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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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October 21, 2008

Things I Won't Work With: Triazadienyl Fluoride

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Posted by Derek

Now this is a fine substance. Also known in the older literature as fluorine azide, you make it by combining two other things that have already made my “Things I Won’t Work With” list. Just allow fluorine (ay!) to react with neat hydrazoic acid (yikes), and behold!

Well, what you’re most likely to behold is a fuming crater, unless you’re quite careful indeed. Both of those starting materials deserve serious respect, since they're able to remove you from this plane of existence with alacrity, and their reaction product is nothing to putz around with, either. The first person to prepare the compound (John F. Haller back in 1942) survived the experience, and made it (rightfully) the centerpiece of his PhD dissertation. But relatively few buckaroos had the fortitude to follow his trail over the years, and it’s not hard to understand why. Haller himself wrote on the subject in 1966 from an industrial position at Olin Mathieson, and got right to the point:

”(Fluorine azide) is described as a greenish-yellow gas at room temperature, liquefying at −82°C when diluted with nitrogen and freezing to a yellow solid at −143°C. Evaporation of this solid generally results in violent explosion.”

Yes, it does, and that does tend to slow down the march of science a bit. Not until 1987 was an improved procedure published, from Helge Willner and group in Hannover. (We'll see him again - most of his publication list falls into the "Things I Won't Work With" category, and I really have to salute the guy). Basically, it was the same reaction, but done slowly and Teutonically. You start off by making absolutely pure anhydrous hydrogen azide, which is a proposal that you don't hear very often around the lab, and is the sort of thing that leads to thoughts of career changes. (Maybe I could go into the insurance business and sell policies to whoever took over the prep). The next step is introduction of the fluorine, and when elemental fluorine is the most easily handled reagent in your scheme, let me tell you, you're in pretty deep. After the reaction, attention to painstaking fractional evaporation at very cold temperatures, in the best traditions of German experimental chemistry, is needed to clear out the reactants along with some silicon tetrafluoride, difluorodiazene, and other gorp. Willner's group managed to make about 20 milligrams of the pure stuff, but strongly recommend that no one ever make more than that. As far as I can tell, no more than a few drops of the compound have ever existed at any one time. This is not really a loss:

”The synthesis of pure N3F by the method described above was repeated more than 30 times without explosion. But if N3F is cooled to -196 C or N3F is vaporized faster than described, very violent explosions may occur. One drop of N3F will pulverize any glass within a 5-cm distance.”

They managed to get pretty full spectroscopic data on the compound while they had it, which was good of them, and even explored its chemistry a bit. Life must have a peculiar vividness when your job is to come in and see if triazadienyl fluoride does anything when you expose it to fluorine monoxide. (Oddly, they report that that reaction is OK – go figure). Still, most of the literature on this compound remains computational, rather than experimental (other than Willner's lab), and unless it turns out to be the secret to faster-than-light travel or something, that situation will continue to obtain. It's already good for accelerating Pyrex fragments past the speed of sound, but there are easier ways.

Comments (28) + TrackBacks (0) | Category: Things I Won't Work With


1. Placebo on October 21, 2008 8:53 AM writes...

It sounds like Helge Willner is a guy that can manage risk. Too bad he wasn't running AIG, Bear Stearns, WaMu, etc.

Great post!

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2. Hap on October 21, 2008 9:54 AM writes...

That would only be true if the risks of failure had come upon the actors. Willners and his students will get hurt or killed if they are not careful and do not manage the risks of their reactions. The companies, on the other hand, were run by people whose incentives may have differed from those of their companies, and who were unlikely to experience the full consequences of their actions. Why manage risk if it only hurts someone else if you fail?

FN3 seems like a barrel of laughs, if you laugh very softly.

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3. Harry on October 21, 2008 10:54 AM writes...

I really enjoy hearing about this sort of thing from (VERY) afar.

I always have to wonder just why anyone would want to make things like this. They seem to me to be the chemist's equivalent of the famous "Rednecks' last Words ("Hey ya'll! Watch this!").

