 61.3x940x10^-4/0.125
wattage=46.0976 wat of tube furnace electrical power get lost by heat transfer from iron nipple at most if inserted the end in water

delta Gibs calculation for T is attached as file

Attachment: G calculation-H3PO4-C RXN.rar (4kB)
This file has been downloaded 540 times

halogenstruck1 - 22-12-2018 at 10:31

assembly for tube furnace. I will update video on youtube soon and put link here.

[Edited on 22-12-2018 by halogenstruck1]

Hunterman2244 - 11-5-2019 at 08:31

Anything new on this project? Haven't got a chance to try myself.

charley1957 - 15-6-2019 at 12:32

Anyone know what happened to blue planet? He was really active in this thread until about four pages back, then he just dropped out of sight. Hope all is well with him.

cyriac1999 - 3-8-2019 at 10:57

Hey,

Since yesterday, I try to develop a method to produce white phosphorus from the red allotrope (400g) with only common glassware, heat mantle and aluminium foil.

naturally, I've chosen to distill the red phosphorus at 400 ° C under an inert atmosphere (argon) with a simple distillation setup without condenser. I've try to do my best to isolate the setup with a huge amount of aluminium foils (to keep heat and to protect the product from sunlight and to collect the potential white phosphorus produced during the distillation, I've used a 2 necks round bottom flask with a small condenser on the second neck to prevent any toxic white phosphorus vapors go to the rest of the assembly (two bubblers in series: one serving as a vial of the guard and the other filled with water to isolate the assembly of the atmosphere).

Honestly, I was very surprised by the result because after 1 day of continuous distillation, after K₂Cr₂O₇/H₂SO₄ purification (which is still in progress) I produced more than 150g of quite pure white phosphorus...

Before any purification :

During purification (1.5L beacker) :

I really didn't think I've could produced as much so I'm pretty happy even if I'm organic so I will not do much ^^

CB

67652629_479826519449201_638987556213489664_n.jpg - 287kB

67731311_376839729700028_2206773682951421952_n.jpg - 133kB

draculic acid69 - 3-8-2019 at 17:44

Now that meth making using red p isn't so common isn't red p a bit easier to get now?

cyriac1999 - 4-8-2019 at 00:29

In USA I don't know, in France it was never a problem to find it...
I've bought 2kg of red p two years ago without any problem

CB

draculic acid69 - 5-8-2019 at 06:22

The lead phosphate and H2 sounds like a good method to work on.if the lead phosphate is easily accessible and common and H2 can be made easily enough from NaOH and Al foil the only hard part is how do you do it? bubble H2 through the molten salt? Sounds easier than welding a ss vessel shut and baking at 1000'c.

[Edited on 5-8-2019 by draculic acid69]

cyriac1999 - 16-8-2019 at 08:03

"The lead phosphate and H2 sounds like a good method to work on.if the lead phosphate is easily accessible and common and H2 can be made easily enough from NaOH and Al foil the only hard part is how do you do it? bubble H2 through the molten salt? Sounds easier than welding a ss vessel shut and baking at 1000'c."

This seems quite hazardous...

draculic acid69 - 19-8-2019 at 04:50

Indeed it does.but it's a choice between two bad choices.pick your poison.hard to reach high temps or lower temperature, flammable hydrogen gas and hot lead.if your at risk of H2 or lead fumes you've got bigger problems with hot p4 fumes.but then again babysitting a 1000'c+ vessel of boiling phosphate salt with phosphine,p2o5 & carbon monoxide being evolved and trying to cool that down without breathing it in or getting it on you doesn't sound to me like less of a risk.

S.C. Wack - 19-8-2019 at 13:51

The choice is doing the reaction the right or wrong way and you are choosing wrong. The wiki for the salt says the mp is over 1000C. The hydrogen reduction is an article and a patent; the process is not shrouded in mystery. More mysterious is C instead of H.

draculic acid69 - 23-8-2019 at 18:12

If it's only mention is a patent then it's not worth more than a mention.it is a nice idea with its balanced equation leaving lead water and phosphorus but if it's not a proven pathway forget it.

S.C. Wack - 24-8-2019 at 05:08

The article and patent is from the govt. labs at Oak Ridge. Their address is P.O. Box X. I'm short on quartz tubes for now, and when I order big nice glazed porcelain boats I receive tiny crude unglazed clay boats.The authors cite as inspiration an author in a French journal and year, (Hutter, Annales de chimie 1953) who apparently tried hydrogen reduction of several phosphates, in a tube furnace, perhaps.

[Edited on 24-8-2019 by S.C. Wack]

Phosphoric acid vapor fed through charcoal in tube furnace at 1000 C under partial vacuum while condenser traps water

Duff - 10-5-2020 at 08:32

I have put a bit of thought into methods to prepare white phosphorus, and the following is the safest and most accessible method that I could devise. I have not tried it yet, since I would like to get the input of others who may have more experience. I tried posting my method on the r/chemistry subreddit to ask for advice. After receiving ~35 upvotes I was subsequently banned. I made my case and promised to not discuss the preparation of white phosphorus there again, and they unbanned me under the provision that I promise to "not post exceedingly dangerous experiments".

I have attached a jpeg with a schematic of my method. I advise you to take a look at it while reading this description. First the system will be flushed with argon gas and vacuum pumped. While that is being done the glassware can be heated a bit to help any moisture evaporate. When that is done a partial vacuum will be developed in the system for reasons that will become apparent.

The method involves packing an alumina tube with charcoal and heating it to 1000 C in a tube furnace. The choice of 1000 C is somewhat arbitrary. Some sources have said this reaction will occur at 850 C, so I have chosen 1000 C to be safe. I will experiment to figure out how the temperature affects the yield. I am open to other suggestions on what to use for the tube material. I have chosen alumina for its low cost and high heat resistance.

