KMnO4/Al/S - IMPORTANT WARNING

[vulture]

As I'm preparing for the 31st right now, I made a batch of 320g of KMnO₄/Al/S. As always I mixed it with a substantial amount of acetone, as the huge difference in density between my Al powder and the KMnO₄ makes dry mixing almost impossible.

After half an hour I suddenly heard some fizzling and when I checked it appeared to be coming out of the box with the KMnO₄/Al/S in it. As I wanted to take a closer look I noticed the container was quite hot to the touch! <img border="0" title="" alt="[Eek!]" src="eek.gif" />
A thermometer showed a temperature of 51C after spreading it out to allow cooling. <img border="0" title="" alt="[Eek!]" src="eek.gif" />
Another typical thing is the flash has a golden colour after this.

A small amount wrapped in paper did not show the heating up and remained silver in color. (burned awesome too :D )

I have no reasonable explanation for this heating up, but I just wanted to warn everyone who intends to make this, runaway with large batches seems to be possible.

[Nika452]

Searching an MSDS of KMnO4, I found:

"Not combustible, but substance is a strong oxidizer and its heat of reaction with reducing agents or combustibles may cause ignition. Contact with oxidizable substances may cause extremely violent combustion."

I suppose this much is obvious because of reacts such as glycerine and KMnO4.

The MSDS also listed powdered metals as an incompatible material, which again should come as no surprise. My idea is the the fine aluminum reacted with the KMnO4 in a spontaneous reaction similar to that with glycerine, which was made more likely by the large amounts of both present.

What mesh was the Al? I would think it would be made more likely with finer or flaked metals.

The golden colour of the partially reacted mixture later could be an indication of slightly burned KMnO4--you know how KNO3 gets brown when heated? I suppose the permanganate, or maybe one of the other constituents could do the same.

Or perhaps I'm just spouting BS, anyone with an actual knowledge of chemistry could probably offer a better interpretation.

[vulture]

Acetone can't be oxidized any further without breaking down the carbon skeleton and that would mean fire.

If the Al would react with the KMnO₄ I would have to see Al₂O₃ crystals and that would certainly go into runaway as this would be very exothermic.
The Al is airfloat, pain in the ass to work with.

According to me the golden color is just fine Al sticking to the sulfur.

Ofcourse the acetone could be contaminated with isopropyl alcohol, which gets oxidized to acetone bij KMnO₄, but that would have to be a very substantial contamination then to produce that much heat.

(I am a chemistry student BTW)

<small>[ December 29, 2002, 04:40 PM: Message edited by: vulture ]</small>

[Rat Bastard]

I have had that happen too, only on a much smaller scale prolly about 80-100 grams. I noticed that in one of my devices, a little water got into it and it was hot to the touch. So keep it away from moisture at all costs!

[A-BOMB]

That weird my KNM04 burns just by its self I just put a flame to if and it burns no fuel just KNM04, weird

[Jumala]

The acetone could also contain water.
Water + Al -&gt; AlOH + H2
AlOH + KMnO4 = ???
Only an idea. I don´t know the next step.

[Nika452]

Al(OH)₃?
Couldn't the aluminum hydroxide react exothermically with aluminum to an extent? Or maybe not. It's not soluble, so I don't see how that would work.

I know that aluminum can react with nitrates spontaneously...and Wouter Visser says the moisture can help the reaction. I don't suppose it works the same way with permanganates though, or does it?
His site says the amides are formed, like
KNO₃ + Al + H₂O =&gt; K₂NH₂ OD
and the K₂NH₂ reacts with the aluminum somehow.
But I don't see how amides could be formed in this case, so as far as I can tell this wouldn't happen...just a thought though.

Maybe my ramblings help someone who knows what they're talking about?

[EP]

I guess there is a reason that all the old timers always say not to use KMnO4! <img border="0" title="" alt="[Wink]" src="wink.gif" />

I just set some off the other day actually, I stored it mixed for several days (poor planning...) before use but had no problems. I think the best thing to learn from this is to keep it dry! I had no problem dry mixing, but I was only mixing 5g, I can definetly see larger amounts being more difficult. I'd probably just dry mix it in several small batches rather than a large wet one.

[mr.evil]

í've mixed 30grams 4 days ago, and made one 10 gram cracker with it, i think i will make a line of flash and light it... just for fun <img border="0" title="" alt="[Wink]" src="wink.gif" />

i never wet my flash, as it burns with a brilliant white flash and extremely quick.

[vulture]

Strange thing is I've stored the stuff for 9 months without any trouble. Just acetone and moisture seem to make it dangerous.

[Pu239 Stuchtiger]

It's the sulfur.

[Mr Cool]

This has been covered before guys, lose the sulphur. It doesn't add much in the way of performance and is known to sensitise many compositions...

[Crazy Swede]

Unsuspected things can happen if acetone is added to some pyrotechnic mixtures. Sometimes water is the the problem, but you should also be aware of the solvating(?) power of acetone. In this case, I suspect that the protective stearic/parrafinic coating on the paint grade Al was washed away which made the fine Al flakes more easily oxidized.

Several years ago, I had a close call when moisting a mixture of black powder, magnesium and iodine crystals with acetone. The mixture quickly heated up and I barely managed to throw it outside before it ignited. Probably, the Mg was attacked by the iodine in a Gringard type of reaction when the acetone was added.

[EP]

Mr. Cool - If you use it without sulfur, do you just recommend the same 7/3 ratio as standard flash?

I'm sure most people use it with S because that's what most of the compositions found use, and as long as you keep it dry and use it quick it's usually fine.

