Question

why benzoic acid doesn't show fridel craft rkn

Answer 1

Hey there!!!

Benzoic acid doesn't undergo Friedel crafts reaction.It is due to the deactivation of the benzene ring by the electron withdrawing effect of the -COOH group.
Friedel craft catalyst is electron deficient and the catalyst (anhydrous AlCl3) reacts with the -COOH group(electron rich) of benzoic acid and gets bounded.The benzene ring is deactivated.
That's why benzoic acid doesn't show Friedel craft reaction.

Hope helps...