Phosphoric acid forms metaphosphoric acid when heated to 316 C. This is undesirable since metaphosphoric acid will probably not react with the carbon in the way we want, to produce phosphorus gas. However the boiling point of phosphoric acid at atmospheric pressure is 407 C [1]. Therefore in order to ensure that the phosphoric acid does not decompose before it can react with the carbon in the furnace, a partial vacuum is created in the system. Then the phosphoric acid can be heated to a temperature under 300 C, vaporizing it so that it can be sucked into the furnace by vacuum pressure, while ensuring it does not form metaphosphoric acid prior to the desired reaction:

4H3PO4 + 16C -> 6H2 + 16CO + P4

There is another problem. The phosphoric acid contains water, and it will reduced by the carbon in the furnace to produce hydrogen gas and carbon monoxide. The danger of these gases in of themselves is not that difficult to address. These could be vented into a flame to oxidize them:

2CO + O2 -> 2CO2
2H2 + O2 -> 2H2O

My concern is that by Le Chatelier's principle if hydrogen gas and carbon monoxide build up in the tube furnace, then the equilibrium will shift so that the reaction between phosphoric acid and carbon will be less favored. Therefore in order to maximize the yield of elemental phosphorus we should remove as much water as possible before the acid/water vapor enters the furnace. That requires more research on my part. I would appreciate advice.

Vacuum pressure will suck gases out of the tube furnace, and passing them through a condenser will allow us to distill out the phosphorus, which will be deposited at the bottom of a Schlenk flask underwater. The water in the flask that collects the white phosphorus may evaporate under the partial vacuum, and that is why there is a second condenser in between the flask as the vacuum pump.

Careful research and setup needs to be done to ensure the phosphoric acid will be volatile and not heated above 300 C prior to entering the furnace, while also not making the partial vacuum so strong that the water evaporates beyond the ability of the condensers to trap it in the flask.

[1] https://pubchem.ncbi.nlm.nih.gov/compound/Phosphoric-acid#se...

[Edited on 11-5-2020 by Duff]

[Edited on 11-5-2020 by Duff]

clearly_not_atara - 10-5-2020 at 21:35

You need to review your understanding of the basics of chemistry if you think that diphosphoric acid will not react with carbon when orthophosphoric acid will. You can't make phosphorus while you're still at the stage of fitting chemicals into reactions like they're ingredients for cupcakes.

Duff - 11-5-2020 at 04:09

I meant to refer to metaphosphoric acid HPO3 which forms when H3PO4 is heated to ~316 C IIRC. I have sources that claim metaphosphoric acid will not react with carbon to form phosphorus, at least not appreciably. It's not hard to believe since HPO3 has two double bonds. That is why my method involves lowering the pressure in the system, so that the acid can be vaporized and passed over the coals at a low enough temperature to prevent the formation of metaphosphoric acid. I'll try to find a source for the temperature where HPO3 begins to form from H3PO4, and a source for the low reactivity with carbon.

Attachment: WO2010029570A1.pdf (592kB)
This file has been downloaded 459 times

FranzAnton - 12-5-2020 at 07:32

Hm, very interesting patent file. But if I would run this at "home" I would do this in a quarz tube an arrange the substances described from left to right in the following way:
Beginning with a quarz wool plug (that the carbon powder will not escape, then 2 inc. carbon, then the mixture of carbon with the phosporos acid, then again 2 inc. carbon then again the quarz wool plug that the mixture will not escape.
Through the pipe a fancy flow of nitrogen.
Then I would place over the 2 inc. carbon on the left and the right an electric heating element which can produce 900°C and start heating both sections to that temperature. After that I would start heating the middle section maybe with a gas burner or also electric... whatever.

It the story of the patent is true, the nitrogen flow will transport the phosphorus in the colder regions of the quarz tube (which may end in some water...

What do you think of that design?
Maybe there is an issue with Phosporus acid an quarz at that temp? But if so maybe a ceramic tube or whatever will do the job.

You cannot produce continous, but for homebrewed things I would be happy if it works also in charges.

Duff - 12-5-2020 at 15:37

Filtering out soot particles so that they do not get sucked out of the furnace is a good idea. Quartz wool might work. Argon is probably a better choice than nitrogen for an inert gas since if there is any water vapor in the furnace it will get reduced by the carbon to form hydrogen gas and carbon monoxide. The hydrogen gas could react with nitrogen to form ammonia, or even radicals consisting of hydrogen and nitrogen.

I don't know anything about the reaction kinetics of phosphoric acid with carbon at 850-1000 °C, or the rate of formation of metaphosphoric acid as phosphoric acid is heated. I'm not even going to try to work out the rate laws since I think it would be a waste of time thinking about all of the possible elementary steps and mechanisms. Let's just assume two things:

1) There is a lower bound on the pressure in the system that would make it possible to trap water in the right-hand flask with the condenser.

2) There is an upper bound on the pressure in the system that would make it possible for phosphoric acid to evaporate from the left-hand flask at a temperature below what is required to metaphosphoric acid to form.

Then a preliminary pressure in the system must be established between those lower and upper bounds. The lower bound is determined by the effectiveness of the condenser. A condenser with a circulated mixture of propylene glycol and water could be chilled considerably, and perhaps that would be sufficient to make the lower bound smaller than the upper bound, so that the process is feasible.

When the system is first flushed system with argon a uniform pressure will be established in the system throughout, from the left-hand flask containing phosphoric acid to the pump, but note that the reaction between phosphoric acid vapor and carbon is going to increase the pressure in the furnace by producing multiple gas molecules; phosphorus, hydrogen, and carbon monoxide. Therefore if we want to maintain some range of pressure in the furnace, gas would need to be let out of the furnace faster than it is let in. That makes the problem much easier, since the pressure on the right-hand side of the system will be higher than on the left-hand side as the gases flow out. That is very convenient since it will make it easier to trap water in the flask while vaporizing the acid.

A two stage regulator might be the perfect type of valve for this job. It would allow us to keep the pressure in the phosphoric acid flask low while the pressure in the furnace and right-hand side is higher.

Anyway, I will have to experiment to find the lower and upper bounds, as well as the temperatures/pressures where metaphosphoric acid begins to form, and all of this is based on the assumption that the story that patent is selling is even true.

WGTR - 12-5-2020 at 17:06

In my unprofessional and likely useless opinion, I suggest that you try this on a very small scale first, before spending money on exotic glassware. If you put your trust in patents, you will oftentimes be sorely disappointed in the final results, spending too much money and time in the process.

As a curiosity I made a tiny amount of phosphorus in a borosilicate test tube once. This was done according to this equation:

6NaPO3 + 10AI + 3Si02 = 3Na2Si03 + 5Al203 + 3P2,

that was first introduced to this forum here:

https://www.sciencemadness.org/whisper/viewthread.php?tid=65...

