Monochlorination of toluene in sunlight followed by hydrolysis with aq. \(NaOH\) yields
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Benzylalcohol
Toluene can be chlorinated in two different places, depending on the conditions:
In sunlight (or on heating, without a catalyst), chlorine forms free radicals and substitutes a hydrogen of the methyl side chain, giving benzyl chloride.
In the dark with a Lewis acid (\( \ce{FeCl3} \)), chlorine substitutes on the ring (electrophilic substitution) and gives o- and p-chlorotoluene.
Here the monochlorination is done in sunlight, so the side chain is chlorinated:
\( \displaystyle \ce{C6H5CH3 + Cl2} \xrightarrow{h\nu} \ce{C6H5CH2Cl + HCl} \)
Benzyl chloride behaves like an alkyl halide (its chlorine is on an sp3 carbon), so aqueous NaOH replaces Cl by OH:
\( \displaystyle \ce{C6H5CH2Cl + NaOH(aq) -> C6H5CH2OH + NaCl} \)
So the product is benzyl alcohol.
Why the other options are incorrect
Option (1) o-cresol — Incorrect. It would need chlorination on the ring (dark, \( \ce{FeCl3} \)), and the aryl chloride would then need drastic conditions (623 K, 300 atm) to be hydrolysed.
Option (2) m-cresol — Incorrect. Ring chlorination of toluene gives o- and p- products, not meta, and an aryl chloride is not hydrolysed by aqueous NaOH under ordinary conditions.
Option (3) 2,4-Dihydroxytoluene — Incorrect. It needs two OH groups on the ring, i.e. two ring chlorinations; a single chlorination in sunlight does not touch the ring.
Note: The same/similar question has been asked in different years by NTA as per the details given below:
| 2026 | 2025 | 2024 | 2023 | 2022 |
|---|---|---|---|---|
| – | – | – | 20-06 S3 | 18-08 S1 |