Disclaimer:
!!!!!!!Educational and informational purposes only!!!!!!!!!!!!!!!
I won't bee held leagally responsible for this cause i don't wanna, but i wanna give it beecause i just wanna. Check your localz laws, if its illegal where you are then its the authors opinion that you should move houses before saving.
Its for educational purposes and i include warnings throughout loud and clear about the dangers. Objective/Aim:To isolate H3PO3(s) from an aqeous solution of it's phosphite salt(s), mono/di-potassium phosphonate.Important numbers & Formulae
H3PO3 = 81.996 g/mol
K = 39.098 g/mol
KCl = 74.551 g/mol
H2O = 18.015 g/mol
KOH = 56.106 g/mol
HCl = 36.461 g/mol
KH2PO3 (Mono-potassium phosphonate) = 120.086 g/mol
K2HPO3 (Di-potassium phosphonate) = 158.177 g/molThis section is simply an analysis of the best and worst case scenarios as far as what the theoretical potential yields actually are. You can read over this section if you wish or skip to the procedure further down...
HClmin is simply a theoretical quantity I made up to denote the amount of HCl that would be used up during the reaction and required by the procedure if the feedstock contained only the mono-K phosphonate form an unlikely event maybee... but nevertheless I think you'll find the information convenient when weighing your final yield as this quantity represents the upper
potential theoretical yield for a given amount of the potion of phosphites.
The
HClmax quantity has a more procedural significance...it represents the amount of HCl you'll actually measure out to guarantee a complete reaction whatever the proportion of mono/di-K forms in your foliar solution, specifically it simply assumes that it all contains
only the Di-K form – The least phosphorous acid rich form, but this reaction requires more HCl.
Your
actual yield will fall between them both, so from 40g, 100ml of 400g/L foliar potion you should get between 20-27g of H3PO3.
If you measure more than 27g, that's great, it just means that you are measuring a little H2O impurity most likely. If you weigh <20g your lab work needs work or your supplier does, because he is a con.
Analysis of HClmin and HClmax reactions and the theoretical outcomesQuantity analysis of.: HClmin:
Formula
KH2PO3(40g, .33 mol) +
HCl(12g, .33 mol) --->
KCl(24.83g, .33 mol) +
H3PO3(27.3g, .33 mol)
Reactants
KH2PO3 = 40g, 100ml@400g/L
HCl = 12.145g, 40.48ml@0.3g/ml
Resultants and theoretical quantities of
KCl = 24.83g
H3PO3 = 27.31gQuantity analysis of.: HClmax:
Formula / QuantitiesK2HPO3(40g, 0.25mol) +
2 HCl(18.44g, 0.5mol) --->
2 KCl(37.5g, 0.5mol) +
H3PO3(20.7g, .25mol)
Reactants
K2HPO3 = 40g, 100ml
HCl = 18.44g, 61.46ml@0.3g/ml
Resultants and theoretical quantities of.:
KCl = 37.5g
H3PO3 = 20.73gMaterials & ChemicalsEquipmentElectric fry-pan sand/oil-bath or hotplate (no COILS)
Table salt* if you use a hotplate. No oil/sand required
Glass Pyrex boiling jug
Empty wine or champagne bottle
Glass Pyrex tray or suitable casserol dish
Squeezable squirting bottle
Plastic scraper or any plastic object with a flat sharp edge
Fan-forced oven
Kitchen plastic wrap
Pestle – no mortar is needed
Reasonably good ventilation
ChemicalsMethylated spirits a.k.a denatured alcohol (simple, vaguely accurate names for simple, rarely accurate people...Yeah pick on ther yanks when life is going badly for ya, thats fine!)
Foliar spray containing aqueous di-potassium phosphonate and mono-potassium phosphonate salt (phosphites)
300g/litre (8.22M) HCl or muriatic acid
Distilled water; but springwater is fine.
