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

1. $-\mathrm{C} \equiv \mathrm{N}$
2. $-\mathrm{SO}_3 \mathrm{H}$
3. $-\mathrm{COOH}$
4. $-\mathrm{NO}_2$

Solution

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

Asked in: NEET 2013 (All India)

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