Chlorobenzene is fused with NaOH at 623 K and 320 atm pressure. Which compound is formed in this step, before acidification?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Sodium phenoxide
Under these drastic conditions the chlorine of chlorobenzene is replaced by an oxygen group. Phenol is acidic and reacts with the excess NaOH, so the fusion gives its salt, sodium phenoxide. Phenol itself is obtained only when this salt is acidified:
\( \displaystyle \ce{C6H5Cl} \xrightarrow[\text{623 K, 320 atm}]{\ce{NaOH}} \ce{C6H5ONa} \xrightarrow{\ce{H+}} \ce{C6H5OH} \)
NCERT (2026-27 edition):
7.4.2 Preparation of Phenols – “1. From haloarenes … Chlorobenzene is fused with NaOH at 623K and 320 atmospheric pressure. Phenol is obtained by acidification of sodium phenoxide so produced…”