Some meta-directing substituents in aromatic substitution are given. Which one is most deactivating?

• A

  $-\mathrm{C} \equiv \mathrm{N}$
• B

  $-\mathrm{SO}_3 \mathrm{H}$
• C

  $-\mathrm{COOH}$
• Correct answer
  D

  $-\mathrm{NO}_2$

Solution

The deactivating tendency of given groups follows the order
$\text {Thus, }-\mathrm{NO}_2 \text { is the most deactivating group. }$

Hence, the correct answer is option: 'D'.