Identify the major product of the following reaction.

Step-by-step solution

The given reactant is 5-hydroxyheptanoic acid, which contains both a carboxylic acid group ( -COOH ) and a hydroxyl group ( -OH ) in the same molecule. In the presence of an acid catalyst like HCl, such molecules undergo intramolecular esterification (lactonization). The lone pair on the oxygen atom of the hydroxyl group attacks the protonated carbonyl carbon of the carboxylic acid group, followed by the loss of a water molecule. Since the hydroxyl group is located on the 5th carbon atom (counting the carboxyl carb