Abstract of procedure1.Measure 100ml of 400g/litre potassium phosphite solution
2.Measure HClmax solution
3.Add diluted HClmax solution to diluted potassium phosphonate solution; wait
4.Boil off H2O
5.Refrigerate resultant concentrate
6.Extract [and, decant off] 3-5 times using cold methylated spirits
7.Boil off alcohol and H2O
8.Repeat Steps 6-7
9.Transfer to a large shallow glass pyrex dish
10.Heat until relatively anhydrous using 70-90C temperatures
11.Cover and cool your H3PO3 using a freezer
12.Transfer to a permanently air-tight container to bee buried
Example of procedure///HUGE WARNING///: PH3 IS PRODUCED UPON DECOMPOSITION OF H3PO3 AT 180C, ENOUGH TO KILL YOU AND PROBABLY ALSO ANYONE WHO ATTENDS TO YOUR LIFELESS BODY. 1.Carefully measure 100ml of a 400g/L potassium phosphonate foliar solution and transfer to a wine or champagne bottle that can accommodate both this solution, aswell as the HCl which will be added. Dilute this with 100-200ml of DH2O.
Leave nothing behind in your measuring instrument, not a trace, cover your tracks using warm water.
2.With good ventilation present, carefully measure 61.50ml of 8.22M(300g/L) HCl solution, carefully dilute this with 200ml of DH2O. Store this in a suitable bottle
3.Using a funnel, add this dilute HCl solution to the wine bottle containing your phosphite salts in 5-10 increments over the course of 1hr, swishing the wine bottle around in a circular motion as you do this to ensure a complete reaction.
Continue this until all of your dilute HCl
max solution has been added to the wine bottle...which now contains H3PO3(aq), KCl(aq) and any excess HCl that wasn't used in the reaction due to the presence of mono-phosphonate salt form.
Shake and settle this reaction mixture for 1-3hrs.
4.Transfer the contents of your wine bottle, a cloudy white H3PO3(aq), KCl(aq) [,and any excess HCl(aq) ] mixture, carefully to your glass pyrex jug.
Cover your tracks from the wine bottle using a generous amount of warm-hot water and add this to your pyrex jug aswell.
5.Pour a generous amount of table salt on your hot plate, (not on coil ones
) to protect the jug against the direct heat. But any type of oilbased sandbath is suitable, even prefered.
Place the pyrex jug on your chosen heating medium and
bring to a boil gently and maintain over the course of a few hours or until you begin to see salt (KCl) precipitate. This just indicates that your H3PO3(aq), KCl(aq) mixture has now reached a point where there isn't enough room for them both..and of course the H3PO3 wins that battle allday everyday being strongly hygroscopic and deliquescent-so the KCl(s) is precipitated.
Remove the jug from the heat and allow to cool – Use the refrigerator when you feel it is safe to do so. Make it cool-cold before the next step.
Note: This step has the biggest question mark over it...the more you boil off the better as far as removing the KCl in this step, but it might also reduce your H3PO3 yields. Late brainstorm! It probably won't decompose in the presence of water, but boil the shit out of it at your own risk.
6.Add methylated spirits to this cold solution in tiny increments-you will notice more KCl precipitating out, as the KCl has yet another substance to compete with which it isn't soluble in to any great extent. Continue adding the methylated spirits until no further KCl is being precipitated. Add some more methylated spirits, you can't overdo it.
Note: Keep in mind that this reaction produces a LOT of KCl, so removing it early on is highly preferable or it is likely to trap H3PO3.
7.Carefully pour off this now much purer (though it still contains some KCl(aq)) alcoholic aqueous solution of H3PO3 in to
another large jug.
For good measure use your squirt bottle to wash down the inside of the jug. Get a pestel and grind the KCl(s) for the 2nd and 3rd pulls so that it releases any H3PO3 in to the methylated spirits.
Transfer it back in to your (WELL RINSED) boiling jug
Note: Either keep the KCl or throw it away or save it for a nano maybee later. But it probably doesn't contain much phosphorous acid.
8.Repeat Steps 6 and 7. But don't expect to see much if any KCl precipitate out while boiling, your more likely to see it when adding the methylated spirits.
9.Now boil down this aqeous alcoholic H3PO3 once more to a cloudy white (maybee a hint of yellow) concentrate.
10.Pour this carefully in to your pyrex evaporation dish. Place in the oven on the very top shelve, with your fan force on, and the
DOOR SLIGHTLY OPEN THROUGHOUT THIS STEP(!!), use a 70-90C heat.
