Sciencemadness Discussion Board - Storage of Manganese heptoxide

Storage of Manganese heptoxide

numos - 3-4-2014 at 21:48

With me recently finding out about the compound Mn₂O₇, I've been tempted to do several interesting things with it. However has anyone ever tried to store it, not a few hours, but long term storage, months/years? Is it even possible?

I've put a small sample in an ampule (see images), as that seemed logical, to prevent contact with air/contaminants which may cause dangerous reactions. I'm keeping the ampule in a small brick box I made outside. I wish to leave it there for a few months and see how it holds out.

My worries: it will spontaneously explode, and the thing is quasi an incendiary device, as if it were to break, it would react with anything organic... a lot of things are organic

Also, this is not designed to be practical, Mn₂O₇ should be prepared right before use... if that. This is more along the lines of chemical duribility, will it hold out w/o being ruined.

Töilet Plünger - 3-4-2014 at 23:17

I wouldn't even THINK about doing this. The chance of disaster is far too high. But brick is the best choice behind smothering it in concrete.

Chemosynthesis - 3-4-2014 at 23:22

I second the above. It has a CAS number, so you could email a manufacturer if you really want to.

forgottenpassword - 4-4-2014 at 00:18

Very nice. How did you prepare/purify it?

woelen - 4-4-2014 at 03:29

What most worries me is that you have ampouled this

How did you do that? The risk is insane, if the stuff becomes too warm, it explodes and for ampouling this you most likely had to apply a propane torch flame or something similarly hot to melt the top of the ampoule. I would not have dared trying to ampoule this stuff.

I expect the ampoule to crack after a few days. This stuff is said to slowly decompose, giving MnO2 and O2. Due to pressure buildup I expect the ampoule to be destroyed soon. If this crack is violent, then the whole lot may explode, it may also be that the crack is not violent but that the material leaks out slowly. If you have organic material nearby (e.g. insects, hidden in the nice humid and dark little hole where you put the ampoule) in that case, the material will explode anyway.

Zyklon-A - 4-4-2014 at 04:53

Well if it indeed is safe in the brick "box", then it wouldn't matter if it exploded, ampuleing would be scary, I remember when I ampuled some Mg shavings. There was some dust that clung to the neck of the ampule. As I melted it, every once in a while, a dust particle started to burn with a white flash, once a relatively large shaving started to burn, I was scared the whole thing would combust, but it didn't. Manganese Heptoxide would be much more scary...

woelen - 4-4-2014 at 06:42

Ampouling magnesium would be no problem to me. Magnesium needs oxygen to react and in the small ampoule the magnesium can only burn for an instant, then all oxygen is used up. I ampouled a flammable and very volatile liquid like acetyl chloride, but this was not really dangerous, albeit inconvenient. Mn2O7 on the other hand, does not need any external supply of air or anything else, it can explode without apparent reason. Ampouling this feels to me as if you are ampouling pure nitrolycerin or some other very unstable explosive, and then even worse!

Fantasma4500 - 4-4-2014 at 06:55

wait.. you .. molted the top together?!?!?
i was just about to say that it seems that you did it safely, but man.. heating something like Mn2O7 or having a heating source nearby.. risky.. consider yourself and organic next time you have Mn2O7 within reach

however sadly alibabba seems to have failed me for once.. ive seen acetone peroxide, MEKP... FOOD GRADE COPPER AND CD's.. but manganese heptoxide.. no dice :/

forgottenpassword - 4-4-2014 at 07:27

According to this post: http://www.sciencemadness.org/talk/viewthread.php?tid=24125&... it is very difficult/impossible to detonate. There are videos on youtube of people reacting it with various chemicals. This one gives a good idea as to its reactivity: http://www.youtube.com/watch?v=shb-kCpidNE
Evidently it is highly reactive, but perhaps the dangers have been exaggerated. A quick search on google scholar showed that there are several reports of explosions under certain conditions, however.

[Edited on 4-4-2014 by forgottenpassword]

unionised - 4-4-2014 at 08:40

It's never been a good idea to ampoule something which is likely to evolve gas.
At best, in time, you will have a vial full of MnO2 and high pressure oxygen.
Glass pressure vessels tend to fail spectacularly.

