Log in

View Full Version : Tetranitro propanediurea


Microtek
January 16th, 2003, 03:45 PM
TNPDU is described in the " New Energetic Materials " pdf from HEDM.
It is in my opinion the best bet an amateur has for preparing a HE that may outperform HMX. A few stats:

Formula: C5H4N8O10
Density: 1.98 g/cc
VoD: 9030 m/s
Sensitivity(100% det): 25 cm ( 10 kg hammer )

It is made by nitrating propanediurea with a HNO3/Ac2O system ( Likely also by HNO3/P2O5 ). Now propanediurea or 2,4,6,8-tetraaza-[3.3.1]bicyclononane-2,7-dione, is easily made by condensing urea with tetraalkoxypropanes in dilute HCl. One such tetraalkoxypropane is tetraethoxypropane which can be made from ethyl orthoformate and vinyl acetate with catalysts such as AlCl3, ZnCl2 etc ( US pat 2459076 ). Now we are getting down to manageable chemicals I think, though I'm certainly considering just buying the tetraalkoxypropane. BTW, if anyone wants to search for tetraethoxypropane it is more commonly found as malonaldehyde bis(diethylacetal) or simply CAS#122-31-6.
If anyone can offer pointers or shortcuts I'd appreciate it.

Mr Cool
January 17th, 2003, 10:40 AM
Do you/they mean -3,7-dione?

As with many of these, it sounds very interesting and would be a nice challenge, but other things would be better for any practical use that we might have.
So would I be right in thinking that it shares its basic structure with TENGU, but with an extra CH2 in the middle? This means it would also suffer problems with hydrolysis...
Probably the tetralkoxypropane could be prepared with sodium ethoxide and a tetrahalopropane, which might open up new OTC routes. A solvent search might turn up a suitable source, although I think tetrachloroethane would be more likely, which I assume could be made into TENGU with a similar method...

Microtek
January 18th, 2003, 01:10 PM
Hmm.. it seems you're right. On both counts. It is 3,7-dione and it seems reasonable to expect vulnerability to hydrolysis due to the DNU structure. Still, it is qouted as being superior to TNGU which may refer to the explosive properties or the chemical stability. BTW, do you know what the mechanism of the hydrolysis is? It would be nice to know if dinitroureas are a dead end, or if it is possible to stabilize them somehow.

Mr Cool
January 18th, 2003, 02:50 PM
I'll have a go, but I always get mechanisms wrong when I try to work them out.

I think a lone pair on the oxygen atom in water forms a bond with the very positive carbonyl carbon atom. Then an H-O bonding pair in what was the water is donated to the oxygen atom that was in the water, and a C-N bonding pair is used to form a bond with the H+ produced. This gives us nitramine and an intermediate, HO(C=O)NHNO2, nitraminoformic acid or something. Then... maybe it's deprotonated, and the C-N bonding pair is used to form a N-H bond with the proton, and the negative electron would form a bond to the positive carbon, giving more nitramine and CO2.
I'm fairly confident that's wrong, but I know it's the high polarity of the DNU that causes its instability because of the very positive C.

Hex
February 10th, 2003, 09:12 AM
That mechanism sounds ok to me...I suppose the RN(NO2)- might pick up a proton later on, as nitramine anions are pretty stable. I wouldn't get too worked up about hydrolysis - gunpowder's pretty incompatible with water too, and it's found the odd practical use or two down the years! The dinitrourea moeity is a bit fragile, but in keto-RDX the hydrolysis has to be done with sodium methoxide to make it go at a reasonable speed

Microtek
February 10th, 2003, 04:16 PM
Yes and it has also come to my attention ( from reading a JPEP article on Lagen's site ) that TNPDU is only hydrolised by alkaline solution, being stable in neutral or acidic aqueous medium.
However, I have already spent the funds allocated to laboratory supplies by ordering 500 g P2O5 which I decided to use for some HMX via hexamine --> DAPT --> TAT --> SOLEX --> HMX.
When I have developed more feel for the procedures involved I'll post my findings in the "HMX synthesis" thread.
BTW, HEX you seem to have quite a lot of experience with many of the more serious compounds so I'd value any input you might have on TAT synthesis. I'm working mostly from patents and especially those by Lukasavage seem promising, however, I can't seem to go from AAHT or DAPT to TAT via the catalytic hydrolysis that he uses ( it is patent number 6,201,117 and a host of references ).
I can make TAT directly by heating acetic anhydride with hexamine under anhydrous conditions, but yields are poor ( ca 25% )
I can also make DAPT in 40% yield from 3 grams of hexamine and expect yield to increase with experience and batch size. When I take the next step, I get a brown syrupy mass that stiffens when it cools and is very hygroscopic. I tried dissolving it it warm acetone or isopropyl alcohol and cooling, but got no precipitate.

