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Your Metal Azide Worries Are Over

You may not have felt the need for a better synthesis of metal azides. Personally, my metal azide requirements are minimal, and very easily satisfied. I can get all I need by looking at a structure drawn on a whiteboard from about twenty feet away, thanks, and have no desire to actually prepare any of these things. I do not see this as an irrational reluctance. For example, last year I wrote about mercury azides, a most alarming class of compounds whose synthesis would be much easier if the two solvent layers didn’t keep getting disturbed by explosions. I’ve also covered selenium tetraazide, a cheerful lemon-yellow solid with the annoying habit of blowing up when it gets warmer than about -64C, which would explain why you don’t run into it very often.
Ah, but perhaps that’s about the change. Thanks to this paper, a collaboration between two groups in Munich (at the TU-München and the Ludwigs-Maximilien-Universität), we now have far easier entry to a wide range of metallic polyazides, oh joy. It turns out that silver azide in liquid ammonia slowly does redox reactions with a variety of other elements, giving a wide variety of otherwise hard-to-obtain compounds. The careful reader will have noted a defect in this scheme: you first have to make a supply of silver azide, which is enough of a show-stopper for me. That Wikipedia article drolly notes that “In its most characteristic reaction, the solid decomposes explosively”, and because it’s a silver salt, that decomposition can be set off by foolhardy behavior like shining a strong light on it.
corundum
So there’s your starting material – now let’s use it to make something lively. Shown is a corundum crucible before and after heating up a sample of the manganese azide product (as an ammonia complex). Again, the careful reader will note a crucial detail about the post-analysis state of this labware: it has been blown to hell and gone. This will surely happen to everything in which you heat up samples of metal azides, and believe me, many of these items will be less sturdy than a corundum crucible. Before performing this operation, be sure to ask yourself: “Do I want this apparatus to be blown to pieces?”
And before making the metal azide in the first place, naturally, you need to ask “Do I want to blow myself to pieces?” That’s because this isn’t one of those set-it-and-forget-it Crock-Pot azide reactions. No, you’re going to have to hand-craft these things:

“. . .The reaction mixtures were intensively stirred using a magnetic stirrer when all AgN3 is dissolved (after approximately one day). As long as there is a residue of AgN3, the vessel only should be shaken very gently to prevent silver azide grains to be ground at the glass wall of the vessel.”

Yes, “grinding” is one of those verbs that you don’t want to hear about when azide preps are being discussed, along with “stomping”, “whacking”, “flinging” and several others to which is only response should be “fleeing”. Ah, but once you’ve dissolved that pesky silver azide, the fun is only just coming over the horizon:

“Crust formation occurring at the fluid level and consisting of silver azide at the beginning of the reaction and the respective metal azide at the end of the reaction have to be carefully scraped off the glass every day with a Teflon spatula. The scraping has to be performed with extreme care. . .”

See, I told you that you didn’t want to do this. “Scraping” is yet another one of those verbs that you don’t want to hear brought up in this context. If your touch isn’t quite delicate enough, someone’s going to have to use a larger spatula to scrape you off the ceiling. I note that the experimental section of this paper not only recommends the leather coats that earlier workers in the field have used, but gives suppliers in Berlin and Cologne. And earplugs. And face shields. And helmets. And Kevlar gloves. If scientific meetings were more like fantasy cons, people would be dressing up like this to win prizes.

34 comments on “Your Metal Azide Worries Are Over”

  1. Anonymous says:

    But how do they *know* they need to stir carefully? Surely that’s just a hypothesis, yet to be tested…

  2. A Nonny Mouse says:

    Heating picoline N-Oxide and tosyl chloride does it for me. 1g left a crater in the stirrer and nothing but powdered glass.
    Clearly, I should have waited for the paper to arrive where solvent is used first and then the residue is heated……

  3. Project Osprey says:

    I thought this line was bad.
    “Interestingly, many of these potential compounds have never been synthesized in quantities larger than a few milligrams.”
    Untill I read this one
    “Finally, the powders of the metal azide ammonia complexes were treated in high vacuum for several days at temperatures between 40 and 110C to liberate NH3.”
    Too unstable to have been synthesised before and they heated them to 110C?