I have ampouled ether- just to prove that it can be done.
That was fairly stupid- but the risks were well known and as well controlled as they were ever going to be.
If I still had that ampoule, it would be no more dangerous than ether "properly" stored in a tin. However a glass vial of Mn2O7 is an accident waiting to happen.

What are you going to do with it?

numos - 4-4-2014 at 12:27

Quote: Originally posted by woelen

What most worries me is that you have ampouled this

I did use a propane torch... The explosive point is at 50-55oC, so it was vital to keep it under that temp. I used a relatively small amount of it, (see image) an I kept the ampule in a three prong clamp, submerged in an ice bath. So the Mn2O7 stayed cool, and the clamp held it (giving me two free hands) and also acted as a heatsink preventing the heat from migrating down.

The decomposition you mention is what I tried to prevent, is there an actual reason? Exposure to air, water, light, ...sound? I know water destroys it, but the ampule is sealed...

Also the brick box, (I'll post a pic later when I get home), is in my driveway, even if the ampule did break, there is nothing within a 4m vicinity that burn or spread the fire, it's where I do all my thermite reactions.

Quote: Originally posted by forgottenpassword

Very nice. How did you prepare/purify it?

I prepared with conc. sulfuric acid and potassium permanganate crystals, an excess of potassium permanganate was used to create a [saturated? not sure if that's the right word] solution, then using a pipette removed the liquid leaving the remaining crystals behind.

Not sure how to purify it... distillation is definitely out of the question, Mn₂O₇ is supposed to be a red oily liquid, and turns green in the presence of sulfuric acid (according to Wikipedia), plus I'm not sure why that purity is even necessary, the green stuff is enough for most [all?] reactions, and I imagine that the red is significantly more dangerous.

Quote: Originally posted by Antiswat

however sadly alibabba seems to have failed me for once.. ive seen acetone peroxide, MEKP... FOOD GRADE COPPER AND CD's.. but manganese heptoxide.. no dice :/

That is unfortunate, probably evidence that it cannot be safely stored, much less shipped.

Quote: Originally posted by forgottenpassword

Evidently it is highly reactive, but perhaps the dangers have been exaggerated. A quick search on google scholar showed that there are several reports of explosions under certain conditions, however.

[Edited on 4-4-2014 by forgottenpassword]

I agree, it does seem overly exaggerated, however one explosion is all it takes to destroy a life. Still it seems very difficult to detonate, I read that striking it (I forget where I read this, sorry

) can cause it to detonate, and I've tried smashing one drop with a hammer, it wouldn't detonate.

Quote: Originally posted by unionised

What are you going to do with it?

I've done all the things I wanted to do with it, this is purely a test to see how well it holds out and if it can be stored.

The_Davster - 4-4-2014 at 12:31

You do not store Mn2O7. It decomposes to ozone and MnO2 after a few days.

Is this even pure stuff? or is it sulfuric and permanganate mixed and ampouled? I hope the latter, because the former would be insane....I have ampouled primaries, and this strikes me as a worse idea....

kristofvagyok - 4-4-2014 at 14:17

Mn2O7 is not a good option if you want to put it in a tight container like an ampoule. From time to time it will decompose releasing a lot oxygen what will cause a high internal pressure.

I have prepared some Mn2O7 a few month ago and tried and oxidation with it what almost ignited.... But here is a few experimental result:
It ignites with contact on chloroform, but it is well soluble in carbon tetrachloride giving a pink/purple solution what could be easily used/stored. If properly sealed it will not decompose as fast if it is in pure form as a liquid.

Another important thing is, that sulfuric acid is NOT soluble in CCl4, so you can get an acid free solution of the heptoxide.

DraconicAcid - 4-4-2014 at 14:54

Quote: Originally posted by kristofvagyok

But here is a few experimental result: It ignites with contact on chloroform, but it is well soluble in carbon tetrachloride giving a pink/purple solution what could be easily used/stored.

It will also burn dichloromethane.

neutralization of Mn2O7 with NaOH

quantumcorespacealchemyst - 25-2-2015 at 18:45

does Mn2O7 neutralize with NaOH?

