γ-Butyrolactone is a hygroscopic colorless, water-miscible liquid with a weak characteristic odor. It is the simplest 4-carbon lactone. It is mainly used as an intermediate in the production of other chemicals, e.g. methyl-2-pyrrolidone. In humans γ-Butyrolactone acts as a prodrug for γ-hydroxybutyric acid (GHB), and it is used as a recreational CNS depressant with effects similar to barbiturates.
γ-Butyrolactone has been found in extracts from samples of unadulterated wines. This finding indicates that GBL is a naturally occurring component in some wines and may be present in similar products. The concentration detected was approximately 5 μg/mL and was easily observed using a simple extraction technique followed by GC/MS analysis. GBL can be found in cheese flavourings but typically results in a content of 0.0002% GBL in the final foodstuff.
γ-Butyrolactone is produced industrially by dehydrogenation of 1,4-butanediol at a temperature of 180–300 °C and atmospheric pressure in the presence of a copper catalyst. The yield of this process is approximately 95%. The purification takes place with a liquid-gas-phase extraction.In the laboratory, it may also be obtained via the oxidation of tetrahydrofuran (THF), for example with aqueous sodium bromate. An alternative route proceeds from GABA using the Sandmeyer reaction.
As a lactone, γ-Butyrolactone is hydrolyzed under basic conditions, for example in a sodium hydroxide solution into sodium gamma-hydroxybutyrate, the sodium salt of gamma-hydroxybutyric acid. In acidic water, a mixture of the lactone and acid forms coexist in an equilibrium. These compounds then may go on to form the polymer poly(4-hydroxybutyrate) as well as the dimer 1,6-Dioxecane-2,7-dione. When treated with a non-nucleophilic base, such as lithium diisopropylamide, GBL undergoes deprotonation alpha to the carbonyl. The related compound caprolactone can be used to make a polyester in this manner.