Some meta-directing substituents in aromatic substitution are given. Which one is most deactivating ?
- -COOH
- -NO2
- -C N
- -SO3H
Answer
(2) -NO2
Solution
All four groups withdraw electrons from the ring by -I and -R effects and are meta directing.
As per NCERT, the nitro group is a strongly deactivating group: its -R and -I effects are the strongest.
Deactivating power: -NO2 > -C N > -SO3H > -COOH
Answer: (2)