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DBL%20Hendrix%20small.png College chemistry, 1983

Derek Lowe The 2002 Model

Dbl%20new%20portrait%20B%26W.png After 10 years of blogging. . .

Derek Lowe, an Arkansan by birth, got his BA from Hendrix College and his PhD in organic chemistry from Duke before spending time in Germany on a Humboldt Fellowship on his post-doc. He's worked for several major pharmaceutical companies since 1989 on drug discovery projects against schizophrenia, Alzheimer's, diabetes, osteoporosis and other diseases. To contact Derek email him directly: Twitter: Dereklowe

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November 11, 2011

Things I Won't Work With: Hexanitrohexaazaisowurtzitane

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Posted by Derek

Let's start with the name. Quite a mouthful, isn't it? Believe me, that one's pretty chewy even for experienced organic chemists. We see lots of more complicated nomenclature, of course, but this one some features some speed bumps, that make you go back to make sure that you're reading it correctly. I'll take you through my own thoughts as an example.

You skip to the end in chemical names - Mark Twain would have felt about them the same way he felt about the German language. But this brings me up short, because very few chemists could walk up to the board and draw an isowurtzitane. And I am not among their number. I have a vague picture of these "wurtz" compounds being funky three-dimensional cage structures, and that much only from having probably read too many photochemistry papers over the years. So the only thing that "isowurtzitane" calls to mind is some complicated framework of fused rings, looking like one of those wire sculptures that unexpectedly fold up flat when you pull on them.

Moving on out, as you do in a systematic name, I see that this is a hexaaza variation, which makes the picture a bit fuzzier. That's a lot of nitrogens substituted for carbons, and the first thought is that this must be some weirdo condensation product of ammonia, some aldehyde, and who knows what. You can get some pretty funny-looking structures that way, like hexamethylenetetramine (which I've actually used a couple of times). I don't know where those nitrogens are, I think to myself, but I'll bet that's how they got there, because any other pattern would be a synthetic nightmare. So far, so good. But now comes the unexpected habanero.

Hexanitro? Say what? I'd call for all the chemists who've ever worked with a hexanitro compound to raise their hands, but that might be assuming too much about the limb-to-chemist ratio. Nitro groups, as even people who've never taken a chemistry class know, can lead to firey booms, and putting six of them on one molecule can only lead to such. And since there are six nitrogens and six nitro groups, the first assumption must be that these are all bonded to each other. I mean, come on, leaving the nitro groups attached to the carbons is for wimps. So that means that someone, somewhere, has perversely made a poly-N-nitro cage compound, as if they'd been dared to cram the most bond energy into the smallest space.
That, as it happens, is exactly the case. Hexanitrohexaazaisowurtzitane, or CL-20, was developed as a highly energetic, compact, and efficient explosive. What makes it unusual is not that it blows up - go find me a small hexa-N-nitro compound that doesn't - but that it doesn't actually blow up immediately, early, and often. No, making things that go off when someone down the hall curses at the coffee machine, that's no problem. Making something like this that can actually be handled and stored is a real accomplishment.

Not that it's what you'd call a perfect compound in that regard - despite a lot of effort, it's still not quite ready to be hauled around in trucks. There's a recent report of a method to make a more stable form of it, by mixing it with TNT. Yes, this is an example of something that becomes less explosive as a one-to-one cocrystal with TNT. Although, as the authors point out, if you heat those crystals up the two components separate out, and you're left with crystals of pure CL-20 soaking in liquid TNT, a situation that will heighten your awareness of the fleeting nature of life.

Stabilized or not, I still won't get near it. For one thing, I'm a drug discovery chemist, and if you think a structure like this is going to be a drug, then you must be on some strong ones yourself. No, the thing about these compounds is that they can be handled as long as they're very pure and formulated just right. The side products from their synthesis, well, those might not be so nice. And if a batch gets contaminated, or doesn't come out so clean, well, that might not be so nice, either. Synthesizing polynitro compounds is no chocolate fondue party, either: if you picture a bunch of guys wheeling around drums of fuming nitric acid while singing the Anvil Chorus from Il Trovatore, you're not that far off the mark. You really have to beat the crap out of a molecule to get that many nitro groups on it, which means prolonged heating of things that you'd really rather not heat up at all.

