My professor wanted me to set up a lab to synthesize Methyl Vinyl Ketone (AKA Butenone) from some MEK we have lying around (2-Butanone).

Now, I know there are multiple ways to do this, but the tricky part is finding out a safe way to go about this as MVK has a very low flashpoint.

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I figured we could do an acid catalyzed alpha halogenation with Bromine and some Acetic Acid, and then follow up with an Elimation using a bulky base such as tert-butoxide.

The only problem is I have no idea how long, how much, or how cold/warm these materials need to be for the reaction to occur. Ideally the entire reaction would take place in an ice water bath due to the danger, but at the same time I don't want to take five hours synthesizing one compound.

Let me know what you think, and feel free to recommend a different (but safe) route of synthesis, as our lab has plenty of chemicals to work with. By the way, we only need to create about 10-20ml of the stuff, but more is better.

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    $\begingroup$ The safest way is just to buy it. ~$120 for 100 mL. $\endgroup$
    – jerepierre
    Mar 12 '15 at 20:53
  • $\begingroup$ Btw, welcome to chemistry.SE! And yeah, I don't have much insight into the topic, but I think I agree with Jerepierre. Purchasing is indeed safer than synthesizing, and probably cheaper. $\endgroup$
    – M.A.R.
    Mar 12 '15 at 20:59
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    $\begingroup$ It can never be made "safe", as methyl vinyl ketone is itself extremely toxic. $\endgroup$
    – Jori
    Mar 12 '15 at 22:48
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    $\begingroup$ @user97462 - Why not look for another supplier? There are a number of ways to look for suppliers. For example, ChemExper finds 103 possible suppliers in multiple countries. $\endgroup$
    – Ben Norris
    Mar 12 '15 at 23:20
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    $\begingroup$ A literature method for the laboratory synthesis of MVK can be found in [White & Haward, "The preparation and polymerisation of Methyl Vinyl Ketone" (1943)][1]. The synthesis is via the acid catalyzed elimination of water from 4-hydroxy-2-butanone with conc. phosphoric acid. They synthesized the 4-hydroxy-2-butanone from acetone and paraformaldehyde polymer, but it is commercially available now. You can find extensive details of the experimental method in the text of the paper. [1]: http:pubs.rsc.org/en/content/articlepdf/1943/jr/jr9430000025 $\endgroup$
    – J. LS
    Mar 13 '15 at 19:13

As pointed out in the comments, there is no way to make it safe, as methyl vinyl ketone itself is a very nasty compound.

I am also not an expert on organic synthesis, but I found some procedures, that might help you in adopting a synthetic route. The one you suggested might work, but be aware, that you are dealing with a methyl ketone, which can undergo the haloform reaction quite easily.

For example, in [1] they describe the bromination with bromine and absolute methanol at the methyl group for 3-methyl-2-butanone at a nice moderate temperature range 0-10 °C. The yield is 95%. But this is not what you want. Adding an acid as catalyst might work in your favour though, as after protonation the partial positive charge is better stabilised at the higher substituted carbon.

In [2] they use N-bromosuccinimide and aqueous hydrogen bromide to introduce the halogen in α position. They convert hexanoic acid with thionylchlorid to the acid chloride and subsequently to 2-bromohaxanoylchloride. The reaction takes place in the also quite nasty carbon tetrachloride at about 85 °C. This might also work for your system, it's a bit warmer than you expected though.

In [3] they use sulfuryl chloride in carbon tetrachloride to convert pantane-3-one to 2-chloropentane-3-one at about 45 °C with about 80% yield. How selective this will work with an asymmetric ketone is not clear.

Once you have obtained the 3-halogeno-butan-2-one, things will not get easier. I found a patent [4], where they convert 3-chlorobutan-2-one via pyrolysis with sodium acetate at 500-550 °C.

I could not find a reference for an elimination, but that should also work as long as you use a bulky base.

Wikipedia [5] has a different route for the synthesis, which might be a bit more economical and easier.

Well, good luck!

  1. Org. Synth. 1976, 55, 24.
  2. Org. Synth. 1976, 55, 27.
  3. Org. Synth. 2002, 79, 251.
  4. J. R. Long: Preparation of methyl vinyl ketone. US 2256149 A, 16. 09. 1941.
  5. http://en.wikipedia.org/wiki/Methyl_vinyl_ketone#Production
  • $\begingroup$ Haloform reactions only happen in base according to Clayden et al. OP is using a acid catalyst. $\endgroup$
    – Jori
    Mar 13 '15 at 9:17
  • $\begingroup$ @Jori I included this as a courtesy warning. What is your suggestion to improve the answer? $\endgroup$ Mar 13 '15 at 9:26
  • $\begingroup$ Wow thanks Martin, that is a seriously good answer, thanks for the help! $\endgroup$
    – user97462
    Mar 13 '15 at 19:15

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