I simply stuck a single-hole stopper in the end of the glass tube and pulled a good vacuum using a two-stage rotary vane pump. To protect the pump, I also used a 1-2 cubic foot vacuum reservoir. I pumped down the reservoir, and then closed off a valve to isolate the pump. The reservoir was then used to maintain a vacuum on the reaction mixture as it was heated.

I used a propane torch to heat the reaction mixture. The borosilicate tube was barely able to handle the temperatures needed while under vacuum. It gradually caved in as the reaction progressed, rendering it useless for future use. If the reaction started at maybe 100C lower then the tube might have survived.

As the reaction progressed, a ring of white/yellow/red phosphorus condensed in the cooler parts of the tube. The vacuum, among other things, kept convective heat loss to a minimum, and kept the upper parts of the tube cool.

After I noticed a sufficient amount of product (and the tube's integrity was beginning to look questionable), I stopped heating and let things cool down a bit. Then I cracked the stopper just a bit...and a big flash of light filled the tube. Turning off the lights showed the otherworldly glow of slowly burning phosphorus gasses swirling around the tube.

At a different time, I heated 1mL of 85% phosphoric acid in a test tube with a few small bits of metallic lead added to it. After some prolonged heating, and with the lights turned off, a glowing ring of phosphorus/phosphine was noted at the upper end of the tube so long as I kept applying strong heating. I did this in a fume hood, of course.

Heated phosphoric acid attacks glass. I would be careful doing that while also applying a vacuum. Protect your vacuum pump, and also protect "you" if you end up suffering an unplanned glass implosion somewhere in the apparatus.

NaPO3 is often used (from reading the thread), because it is a relatively low melting point phosphate salt, and it contains no hydrogen. This avoids the possibility of producing the gaseous and toxic product phosphine during the reaction.

In light of your proposed reaction, I would suggest first packing a small amount of your reactants (phosphoric acid mixed with charcoal, not graphite powder) into an extra long test tube and heating it gradually under vacuum, just to see if there is any reaction at all under strong heating. To do this more exotically, use electric heating around the test tube, and heat the tube inside of a vacuum chamber to equalize the pressure on the tube and prevent it from collapsing under vacuum.

FranzAnton - 13-5-2020 at 00:47

I fully agree. Not that I think about trying this out. I was only thinkin how I would "translate" the patent content in an apparatus which I think I can handle better than graphite pot...

I don't need phosphor I have filled my time with nitrogen and it's oxides

,
But it's always interesting to learn how other people are dealing with problems and how creative they are in finding cheap and sometimes simple solutions!

Duff - 13-5-2020 at 06:06

Your opinion is greatly valued. I am not a professional either. I think I got a D in high school chemistry. I skimmed through a few chemistry books recently to recall whatever I did manage to learn, but after skimming through 58 pages of this thread I've realized what others have mentioned. This is really an engineering problem and not a chemistry one. Not that I am a professional engineer either.

The equipment I would have to buy for this process will be useful for other processes I am interested in, so if doesn't work out I will not have wasted my cash. The reaction between phosphoric acid and carbon has already been reported to happen on a small scale, in this thread, and even in old chemistry manuals. See the attached pdf, taken from the 412th page of the Manual of Chemical Technology (1897) by Rudolf von Wagner. The question is about yield. Can we improve the yield of phosphorus by preventing the formation of metaphosphoric acid? There is no way to know unless I perform my process as described.

The major pieces of equipment I need are:

1) Schlenk line and flasks
2) Tube furnace
3) Alumina or quartz tube
4) Vacuum pump with regulator
5) Two stage regulator valve for connection between phosphoric acid flask and furnace
6) Pressure relief valve for connection between furnace and water flask
7) Argon cylinder

I have other uses for that equipment anyway, so I might as well try.

Attachment: manualofchemicalpage412.pdf (81kB)
This file has been downloaded 422 times

[Edited on 13-5-2020 by Duff]

FranzAnton - 13-5-2020 at 11:09

Hm, the attached phosphorus paper deals with temps much higher then 850C something about white glowing so 1200C...
This experiment is shown several times on Youtube operating outside with a isolated gas oven and a metal can instead of a ceramic Retort and it woked very well... a little bit nasty but realistic so get some 100g Phos. if one is patient.

draculic acid69 - 14-5-2020 at 07:14

Every YouTube video I've seen makes only a few grams out of each run.totally not worth the effort except for novelty. To make 100g would take a long time and lots of gas and heaps of empty paint tins

FranzAnton - 14-5-2020 at 08:04

OK, I see, so what would you suggest if 100g charge should be done in one run? Would you stick at a high temp. process based on Ca3(PO4)2, or would you use other phosphates? e.g. sodium pyrrophoshate.
Is there an electrolytic way?

Duff - 15-5-2020 at 17:59

The attached article published by Canadian Science Publishing (formerly NRC Research Press) shows that heating has little effect on the composition of strong phosphoric acid. However it does show that there is a relationship between concentration and composition. I trust this research more than the patent I posted earlier, and it suggests that lower concentrations of phosphoric acid should be preferred. That goes against my initial assumption.

In fact much of what I initially assumed seems to be wrong. Oligophosphoric, polyphosphoric, and metaphosphoric acids form by the condensation of water.

From Wikipedia:

Quote:

For example, pyrophosphoric, tripolyphosphoric, and tetrapolyphosphoric acids can be obtained by the reactions

2H3PO4 → H4P2O7 + H2O
H4P2O7 + H3PO4 → H5P3O10 + H2O
H5P3O10 + H3PO4 → H6P4O13 + H2O

Condensation between two –OH units of the same molecule, on the other hand, eliminates two hydrogen atoms and one oxygen atom, creating a cycle, as in the formation of trimetaphosphoric acid:

H5P3O10 → H3P3O9 + H2O

In the attached article 68.8% w/w phosphoric acid is found to contain ~100% orthophosphoric acid. The heat of formation for these phosphoric acid molecules decrease (become more negative) as they join by condensation, and therefore in order to make the heat of reaction as small as possible for the reduction of phosphoric acid by carbon a concentration of phosphoric acid not greater than 68.8% w/w should be used.

Now I see what has gone wrong in prior attempts. As the phosphoric acid is heated water evaporates, and then condensation to form larger phosphoric acid molecules becomes energetically favorable. It is the condensation of water which occurs during heating that causes the formation of larger phosphoric acid molecules. It is difficult to reduce these large phosphoric acid molecules using carbon since their heat of formation is so low. Then the best method to maximize the yield of phosphorus is to use 68.8% w/w phosphoric acid while preventing the condensation of water, but how can we prevent the condensation of water while heating the acid?

