15

Overall reaction

What is the mechanism of the above reaction? I have thought of one possibility:

proposed mechanism

Would this work? How exactly is the chlorine installed on the alkyl chain?

orthocresol
  • 71,033
  • 11
  • 239
  • 410
justbehappy
  • 1,789
  • 2
  • 16
  • 30
  • The actual mechanism turns out to be in different order when you use ZnCl2 instead of AlCl3. It is probably the same case here. See: https://en.wikipedia.org/wiki/Blanc_chloromethylation – wuschi Oct 18 '15 at 13:40

1 Answers1

13

This reaction is chloromethylation, similar to Blanc chloromethylation, but using $\ce{AlCl3}$ as co-catalyst instead of $\ce{ZnCl2}$. These are reactions belonging to a group related to Friedel-Crafts reactions, but characterized by usage of protonation instead of coordination with molecular Lewis acids

Mechanism of your reaction (not accounting for influence of co-catalyst) can be written as:

(source)

$\ce{AlCl3}$ coordinates to $\ce{HCl}$ creating adduct ($\ce{HAlCl4}$) which is much stronger acid.

Mithoron
  • 4,546
  • 14
  • 40
  • 61