Reaction of toluene with CrO2Cl2 in CS2 followed by acidic hydrolysis gave compound A . The structure of compound A is
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → benzaldehyde
The Etard reaction converts a methyl group on a benzene ring into an aldehyde group. Toluene is treated with chromyl chloride in \( \ce{CS2} \), which forms a chromium complex, and acidic hydrolysis of the complex gives benzaldehyde. Chromyl chloride stops the oxidation at the aldehyde stage; a strong oxidising agent such as \( \ce{KMnO4} \) would go on to benzoic acid.
Why the other options are incorrect
Option (2) benzene-1,2-dicarbaldehyde — Incorrect. Toluene has only one methyl group, so only one –CHO group can form.
Option (3) benzylidene diacetate — Incorrect. This compound forms when toluene is oxidised with chromic oxide in acetic anhydride; it is then hydrolysed to benzaldehyde. It is not formed with \( \ce{CrO2Cl2} \).
Option (4) the diacetate of benzene-1,2-dicarbaldehyde — Incorrect. It needs two methyl groups and the chromic oxide/acetic anhydride route; neither applies here.
NCERT (2026-27 edition):
Use of Chromyl Chloride