Attachment: v56-102.pdf (651kB)
This file has been downloaded 603 times

[Edited on 16-5-2020 by Duff]

Duff - 20-5-2020 at 16:10

Update: I decided that the best way to avoid condensation reactions resulting in the formation of larger phosphoric acid molecules is to avoid heating the acid until the last moment when it comes in contact with the hot carbon. A peristaltic pump can deliver a room temperature mixture of aqueous phosphoric acid and carbon powder into the furnace.

I've ordered much of what I need to try my method. So far I've bought the following:

Tube furnace from China, including quartz tube, flanges, thermocouple, temperature control, ... Actually the manufacturer in China worked with me to install a custom check valve on the furnace to allow fluid to flow in only one direction, see the attached picture they gave me. Total cost $1500 USD
Schlenk line from ebay. Got a used Chemglass one for $410 USD
2 brand new Chemglass Friedrichs condensers for $170 USD
Won an auction for a laboratory vacuum pump on ebay for $125 USD
1 gallon phosphoric acid 85% lab grade $100 USD
39 oz activated carbon lab grade $10 USD
other knick-knacks like vacuum grease, fountain pumps, peristaltic pump, tube clamps, mineral oil $150 USD

I still need to buy an argon canister, two stage regulator (might need 2 of these), adapters for Schlenk line to hose, tubing, flasks and beakers, bubblers, check valve for inert gas line, and other laboratory knick-knacks like safety stuff.

Yeah uh, it's all coming together. I already have a good conception in my mind of all of the little details on how the preparation will be done, I'll write it down sometime and share all the gory details. It'll take a month or two to get all this stuff and set it up, but I'll be sure to share when I'm done. So far I've spent $3500 CAD, and I wanted to stay under a $5000 CAD budget for this project. I probably will have to go over a budget a little bit, but oh well.

Cou - 11-6-2020 at 18:20

God I wish they would just ban pseudoephedrine instead of banning elements like iodine and phosphorus.
When I get a cold, I don't go crazy with crap from the drug store (unlike my sister who hoards a collection of like 4 OTC medicine bottles every time she gets a respiratory infection). I tough it out.

[Edited on 12-6-2020 by Cou]

draculic acid69 - 11-6-2020 at 18:57

They already have around here. It's now prescription only.

Cou - 16-6-2020 at 15:07

https://youtu.be/NxQrqXIMEh8

Where can I buy the equipment in this video? The propane torch, the steel vessel heated above the tank, and the long clear condensation tube, and the retort tube?

B(a)P - 16-6-2020 at 20:10

The steel vessel is just another propane tank with the tap removed and the handle/tap guard cut off.
You can buy flame weeders or heating wands for laying asphalt that you could use for the torch.
Otherwise it looks like they have just found some metal fittings that will go into the top of a propane tank and an expander to go out to the larger steel pipe that is used.
I wouldn't know where to start with the glass receiver, maybe a giant vase would suffice, but maybe it needs to be borosilicate glass....

Edit - a quick look on alibaba shows plenty of options for the closed glass tube

[Edited on 17-6-2020 by B(a)P]

Yttrium2 - 20-6-2020 at 15:56

what about this video, what is heating the mix?

https://www.youtube.com/watch?v=mibM4WUx74Q

any other details of the video? What is the mix here?

metalresearcher - 22-6-2020 at 06:31

Three yars later I stumbled upon this thread and found my failed attemps te make P4 in a 1400 C retort.

Quote: Originally posted by Magpie

"Magpie: How to make NaPO3 ? Or can I order"

Order sodium hexametaphosphate from Kyantec.

FYI: mp for Ca(PO4)2 is 1657°C. With (NaPO)6 mp is about 800°C IIRC.

I want to try it again and ordered 1kg of (NaPO3)6 via ebay.
I have a retort which should withstand at least 800 C.
Over 1200 C I don't do anymore with mild steel retorts as they burn and possibly melt.

Here a picture of two parts from plumbing pipes, the top one is a copper tube, so I want to mix (NaPO3)6 + SiO2 + C in the retort, dip the copper tube into water and heat it to 800 C.

Would this work, or should I make a different retort ?

Ubya - 22-6-2020 at 07:00

Quote: Originally posted by metalresearcher

Three yars later I stumbled upon this thread and found my failed attemps te make P4 in a 1400 C retort.

Quote: Originally posted by Magpie

"Magpie: How to make NaPO3 ? Or can I order"

Order sodium hexametaphosphate from Kyantec.

FYI: mp for Ca(PO4)2 is 1657°C. With (NaPO)6 mp is about 800°C IIRC.

during operation the reaction mixture should foam a bit, so remember to let enough free space

Yttrium2 - 25-6-2020 at 11:28

What are the ingredients/ratios for each mixture?

What is working best?

I will compile a list of ingredients/ratios that are working

EDIT - Nevermind, I am lazy, these pages are long, and there is 58 of them.

[Edited on 6/25/2020 by Yttrium2]

Duff - 1-7-2020 at 09:50

Great news! A 2019 paper (attached) published in the International Journal of Materials and Metallurgical Engineering describes the process of producing phosphorus from the carbothermic reduction of phosphoric acid. This is strong evidence that the method I am trying can work.

Rather than heating the acid gradually in the tube as the Japanese researchers did, I am planning to pump the acid in with a peristaltic pump once the carbon is already hot. The procedure will be as follows:

1) Placing both ends of the peristaltic pump's tube into a beaker of phosphoric acid, purge the peristaltic line of all air by pumping the acid in a loop out and back into the beaker
2) Flush system (furnace, phosphorus collection flask, schlenk line, ...) with argon
3) While keeping peristaltic line and furnace connection tubing submerged in the acid, use tubing joiner to connect peristaltic line to furnace connection tubing (the tubing can be lifted out of the acid once the tubes are joined and a seal is made)

See the attached picture for a visual.

Attachment: Carbothermic-Reduction-of-Phosphoric-Acid-Extracted-from-Dephosphorization-Slags-to-Produce-Yellow-Phosphorus-.pdf (431kB)
This file has been downloaded 701 times

[Edited on 1-7-2020 by Duff]

Cou - 3-7-2020 at 10:53

I cant find any iron retorts online x( gonna have to learn metalworking at the makerspace, or buy a custom part.

