Question

When o-phthalaldehyde is treated with base, o-(hydroxymethyl)benzoic acid is formed. Show the mechanism of this reaction.

Short answer

Formation of desired product

Step-by-step solution

Cannizaro reaction

Cannizzaro reaction is a base-induced disproportionation reaction. In this reaction, two moles of aldehyde react to give one molecule of carboxylic acid and another molecule of primary alcohol.

 Mechanism of this reaction

Initially, the addition of hydroxyl group to O-phthaladehyde takes place, then expulsion and addition of hydride ion occur. This shift of proton takes place followed by protonation to get the desired compound.

Formation of the desired product