Esters can be prepared by the reaction of carboxylic acids with alcohols. propose a route to the preparation of γ-butyrolactone.

4-hydroxybutanoic acid + H⁺ ⇒ γ-butyrolactone + H₂O

Explanation:

The simplest route to prepare γ-butyrolactone is the intramolecular reaction of an alcohol with an acid. The required starting material is 4-hydroxybutanoic acid (γ-hydroxybutyric acid). See attachment for the condensed reaction mechanism. The H⁺ acts as a catalyst.