No, I'll leave the can-you-top-this nitration chemistry to those that love it. You guys just go ahead and stuff as many energetic bonds as you can into the smallest tangles; I'll be over here in the bunker cheering you on, and jumping a foot in the air every time someone sneezes. I'm not cut out for hexanitro anything.

Addendum: it's an odd thing, but when you search for information on this compound, a significant number of the Google hits are for its environmental effects. This is an explosive, meant for munitions and destruction, but there are all kinds of studies on its effects on earthworms, fish, soil microorganisms, and so on. Steven Pinker must be right when he says that violence is getting tamer all the time.

Comments (67) + TrackBacks (0) | Category: Things I Won't Work With


1. Quintus on November 11, 2011 10:35 AM writes...

They have obviously done all the ecological studies on this compound. Fish tox etal all has to be done before the compound gets produced commercially!

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2. Hap on November 11, 2011 11:00 AM writes...

"Limb-to-chemist ratio" is pretty good. Does it include fingers?

If you're going to make explosives on scale, their environmental hazards might be relevant, considering 1) all the trouble the DOD has over perchlorate and dioxin contamination, and 2) the unintended side effects the weapons might have (note - Vanity Fair link kills my browser and is probably not for the squeamish). Creating a moonscape on land you might want is undesirable, after all.

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3. Hasufin on November 11, 2011 11:01 AM writes...

Well, you've got to salute the dedication it takes to come up with a compound like that. Might be rude, though, I mean, showing off that you still have HANDS, unlike some of those chemists.

It's notable that it's being explored as a propellant, not an explosive. Granted, there's not all that much difference between the two, but that's one hell of a propellant.

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4. DLIB on November 11, 2011 11:03 AM writes...

Yep...lots of research being done for "high" energy metastable ( kinetically trapped ) compounds. We got asked to make some special calorimeters to measure these things for Livermore. Hopefully grab a signal before the calorimeter is shattered.

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5. David P on November 11, 2011 11:32 AM writes...

A hugely entertaining piece of writing, Derek!

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6. milkshake on November 11, 2011 12:16 PM writes...

As far as I remember, HNIW is the record-holder for detonation speed/pressure impulse among all practical high explosives. Apart from armor-piercing applications, they were interested in using HNIW as an oxidizer in solid propellant for missiles with low exhaust signature. I suppose if they make it in bulk for rocket propellant they will need to do the enviro impact.

HNIW is little highly shock sensitive (more than HMX), has several polymorphs that can crystallize at the same time during recrystallization, I think only the one with chunky prisms has the (relatively) manageable shock sensitivity. Formulating it with a binder must be a bitch because HNIW can blow up easily even as a wet slurry.

I like more the high-performance insensitive explosives like FOX-7, 1,1-dinitro-2,2-diaminoethylene, a more powerful cousin of TATB.
By the way, TATB is so insensitive that it is practically impossible to detonate it by accident and since old TATB from disassembled nuclear weapons cannot be recycled it is routinely disposed of by incineration in regular chemical waste furnaces.

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7. Chemjobber on November 11, 2011 12:55 PM writes...

The distinction from "explosive" is sometimes not entirely clear to me.

I assume there's some sort of technical term for "whoosh-yness" versus "boominess." :-)

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8. Tim McDaniel on November 11, 2011 1:17 PM writes...

Hooray! Another TIWWW!

"Nitro groups, as even people who've never taken a chemistry class know, can lead to firey booms": I only learned that from Things I Won't Work With. But now I know enough to flinch when I saw "Hexanitro", and to grin in antici-pation when I saw "hexaaza".

The Wikipedia article says that it was developed as rocket fuel. The distinction from "explosive" is sometimes not entirely clear to me.

Oh, and says that they stabilized it by mixing it with TNT, forming a cocrystal. And you can even separate them out again just by heating the mix ... except that the resulting CL-20 is then even more unstable than before.

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9. gippgig on November 11, 2011 1:23 PM writes...

Nitroglycerin is a drug.

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10. Pig Farmer on November 11, 2011 1:39 PM writes...

Just looking at that structure gives me the shakes! Nitrogen tri-iodide is the most explosive compound I've ever made, and I think I'll keep it that way!

