JEE Main · 2022 · 29 Jun 2022 · Shift 1 · Haloalkanes and Haloarenes

The reaction sequence shows a Reimer-Tiemann reaction followed by oxidation. In the Reimer-Tiemann reaction, phenol reacts with ${\mathrm{CHCl}}_3$ and $\mathrm{NaOH}$ to form salicylaldehyde (o-hydroxybenzaldehyde). However, if there is a substituent ortho to the hydroxyl group, the formyl group enters the para position. The subsequent oxidation with ${\mathrm{KMnO}}_4$ converts the aldehyde to a carboxylic acid. Looking at the options, compound A must be o-cresol (2-methylphenol), which upon Reimer-Tiemann gives 4-hydroxy-3-methylbenzaldehyde, and oxidation yields the final product. The answer is (B).