I have brown precipitate after slowly adding an excess of NaOH to a solution of Sulfuric acid and KMnO4 which earlier had Mn2O7 in it.
On neutralization, the solution darkened from light yellow to brownish and on standing, the brown precipitate rises to the top of the flask. the solution also had a little Terbium sulfate, not enough to be the precipitate it seems.

I don't know if it will decompose slowly on standing at slightly under room temperature.

It might be Manganese dioxide though.

[Edited on 26-2-2015 by quantumcorespacealchemyst]

quantumcorespacealchemyst - 25-2-2015 at 19:02

ah, http://woelen.homescience.net/science/chem/solutions/mn.html... thank you woelen
" lower. Aqueous manganese (III) ions have a nice pink/brown color, as is shown on the picture below. When such a solution is added to a solution of sodium hydroxide, then a brown hydrous precipitate of Mn(OH)3 or MnO(OH) is produced."

or it could be the brown precipitate in "Oxidation state +4" MnO2. seems mostly like the III species.

[Edited on 26-2-2015 by quantumcorespacealchemyst]

subsecret - 25-2-2015 at 20:07

Not a bad experiment to be repeated if you work behind plexiglass with leather welding gloves and very heavy sleeves. Use a face shield the whole time, but especially when carrying it outside to the brick box. Even better would be to seal the ampoule outside and immediately put it under the flower pot. An inverted flower pot would be a good way to keep it confined if you want to see what happens. By all means, design a way to break the ampoule while it is in the pot. Perhaps heat from the bottom while standing a ways back.

@kristofvagyok: Depending on the concentration of the Mn2O7 solution, it may or may not ignite other organic materials. It would be cool to drop this solution on paper and wait for the CCl4 to evaporate. I think the reaction may be too slow to ignite the paper unless you had a very concentrated solution which deposited more on the paper.

[Edited on 26-2-2015 by Awesomeness]

franklyn - 26-2-2015 at 01:45

Quote: Originally posted by numos

" about the compound Mn₂O₇, I've been tempted to do several interesting things with it."

As you enjoy living dangerously , given that ionic compounds are miscible as a melt , I have wondered if Manganese Heptoxide might solvate Copper Acetylide. It may actually solidify as a co-crystal or form Permanganyl Acetylide. Having zero oxygen balance , high density , and endothermic character , such a formula will exhibit high detonation velocity and brisance. Placing a drop of Mn2O7 near a small amount of CuC2 and tipping the substrate to roll the drop into contact seems a good approach to test this idea best tried as cool as practical ~ 10 ºC.

Mn2O7 + CuC2 => {2 MnO3(+) , O(-2)} + {Cu(+2) , C2(-2)} => CuO + (MnO3)2C2 => 2 MnO + 2 CO2

CuC2
http://www.youtube.com/watch?v=QY9UtFDtClw

Related threads _
http://www.sciencemadness.org/talk/viewthread.php?tid=61173
http://www.sciencemadness.org/talk/viewthread.php?tid=5557

.

MrHomeScientist - 26-2-2015 at 07:33

Quote: Originally posted by quantumcorespacealchemyst

the solution also had a little Terbium sulfate

Because it wouldn't be a quantumcorespacealchemyst 'experiment' without a random rare or toxic element thrown in for no reason.

blogfast25 - 26-2-2015 at 07:38

Quote: Originally posted by franklyn

As you enjoy living dangerously , given that ionic compounds are miscible as a melt , I have wondered if Manganese Heptoxide might solvate Copper Acetylide.

Manganese heptoxide is unlikely to be ionic in any meaningful sense of the word.

fluorescence - 26-2-2015 at 09:34

Some years ago a Ph.D. Student at our University worked a long time on stabilizing that stuff.
It ended with a test whether he could slowely drive off everything liquid and get a crystalline form.
That thing exploded and since it was on a heatplate it had so much energy that the whole heat plate
was shot through the bench in the fume hood. There was a hole later.... so I wouldn't really want to ampoule that.

franklyn - 26-2-2015 at 12:52

@ blogfast25

I just go by what I read. Reaction (2) indicates it starts with ionic pairs, though after It may exhibit polar covalence.