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11. RB Woodweird on November 11, 2011 1:42 PM writes...

In 1988 I was attending a meeting at the convention center in Las Vegas when the ammonium perchlorate plant in Henderson, about 6 miles away, detonated. The shock wave rolled through the convention center, knocking rolling doors from their channels and dropping a few ceiling tiles. I could feel the pressure differential in my chest as the shock wave passed. Everyone looked around with a wtf face, because no body had ever experienced anything like it and no body knew what it could have been.

I have no desire to get any closer to high explosives than that.

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12. Simon on November 11, 2011 2:04 PM writes...

My personal favourites for nutty compounds you wouldn't want to duplicate are all those per-azide compounds and complexes made by those, er, brave people in Munich.

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13. RD on November 11, 2011 2:12 PM writes...

Are you sure that's not just a virtual compound? Virtual monstrosities aren't all that uncommon. Modelers dream them up all the time. We're not afraid of chiral carbons either.
You synthesis people are wimps.

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14. Lu on November 11, 2011 3:04 PM writes...

that might be assuming too much about the limb-to-chemist ratio

That. Is. Brilliant.

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15. MLBpitcher_and_MedicinalChemist on November 11, 2011 3:05 PM writes...

I'm surprised that an MLB player like Derek Lowe knows about this molecule.

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16. Nick K on November 11, 2011 3:39 PM writes...

I vaguely remember Phil Eaton et al. several years ago trying to make polynitro derivatives of cubane, the idea being that the strain energy of the cubane would give an added "zing" to the bang. Does anyone know what became of this work?

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17. HelicalZz on November 11, 2011 3:43 PM writes...


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18. HelicalZz on November 11, 2011 3:50 PM writes...


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19. cirby on November 11, 2011 4:06 PM writes...

The environmental study would be summed up very nicely as "this compound is designed to move the environment from right here to somewhere over there."

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20. Hap on November 11, 2011 4:07 PM writes...

16: Octanitrocubane here. Octanitrocubane apparently goes bang nicely (in a matter of speaking), but not as well as expected, and since it's hard to make, it probably won't be used as an explosive anytime soon.

BRSM has a piece on cubane referencing that article.

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21. Chemjobber on November 11, 2011 4:11 PM writes...

@16, Nick:

Google "octanitrocubane" and you'll get the Wikipedia page for it. Synthesized and reported in 2000.

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22. Nick K on November 11, 2011 5:17 PM writes...

Thanks Hap and CJ. I won't try to make it, if you were wondering...

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23. Mildweasel on November 11, 2011 5:54 PM writes...

If I'm reading it right the excess hydrogen makes this a propellent. This thing must have a ferocious impulse.

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24. Bunsen on November 11, 2011 6:18 PM writes...

That name, aside from being a mouthful and slightly terrifying, has quite an appealing meter. One that seems somewhat familiar, in fact. You all know the tune... Everybody now!

Um diddle diddle diddle um diddle boom!
Um diddle diddle diddle um diddle boom!
Even though the synthesis
is something quite insaaane
If you hit it hard enough
You'll lose a window paaane

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25. Anonymous on November 11, 2011 6:35 PM writes...

I know this is off-topic, but seriously WTF?

"Penn state names Merck's CEO Ken Frazier head of investigative team in sex scandal."

Seriously, Google it. Isn't he supposed to be saving his company?!

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26. Stuff that I will not work with on November 11, 2011 7:12 PM writes...

Anything that can only be isolated in an argon matrix.

I wonder how much bioaccumulation of this compound would be necessary to make an organism detonate? The nitros would probably be inactivated by reductases, but then you would be left with a polyhydrazide...mmm...

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27. Anonymous on November 11, 2011 7:53 PM writes...

SFChronicle reported it. I hope he's better at leading the investigation than he is at leading the company...

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28. Slurpy on November 11, 2011 7:59 PM writes...

@11 Chemjobber

The technical difference between "whooshiness" and "boominess" is whether the shockwave occurs faster than the speed of sound, i.e. deflagration versus detonation.

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29. Jeffrey Soreff on November 11, 2011 9:18 PM writes...

Wonderful column!
"Limb-to-chemist ratio" - Now that is a
_memorable_ phrase!

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30. Doug on November 12, 2011 7:17 AM writes...

