Question

Although chlorine shows strong −I effect, it is ortho–para directing in electrophilic aromatic substitution. Why?

Hint:

Halogens are deactivating but ortho–para directing due to resonance.

Answer 1

Chlorine has:

• −I effect (electron withdrawing)
• +R effect (lone pair donation)

Resonance donation increases electron density at ortho and para positions. Thus:

• Deactivating overall
• Ortho–para directing