Hydroxybutyric acid

Skeletal formula of α-hydroxybutyric acid

Skeletal formula of β-hydroxybutyric acid

Skeletal formula of γ-hydroxybutyric acid

Skeletal formula of 2-hydroxyisobutyric acid

Skeletal formula of 3-hydroxyisobutyric acid

Hydroxybutyric acid is a group of four-carbon organic compounds that have both hydroxyl and carboxylic acid functional groups.^[1] They can be viewed as derivatives of butyric acid. The carboxylate anion and the esters of hydroxybutyric acids are known as hydroxybutyrates. β-hydroxybutyric acid is relevant to human health as it is a member of a class of products of fatty acid oxidation referred to as ketone bodies.

The isomers are distinguished by the distance between the two functional groups and the branching.

• alpha-Hydroxybutyric acid (2-hydroxybutyric acid)
• beta-Hydroxybutyric acid (3-hydroxybutyric acid)
• gamma-Hydroxybutyric acid (4-hydroxybutyric acid, GHB)
• 2-hydroxyisobutyric acid
• 3-hydroxyisobutyric acid