bicyclo-HMX synthesis and properties...

[klasac]

Hi, everyone!;)
Recently I did some research on this interesting compound (chemical name 2,4,6,8-tetranitro-2,4,6,8-tetraazabicyclo (3.3.0) octane) and found out that despite its predicted favorable properties it has not been synthesized in satisfactory yield even though an tedious and intense efforts were made in order to obtain this explosive at different laboratories.

All that is available on the internet and patent and chemical databases is some 4 articles, mostly dealing with theoretical properties like density, crystallography and explosive properties.

One article describes its synthesis as feasible for industry, but when I read it closely they don't mention the yield (which I suppose is not high at all) and the synthetic route to its synthesis (in mg quantities) :
http://www.patentstorm.us/patents/5659032-description.html
Since I am innovative type and like to develop new syntheses to known/unknown energetic materials rather than parrot given procedure, I posted this thread in case someone here is as much interested in this compound as I am and has valuable thoughts or practical experience on synthesis of this fairly new explosive:-)

[NameWithheld]

That sounds like a rather fantastical undertaking. Synthesizing something that has never been successfully produced in quantity? I'm afraid that's far beyond something I could even begin to attempt. I wish you the best of luck nonetheless :P

[VasiaPupkin]

Unfortunately the calculated properties somethimes is not concured with real properties. Real bicyclo-HMX has explosive properties is equal to much more cheap HMX. Therefore its not interesting for militaries. It has density only 1.868g/cm3. And VoD 8700m/s at 1.77g/cm3. There is nothing outstanding. AFAIK its used in Biysk, Russia for diamond synthesis. They have a pilot-scale mount for preparing. Besides usual synthesis from methylene-bis-acetamide it can be easilly prepared by nitration of formaldehyde, glyoxal and potassium sulfamate condensation product.

[klasac]

Hi,Vasia (and others)! Yes, you are right in this case the density and other promising favorable properties did not become a reality and cannot compete with the ones of HMX (crystal density 1,96, max. practical 1,91 and VoD cca 9100m/s). Mostly caused by fact that it crystallizes in stable monoclinic system and instead of cis-(alpha) more stable is trans (beta) form which offers much less space for predicted hydrogen bonding of molecules within the crystal-thus lowering the theoretical density. And yes, the preparation of bicyclo-HMX via methylenebisacetamide (MBA) is not very feasable in comparison with well researched and developed methods for HMX manufacture on industrial scale. Low feasibility of the abovementioned process (see link in 1st contribution) is caused by many-step reaction.

First, the glyoxal doesnt react with methylenebisacetamide in molar ratio 1:2 to form bicyclic structure. Instead, it reacts in a way so dihydroxy-N,N-diacetateimidazolidine is formed. This, before condensed with second molecule of MBA needs to be stabilized by acetylation of OH groups and then the bicyclotetraacetyloctane structure is obtained. And then it is nitrated using fairly expensive nitrating agent in polar organic solvent with low yield. Not to mention the cost of recyclation and waste removal which is hard to get around considering nowadays` "green chemistry" demands. No wonder HMX wins.....in this case....what draw my attention though (and that`s why i started this thread), is the second method using simple 2-step condensation of glyoxal, formaldehyde and sulfamic acid followed by nitration od formed condensation product.

Dont think manufacture of HMX is cheaper in this case. Generally known, none of the used reactants (K-sulfamate,glyoxal and formaldehyde solution) is expensive and the yield of bicycloHMX is incomparably higher than in patent-mentioned process. The problem might be reaction conditions (molar ratio of reactants, pH, concentration, catalysis, temperature, etc.) Formaldehyde is more reactive than glyoxal and therefore some amount of white salt forms together with desired bicyclotetraazaoctanetetrasulfonate, thus contaminating the nitrated product with some RDX. If glyoxal is added first, significant amount of tetrahydroxydisulfopiperazine will form-lowering the yield of biHMX as well. So, preparing bicycloHMX using this method is not as easy as might seem, but when optimalized, it should be relatively cheap source of bicycloHMX.

I wouldnt say VoD apx 8700m/s is a low one;-) Didn't see much about sensitivity and other properties of this compound, but when you check out the dates of articles some work is being done even after discovering the somewhat disappointing properties of biHMX (meaning in comparison with HMX), so there is a potential seen in this EM. I think as a rocket propellant with slightly better oxygen balance than HMX it should serve the purpose. As a military explosive... well, depends on sensitivity which needs to be investigated more thoroughly.......;)