Note: I know it takes a long time but you have to wait. Check it regularly, shine a torch across the liquids surface and tilt it to see how it's going.
When the H3PO3's ready it will STILL BEE A LIQUID, BUT SLIGHTLY VISCUOUS AND SYRUPY, it's melting point is 70C so it'll bee obvious when the ethanol and H2O has gone.
Prepare a big section of plastic kitchen wrap with a sache of drying agent taped to one side. The drying agent isn't necessary, but it will absorb any steam coming off the hot H3PO3...if you don't use it you'll still have the wax.
11.Carefully take your evaporation dish of delicious smelling phosphorous acid out of the oven, and plastic wrap it carefully (no air leaks!). Place in the freezer. Come back in 30min-1hr and as you can see
you are the owner of Excellent-Whoa! PHOSPHOROUS ACID!12.Use plastic to transfer the goodies...do it in the freezer, the freezer is dry and cold. Weigh the shit. You did good. It's not meth but you can pretend! This shit is reagent grade man, I'd bet my dick on it.
DiscussionThe procedure produces a white-yellow pleasant-smelling waxy solid strongly suspected to be made up of predominantly the compund H3PO3 (phosphorous acid) in excellent yields.
Yield90% yields are quite do-able, of course you'll never
know but during testing mine were closer to the HCl
min theoretical so I know I probably got close..
If you use the basic lab technique of
“covering your tracks” with a solvent that dissolves your desired end product, and carries it from every surface it touches during the procedure to the end-point of the procedure – the freezer.
Don't have any spills. So, think about what your going to bee forced to pour out of. If you have a spill, the work you've put in to covering your tracks seems worthless.
Quality i.e. H3PO4, Other impurities, Hydration.There may well bee a
small KCl impurity at the end, certain steps repeated will reduce this, with no expense to yield as for example with maybe boiling a concentrated aqeous solution of H3PO3 and KCl.
The use of cold OH really helps with the KCl impurity. Small pulls/extractions also helps because of reasons Rh explained recently in the Solvent Miscibility chart sticky thread in the Newbee forum (where I belong)
HCl impurity will bee near non-existant, the addition of the ethanol may even cause some formation of ethyl chloride with any excess HCl, and bee burnt off during the second boil. Either that, or it is fumed off at the final evaporation in the fan-forced; one of the final steps.
So in one sense, the more excess HCl there is the better, because it means that your solution wasn't entirely made up of the less phosphorous acid rich di-K phosphonate salt.
Worried about
H3PO3 impurity? So was I, because at one point I had only seen it as a frozen solid, so to test it I heated the container to about 30C+ in front of the heater. There was only a very small amount of liquid, very insignificant, the vast bulk of it remained a firm solid. I do mean tiny amounts too, not ¼ of it swishing around, I'm talking minute amounts! -1% visually. This is shit that was from a traumatic test procedure I spent days carefully drying.
Keep it in a cold place, as cold as possible, I doubt it will oxidize much at all.
Novel quickiesOkay so the problems associated with this substance as you all probably know are natural oxidation of the substance in the presence of free oxygen(1), drying(2); and the problems this causes for measurment as a reagent(3). So these are what the novel ideas are mainly focused at attempting to solve.
1.Funnel molten h3po3 into PVC tubes or sticks or a large syringe.
2.Add a sache of activated carbon to your container to keep O2 levels down.
Other possible uses1.Drying agent?
2.A new waterless A/B ingredient?
ConclusionUsing this procedure the waxy solid phosphorous acid (H3PO3(s) can be easily extracted and isolated from an aqeous solution of it's phosphite salt(s), mono/di-potassium phosphonate.
The yields are excellent, the quality although untested in a HI reaction to any extent whatsoever should be quite suitable for the said reaction.
I'd really like a simple way of testing purity, and/or isolating either the phosphoric or the phosphorus acid, but we don't always get what we want...in a reasonable timeframe.
If you need help converting any numbers or concentrations or anything just let me know and we can edit it in to the write-up for future reference. This includes internationalisation of anything.
Best of care,
halfkast