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4. Liberal Chemist on October 21, 2008 10:55 AM writes...

Loved the tone of this post. We need to hear "Fun Derek" more often.

I worked in an inorganic synthesis lab where we routinely worked with fluorine and metal azides. In fact, I got my summer job in the lab because the person I was assisting had sheared the ends off the fingers of one hand working on tellurium azides. They told me it would be safer when I did it because I would be working in glass vessels (not metal) and the bursting pressure *when* the vessel exploded would be much less. They had me at fluorine and the explosions were just gravy.

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5. Jose on October 21, 2008 11:03 AM writes...

The level of truly bold planning, raw intellect and pure curiosity it must take to tackle such projects simply amazes me.

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6. Rhenium on October 21, 2008 11:17 AM writes...

Don't forget to add, forgiving grant agencies. Pure curiosity is out of style these days.

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7. CMC guy on October 21, 2008 12:44 PM writes...

Deep inside (or maybe not so buried) most chemists I know have a bit of pyromaniac in them. Squirting small amounts BuLi from syringes into hood or dropping Na into sink were just forms of entertainment.

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8. pete on October 21, 2008 12:59 PM writes...

Fun read !

As a biologist I had a lesson in chem-respect with hydrofluoric acid -- ok, maybe it's not the baddest but remember, I'm a biologist OK?

I was using an old style Pi Pump pipettor and glass micropipet to dispense a smidge and misjudged how quickly the liquid zipped up the narrow bore pipet. I vividly remember a wisp of smoking HF coming from the Pi Pump nozzle as I removed the pipet. Oopsie.

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9. Seth Davidson on October 21, 2008 2:19 PM writes...

This was a really funny and informative post, particularly reading it as a non-chemist. Risk management in the lab while handling chemicals pretty much guaranteed to blow you into bits. Who knew?

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10. Sili on October 21, 2008 2:59 PM writes...

Hmm - this looks small enough that it might be amenable to rotational spec.

But who in their right mind would want to try to do isotopic labelling and then hit this stuff with microwaves?

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11. MTK on October 21, 2008 7:17 PM writes...

A lab partner of mine once described the "Triple Crown of Chemistry Lab Disasters"; fire, flood, explosion.

I've had the first two, but never an explosion. Not for lack of trying, however. I once worked with mesyl azide which I had a healthy respect for, although I'll admit I really don't know how explosive it might be. Anyway, when I worked with it I put the reaction flask in a beaker with foam peanuts, behind a blast shield, with the hood sash down as far as possible. As a joke I one time put on the face shield too.

As Justin Wilson once said, "I don't believe in taking chances which is why I wear a belt and suspenders."

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12. weirdo on October 21, 2008 7:18 PM writes...

Far more fun than BuLi (either n- or t-) is neat diethylzinc. Squirt 100 microliters into the corner of your hood just for the heck of it.

I never had the guts to do the same with neat dimethylzinc.

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13. Anonymous BMS Researcher on October 21, 2008 10:15 PM writes...

When I showed this entry to my wife she said "I can feel the strains in the molecular bonds from here!"

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14. Anonymous BMS Researcher on October 21, 2008 10:29 PM writes...

Here's another lovely substance, which I don't expect ever to be used in my workplace:

This stuff was the reason they invented Teflon.

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15. LiqC on October 22, 2008 3:55 AM writes...

What's with the name? "Triazenyl" seems more appropriate, if you are unhappy for some reason with "fluorine azide". Yes, putting fluorine on a place of electopositive element is bad, but the compound isn't happy with itself either.

12: I'd like to try out trialkylborane...

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16. Charlie on October 22, 2008 4:13 PM writes...

Coincidentally, there's an article in the latest American Scientists by J. Castellano about the secret development of rocket fuels, specifically organics with -NF2 groups. Would you ever want to work with perfluoroguanidine!!?? The author suggests the difluoroamino group might be interesting for biologically active materials. I wonder if that idea would ever make it to the synthetic lab. I remember a post a while back where you wanted a new fluorine (or new halogen). Could this be it?

