Replacement of $\mathrm{Cl}$ of chlorobenzene to give phenol requires drastic conditions but chlorine of 2,4…

Replacement of $\mathrm{Cl}$ of chlorobenzene to give phenol requires drastic conditions but chlorine of 2,4 -dinitrochlorobenzene is readily replaced This is because
  1. $\mathrm{NO}_{2}$ makes the ring electron rich at ortho and para positions.
  2. $\mathrm{NO}_{2}$ withdraws $\mathrm{e}^{-}$ from meta-position.
  3. $\mathrm{NO}_{2}$ donates $\mathrm{e}^{-}$ at meta-position.
  4. $\mathrm{NO}_{2}$ withdraws $\mathrm{e}^{-}$ from ortho/para-positions.

Solution

$-\mathrm{NO}_{2}$ group withdraws electrons from $o$ - and $p$ -positions and hence activates the $-\mathrm{Cl}$ present on that position towards nucleophilic substitution. .

Asked in: JEE-TOPICTESTS-CHEMISTRY

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