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Author: Subject: Ammonium permanganate preparation
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[*] posted on 20-5-2002 at 18:32
Ammonium permanganate preparation


Ammonium permanganate, contrary to popular belief, is actually a relatively stable compound (although not a stable explosive). Preparing NH4MnO4 requires a solution of HMnO4 (it can't exist on its own). The simplist way to prepare a solution of HMnO4 is to add Mn2O7 to water. This route is dangerous because of the involvement of Mn2O7, a dangerously explosive oily liquid. I have designed an alternative process for preparing an aqueous HMnO4 solution.

(COOH)2 + KMnO4 --> KOOCCOOH + HMnO4

That is the reaction that I used to prepare the HMnO4. I tried two experiments.

1) I heated 200mL of water to 90C. I was planning on cooling the solution to around 0C after the reaction, so that I could filter out virtually all of the KOOCCOOH formed. I then added 10g KMnO4 to the solution. I added 6g (COOH)2 to the solution; fierce fizzling began. HMnO4 gas wasn't being given off; it has a strong odor and color, which wasn't observed. I believe the H3O+ ion was being oxidized by the MnO4- ion, causing (COO-)2 ions to decompose. Anyways, I ended up dumping the solution down the drain.

2) I decided that since in experiment #1 the H3O+ ion was being oxidized, causing the decomposition of the (COO-)2 ion, I would use far lower temperatures this time. I took 200mL of water at the temperature of 10C, and added 5g KMnO4. I then added 3g (COOH)2. There was a slight amount of fizzling. I continued to cool the contents of the beaker until the temperature was at 5C; then I filtered the contents of the beaker. The filtered liquid, an *intense* purple aqueous solution of HMnO4, did not fizzle (because of the absence of the (COO-)2 ion). I then added 20mL of 10% NH4OH solution (I wanted to make sure that all of the HMnO4 was fully reacted) while keeping the beaker in an ice bath. The temperature rose about 5C despite the ice bath. As of right now, I am waiting for the water to evaporate off. More news on this experiment later.

[Edited on 21-5-2002 by madscientist]




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[*] posted on 21-5-2002 at 16:03


A problem with preparing ammonium permanganate in aqueous solution has just occured to me. The NH4MnO4 will slowly decompose into NH3, H2O, and Mn3O4.

NH4MnO4 + H2O --> [NH4+] + [MnO4-] + H2O

[NH4+] + [MnO4-] + H2O --> NH3(g) + [MnO4-] + [H3O+]

12[MnO4-] + 12[H3O+] --> 4Mn3O4 + 13O2 + 6H2O

And, obviously, reaction of the NH4MnO4 with the Mn3O4 will occur...

Precipitation of Mn3O4 from the solution of NH4MnO4, from experiment #2 (referring to the above post) has already been observed.




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[*] posted on 22-5-2002 at 17:40


Well, the reactions posted in the post directly above have spelt the end of the ammonium permanganate I had prepared, which was in solution. There is now nothing but a precipitate of Mn3O4 resting on the bottom of the beaker, and the faint scent of ammonia.

I have, however, thought of an idea for extracting the ammonium permanganate from solution. In ice, since it is a solid, the particles inside have very restricted movement. Therefore, the ammonium permanganate in a frozen aqueous solution will not be decomposing. Ice slowly sublimes. Therefore, if a solution of ammonium permanganate is frozen, and left frozen, eventually all of the H2O will be gone, leaving pure NH4MnO4 crystals.

[Edited on 23-5-2002 by madscientist]




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[*] posted on 27-5-2002 at 11:55
This sounds like a job for...


...Vacuum Sublimation Man! Seriously, unless you want to wait months for the results of your experiment, you're going to have to sublime the ice under vacuum. It may not even be necessary to keep the ice frozen the whole time. Add your ice, pump air out, and slowly raise the temperature. If the liquid water is removed almost as fast as it appears, you shouldn't have to worry too much about decomposition.
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[*] posted on 14-6-2002 at 13:11


Here's a way of preparing high-purity NH4MnO4 that has been tested, and works. Simply mix a stoichemical amount of ammonium oxalate and potassium permanganate; dump it in a small amount of water in a jar, and allow the NH4MnO4 crystals to form on the sides of the container. I recommend using a lid with a small punched in it. The crystals are spiny, and are obviously a dark violet color; they however are not as intensely violet as potassium permanganate. This is how it works:

(COONH4)2 + 2H2O --> (COO)2[-2] + 2NH3 + 2H3O[+1]

The ammonia evaporates out of solution.