Does anyone know where to buy a metal retort, or how I can make one from stuff you can get at home depot? Cant use glass for this.

[Edited on 7-4-2020 by Cou]

metalresearcher - 15-7-2020 at 11:30

I succeeded.

I heated 7g (NaPO3)6 + 3g Al + 2g silica sand in a steel tube retort with a copper tube leading into a jar with water. I heated it to 700 C, after 15 minutes I did not see anything, I removed the retort, the bum of the retort was 900 C (measured with my infrared pyrometer). Then I saw 'water' dripping from the retort tube, but it catched fire with a small bright yellow flame smoking with dense P2O5 smoke. So it were drops of liquid P4 which spilled. Fortunately the amounts were less than a gram and my fumehood is completely fire resistant and I was aware of the dangers of P4, but a WARNING applies !

When you distill P4, be prepared that P4 might spill and keep bare hands, clothes or anything AWAY and use leather gloves and a face shield and perform outdoors or in a well ventilated fire resistant fumehood !
My experiment went well, but when it goes wrong it goes BADLY wrong !
P4 on your skin results in nasty and painful burns !

[Edited on 2020-7-15 by metalresearcher]

garphield - 2-8-2020 at 20:06

Not sure if this would work, and due to using metal phosphides it would be pretty dangerous even if it did, but would it be possible to reduce a phosphate salt with aluminium in a thermite-style reaction, then oxidize the aluminium phosphide in the slag to AlCl3 and PCl3/PCl5 via putting the ground-up slag in an inert solvent and bubbling chlorine gas through? If you need elemental phosphorus you could probably use zinc powder or something to reduce the phosphorus chlorides to zinc chloride + phosphorus. No idea if this would work tho.

clearly_not_atara - 2-8-2020 at 20:26

Quote: Originally posted by metalresearcher

I succeeded.

I heated 7g (NaPO3)6 + 3g Al + 2g silica sand in a steel tube retort with a copper tube leading into a jar with water. I heated it to 700 C, after 15 minutes I did not see anything, I removed the retort, the bum of the retort was 900 C (measured with my infrared pyrometer). Then I saw 'water' dripping from the retort tube, but it catched fire with a small bright yellow flame smoking with dense P2O5 smoke. So it were drops of liquid P4 which spilled. Fortunately the amounts were less than a gram and my fumehood is completely fire resistant and I was aware of the dangers of P4, but a WARNING applies !

Very nice!

The success with silica makes me wonder if other acidic oxides might liberate P2O5 from NaPO3. V2O5 is the most acidic solid oxide I can think of that will withstand the high temps.

Triflic Acid - 5-11-2020 at 18:04

Just a thought, but reacting sodium hypophosphite with an oxidizer should make elemental phosphorus. Its a byproduct in electroless nickel plating: https://en.wikipedia.org/wiki/Electroless_nickel-phosphorus_...

Bedlasky - 5-11-2020 at 18:14

If you mix hypophosphite with oxidizer you get phosphite or phosphate.

Phosphorus which forms in nickel plating is in form nickel phosphorus alloy, it doesn't form as a pure element.

Triflic Acid - 5-11-2020 at 19:09

Then dissolve away the nickel with an acid, that might work

B(a)P - 5-11-2020 at 19:34

This is an interesting concept.
Not that many will have the ability to perform electrolysis on a liquid at 850 C.....
https://pubs.acs.org/doi/pdf/10.1021/acssuschemeng.0c04796

Attachment: yang2020.pdf (3.8MB)
This file has been downloaded 606 times

Cou - 5-11-2020 at 19:44

I decided to just buy red phosphorus from chemcraft.su. I need it for regioselective bromination of alcohols. I don't do any illegal drugs so I'm not worried about the possibility of police coming knocking. If they search my house expecting to find empty Sudafed boxes, they're wasting their time.

My life will not be complete until I can regiospecifically brominate alcohols. Civil asset forfeiture a risk I'm willing to take.

[Edited on 11-6-2020 by Cou]

teodor - 6-11-2020 at 07:37

Quote: Originally posted by Cou

I cant find any iron retorts online x( gonna have to learn metalworking at the makerspace, or buy a custom part.

Does anyone know where to buy a metal retort, or how I can make one from stuff you can get at home depot? Cant use glass for this.

[Edited on 7-4-2020 by Cou]

I accidentally found these examples:
https://indonesian.alibaba.com/product-detail/high-recovery-...
https://indonesian.alibaba.com/product-detail/mercury-retort...

It seams that this type of retorts is used for distilling of mercury from gold amalgam (so, search "mercury retort". I don't know whether this type of retorts is suitable for producing of white phosphorus because they have a very narrow pipe.

[Edited on 6-11-2020 by teodor]

[Edited on 6-11-2020 by teodor]

Duff - 11-11-2020 at 22:14

Thought I'd give an update. The amount of time I've been able to spend on chemistry has been limited over that past few months, but hopefully I can spend more time on phosphorus production in the coming months. Right now I'm thinking hard about how I can effective do "unit testing" of various parts of my setup, e.g. can the o-rings on my flange valves withstand the required pressure and temperature, can my condensers sufficiently cool the gases exiting the furnace, dealing with possible phosphine formation, etc.

Another problem I've been wrestling with is how to place the activated carbon in the furnace's quartz tube in a way that ensures any phosphorus produced will not condense before it leaves the tube. The tube is 30 cm long, but the heating zone in the furnace is 10 cm long. I may have to place the tube so that the exit flange is closer to the heating zone.

There might be an easy solution to the problem of phosphine formation. The attached document claims that

Quote:

Sodium hypochlorite in aqueous solutions reacts practically instantaneously with phosphine so that such solutions are particularly suitable for removing traces of phosphine from a gas stream

So passing the gases through a solution of sodium hypochlorite at some point might be an idea.

I want to minimize the amount of combustible or toxic gas that enters my pump, so if I can remove phosphine from the gas stream before it gets there that would be fantastic.

There are so many hypotheticals, I think at some point I just have to admit that I can't account for everything, and just go ahead and try to do it, if something doesn't work out I can try to understand why and try again. I just haven't had time to work on this for a while.

Attachment: 2494-The-Chemistry-of-Phosphine807f.pdf (857kB)
This file has been downloaded 415 times

MidLifeChemist - 13-11-2020 at 09:22

Quote: Originally posted by Duff

but hopefully I can spend more time on phosphorus production in the coming months.

