1,3-Butanediol is an organic compound with the chemical formula CH₃CH(OH)CH₂CH₂OH. It is classified as a diol because its structure includes two alcohol functional groups. This compound is one of four common structural isomers of butanediol. It finds various applications across different industries and can also be metabolized by the human body.
Chemical Identity and Properties
1,3-Butanediol is a clear, colorless, and viscous liquid that possesses a characteristic, slightly bittersweet taste. It is highly soluble in water. The compound’s molecular formula is C₄H₁₀O₂, and its molar mass is approximately 90.122 g/mol.
It is chemically stable under normal conditions. The presence of two hydroxyl (-OH) groups contributes to its ability to form hydrogen bonds, influencing its physical properties like viscosity and boiling point. It is also known by other names, such as 1,3-butylene glycol or butane-1,3-diol.
Diverse Industrial and Consumer Applications
1,3-Butanediol serves as a versatile ingredient across numerous industrial and consumer products. In cosmetics and pharmaceuticals, it functions as a solvent. It also acts as a humectant and as an emulsifier.
Beyond personal care, 1,3-butanediol is a building block in the production of polymers like polyesters and polyurethanes. These polymers are used in various materials, including plastics, foams, and coatings. The compound is also utilized in food flavorings, particularly in grape flavoring. It has been explored as a nutritional energy source in specialized diets, providing approximately 6 kcal/g when incorporated into the diet at appropriate levels.
Metabolism in the Human Body
When ingested, 1,3-butanediol converts into beta-hydroxybutyrate (βHB). Beta-hydroxybutyrate is a ketone body, which the body can use as an alternative energy source, especially during periods of low carbohydrate availability or in ketogenic states. The metabolism of 1,3-butanediol primarily occurs in hepatic cells, involving both cytosolic and mitochondrial pathways.
Enzymes such as alcohol dehydrogenase are involved in this conversion. This metabolic pathway allows 1,3-butanediol to contribute to the body’s energy supply, particularly when glucose is limited. Research has focused on understanding the stereospecific metabolism of its different forms, with the (R)-enantiomer showing efficient conversion to β-hydroxybutyrate.
Safety Considerations and Regulatory Oversight
1,3-Butanediol exhibits a low toxicity profile. The U.S. Food and Drug Administration (FDA) has recognized 1,3-butanediol as Generally Recognized As Safe (GRAS) for specific uses, such as a flavor molecule, when used in accordance with good manufacturing practices.
While high doses of 1,3-butanediol may lead to mild side effects. These can include gastrointestinal upset or central nervous system depression, but such effects are rare with typical exposure levels. Very high concentrations, such as 20% in drinking water, can lead to side effects like body mass loss, dehydration, and metabolic acidosis. However, lower concentrations are well-tolerated and do not present these adverse effects.