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Author: Subject: (not) RDX from hexamine and mixed acids?
wmacturk
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[*] posted on 17-10-2021 at 15:41
(not) RDX from hexamine and mixed acids?


Just for funsies, I mixed hexamine with mixed acids (50/50 H2SO4/HNO3, both ~99% purity) at about 4C and kept the reaction under 18C. I now have some insoluble precipitate (that looks about the same mass as the hexamine I added) with a deep orange-red supernatant.

I know hexamine and mixed acid doesn't make RDX, but I was just curious what it did make, and what I have now that looks so pretty in my flask (and if I should be scared of it!)

I wasn't sure how the nitronium ion (or the HSO4- groups) would react with hexamine, so I thought I'd ask those who know much more than I do.
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fredsci93
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[*] posted on 18-10-2021 at 14:13


well, it's not impossible that the precipitate is in fact RDX since RDX itself is stable in mixed acid solution at low temps (>4C isn't that low though) I would recommend running a burn test and solubility tests on the insoluble compound if you want to know what it is. As for the orange color, that's defiantly due to the hexamine decomposing, I had an accident where a hexamine/nitrourea mixed acid nitration which ran away and ended up orange, it just tends to happen at higher temps (anything above 0C really, I usually do it bellow -3 to -5C however in the runaway I screwed up and it got much hotter to the point of boiling/extreme effervescence).

RDX COULD be produced from a mixed acid solution (I only have experience with mixed acid+urea solutions producing RDX) and at low temps, RDX is completely stable in anhydrous (or slightly wet) mixed acid. test a small amount of the compound, it is unlikely to be particularly dangerous as there are not any viable routes to an unstable primary in the solution you described (mixed acid + hexamine)



[Edited on 18-10-2021 by fredsci93]
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Alkoholvergiftung
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[*] posted on 19-10-2021 at 00:28


Would it be possible to make RDX with an Nitric Acid, Glacial Acetic acid mix?Should be very similar to acetic anhydrid way.
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[*] posted on 19-10-2021 at 02:58


Quote: Originally posted by wmacturk  
Just for funsies, I mixed hexamine with mixed acids (50/50 H2SO4/HNO3, both ~99% purity) at about 4C and kept the reaction under 18C. I now have some insoluble precipitate (that looks about the same mass as the hexamine I added) with a deep orange-red supernatant.

I know hexamine and mixed acid doesn't make RDX, but I was just curious what it did make, and what I have now that looks so pretty in my flask (and if I should be scared of it!)

I wasn't sure how the nitronium ion (or the HSO4- groups) would react with hexamine, so I thought I'd ask those who know much more than I do.


Mixed acid can make RDX. Read about keto-RDX and its preparation. Mixed acid, urea, and hexamine. Preparation is simple and gives the mix- RDX + keto-RDX.




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fredsci93
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[*] posted on 20-10-2021 at 15:32


Quote: Originally posted by Alkoholvergiftung  
Would it be possible to make RDX with an Nitric Acid, Glacial Acetic acid mix?Should be very similar to acetic anhydrid way.


Yes, acetic acid is relatively inert towards RDX and is a mild dehydrating agent, it would work but it would also provide no measurable benefit, Acetic anhydride is a much better choice as it is a very strong dehydrating agent and readily forms a very reactive nitro-acetyl intermediate which is a more active nitrating agent towards RDX.
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[*] posted on 25-10-2021 at 03:34


What is the precipitate insoluble in? Water? Or the supernatant? If the latter is the case, the crystals may simply be hexamine salts (nitrate, sulfate or mixed). I would suggest you do some solubility tests in different solvents. HDN is soluble in water, but not in alcohols or acetone. RDX is quite soluble in acetone, but not in water or alcohol.
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