Fulmen - 2-4-2006 at 00:44
I got hold of a bit of TNT from an old grenade (1937), and it is quite discolored (caramel tan). Should it be purifyed and if so, how? Other than the
color it looks fine, it's dry and without any smell or oily redidue.
Also, what would be the best mixture if one wants to get the most out of it? I'm thinking of ammoal (AN & Al), any other ideas?
IPN - 2-4-2006 at 03:30
You could recrystallize it from toluene or ethanol few times to get it relatively pure. Check the solubility tables from Urbanski vol 1 pages 294-295.
You can get the Urbanski books here.
Cloner - 6-4-2006 at 08:48
TNT gets this color pretty quickly. I wonder if it is destabilized by it?
praseodym - 6-4-2006 at 18:30
TNT can be purified by recrystallizing it from ethyl alcohol, (by dissolving the crystals in 60 °C ethyl alcohol and allow the solution to cool
slowly). A second method of purification is to digest the TNT in 5 times its weight of 5% sodium bisulphite solution heated to 90 °C while stirring
rapidly for 30 minutes. Wash the crystals with hot water until the washings are colorless, then allow the crystals to granulate.
Fulmen - 7-4-2006 at 06:54
Originally I was thinking in the lines of sulphite-wash, but recrysting with EtOH seems like a good option. Thanks for the link, IPN.
Boomer - 7-4-2006 at 08:10
I'd go with rextallisation. The bisulphite wash is used in production to get rid of isomers IIRC (and lower nitrated stuff?).
Unless it contaced bases/amines etc there is a good chance it is not more sensitive even as-is though. WW2 TNT was used by mafia for 4+ decades, they
got if from a sunken ship...
Fulmen - 7-4-2006 at 09:54
I know, when stored properly TNT should be stable for a loooong time. I guess it's more to do with being abso-fucking-lutely sure it's safe, as well
as the aesthetic part of pure, white TNT :-)
Update:
Well, I can't say I'm too impressed with the method. While the first product to crystallise was fairly pure, the ethanol didn't seem to hold the
impurities in solution once cold. But what the heck, guess it's pure enough as it is...
[Edited on 7-4-06 by Fulmen]
Cloner - 8-4-2006 at 04:15
The problem with TNT is the fact that it is unstable to bases, and the isomers in it. Pure sulfited TNT, if not basic due to sulfitation (!) should be
one isomer only.
In my hands, TNT has NEVER remained white, though, using all methods available, once it has been exposed to air for some time
... and when I recrystallized it in gasoline, the bad color came very very quickly!
[Edited on 8-4-2006 by Cloner]
Nerro - 8-4-2006 at 06:01
Just detonate it and enjoy. It doesn't generally take a whole lot of polutant to colour a product.
Fulmen - 8-4-2006 at 06:44
After some thinking I'm not that displeased with the result. Considering that during the most part of the crystallisation the precipitate was pretty
white, and that the filtrate is fairly discolored, it's pretty likely that there is only a small amount of impurities on the surface of the crystals.
Using more alcohol would probably yield a better result, but I'm happy with it as it is now.
Boomer - 8-4-2006 at 07:06
WHITE TNT? Me starts to think you had an amatol filled grenade, and dissolved *all* TNT out, leaving the ammonium nitrate only. The stuff is supposed
to be yellow, though not as staining as picric. And all nitroaromatics I know turn brighter if acidic, and darker (towards orange or even red) if
basic. Still, if neutral it shouldn't be white, maybe yellowish off-white (brighter than a lemon).
"once it has been exposed to air ... the bad color came very very quickly"
What is bad about yellow HEs? 
And IIRC it is the light, not the air that colors it. And this coloration (in contrast to that caused by bases) does not make it dangerous!
Fulmen - 8-4-2006 at 07:28
No, I'm pretty sure it's pure TNT. The grenade was pre-WWII, and it melted at app. 80°C without any signs of foreign material (AN isn't soluble in
TNT, so melting it should be a dead give-away). As for the color mof pure TNT, I belive it's more of a pale yelowish off-white hue, I remember seeing
TNT that was fairly white once.
As for light, it can't be the source of the discoloration in this case, as it's been stored perfectly dark for 70 years.