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Almost two years ago to the day I wrote a post about how much I wanted to see a reaction of the type called “explosive polymerization.” That phrase appears here and there on hazard warnings for certain compounds and in the general context of chemical safety, but I could find little online info about exactly what an “explosive polymerization” really was. I’m sure whoever puts those words on warning labels doesn’t really count on the OMG-that-sounds-awesome-how-do-I-do-it? reaction, but apparently I am not the only one who had it.

This video is by Adrian McLaughlin, aka YouTuber plasticraincoat1. In it, what appears to be about 1/2 tsp of p-nitroanline (which is short for para-nitroaniline, which is also called 4-nitroaniline) is treated with a few drops of concentrated sulfuric acid, in a ceramic dish, over a Bunsen burner flame.  About 50 seconds later, a reaction that certainly seems like it could be described as “explosive polymerization” occurs.  The good stuff starts around 1:20. [Thanks, Fred!]

Sean Michael Ragan

I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I write for MAKE, serve as Technical Editor for MAKE magazine, and develop original DIY content for Make: Projects.


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Comments

  1. Caleb Robertson says:

    Black magic

  2. Wilson! says:

    Its a giant Black Snake firework!!

  3. peter says:

    Is this really “explosive polymerizaiton?” It seems from the description that it’s simply the rapid decomposition of p-nitroanline into gases, which puff up the carbon snake as they evolve.
    This is essentially the same as your garden variety explosion, for instance, of 2,4,6-trinitrotoluene (TNT):

    2 C7H5N3O6 → 3 N2 + 5 H2O + 7 CO + 7 C
    2 C7H5N3O6 → 3 N2 + 5 H2 + 12 CO + 2 C

    Note that the products are primarily gas, with a little extra carbon–the expansion is the explosion. I would expect “explosive polymerization” to involve either 1) the rapid formation of a polymer larger than the monomers it formed from or 2) the explosive evolution of a gas during the formation of a polymer. This could be 2), but isn’t the snake just elemental carbon?

    1. Sean Ragan says:

      Peter-

      Thanks for this very chem-literate comment. I am inclined to agree with you. I deliberately put the title in “scare quotes” and used the ambiguous phrase “could be described as,” but am now regretting not sticking by my chemistry guns a bit more strongly. If, in fact, the product really is elemental carbon, as it appears to be and as the video callout claims, then I don’t really think this is technically a “polymerization.” No doubt it’s extremely cool, and a lot like the “snake” firework, as others have said, but much faster than any other snake reaction I have seen. “Explosive reduction,” maybe?

      Cheers-
      SMR

  4. That is amazing. Like Wilson! says, reminds me of the snake “fireworks” from when I was kid…

  5. Have to love chemistry.

  6. Dave6d6ky says:

    We would often talk our chemistry teacher into adding sulfuric acid to sugar – to kill some time. You’d get about the same results.

    1. Sean Ragan says:

      That reaction is not that fast, in my experience. Was it when you saw it?

      1. Dave6d6ky says:

        No – nowhere near as fast. Just same column of carbon, rising out of the beaker.

  7. [...] Don’t mix things! A good general rule to follow. Because, well, you never know! [...]