(2) , MnO3(+) + MnO4(-) => Mn2O7
http://www.nature.com/srep/2013/130911/srep02636/full/srep02...
in pdf
http://yfzhang.sjtu.edu.cn/en/publications/2013/10.pdf

.

xfusion44 - 27-2-2015 at 11:37

What about storage in the freezer? Melting point is at 5.9°C Would that make it less reactive and slow down decomposition?

[Edited on 27-2-2015 by xfusion44]

Molecular Manipulations - 27-2-2015 at 11:50

Probably, but it's a gamble I wouldn't risk. I would not be happy to open my fridge to find a huge mess of broken bottles, and ruined reagents just for one pissy ampule of a practically uselessly unstable oxidizer.
I can't think of a single good reason to store it, when it can be made so easily on spot, if it's ever needed in the first place.

DraconicAcid - 27-2-2015 at 12:06

Quote: Originally posted by franklyn

As you enjoy living dangerously , given that ionic compounds are miscible as a melt , I have wondered if Manganese Heptoxide might solvate Copper Acetylide.

Do you think copper acetylide would be less reactive towards oxidizers than dichloromethane? You'd have a flame on contact.

franklyn - 28-2-2015 at 05:02

Solvate crude Mn2O7 liquor in CCl4 to partition the acid impurities, decant those and remove the CCl4 by vacuum distilling. With pure Mn2O7 devoid of catalytic instigators, there's little reason for two inorganics to hypergol. There is ample comparison to blended inorganic salts and complexes and also dinitrogen tetroxide or hydrogen peroxide.

Speaking of oxidizers, one can try to peroxidate Mn2O7 to peroxy permanganyl Mn2O8 , with Mn(MnO4)2 (Manganese Permanganate) and Mn(SO4)2 (Manganese Persulfate) + H2SO4 ( Caro's acid ) => Mn(MnO4)2 + Mn(SO4)2 + H2SO4 => Mn2O8 + 2 MnSO4 + H2SO4
http://books.google.com/books?id=a4YGAQAAIAAJ&lpg=PA430&...
" unlike hydrogen peroxide, it (Caro's acid) does not reduce permanganates "

Permanganic acid
http://en.wikipedia.org/wiki/Permanganic_acid

Mn2O7
http://www.youtube.com/watch?v=gPcfwiJcqSY

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Fegie - 15-10-2016 at 07:52

Quote: Originally posted by numos

) can cause it to detonate, and I've tried smashing one drop with a hammer, it wouldn't detonate.

Hard to detonate?
Jesus i had just a drop of it detonate just now.
I dropped a drop of it on a piece of wood, instant detonation, loud enough to leave my ears ringing....
Also, my manganese heptoxide wasnt a greenish liquid, it was a black paste that had greenish outer layer, this has never happened before.
The longer i had it standing there in the container the more "puffed" it got, it kept expanding, becoming more and more solid.
I added a few drops of water to it, which was followed by small amounts of smoke.
After this i thought "something is not right" and i took the container far away from any property to a field and left it there, because i had no idea what the hell was going on...

Manganese heptoxide has NEVER detonated on me before, this scared me shitless, i dont think il be making this stuff in a while....

[Edited on 15-10-2016 by Fegie]

AJKOER - 20-10-2016 at 14:06

Adding a few drops of chlorinated tap water to Mn2O7 would be a very interesting experiment.

I would expect the HOCl in the chorinated tap water to attempt to induce a higher valence state in the manganese, as occurs in Fenton-type reactions with hypochlorous acid with a Manganese salt.

The action of HCl appears to lower higher valence states.

The combined effect may be unsettling contributing to instability. Translation: boom!

aga - 20-10-2016 at 15:12

Why would one wish to store it ?

If there no immediate Purpose, what's the point ?

For example, if i wished to make nitroglycerine, i would do so.

I have no immediate need of nitroglycerine, so Storage would be a HUGE problem.

Perhaps there should be a new Topic :

Methods to Store Chemicals That Maybe One Day i Might Use, Maybe, if Ever.