KMnO4 --(H2O)--> K[+1] + MnO4[-1]

MnO4[-1] + H3O[+1] --> HMnO4 + H2O

The HMnO4 evaporates out of solution.

HMnO4 + NH3 --> NH4MnO4

The ammonium permanganate crystals form in the air, some crystalizing on the sides of the container, given a starting point for more ammonium permanganate crystals to add on to the starting crystal.




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[*] posted on 15-6-2002 at 10:20


So mixing ammonia and potassium permanganate and then adding sulfuric acid (to the solution!) should also work?
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[*] posted on 15-6-2002 at 10:46


I would think it would; but not nearly as well as the method I posted previously. :)



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sad.gif posted on 16-8-2002 at 08:57


Oxalic acid can be mesured via permanganatimetry (KMnO4 in basic or acidic media)!
Again oxalic (you seem to like oxalic, oxamide, nitroxamide, .... ;) ) is a reducer and KMnO4 is an oxydiser...oxydoreduction will occure always freeing CO2 and leaving MnO2 (brown)!
2KMnO4 + 3HO2C-CO2H --> K2CO3 + 5CO2 + 2MnO2 + 3H2O

If you want permanganate of NH4; use a salt of ammonium that can't be oxydised like NH4 sulfate, NH4 phosphate, NH4 nitrate (there is a risk of detonation here), NH4 perchlorate (here too).The idea is to find a salt of K (KX) that is less soluble than KMnO4 and NH4 brother (NH4X); then the reaction will go easy!

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[*] posted on 17-8-2002 at 12:02


hmm
KMnO4(aq)+NH4ClO4 (aq)=>

KClO4 (s) + NH4MnO4 (aq)

it relies on the fact that KClO4 is less soluble than the other possible compounds. It s is somewhat soluble in cold water though, but the contaminants
NH4ClO4 and KMnO4 would probably not be a problem..

/rickard
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[*] posted on 31-8-2002 at 15:19


Hmm, Rickard's method sounds good to me. If you want all of your ammonium permagnanate to be in solution, you're going to have to perform the reaction in at least a liter of water. Otherwise, the ammonium permanganate, which is not very soluble at all (8 g per 100 ml at 15 degrees), will precipitate out along wtih the potassium perchlorate, and how the hell do you separate those two, if they're a solid mixture?

Rickard, it's not somewhat soluble in cold water at all. At 1 degree celsius, 1 gram of KClO4 will dissolve in 100 ml of water - hardly a critical amount.

Maybe you could take the solid mixture of NH4MnO4 and KClO4, and dissolve it in alcohol. KClO4 is practically insoluble in alcohol, but I'm guessing that NH4MnO4 is (anyone care to clarify that?).

Either way, I would certainly like to prepare this compound.

David Hansen
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[*] posted on 31-8-2002 at 21:47
Not Rickard...


:mad: ...it's Rikkitikkitavi.

Pretty awesome book from what I can remember (all of 15 years ago) :D
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[*] posted on 9-9-2002 at 15:32


Fusion of MnO2 + KOH + KNO3 --> dark green managanates K2MnO4
Manganates are stable in strongly alkaline solution but disproportionate in neutral or acidic conditions into permanganates!
3K2MnO4 + 2H2SO4 --> 2KMnO4 + MnO2 + 2H2O + 2K2SO4
2K2MnO4 + 2H2O --> 2KMnO4 + 2KOH + H2
Oxydation in aqueous solution of Mn(2+) salts by strong oxydiser like NaBiO3 or PbO2 also forms permanganates!

So based on those datas!
It seems a good idea to try to fuse:
MnO2 with Ca(OH)2 and Ca(NO3)2 or Ba(OH)2 and Ba(NO3)2 to get CaMnO4 and BaMnO4.

The later upon treatment with H2SO4 should leave...
3CaMnO4 (solution)+ 2H2SO4 (diluted) --> Ca(MnO4)2 + MnO2 + 2H2O + 2CaSO4
finally Ca(MnO4)2 + H2SO4 --> CaSO4 + 2 HMnO4
CaSO4 is quite unsoluble (plaster), MnO2 is unsoluble too; thus it would be quite easy to dissolve NH4OH in the filtrated solution to get...NH4MnO4!
Thadaaahhh!

