Which compound is formed when ${\text{C}}_6{\text{H}}_5\text{OH}$ reacts with ${\text{CHCl}}_3$ in the presence of aqueous $\text{NaOH}$?

Solution

1. The reaction of phenol with chloroform and $\text{NaOH}$ is the Reimer-Tiemann reaction.
2. The active electrophile generated is dichlorocarbene, ${\text{:CCl}}_2$.
3. The electrophile attacks the ortho position of the phenoxide ion.
4. Hydrolysis of the intermediate yields salicylaldehyde.
5. Hence the answer is (B).