Statement I: Chlorobenzene can be converted into phenol by heating it in aqueous sodium hydroxide solution at a temperature of 623 K and a pressure of 300 atmospheres.
Statement II: A nitro group at the meta-position has no effect on the reactivity of a haloarene towards nucleophilic substitution.
In the light of the above statements, choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Both Statement I and Statement II are correct.
Aryl halides are much less reactive than alkyl halides towards nucleophilic substitution, so the halogen is replaced only under drastic conditions, or more easily when an electron withdrawing group sits at the right place on the ring.
Statement I: Chlorobenzene can be converted into phenol by heating it in aqueous sodium hydroxide solution at a temperature of 623 K and a pressure of 300 atmospheres. — True. The high temperature and pressure force the –OH group to replace chlorine. Sodium phenoxide is formed first and acid then gives phenol:
\( \displaystyle \ce{C6H5Cl + 2NaOH} \xrightarrow[\text{300 atm}]{\text{623 K}} \ce{C6H5O^-Na^+ + NaCl + H2O} \)
\( \displaystyle \ce{C6H5O^-Na^+ + H+ -> C6H5OH + Na+} \)
Statement II: A nitro group at the meta-position has no effect on the reactivity of a haloarene towards nucleophilic substitution. — True. The attack of the nucleophile gives a carbanion whose negative charge appears at the ortho and para positions. A nitro group there stabilises this charge; at the meta position none of the resonance structures puts the charge on the carbon bearing –NO2, so no effect is seen.
NCERT (2026-27 edition):
6.7.2 Reactions of Haloarenes – “Chlorobenzene can be converted into phenol by heating in aqueous sodium hydroxide solution at a temperature of 623K and a pressure of 300 atmospheres.”
“The effect is pronounced when (-NO2) group is introduced at ortho- and para- positions. However, no effect on reactivity of haloarenes is observed by the presence of electron withdrawing group at meta-position.”
“…in case of meta-nitrobenzene, none of the resonating structures bear the negative charge on carbon atom bearing the –NO2 group.”