Mr Cool
February 10th, 2003, 05:27 PM
That sounds like interesting work, Microtek. I had a go with that route a while back, but didn't get very far. My yield of DAPT was always rather low (IIRC the highest I got was in the 20's), low enough in fact that it would have been better to use HNO<sub>3</sub> to get RDX. I wasn't too bothered about getting HMX, I just thought it might have been a practical route to a good HE, but it turned out that others were more practical from the same precursors for me. I was generally using 1 or 2 gram batch sizes, some of the problem might lie there.
Are you using HDN + H<sub>2</sub>SO<sub>4</sub> to get the DAPT, or some other method? (It's been a while since I did this, DAPT is the dinitro-HMX-like compound with the CH2 in the middle, right?)
So I just gave up in the end. No sense of adventure, that's my problem!

Please post the methods you've been using so far, I might have another go some time and it would make sense to be doing it the same way, to compare results.
Damn it, my ammonium phosphate still hasn't arrived. Part of the beauty of having phosphorus available would be P<sub>4</sub>O<sub>10</sub> for stuff like this. I don't have any need for phosphorus, it'd just be neat to have, but the oxide would be truly useful...

Hex
February 11th, 2003, 08:04 AM
Microtek,

Prep of DAPT

14g hexamine and 6.2g ammonium acetate are slurried in 7ml water, before the dropwise addition, over the course of an hour, of 30.6g acetic anhydride. The temp is maintained between 5-10C during this time. Following the addition, the solution is stirred at 10C for a further 30mins. The excess acetic acid/anhydride is evaporated off (I've got access to a rotary evaporator, but I guess it could be done by heating in a stream of air)

The crude material can be re-crystallised from boiling acetone. Yield is upwards of 98% based on hexamine, even after re-crys (there is "re-synthesis" of hexamine from ammonium and "lost" formaldehyde in this reaction).

Alternatively, solution obtained after the 30 minutes of stirring can be directly nitrated to 1,5-diacetyl-3,7-dinitro (DADN):

The DAPT solution is added dropwise, over 80mins, with VERY good stirring (magnetic stirrer? - forget it!!) to a mix of 99% nitric (63g) and 96% sulphuric (221g) at 18-20C. The solution is stirred for a further 20mins at 20C, poured over 1kg ice, then precipitated by the addition of 1.5 l of water. 95% yield based hexamine is claimed - I've never tried this nitration, so I can't confirm. DAPT from hexamine I have done, and it works really well. You'll need a really good cooling bath, and a good paddle stirrer.
Unfortunately, you can only get decent yields of HMX from DADN using P2O5/nitric...but I'm assuming you've got some if you were going to try the SOLEX route?

ps I never even managed to make AAHT using Lukasavage's method (and I tried 5 or 6 times)- I notice he gives no characterisation data on it or any of his other esters - I smell bullshit in that patent...

Microtek
February 11th, 2003, 09:07 AM
HEX: Thank you very much ! This kind of process exceeds my "best case" expectations. I can get plenty of hexamine though it is a little expensive, but acetic anhydride must be ordered three weeks ahead and with all the shipping costs it gets really expensive.
I'm not so sure I got AAHT either as I haven't got any advanced analytic equipment and so rely on melting point, appearance, etc to identify my products and as you say, Lukasavage doesn't supply much data.

PS: Is DAPT susceptible to hydrolysis once it is made ? I would prefer to hydrolyse the acetic anhydride before evaporating.

Mr Cool: In the interest of keeping things on topic, I'll describe my current progress in the "HMX synthesis" thread.

<small>[ February 11, 2003, 08:59 AM: Message edited by: Microtek ]</small>

Mr Cool
February 28th, 2003, 03:59 PM
I haven't been able to find a tetrahalopropane/ethane for this or TENGU, but I did come accross tetrachloroethene as a dry cleaning fluid. I wonder what this would do with an alkoxide followed by urea. Any thoughts? I can't see why NS to replace the Cl's with RO's wouldn't work, but maybe someone can correct me.