  4. oldnuke says:

    They must have a healthy budget for all of the apparatus and instrumentation that is destroyed accidentally on purpose.
    Ooopsy, there went the NMR…

  5. Anonymous says:

    @4 I’m not an expert, but I can’t imagine detonation in an NMR machine would end well?

  6. Carl 'SAI' Mitchell says:

    If it were me doing this sort of chemistry I’d build robots to do the interactive bits of the prep. Precise control of stir rate, applied force, etc, and I could be in the next building over!

  7. Anonymous says:

    Or just out-source it to China.

  8. Hap says:

    “Scraping” is yet another one of those verbs that you don’t want to hear brought up in this context. If your touch isn’t quite delicate enough, someone’s going to have to use a larger spatula to scrape you off the ceiling.

    I don’t think any scraping will actually be required at that point, just a hose, as long as no more azide is left lying around.

  9. tocket says:

    Silver azide isn’t all that bad. I’ve prepared it on several occasions for, erm… recreational purposes. Sure, it is a primary explosive and as such sensitive to heat, shock, friction and static electricity, but compared to many other primary explosives it’s quite predictable with regard to what will make it explode.

  10. Heteromeles says:

    Sadly, the crucible picture only partially loaded, so I missed a belly laugh.
    Thank you for brightening my day! Those leather jackets look so stylish, too. Just what you want to see a chemist running in terror wearing, along with those cool kevlar gloves. Shouldn’t they invest in something a bit more durable, like this?

  11. milkshaken says:

    the new system would be perfect for reacting AgN3 with NI3.NH3 or NCl3; I am sure something potent would come out

  12. Anonymous says:

    Smiles from beginning to end! Thanks, Derek!

  13. anon says:

    @10
    “Sadly, the crucible picture only partially loaded, so I missed a belly laugh”
    Yep, not only these compounds shatter the labware, the force of explosion even rips the bits out the server hard drives containing the photographs…

  14. You are the Bill Bryson of big pharma blogging, Dr Lowe.

  15. sepisp says:

    From SI: “X-ray Powder patterns were recorded in flame-sealed glass capillaries or prepared on Scotch-Tape …”
    I wonder who had the fun task of flame-sealing the capillary with azides in it!

  16. Anonymous says:

    @10 and 13
    The picture can be found in the supplementary information, which isn’t paywalled.

  17. Anonymous says:

    @10 and 13
    The picture can be found in the supplementary information, which isn’t paywalled.

  18. NoniMausa says:

    “…I’d build robots to do the interactive bits…”
    Or Waldoes. Why don’t we have decent Waldoes yet? They would allow people to do these reactions from the next county, which sounds like a goal well worth pursuing, at a safe distance.
    Of course, good Waldoes might cost more that the bakers dozen of NMR machines you need to have on hand for these processes. Maybe go in on an order with A. G. Streng, who likely gets a discount for volume?
    Noni

  19. patently says:

    So “the vessel only should be shaken very gently”?
    I’m imagining the appropriate level of shaking would be generated by holding the vessel and thinking about what’s in it?

  20. Karl says:

    “…holding the vessel and thinking about what’s in it?”
    That’s probably too vigorous. Probably more along the lines of ensure that the flask is well coupled to a countertop, then tiptoe out of the building and jump up and down in the parking lot.

  21. Jakkob says:

    Quote from the Supplementary Information:
    “To avoid decomposition all further steps were
    carried out under the exclusion of light.”
    Ahh… So they prepared the wildly explosive Silver Azide IN THE DARK?
    The price of that PhD is starting to look pretty high…

  22. Jared says:

    > 15. sepisp on June 17, 2014 7:05 AM writes…
    > From SI: “X-ray Powder patterns were recorded in
    > flame-sealed glass capillaries or prepared on
    > Scotch-Tape …”
    >
    > I wonder who had the fun task of flame-sealing the
    > capillary with azides in it!
    From the Scotch-Tape comment, who are we to say that the actual author was certain what technique the red-shirts had used?

