JEE Main · 2024 · 05 Apr 2024 · Shift 2 · Alcohols Phenols and Ethers

In reaction (2), the $-OH$ being replaced is attached directly to an $s{p}^2$ (aromatic-ring) carbon — a phenolic $-OH$. Unlike an alcoholic (aliphatic, $s{p}^3$-carbon) $-OH$, the C–O bond of a phenol has partial double-bond character because the oxygen lone pair delocalises into the ring; this strengthens the C–O bond and leaves the ring carbon unavailable for nucleophilic attack. Simply treating the phenol with HCl therefore does not substitute $-OH$ by $-Cl$ the way it would for an alcohol, so this reaction is not possible.