Thank you for another in your most awesome 'things I won't work with' series. Stellar, as always.

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31. smurf on November 12, 2011 8:32 AM writes...


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32. Moiety on November 12, 2011 8:44 AM writes...

@ 8 Tim McDaniel

Think instead of detonation and deflagration. A detonation in the simplest of terms is one that is supersonic and its propogates by its shock compression. A deflagration is an explosion below supersonic that propogates though thermal activity. This can also be used as a definition of most fires. However they are also seen in ICE's and guns.

@ 11 RB Woodweird
To add the explosion is documentated on youtube. Look it up directly as well as BLEVE.

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33. Kevin on November 12, 2011 10:02 AM writes...

I did some technical support once for a couple of labs in the SW that test or develop explosives and propellants, both of which use DSC to study explosives. No surprise that both use very, very small sample size. They used the shape of the DSC exotherm, particularly the leading edge, to determine "boominess." In both places, the limb to chemist ratio was fully normal. (Great line that) It was a bit distracting to work next to a room full of C4 however.

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34. Anonymous BMS Researcher on November 12, 2011 10:32 AM writes...

I have sat through MANY a PowerPoint presentation at a working group meeting with SAR tables -- lots of structures with PK and EC90 numbers. How I wish I dared stick THAT structure in the middle of them to see how high people jumped!

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35. 122 on November 12, 2011 10:45 AM writes...

Is it commercially available; I am thinking of adding more "nitros" on to the carbons.

I am disappointed that N is only trivalent.

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36. Nick K on November 12, 2011 11:50 AM writes...

Five star rating to #24 for the lyrics!

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37. Anonymous on November 12, 2011 10:36 PM writes...

Let's push the envelope, so what's the ultimate explosive molecule to date? Just curious....I think it would be cool to compare PETN, nitroglycerin, tnt, NI3 with HNHNW (Hexanitrohexaazaisowurtzitane ) and others including some emulsion explosives. Cap sensitivity and other features such as storage stability and temp. and pressure of detonation when tested in the "pond".

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38. HFM on November 13, 2011 1:57 AM writes...

Now you've got me tempted to play "spot the chemist" with my next presentation. "Before Johnson left, he synthesized this new fluorophore for us...if anyone wants to try it, I've got the bottle here..." (shake shake shake)

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39. Kevin on November 13, 2011 9:44 AM writes...

Did #24 use "2 Ladies" as the melody? 'Cause that's what comes to mind when I hum it...

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40. Dan on November 13, 2011 12:27 PM writes...

Kevin (39): I think he was going for "Supercalifragilisticexpialidocious". And quite well at that.

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41. Karl on November 13, 2011 2:39 PM writes...

The shortened name for the compound cl-20...
the cl stands for China Lake...a military
explosives (among other tings) facility.
As for all those tox. studies....Uncle Sam
has an Eco-friendly face these days, and is
worried about effluents and such.
One scary thing about this beastie is that
it is in semi-commercial scale production.
We are talking multi-kilo batches.
(I, once) cosidered making a gram or two.
It has a significant space in the US Patent


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42. Trottelreiner on November 13, 2011 6:00 PM writes...

Well, it might be the drugs I'm on(though that's only caffeine), but I'm not that sure there are no drugs that look like that. As already mentioned, there are some NO donors that look kinda, err, strange(think nitroprusside), so if this stuff released NO without depleting thiol groups like nitroglycerin, it might be interesting.

OTOH, those cagy structures are quite nice with channel blockers, like memantine or tetrodotoxine. So well, NO donor and ion channel(like calcium or potassium) blocking, well, could be something for the cardiovascular guys. Explosive blood pressure, you know.

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43. Demon Pit on November 13, 2011 6:29 PM writes...

I wonder if it could be used in a plutonium-implosion type nuclear device. Something with that much bang might be able to produce criticality with a smaller amount of fissile material. Pocket nukes, anyone?

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44. PharmaHeretic on November 13, 2011 9:25 PM writes...

Pfizer Inc. (PFE) and Bristol-Myers Squibb Co. (BMY)’s experimental drug apixaban wasn’t safer or more effective than a standard treatment in stopping blood clots in the legs and lungs of patients after hospitalization, a study found.

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