<small>[ January 02, 2003, 12:09 AM: Message edited by: EP ]</small>

[Al Koholic]

Sulfur: acetone dissolves 2.65% at 25 degrees C.

Obviously the sulfur is already a hazard in many respects but dissolving it and therefore increasing its intimacy with the oxidizer probably caused the heating to be more of a problem.

BTW vulture...acetone can be oxidized further without degradation of the carbon skeleton. Methylglycoxal or pyruvaldehyde is one form of oxidized acetone.

This is from Merck
-Physiological metabolite formed by the fragmentation of triosephosphates and by the metabolism of acetone; synthe sized by microorganisms. Also occurs in a variety of foods and beverages such as coffee. Reacts with nucleic acids and proteins under physiological conditions serving as a signal for their degradation.

It looks like acetone except at the 1 or 3 position there is a CHO group instead of a CH3
Al

[Marvin]

vulture, You seem to be much more moderate normally, I'm a little dissapointed. <img border="0" title="" alt="[Wink]" src="wink.gif" />

Permanganates have no place in pyrotechnics. Its an active oxidising agent at room temperature and thats unacceptable. Nika, your first post was spot on. Pile of permanganate, few drops of glycerol, and it bursts into flames after a delay. Its very easy to dismiss this as the glycerol being very easily oxidised, but there are a lot of other organic chemicals in regular use that have the same problem, binders, fuels, sugars....

Manganate chemistry is very similar to chlorate chemistry, except manganates are much more reactive at room temperature. Using these with sulphur isnt a good idea, but then using them at all isnt a good idea either. I tried using it a long time ago, and the mixtures did go golden/brown, its the manganese oxides/permanganates in reflected light until they react completely enough to render it dark brown.

Aluminium dust and water are incompatable, and can cause mixtures to self ignite. Permanganate will destructivly oxidise carbon chains without fire, as a more obvios example, the reaction that makes benzoic acid from toluene works on any length carbon chain to leave the benzoic acid and the corrisponding aliphatic carboxalic acid, which may furthur be broken down.

The idea that carbon chains dont alter much, is drilled into pre degree chemists and they get the idea that chemistry is all about finding precursors with the right carbon skelleton and swapping the functional groups. When they go to university they then learn aldol and you can hear paradigm shifting without use of the clutch. Speaking of which, with acidic sulphur aldol will happen and so you have the potential for much more easily oxidised molecules flying around in solution.

Acetone isnt stable enough to do reactions in, it has keto group and acidic (for a carbon atom) alpha keto hydrogens. Its used in very few reactions where it isnt specifically a reactant.

I didnt know acetone dissolved a reasonable amount of sulphur, that could be very useful.

[Al Koholic]

Yes Marvin, the solubility of sulfur is indeed quite useful for myself. It is only sparingly soluble in alcohol and the only other organic solvent which would be satisfactory for dissolving sulfur is toluene (which is better than acetone I beleive) since being around things like liquid benzene and carbon disulfide is not exactly my idea of fun.

Anyway, I'm working on a system to purify my sulfur (90% gardening grade) for use in my reactions... The system is being designed to effect a nice low temp (35-40 degree) evaporation and condensation of the solvent to yeild crystalline sulfur. I'll also be using it for ASA recrystalization but this is getting off topic...

Al

PS: I liked the thoughts on carbon skeleton chemistry and its compatibility with university students! Mwa HHAHAHAHHAAHA

[vulture]

As you can probably tell, my knowledge of organic chemistry isn't all that great...*cough*. I can't wait till the 3rd term till I get some decent organic chem, damn lousy chem teachers! :mad:

So basically you are saying the acetone reacts with the permanganate with the dissolved sulfur as a catalyst?

I know permanganate shouldn't be used in pyrotechnics, but it's easy to get and very powerful. Storage stability is no issue since I stored a batch of 100g over 9 months.
And I still think working with this flash is more safe than playing with AP... :p

I mean the stuff works too good and is too temptative to drop.... I love the fast burn of it..
Anyways I'll probably be switching to KMnO₄/Al or Mg without sulfur,now that I've acquired a sufficiënt amount of both.
A bit of added BaCO3 should improve stability and mixing.

<small>[ January 12, 2003, 03:35 PM: Message edited by: vulture ]</small>

[zylion]

In WOII the germans used it(KMnO4) in their rockets along with hydrogen peroxide. Just got the plans for building a liquid propelled rocket.
I'am a little bit disappointed thow, because it isn't a construction manual with drawing ect. but a booklet just a how to build it with parts prefabricated by this company. It does look awesome. The general construction is clear for me, it isn't that difficult.

<a href="http://www.total.net/~launch" target="_blank">http://www.total.net/~launch</a>

<small>[ January 16, 2003, 12:55 PM: Message edited by: zylion ]</small>

[vulture]

What the hell has this got to do with KMnO4/Al/S flash??

The KMnO₄ merely makes the hydrogen peroxide decompose.

<small>[ January 16, 2003, 02:50 PM: Message edited by: vulture ]</small>

[zylion]

Nothing, but it's what I read about the strong oxidizing nature of the stuff.Just some information. The combination KMnO4/50%hydrogen peroxide/high octane gasoline is responsble for going a rocket fly like hell. This forumside is about pyrotechnics. ain't it. :confused: I think rockets are a part of it. There is a discussion going on about the dangers ect. involving KMnO4 in flash powders, so!!!

[Anthony]

Now, play nicely children <img border="0" title="" alt="[Wink]" src="wink.gif" />

zylion, let's please try to keep this thread about the dangers of KMno4, particularly in flash.

If you'd like to start a thread on the progress in construction of your rocket, then you are welcome to do so.