Γ-Butyrolactone

Γ-Butyrolactone (GBL) is a hygroscopic colorless liquid with a weak characteristic odor and profoundly bitter taste. It is a common solvent and reagent in chemistry and is used as an aroma compound, as a stain remover, as a superglue remover, and as a solvent in some wet aluminium electrolyte capacitors.

Chemical Properties

GBL is a lactone. It is hydrolyzed under basic conditions, for example in a sodium hydroxide solution into sodium gamma-hydroxybutyrate, the sodium salt of gamma-hydroxybutyric acid. Under acidic conditions, it forms an equilibrium mixture of both compounds. These compounds then may go on to form the polymer poly(4-hydroxybutyrate).

Uses

GBL is not active in its own right; its mechanism of action stems from its identity as a prodrug of gamma-hydroxybutyric acid (GHB). The hypnotic effect of GHB is enhanced by combination with alcohol. A 2003 rat study showed that GBL in combination with ethanol showed a potentiated hypnotic effect, as the sleep-timing measure was longer than both of the individual components combined.

Safety

Overdose of GBL can cause adverse effects, including sedation, vertigo, nausea, and death. GBL has a distinctive taste and odor, described as being comparable to stale water, synthetic melon aroma, or burnt plastic. This differs significantly from GHB, which is described as having a decidedly salty taste. People who ingest GBL may not be aware they are consuming a drug.

Legal Status

In many countries, including the United States and Canada, the production, sale, and possession of GBL are illegal since it can be used as a prodrug of GHB. In the United Kingdom, GBL is classified as a Class C drug.

See Also

• 1,4-Butanediol
• Gamma-Hydroxybutyric acid
• Lactone
• Hygroscopy