Mechanism for chloromethylation of Salicylaldehyde [closed]








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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](https://i.stack.imgur.com/PSOwA.jpg)](https://i.stack.imgur.com/PSOwA.jpg)
[![2](https://i.stack.imgur.com/KBHSC.jpg)](https://i.stack.imgur.com/KBHSC.jpg)
[![3](https://i.stack.imgur.com/MF6hB.jpg)](https://i.stack.imgur.com/MF6hB.jpg)


 1