Have you produced any phosphorus yet?

zed - 17-3-2021 at 03:48

Ummm. We talked about this a decade ago. It seems that no-one followed through.

"When triphenyl phosphate was reduced with a solution of LiAIH 4 in carbitol, which was prepared as described in [9], the formation of red phosphorus was observed and not even traces of phosphine were present."

LiAlH4 or NaAlH4, are not easy "gets"... But, Phosphorus has become much harder. Metal Hydrides can still be purchased. Phosphorus and Phosphorus Chlorides, have become highly restricted.

So... Back to the original paper, wherein some guys were failing to produce the desired Phosphine, and they were instead producing useless "Red Phosphorus"

https://www.sciencemadness.org/whisper/files.php?pid=191992&...

[Edited on 17-3-2021 by zed]

[Edited on 17-3-2021 by zed]

draculic acid69 - 17-3-2021 at 05:53

Interesting rxn. P4 production with glassware and normal temperatures.gamechanger. weird solvent though.

clearly_not_atara - 17-3-2021 at 12:26

zed, that's a great find. But I'm wondering: how do you produce triphenyl phosphate? Maybe you can vacuum distill a mixture of metaphosphoric acid and phenol at equilibrium?

PhOH + (HPO3)6 >> 4 H3PO4 + (PhO)3PO (g)

Presumably the formation of triphenyl phosphate is disfavored but the lack of H-bonding may imply some higher vapor pressure? bp 244 C at 10 mm Hg. I've never heard of esterifying phosphoric acid directly, though, but this patent implies that the big problem is olefin beta-elimination and that might be avoided with phenol:

https://patents.google.com/patent/US4921990A/en

But phenol itself is already more volatile than triphenyl phosphate...

RustyShackleford - 17-3-2021 at 17:02

Thats an insanely expensive reaction to run for something as mundane as red p.

zed - 21-3-2021 at 01:59

Red Phosphorus is insanely hard to acquire in the USA. Guys that want it, may have to scrape it off of matchbox strikers. Yellow, AKA White Phosphorus, is hard to come by also, but it is more "makable".

Completely converting White to Red, isn't totally easy.

Initially, the restrictions had to do with Domestic illegal Methamphetamine Manufacture. Now, it is restricted six ways from Sunday. Chemical Weapons Ban, etc... There are restrictions on international commerce, as pointed out in that Japanese Procedure at the top of the page. Nations that don't normally produce their own P, are concerned.

And yet, for many reactions, chemists must have it. In the USA, Colleges and Universities, are often doing without. Too much paperwork. No problem for large corporations, I suppose. But, for the amateur, damned hard to come by. I'm gonna go back and swipe a quote from that paper.

"Due to this huge energy consumption, current yellow phosphorus producing countries are limited to China, the United States, Kazakhstan, and Vietnam. After the United State banned the export yellow phosphorus as a strategic commodity from 1996, other yellow phosphorus producing countries also limited their export. Thus, Japan's imports of phosphorus ore, as well as yellow phosphorus, are becoming increasingly severe year by year."

White Phosphorus isn't especially hard to make, but the process requires a committed approach. Brutal perhaps. A backyard, An old BBQ, wood or charcoal, and a source of forced air, are required.

Argon forced through your reaction mixture might improve yields by conveying Gaseous Phosphorus out of the reaction mix. Most mixes work something like this: Mix up Phosphate, Carbon, and Sand, then heat it up hotter than the hinges of Hell. The Carbon reduces the Phosphate to P, then exits as CO2. The Silica or Sand... Helps. As I said, additional Gas flow might help the P to get to where it needs to go.

Here, Rogeryermaw, shows you how it is done. https://www.youtube.com/watch?v=mibM4WUx74Q&t=2s

https://www.youtube.com/watch?v=4YjUC2dmNV0

https://www.youtube.com/watch?v=23bXKpLyXJk

A further procedure by Canadian Chemist

Also brutal.... https://www.youtube.com/watch?v=NxQrqXIMEh8

[Edited on 21-3-2021 by zed]

Triflic Acid - 13-4-2021 at 06:13

Going back to something that was said earlier, https://pubs.acs.org/doi/pdf/10.1021/acssuschemeng.0c04796. Possibly using a deep euctectic mixture of Calcium chloride and urea/choline chloride spiked with calcium phosphate would be electrolyzed to give phosphorus? The temp doesn't seem to play a part, and if we can keep it around 100C or so, then it solves the problem of molten salt electrolysis.

njl - 13-4-2021 at 06:20

Link doesn't work for me

draculic acid69 - 13-4-2021 at 07:00

Quote: Originally posted by Triflic Acid

Going back to something that was said earlier, https://pubs.acs.org/doi/pdf/10.1021/acssuschemeng.0c04796. Possibly using a deep euctectic mixture of Calcium chloride and urea/choline chloride spiked with calcium phosphate would be electrolyzed to give phosphorus? The temp doesn't seem to play a part, and if we can keep it around 100C or so, then it solves the problem of molten salt electrolysis.

Wouldn't electrolysing calcium chloride and a phosphate give off some pcl3 ?
Or does the phosphorus form at the opposite electrode than the chlorine?

Triflic Acid - 13-4-2021 at 13:15

The paper is called: A New Concept for Producing White Phosphorus: Electrolysis of Dissolved Phosphate in Molten Chloride

clearly_not_atara - 14-4-2021 at 06:59

You need to ensure that phosphorus is reduced before any other component of the solution. That isn't going to be easy. Urea will likely react before phosphate does, or it will react with the byproduct. You also need not only to melt CaCl2 but to dissolve Ca3(PO4)2 in it.

Now, you might be able to just electrolyse molten sodium metaphosphate, which melts at 628 C. That already gets you a bit lower. But it's extremely corrosive. Electrolysis in CaCl2 has received intense attention lately due to its role in the refinement of Ti and Zr.

The eutectic of NaCl and CaCl2 has a composition of about 49:51 [NaCl]:[CaCl2] or about 43 grams NaCl to 85 grams CaCl2, and melts around 500 C:
http://www.energy-proceedings.org/wp-content/uploads/2020/03...

So you might start there. If you're lucky, you could run the process at around 550 C instead of 850 C, which puts you in the operating range of more ordinary materials, but still not Pyrex.