  23. Mechalith says:

    It probably says something uncomplimentary about me that every time I read one of these articles it re-ignites me desire to look into a degree/career in chemistry.

  24. swampyankee says:

    Once again, I’m glad I didn’t follow a career path involving chemistry.
    Seeing all these preparations involving shaking and stirring psychotic compounds, I can see why they don’t use robots. Grad students are so much easier to replace, as the new robot requires dealing with the purchasing department.

  25. Alchemist says:

    @Mechalith
    It probably says something similarly uncomplimentary about me that every time I read one of these articles I can’t finish it without tears of laughter cascading down my face and I dare not read more than one or I find myself in a stated of near asphyxiation because I am laughing so hard.
    What I can never wrap my head around is how enough azide chemists survive to perpetuate the field.

  26. Phil Stracchino says:

    Derek,
    FYI, only about the top 30% of the crucible image in this post is appearing, and the Things I Won’t Work With page itself cuts off towards the end of the seventh line of your August 28th, 2013 post.
    Something Is Wrong…

  27. Gregg Eshelman says:

    If only there really was such a compound as duodecaplyatomate, described by Edward Elmer Smith, Ph.D. as being composed of “324 atoms of heptavalent nitrogen, combined in twelve linked molecules of 27 atoms each”.
    If such existed, you wouldn’t just not want it in your lab, you wouldn’t want it on your planet.
    E. E. “Doc” Smith graduated from the University of Idaho in 1914 with two degrees in chemical engineering. He got a masters degree in chemistry from George Washington University in 1917 and completed his PhD in chemical engineering in 1919.
    All that education on chemistry and he put it to use working for the National Bureau of Standards in Washington, D.C., developing standards for butter and for oysters, then as a food engineer working mainly on breads and pastries.
    So nom on a fluffy doughnut while reading the Skylark of Space and the Lensmen series – because the processes used to make it so light and fluffy were very likely developed by the author.

  28. cometaryorbit says:

    “Doc” Smith also used a pentavalent nitrogen explosive in the much lesser known “Spacehounds of IPC”.

  29. loupgarous says:

    “I note that the experimental section of this paper not only recommends the leather coats that earlier workers in the field have used, but gives suppliers in Berlin and Cologne. And earplugs. And face shields. And helmets. And Kevlar gloves. If scientific meetings were more like fantasy cons, people would be dressing up like this to win prizes.”
    Cosplay with fireworks…

  30. loupgarous says:

    @Noni: the world of metal azide chemistry missed a real opportunity to get great surplus gear when (at the strong urging – an FBI raid was involved at one point – of the Environmental Protection Agency) the Rocky Flats Plutonium Reprocessing Plant just north of Denver, Colorado was disestablished.
    Just think, all the waldoes you could ask for, if you’d just sign your life away getting a security clearance to scrub those stubborn plutonium nitrate stains off of them.
    It’s not just plutonium, and if you think the issue was mere political correctness, a tollway bypass was only approved on the outskirts of the former Rocky Flats property on the condition it was built so that motorists wouldn’t stop or even slow down through the areas where americium-241 residues were still detectable 20 years after the plant was carted off to the Idaho National Energy Laboratories to make the US-Canadian border glow in the dark.

  31. Jeff Dickey says:

    @26 My understanding is that it’s rather a booming business.

  32. Jeff Dickey says:

    @26 My understanding is that it’s rather a booming business.

  33. Drew says:

    This is an interesting one, I won’t say near or dear to my heart, but having used silver azide as a prep for lead azide, silver is pretty tame by comparison.
    And yes, I’m one of those people in the business of things that go boom.
    The more interesting part, is that most of the experiments going on now (they’re more engineering challenges than science) is perfecting Non-mercuric Non-Corrosive primers that also omit heavy metals (i.e. Lead Azide, Lead Picrate (styphnate)). Most of the development on this front has been moving towards explosive ammonia complexes with copper.

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