What happens when salicylic acid reacts with acetic anhydride in the presence of H2SO4?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Aspirin is produced
Salicylic acid (2-hydroxybenzoic acid) has a phenolic –OH group. Acetic anhydride, with a little concentrated \( \ce{H2SO4} \), puts an acetyl group (\( \ce{CH3CO-} \)) on this oxygen. This acetylation gives acetylsalicylic acid, that is, aspirin:
\( \displaystyle \ce{HOC6H4COOH + (CH3CO)2O} \xrightarrow{\ce{H2SO4}} \ce{CH3COOC6H4COOH + CH3COOH} \)
NCERT (2026-27 edition):
7.4.4 Chemical Reactions – “The reaction with carboxylic acid and acid anhydride is carried out in the presence of a small amount of concentrated sulphuric acid. … The introduction of acetyl (CH3CO) group in alcohols or phenols is known as acetylation. Acetylation of salicylic acid produces aspirin.”