Q.Acetylation of salicylic acid produces a compound which has anti-inflammatory and antipyretic property. The compound is

From a Painkiller Back to Its Chemistry

Aspirin is a compound almost everyone has heard of — but few connect it back to a phenol reaction from the "Alcohols, Phenols and Ethers" chapter. Its synthesis is one of the cleanest real-world examples of acetylation (a specific type of esterification) applied to a phenolic –OH group.

The Starting Material: Salicylic Acid

Salicylic acid is a benzene ring bearing two substituents ortho to each other: a carboxylic acid group (–COOH) and a phenolic hydroxyl group (–OH). It is this phenolic –OH — not the –COOH — that reacts in aspirin's synthesis.

The Precise Reaction

Acetic anhydride, $\ce{(CH3CO)2O}$, is the acetylating agent. Under acid catalysis, one of its two acetyl groups is transferred onto the phenolic oxygen of salicylic acid, converting the free –OH into an ester linkage (–O–CO–CH₃), while the other half of the anhydride is released as acetic acid.

Why Acetylate Salicylic Acid At All? …