"Explosive Polymerization"

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!]

10 Responses to “Explosive Polymerization”

Caleb Robertson on March 22nd, 2012 at 1:52 pm said:

Black magic

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Wilson! on March 22nd, 2012 at 2:12 pm said:

Its a giant Black Snake firework!!

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peter on March 22nd, 2012 at 2:44 pm said:

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?

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- Sean Ragan on March 22nd, 2012 at 3:12 pm said:
  
  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
  
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Jake Spurlock on March 22nd, 2012 at 2:50 pm said:

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

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Tyler Moskowite on March 22nd, 2012 at 2:54 pm said:

Have to love chemistry.

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Dave6d6ky on March 23rd, 2012 at 4:43 pm said:

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

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- Sean Ragan on March 23rd, 2012 at 7:38 pm said:
  
  That reaction is not that fast, in my experience. Was it when you saw it?
  
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  Dave6d6ky on March 24th, 2012 at 5:40 am said:
  
  No – nowhere near as fast. Just same column of carbon, rising out of the beaker.
  
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