Question

Replacement of chlorine from chlorobenzene to give phenol requires drastic conditions but chlorine of 2, 4-dinitrochlorobenzene is readily replaced because

• A. $N{O}_2\text{makes the electron rich ring at ortho- and para- positions}$
• B. $N{O}_2\text{withdraws electrons at meta position}$
• C. $N{O}_2\text{donates electrons at meta position}$
• D. $N{O}_2\text{withdraws electrons from ortho- and para- position}$

Answer 1

The correct option is D $N{O}_2\text{withdraws electrons from ortho- and para- position}$

Substitution of halide group by hydroxyl group through nucleophilic substitution reaction is known as Dow's process.
As, the number of EWG increases at the benzene ring, the lower the temperature and pressure is required.​ Hence, the rate of nucleophilic substitution reaction increases. $N{O}_2$ group increases the reactivity towards nucelophilic substitution by increasing the electrophilicity of the Carbons at the ortho and para position. Hence, the correct answer is option (d).