Reaction mechanism for following reaction :

Salicylaldehyde + formaldehyde +con. HCl $\ce{->}$ 5-(Chloromethyl)salicylaldehyde


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So now on the answer,

this is a really simple and a nice case of Friedel-Crafts Alkylation . the mechanism go as follow :

  1. The Oxygen atom on formaldehyde gets protonated, leaving a carbcation.
  2. This carbcation gets added to the Salicylaldehyde by EAS (Electrophilic aromatic substitution).
  3. The alchol so formed gets dehydrated to again get a carbcation which finally gets attacked by $\ce{Cl-}$ to form the final product .

The mechanism scheme is as follow : 1 2 3

  • $\begingroup$ There is a formation of carbocation but not carbanion $\endgroup$ – Bhargavi Mar 10 '19 at 6:38
  • $\begingroup$ Ohh... sorry I wanted to write carbcation but wrote carbanion by mistake I will correct it $\endgroup$ – Advil Sell Mar 10 '19 at 6:51

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