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[*] posted on 10-9-2002 at 06:37


Nice idea. It seems that MnO4- salts with 2+ or 3+ metals are much stronger oxidizers than KMnO4, is this correct?



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[*] posted on 13-9-2002 at 07:40


Rectification:
Not stronger oxydisers but higher in oxygen contain (active oxygen %)!

PH Z
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smile.gif posted on 8-10-2003 at 17:41
Ammonium permangante


Here is another thought. what about oxidizing fusion using MnO2, NaOH, + a little NaClO3 or PbO2 then converting this to sodium permanganate; then after adding strong ammonia, you could bubble CO2 or add dry ice until you get a sparingly soluble NaHCO3 precipitate?
I have seen various Patent literature that uses the Solvay process to make ammonium compounds
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[*] posted on 8-10-2003 at 17:44


...but then again this ammoniation followed by carbonation is based on the principle that the ammonium salt desired is VERY soluble in which case the permanganate might not be. IF that did not work you could always make barium permanganate and use ammonium sulfate solution.
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[*] posted on 18-10-2004 at 08:44


As per pm request,

The ammonium permanganate vid I have <a href="http://geocities.com/roguemovies7/">here</a> shows the result of the following synth:

20 grams of potassium permanganate is dissolved into 200ml of boiling water, to this mix is added 250g of ammonium nitrate and allowed to dissolve. The solution is poured off into another beaker to leave any undissolved or decomposed products in the bottom. Chill the solution to 10°C to precipitate the NH4MnO4, the solution can be poured off to retrieve the reddish-purple crystals. Place the product onto absorbent paper and leave to dry at room temperature.

So I just used a great excess of ammonium salt to drive the precipitate into being the ammonium permanganate. The precip will initially be granular, if cooled further it will be needles, you want the granular stuff not the needles.

Drop test of this stuff gives 15-20cm (ETN=30-35 PETN=40-45) so pretty sensitive, and low powered(1700m/s), therefore novelty purposes only!
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[*] posted on 19-10-2004 at 05:36


PHILOU Zrealone, disproportionation of manganates will not give hydrogen.



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[*] posted on 23-10-2004 at 16:16


Axt
Is it possible to use Ammonium sulphate in your reaction? Due to this new anti-terror crap I no longer have accesses to NH4NO3. Your reaction seems to be as follows:

KMnO4 + NH4NO3 à NH3MnO4 + KNO3

My proposed reaction is:

KMnO4 + NH3SO4 à NH3MnO4 + KSO4

Does this seam feasible?

(I hope I am not breaking any forum rules)
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[*] posted on 23-10-2004 at 16:47


You mean:

KMnO<sub>4</sub> + (NH<sub>4</sub>;)<sub>2</sub>SO<sub>4</sub> -> NH<sub>4</sub>MnO<sub>4</sub> + K<sub>2</sub>SO<sub>4</sub>

Sounds possible to me.
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[*] posted on 23-10-2004 at 21:55


I think the reaction is possible, however extraction will be a problem because potassium sulfate has a lower solubility than potassium nitrate, and thus when cooling potassium sulfate may also crystalize out in addition to the ammonium permanganate.



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[*] posted on 24-10-2004 at 05:25


K<sub>2</sub>SO<sub>4</sub> = 11g/100g H<sub>2</sub>O @ 20*C

NH<sub>4</sub>MnO<sub>4</sub> = 0.8g/100g @ 15*C

It shouldn't be too hard to separate them.
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[*] posted on 24-10-2004 at 12:05


Quote:
Originally posted by neutrino
NH<sub>4</sub>MnO<sub>4</sub> = 0.8g/100g @ 15*C


Sure that aint 8.0g! The problem is more in that KMnO4 is less soluble, therefore it really has to be driven towards the ammonium salt with excess AN. Using 250g AN to get 10g AP, not good.

I think PATR gives a synth using (NH4)2SO4. But AN looked the better option to me, for the reason RC (<--bad acronym dude! :P) mentioned, as well as AN's higher solubility.

[Edited on 24-10-2004 by Axt]
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[*] posted on 24-10-2004 at 12:13


Yeah, I realized that Axt a couple months ago. I f I could go back and change it I would make it something less kewl and not have the acronym of a suicide bomber:(



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[*] posted on 25-10-2004 at 16:19


It says 0.8 quite clearly in my pdf of Lange's 15th.

By the way:
KMnO<sub>4</sub> = 6.34g/100g H<sub>2</sub>O
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