Concept:Meta-directing groups withdraw electron density from the benzene ring, typically via resonance, possessing an atom with a partial positive charge directly attached to the ring.
Solution:- The cyano group (\( -\text{C}\equiv\text{N} \)) consists of a carbon atom triple-bonded to a highly electronegative nitrogen.
- The nitrogen pulls electron density, placing a partial positive charge on the carbon. This carbon subsequently withdraws electrons from the benzene ring through resonance.
- This makes \( -\text{CN} \) a strong deactivating, meta-directing group.
Why other options are incorrect:- \( -\text{OH} \), \( -\text{NR}_2 \), and \( -\text{OR} \) all have atoms (O or N) directly attached to the ring containing lone pairs. These lone pairs are donated into the ring via resonance, rendering them activating, ortho/para directing groups.
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