Question

Which of the following compounds will not undergo Friedal-Crafts reaction easily?

• A.
• B.
• C.
• D.

Answer 1

The correct option is D

Friedel Crafts Alkylation:
In this reaction, one H-atom of the ring get replace by alkyl group. The attacking electrophile is an alkyl carbocation (R+) made available by the reaction of alkyl halide and an anhydrous lewis acid.

Alkyl groups at benzene ring will increase the electron density on the benzene which will activate the ortho and para position and the compound undergo electrophilic substitution reaction (Friedel craft) readily.

$N{O}_2$ group shows $-M$ effect. Thus, it will decrease the electron density on benzene and deactive the benzene ring towards the electrophilic substitution reaction ( Friedel craft reaction).
Hence, compound (d) will not undergo Friedel-craft reaction readily.