The MgCl2-NaCl-CaCl2 eutectic melts at 420 C which is still just a bit too high for glassware, and anhydrous MgCl2 is difficult to prepare, but that gets you a bit lower. The MgCl2-NaCl-KCl eutectic (55:24.5:20.5 wt%) is around 387 C:

https://www.osti.gov/servlets/purl/1440736

Whether a useful amount of phosphate can be dissolved in the chloride salts and electrolysed at these low temperatures is not at all guaranteed, but I suppose you can always try. However, glassware is still not recommended because phosphates will corrode it. Chlorides attack steel.

njl - 14-4-2021 at 07:08

If I understand the paper, only 2 percent of the molten salt solution is phosphate by weight so even if this is feasible for the amateur, at a small scale it seems quite pointless.

Triflic Acid - 14-4-2021 at 10:51

But possibly topping up the phosphate periodically will solve that problem. And maybe a euctic that won't be reduced first would work. I think I'm going to try this some time in the next few months.

clearly_not_atara - 17-4-2021 at 07:04

I don't know what you mean by "small scale". It's hard enough to deal with electricity at high temperatures, and even a kilo of MgCl2 isn't breaking anybody's budget. You need all kinds of insulation and temperature control, so it's simpler to set up the equipment to hold around a liter of molten salts anyway. At that scale, you get a few grams of P per run, which really isn't bad.

The big advantage of not running a "bomb" process like carbo/metallothermal reduction is that the damage to equipment and clean-up should be much less.

Triflic Acid - 27-4-2021 at 05:55

You know, maybe setting the system up so that you occasionally top it off a mixture of chloride and phosphate would allow you to keep going indefinitely. Also, I found two papers that give a pretty good idea: https://www.sciencedirect.com/science/article/pii/S092702481... for the euctic, and https://pubs.rsc.org/en/content/articlelanding/2009/gc/b9063... for the electrostablility of the euctic. The first paper basically says that a choline chloride euctic works. The second paper I found a bootleg copy of online. Any thoughts? Looks promising to me.

Attachment: Greenchemistrypublished.pdf (210kB)
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njl - 27-4-2021 at 06:18

Atara, if you do the math: 2 percent solution of Ca3(PO4)2 in 1 Kg molten salt = 20 grams Ca3(PO4)2 = .0645 mols. With 100 percent recovery of phosphorus that's 1.9 grams per run. What I mean by small scale is 1 Kg. Or 10 Kg for that matter. Not to mention even if one gets this to work you have to deal with gaseous WP.

clearly_not_atara - 27-4-2021 at 09:04

njl: You've used a density of 1 for the molten salt (I said "liter", you said "kilogram"), which is only a little wrong when you're dealing with organic chemicals, but the density of alkali chloride salts is about 2-2.5, which raises your raw numbers to about 4 grams. There was also a proposal of using (NaPO3)x as the phosphorus source instead of CaPO4, which may significantly increase the phosphorus content (unclear).

For amateur-feasibility, we are already forced to improvise because 850 C is a difficult temperature. It is also plausible that the reaction doesn't work at all at lower temperatures. But while we're on the subject, the KCl-LiCl eutectic is shockingly low: 352 C!
https://pubs.acs.org/doi/pdf/10.1021/ja01538a001

In this context, it's worth remembering that elemental phosphorus is a precursor to various reagents and catalysts that support difficult reactions under mild conditions in high yield on delicate substrates. A few grams of phosphorus is all you need to make a lot of PPh3-ligated catalysts, for example.

The gaseous WP thing is a moot point because all practical phosphorus refinement techniques give a gaseous product. Electrolysis should give WP at a lower temperature and in higher purity than carbothermal reduction.

Triflic Acid: Neither of these papers shows anything about choline chloride being effective at the potentials required for phosphate reduction...

Triflic Acid - 27-4-2021 at 09:06

Is no one thinking about the euctic :mad:

Why would it be gaseous WP if it is a euctic. WP boils at 280C, and with a bit of work a euctic could be made so that it is liquid below this temp. Also, constantly topping up the CaCl2 with Ca3(PO4)2 would let you get out more than 1.9g per kg. Even then, this could be played around with to get a better ratio of chloride to phosphate, by trying different cations like sodium. I think that this is worth trying. I'll post when I get around to trying this.

clearly_not_atara - 27-4-2021 at 10:14

See ref for LiCl-KCl eutectic production reference:

https://iopscience.iop.org/article/10.1149/1.2428639/meta?ca...

352 C is pretty good; it's not at all difficult to condense something coming over at 400ish. I think that getting the working temperature safely under 500 C opens up a lot of doors, because a lot of equipment is rated to around 500 C.

The truth is that if the phosphorus product weren't gaseous you'd have a whole host of new problems, like whether it passivates the cathode, reacts with the membrane, forms complex dissolved salts, floats, sinks, foams, etc.

Triflic Acid - 27-4-2021 at 10:29

I don't know, I'm thinking that, assuming that the P floats, we could just have an inverted test tube over the cathode, like in a hofmann voltmeter. Airtight and to remove the white P you just flood with water and remove the test tube. On the other hand, if it sinks, just flip the test tube over and the white P will collect under the euctic, still airtight and easy to collect.

[Edited on 27-4-2021 by Triflic Acid]

njl - 27-4-2021 at 10:37

Yes, I think it would be necessary to remove the phosphorus as it forms by distilling it off. But this means that the cell and distillation apparatus must be well sealed against the atmosphere and evacuated. That's the problem with this batch process, there's no convenient way to periodically add phosphate without disassembling the entire setup. Unlike in a retort where the atmosphere within the apparatus is consumed (leaving an inert space for distillation) this design reintroduces oxygen with every batch (which again have a yield of maximum 1.9 grams WP). There is a lot of room for improvement, but I can't see how this would be practical until at least the yield per batch is optimized.

Jimmymajesty - 20-2-2022 at 13:12

I took 60um silicagel for chromatographic purpose calcined it at 1200°C for 15min
60um (unreactive) aluminum powder
Na3PO4*12H2O mixed with H3PO4 based rust remover to get NaH2PO4, this heated to 200°C for 4 hours then 800°C for 30mins, there were small flaming pops at 800°C indicating that there were organic crap in the rust remover.

