Question

Give reasons for the following:
Benzoic acid does not undergo Friedel-Crafts reaction.

Hint:

Always check if a substituent withdraws electrons — deactivation blocks substitution!

Answer 1

Benzoic acid has a –COOH group attached to the benzene ring.
The –COOH group is strongly electron withdrawing due to its –M (–mesomeric) and –I (–inductive) effects.
This deactivates the benzene ring towards electrophilic substitution reactions like Friedel-Crafts alkylation or acylation.
Also, the –COOH group can coordinate with the Lewis acid catalyst (like AlCl$_3$), forming a complex that reduces the availability of the catalyst for generating the electrophile.
Therefore, benzoic acid does not undergo Friedel-Crafts reaction.