I have one doubt about the dimerization of methacryloyl chloride into the product 3: enter image description here

The dimerized product was observerd around 10-15mol% in different commercial samples of methacryloyl chloride, as it is explained in this research paper: https://doi.org/10.1016/j.tet.2014.07.019

My question is why the product 3 is observed and no the other possible dimer X: enter image description here

Taking into account the partial charges of the different atoms, would it not be more logical to obtain the X dimer regioselectively?


  • 2
    $\begingroup$ The ionic mechanism does not work as you have discovered. It is a "tail-to-tail" dimerization best handled as a radical reaction. This may help: $\endgroup$
    – user55119
    Aug 30 at 16:42
  • $\begingroup$ Thanks for answering, first of all! Sorry for my ignorance, but I don't get the radical mechanism and why it is a radical reaction instead of normal Diels Alder. Then, I've found next paper 10.1039/d0ra10084f talking about that it is unclear the origin of the regioselectivity of dimerization of acrolein (similar to the dimerization of methacryloyl chloride) and they do not comment on the possibility of being a radical reaction. Sorry but I am a mess now jaja! $\endgroup$
    – Elnani
    Sep 3 at 18:04
  • $\begingroup$ I'm not implying that it is radical mechanism but rather treat it as one that allows you to get two stabilized radicals that couple. $\endgroup$
    – user55119
    Sep 3 at 20:13


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