This was mixed in 3,4 NaPO3 1,75 Al 1 SiO2 weight ratio, ball milled for 4 days in acetone, then dryed

10g of said powder packed into alufoil the pack is fixed into a qartz tube, top end was purged countinously with CO2 bottom was immersed to about 10cm water

I started the raction by heating the quartz tube at one spot, when the reaction started, some expansion of the slag took place clogging up the quartz tube, then shooting out the top plug, then at the bottom the gases escaping the water bottle instantly catched fire, after cooling there were only a sub gram quantity of P4 at the bottom of the collector. I removed the slag from the tube and it instantly catched fire maybe a gram worth of white P4 was still inside the tube estimating by the amount of smoke

After the whole mess I scanned the desktop with a bunsen burner and there were small pops and sparks all around the table. A lot of things on the table catched fire/made a small flash during the cleanup here and there, so I only recommend repeating this if you have a shitty garage like me and you do not mind making it inhabitable for a while

Keras - 20-2-2022 at 22:33

Quote: Originally posted by clearly_not_atara

In this context, it's worth remembering that elemental phosphorus is a precursor to various reagents and catalysts that support difficult reactions under mild conditions in high yield on delicate substrates. A few grams of phosphorus is all you need to make a lot of PPh3-ligated catalysts, for example.

If PPh₃ is what you need, there’s no need to fancy weird or risky reactions. It can be bought easily here, and it is quite cheap.

Jimmymajesty - 8-5-2022 at 10:35

I modified above procedure as follows:
Ignited silical gel was replaced with expired transparent saniter silicone (caulk in US terms I think) that was burned to SiO2 on a pan.
Na3PO4 was treated with pure H3PO4 then dryed and ignited in a SS bowl to give presumably NaPO3 of something similar, it is a transparent glass that breaks on cooling to 2-3cm bits.

The Al SiO2 NaPO3 mixture was poured into the ball mill with some hexane instead of acetone, acetone reacts with Al during the milling process evidenced by evolution of H2.

The mixture was milled for 6 days, hexane was recovered @ 90°C, the powder then dryed @ 45°C for 4 hours, the initially inert grey powder turned black it is as easily ignited as black powder, also impact sensitive, a moderate blow from a hammer can set it off.

Igniting this gave off white smoke and beneath the pile there was a stain of phosphorous by scraping the stain it gave off small flashes. It is good to make some smoky stuff with this for new years eve but i think it is too aggressive to isolate P from this, maybe diluting the mixture with some carbon can curb the burn rate, pressing it into pellets can also help.

clearly_not_atara - 27-6-2022 at 19:56

https://chemistry-europe.onlinelibrary.wiley.com/doi/pdfdire...
"The Dean–Stark esterification of H3PO3 with 1-butanol (1.5 equiv.) gave a mixture of H3PO3, HOP(O)(OBu)H, and (BuO)2P(O)H in a 11:56:33 molar ratio."

Okay, it's not quite phosphorus, but sodium phosphite is OTC in some places. The dialkyl H-phosphonates can most likely be brominated or chlorinated to the dialkyl halophosphates, offering the possibility to activate a wide variety of carboxylic acids, alcohols, phenols, oximes, etc, as would be done with POCl3. Trialkyl phosphates, hiterto considered impossible, would also be accessible.

In the particular case of trimethyl phosphate, I don't know if the esterification of methanol with phosphorous acid works, or if the boiling point is too low.

yobbo II - 26-1-2023 at 11:06

I posted this in another thread so it's a bit of a double post.

The following is from the Bell Jar, the first five years page 3 - 8:
A magazine dedicated to vacuum.

Low temperature chemical reactions:

The reaction
NaHCO3 = Na2CO3 + H2O + CO2
which normally takes place at 270° C will take place at
room temperature in a vacuum of about 1 mm Hg.

Other reactions which take place at much lower
temperatures in a vacuum are the following:
Cr2 O3 + 3C = 2Cr + 3CO
CaC2 + 2 NaCl = CaCl2 + 2Na (vapor) + 2C
2MgO + CaO + Si + 2Mg (vapor) + CaSiO3
FeO + C = Fe + CO
These reactions are of great commercial importance.
Any reaction evolving gas will proceed at lower
temperature in vacuum.

END OF QUOTE
___________________________________

Would this be applicable to making P ?

It sounds too good to be true. Forgive me it is has already been mentioned up the thread.

You would need a water aspirator as you are not going to use your mechanical pump, though you could use a piston (the type used nowadays) pump from a fridge which I belived will pull a vacuum of about 1mm of Hg.

Yob

blogfast25 - 27-1-2023 at 06:53

Quote: Originally posted by yobbo II

The reaction
NaHCO3 = Na2CO3 + H2O + CO2
which normally takes place at 270° C will take place at
room temperature in a vacuum of about 1 mm Hg.

Other reactions which take place at much lower
temperatures in a vacuum are the following:
Cr2 O3 + 3C = 2Cr + 3CO
CaC2 + 2 NaCl = CaCl2 + 2Na (vapor) + 2C
2MgO + CaO + Si + 2Mg (vapor) + CaSiO3
FeO + C = Fe + CO
These reactions are of great commercial importance.
Any reaction evolving gas will proceed at lower
temperature in vacuum.

END OF QUOTE
___________________________________

Would this be applicable to making P ?

It sounds too good to be true. Forgive me it is has already been mentioned up the thread.

Yob

The 'pulling a vacuum' trick works because removing volatile compounds from the reaction mix pulls the equilibrium to the right, according to Le Chatelier:

Le Chatelier.

Will this work with P? I doubt it on the grounds that no one seems to be using it.

But there's only one way to find out!

clearly_not_atara - 11-2-2023 at 15:09

Quote: Originally posted by clearly_not_atara

https://chemistry-europe.onlinelibrary.wiley.com/doi/pdfdire...
"The Dean–Stark esterification of H3PO3 with 1-butanol (1.5 equiv.) gave a mixture of H3PO3, HOP(O)(OBu)H, and (BuO)2P(O)H in a 11:56:33 molar ratio."

f/u: direct reduction of sodium tripolyphosphate to sodium phosphite by ball-milling Na5P3O10 or Na4P2O7 with alkali metal hydrides or NaBH4:
https://pubs.acs.org/doi/full/10.1021/acscentsci.1c01381

The ideal hydride source is potassium hydride, but NaH, LiH and NaBH4 also give some yield. Sodium fluorophosphate gives a higher yield but is not necessarily OTC. Reaction conditions with borohydride were not optimized.

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