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17. Charlie on October 22, 2008 4:13 PM writes...

Coincidentally, there's an article in the latest American Scientist by J. Castellano about the secret development of rocket fuels, specifically organics with -NF2 groups. Would you ever want to work with perfluoroguanidine!!?? The author suggests the difluoroamino group might be interesting for biologically active materials. I wonder if that idea would ever make it to the synthetic lab. I remember a post a while back where you wanted a new fluorine (or new nitro group?). Could this be it?

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18. Quinn on October 23, 2008 4:52 PM writes...

This post exemplifies why I love this blog.

This is sort of like kids talking about Godzilla vs King Kong. Even after years in the lab, it's still possible to have a child-like glee about chemistry, whether it's super-reactive reagents or stuff that stinks.

Makes me remember the time I dropped an inch of copper wire into a beaker of nitric acid. Interesting to watch-

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19. KinaseJunkie on October 27, 2008 11:08 AM writes...

Helge Wilner lost most of his hearing capacity on one ear to his tendency to work with not so nice inorganics and there are quite a number of people around who think that he lost more than that.

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20. Jonadab on November 9, 2008 10:17 PM writes...

How much danger can you pack into one small molecule? Someone should go for the prize and synthesize 1,1,1,1 cyano-fluoro-azido-pollonio-methane.

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21. Zemyla on January 5, 2009 3:10 PM writes...

Azides are bad enough, but forcing it to be positive instead of negative looks to me to be even worse. Oxygen fluoride is unhappy enough.

So you can tack an azide group onto a fluorine atom, and you can stick four (!) onto a carbon atom. Has anyone ever figured out how to make nitrogen triazide (N10)? Or do we still lack someone with the right mix of chemical know-how and complete disregard for safety?

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22. Matthew Goldfinch on January 8, 2010 3:17 PM writes...

Zemyla, don't you think that tetraazoammonium azide would be more ludicrous?

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23. Dan on February 28, 2011 11:51 PM writes...

I know this post is old enough that no one is likely to read it, but:

LiqC (#15): I think it's "...dienyl" because the azide group has two N=N double bonds. I'm not an expert on chemical naming conventions, but I remember that carbon chains with two double bonds are named something-something-diene. Just a guess.

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24. Goyta on May 22, 2011 7:54 PM writes...

You really have to salute the *girl*. Helge is a woman's name, and Helge Willner is no doubt a brave woman!

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25. Rayner on May 28, 2011 9:16 AM writes...

If this is him, I'm pretty sure he's a guy:

I salute him either way. From a safe distance.

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26. Don on March 12, 2012 12:56 PM writes...

I worked in a lab at 3M where we made perfluoroguanidine. We added ethanolamine perchlorate to it and flourinated the adduct to product the solid ionic salt we called 635 that was tested as a candidate for a solid rocket propellant - supposedly for the first manned moon mission. But of course the Apollo mission did not use solid propellants at all.

There was an explosion one day in the bay where the perfluoroquanidine was being made. We were making 20 grams of the stuff in a stainless steel reactor with one-inch thick walls. We found no pieces of the reactor but the pressure gauge on top survived and still had the last recorded reading. The reactor bay was demolished. The pieces we found of the cast-iron radiator that heated the place were the size of silver dollars. I was one very impressed 19-year old.

The formula for 635 BTW is (NF2)3COCH2-
CH2NH3 CLO4. I have been keeping that secret for almost 50 years but today I found a document online that shows that it was long ago declassified.

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27. Don on March 12, 2012 1:08 PM writes...

The full correct chemical name of 635 is (2-tris (difluoramino) methoxy) ethyl ammonium perchlorate. It appears to have been called INFO-635 by the people at the Air Force Rocket Propulsion lab at Edwards AFB where it was tested for use as a burn-rate modifier in a solid propellant system. These are things I learned only today.

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28. Esko on May 11, 2012 3:40 AM writes...

Clearly this N3F "asks" for reaction with NaN3. - How clean chemistry!

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