TNT discoloration

[bobo]

SWIM has hidden some TNT in a remote place for 'bad times' and recently looked it up. It's getting very brown:confused: He asked me why. I thought TNT was rather stable? I told SWIM to make this acid-hungry explosive for his stash because I thought it was the most stable choice.

The compound was perfect when buried, melting point and hardness typical of TNT and no smell of DNT in it.

It was neutralized with sodium carbonate solution before being stored. Is this the problem?

[simply RED]

TNT is very well stored melt-casted in some sheets of nylon. A layer of parafine is also a good idea, created by putting the TNT form in molten parafine.

Anyway, moisture or sunlight causes discoloration of the surface (brown, dark yellow or white are most common) .

[nbk2000]

'Parafine' can have two different meanings, depending where you are from.

Are you referring to the solid wax used for food canning and candle making, or the liquid lantern fuel?

[simply RED]

I was refering to the solid wax used in candle making (low melting wax is preferable - and just put the TNT in and out - fast, otherwise it melts and dissolves).
Vaseline could also be used, just cover all the surface with it.

Melt casting in hard paper and then parafinating is another option.
Quite smart is: to melt-cast the TNT in 330ml alluminium canister from coca-cola (this sets off with 20g (PETN/TNT = 50/50) booster equivalent). I've seen an experiment in which such canister bahaves almost like a shaped charge (directly placed on concrete). Mixing TNT with PETN and RDX is the best choice for long lasting explosive as these mixtures are easily innitiated.

[bobo]

The intent was to have explosive material ready when it might be needed. it should work off the shelf or after minimal preparation, ten or more years from now. Who knows what occupying force or anarchy might terrorize our country, and when.

Because mines and shells from WWI and II are still dangerous and contain TNT mostly, TNT was chosen. And as stable as it can be. RDX has the disadvantage of requiring more acid, and SWIM co-stashes PETN with the TNT; as boostere as well as for main.

Intriguing idea to put it in ready cast portions of coke canisters though. I suppose that's enough for several purposes. It can still be molten and mixed with AN for a more impressive charge.

Why do you say it is more useful in mixture with PETN and RDX though? If you use 330 ml, and 20 g of booster will initiate it, then it doesn't mater or?

By the way, this booster you mention, is that just as storeable? Are you sure? I was told that nitrate esters and nitroaromatics should not be stored mixed for long, but perhaps this is only for ETN and such.

[simply RED]

TNT mixed with RDX is the best choice for long storage.
Anyway TNT + PETN is sold as TNT boosters here and it is still useful after 10 years.

The best main charge in your situation will be 95%TNT and 5%RDX just for sensitizing.
What else to say... melt the TNT and keep it in nylon bags, keep the boosters dry too...

[bobo]

the best way to recrystallize smaller amounts is to use a large amount of ethanol with 15-20% water in it. This way, the red stuff does not co-crystallize, as happened when using ethanol distilled over CaO. Downside is that TNT is much less soluble in this mixture even at high temperatures. It took my friend several cycles with a few liters of solvent to handle a kilo of red TNT. The product was white and fluffy flakes though, not a trace of oil on them.

[simply RED]

I tend to buy TNT (noone here knows is it legal or illegal, because it is sold sometimes without permission and noone asks questions, like MNT, DNT, MNB, DNB, even TriNitroBenzene and picric acid (for ana{rch}lytical purposes) ).

Chemistry sets for children are banned, so they have the option to purchase DNB Merck grade and use it on task.

It was a pain in the ass to synthesize these, very much toxic fumes...

[The_Duke]

Even commercial samples of TNT will darken to some extent over time; the color change and the length of time depend mostly on the impurities present and the standing temp. of the TNT during storage. The color change in SWIM’s TNT is most likely due to decomp. of unsymmetrical and lower nitro Toluene isomers and nitrated Phenolic compounds caused by side rxns during nitration of Toluene or by trace amounts of acid reacting with other impurities to cause gradual decomp. of said TNT.

When producing TNT with the intent to “store it away for a rainy day” it is necessary to clean it from 99.99% of all impurities. This is most easily done by washing the crude TNT first with several washings of clean water. Then with a solution of Sodium Sulphite in order to convert the unsymmetrical nitro bodies into Sulphonic acid compounds which are then more easily washed away by further treatment with an alkaline solution and several more water washings to produce TNT of the highest quality with a melting point which is extremely close to that given by most authors to be the correct MP. Also, a re-crystallization step is a good idea here too!
:)

[Diabolique]

The color of TNT is buff (light tan) to light brown according to Urbanski and LLNL Explosives Handbook. When it starts getting darker than this, you should get rid of it.

If not an option, put the TNT in a 2.5% solution of sodium carbonate with 5% ethanol, warm in a water bath until the TNT melts. Aggitate with air bubbles until its color lightens. The TNT is seperated from the water and cast into blocks.

I prefer blocks of 1/3/9 dimentional ratio. The 1/3 aspect has been found about optimal for steel cutting (with 1:3 steel:explosive rthickness ratio). Do not forget to include a hole for a reinforced blasting cap (detonator).

The likely culprit is tetranitromethane (TNM). If anything resembling 'sweat' appears on the surface of the TNT, BEWARE. TNM mixed with organics is very sensitive, and if possible, burn the TNT in place. TNM is why I prefer other explosives, like RDX.

Here in the US, it is best to have the precursors, usually they are legal. The finished product gets you a vacation to Club Fed.

[lucas]

I believe that you should avoid neutralising the TNT with a base when washing. TNT reacts with alkaline solutions to form sensitive red materials which are undesirable. This is in contrast to the washing of nitric esters where a dilute carbonate solution is ideal before washing with water again. Stick to multiple water washings and a recrystalisation from ethanol or a sulphite washing.


From COPAE page 151

Trinitrotoluene, in addition to the usual reactions of a nitrated
hydrocarbon with alkali to form dangerous explosive materials,
has the property that its methyl group in the presence of alkali
condenses with aldehydic substances in reactions which produce
heat and which may cause fire. Aldehydic substances from the
action of nitrating acid on wood are always present where TNT
is being manufactured, and alkali of all kinds ought to be excluded
rigorously from the premises.

[The_Duke]

From ‘TNT, Trinitrotoluenes & Mono & Dinitrotoluenes by Smith

“Various other chemicals, such as sodium carbonate, sodium bicarbonate, etc. have been used with more or less success. It has been found that these more distinctly alkaline salts tend to darken the TNT, and also tend to render it unstable. There are, in fact, some sodium salts of TNT which explode as low as 160° C.”

It should also be mentioned that some of these sodium salts are more sensitive to impact and flame than TNT.