Lactone, the English name is lactones, means that it contains both carboxyl and hydroxyl groups in the same molecule.

Organic matter produced by dehydration of the two. Lactone is formed by dehydration of a molecule through esterification reaction, and it is also a molecule after hydrolysis. There is only one ester group (—COO—) in the lactone ring. If there are more than two ester groups in one ring, it is not a lactone but a lactide.

Properties:

The properties are similar to those of open-chain carboxylic acid esters. They react with water (in the presence of acid or alkali), alcohol or ammonia to generate the corresponding hydroxy acid, hydroxy acid ester or Hydroxyamide. β-lactone is usually produced by reacting ketene with aldehydes and ketones. γ- or δ-lactone can be prepared from γ- or δ-halogenated acid. Some macrolides isolated from natural products have biological activity.

Lactones are generally insoluble in water, easily soluble in organic solvents such as ethanol and ether, and their density is generally smaller than that of water. Lower lactones are liquids with an aromatic odor.

Low molecular weight esters are colorless, volatile aromatic liquids. High-grade lactones are often colorless and odorless waxy solids. Low molecular weight esters can be used as solvents for many organic compounds and can also be used as solvents for varnishes.