Hexanitrobenzene

[Dhzugasvili]

I read in "The Chemistry and Technology of Explosives" by Tadeusz Urbanski, that hexanitrobenzene was synthesized during WWII in Germany, and patented, but its practical application was never realized due to the fact that this compound proved to be too sensitive for loading and casting and in general, just too sensitive and too powerful for use other than a novelty explosive. This is all the information i have so far on this explosive, im wondering if anyone has heard of a way to synthesize/stabilize it.

[Madog555]

ok, im posting some pretty obvious stuff but here it goes.

chem formula:C6H4(NO2)6

structure: benzene with an NO2 group on each corner

synthisis: ok, this is a semi-inteligent guess

C6H4(NO2)2 + 2N2O5 --> C6H4(NO2)6 + O2

[Lagen]

HNB can outpower PETN under circumstances. The starting material for HNB is 1,3,5-trinitrobenzene. This has to be reduced, trinitrated and reoxidized. These steps are so complicated that HNB is just impractical to make, for what it is.

[cutefix]

Hexanitrobenzene is indeed a powerful explosive with calculated detonation pressures of 405 kilobars,at a density of slightly more than 2g/cc. It is still inferior compared to CL-20 giving about 428 kilobars.Besides this explosive has rather poor storage stability,and if compared with other stable arene explosives like TNT,TATB,HNS,etc.It is like TNGU, sensitive to moisture also.Therefore HNIW is preferable than HNB.
Another way of synthesizing HNB is from pentanitroaniline,which is by dissolved in oleum and oxidized with highly concentrated H2O2.It will crystallize out and yield is about 58% based on pentanitroaniline.
Now pentanitroaniline is obtained by reducing TNT with H2S to produce aminodinitrotoluene.This aminated dinitro-compound if nitrated with mixed acid will yield pentanitroaniline.
I think this is somewhat an easier way than from making HNB from trinitrobenzene,which is difficult to derived from benzene; and the practical way of making it is by demethylating TNT in order to form trinitrobenzene.

<small>[ March 31, 2002, 02:29 AM: Message edited by: cutefix ]</small>

[Madog555]

so my reaction is correct?

i caould definately see this as being very powerful. it is highly nitrated.

[cutefix]

Indeed polynitrated compounds usually are powerful explosives;yet it does not mean that less nitrated materials are weak.Continious developments in explosive chemistry resulted in producing energetic materials that are less nitrated but powerful as well.See for example NTO(3-nitro-1,2,4-triazole-5-one) This explosive is just mononitrated, but it has detonation velocity(8300m/s) that is almost equal to PETN which has 4 nitrate groups in the molecule.
There are still other exception for less nitrated explosives that are also very powerful,implying that its not the nitro/nitrate group that is mainly responsible for power,but the nature of the chemical structure.

[Dhzugasvili]

Hmmm...i suppose i could try to get a formal recipe, but for what it's worth, im not sure that this is such a good candidate for a home chemist. I guess the deciding factors that (for me) make an explosive a good choice are: availability and price of reactants, YIELD, procedure acrobatics, stability, toxicity, handling ease + incompatibilities.

[cutefix]

Yeah,making this particular explosive is indeed complicated and not for home chemist.It is a multi step process,and (as far as I know) you have to make(or obtain) TNT first in order to convert it to HNB through aminodinitrotoluene by reductive amination,then nitration to pentanitroaniline and finally oxidation to hexanitrobenzene .As I related earlier it is not as stable as other powerful explosives and you have to handle it in anhydrous conditions;even using oleum as reacting medium/solvent for pentanitroaniline. You have to connect a drying tube to the outlet of the reaction vessel so as to prevent any moisture influx from the atmosphere.In addition you have to use a difficult to obtain +90 % hydrogen peroxide that will convert the pentanitroaniline satisfactorily to hexanitrobenzene.
You will need to wash the crystal with concentrated H2SO4,then and extract it with methylene chloride…..chilled and then yellow HNB crystals form ....To purify you have to sublimate it carefully in moisture free conditions..The yield is measly also and not practical to warrant the use of difficult to obtain chemicals.
Being difficult to handle in normal conditions that you usually practice for other stable explosives adds to its impractical utility .This is maybe the one of the reason that it was seldom(if ever) used in explosive application.

On the other hand if you really want to prove your skill in organic chemistry this will be a good candidate for experiments!

<small>[ March 31, 2002, 03:36 AM: Message edited by: cutefix ]</small>

[Dhzugasvili]

Oh well, just another one of those many, many explosives that remain in the novelty spectrum...maybe when im a millionaire and have a proper lab!! Don't we all wish!