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Butyrolactone

gamma-Butyrolactone
Gamma-Butyrolactone.svg
GBL-from-xtal-3D-balls.png
Names
IUPAC name
Dihydrofuran-2(3H)-one
Other names
GBL, butyrolactone, 1,4-lactone, 4-butyrolactone, 4-hydroxybutyric acid lactone, gamma-hydroxybutyric acid lactone, and oxolan-2-one
Identifiers
3D model (Jmol)
ChEBI
ChemSpider
DrugBank
ECHA InfoCard 100.002.282
KEGG
PubChem CID
RTECS number LU3500000
UNII
Properties
C4H6O2
Molar mass 86.09 g·mol−1
Appearance Colorless liquid
Density 1.1286 g/mL (15 °C), 1.1296 g/mL (20 °C)
Melting point −43.53 °C (−46.35 °F; 229.62 K)
Boiling point 204 °C (399 °F; 477 K)
Miscible
Solubility soluble in CCl4, methanol, ethanol, acetone, benzene, ethyl ether
Acidity (pKa) 4.5
1.435, 1.4341 (20 °C)
Viscosity 1.7 cp (25 °C)
Hazards
Main hazards Harmful
R-phrases R22 R36
S-phrases S26 S36
Flash point 98 °C (208 °F; 371 K) (closed cup)
Lethal dose or concentration (LD, LC):
LD50 (median dose)
17.2 mL/kg (orally, rat)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY  (what is YesYN ?)
Infobox references

γ-Butyrolactone (GBL) is a hygroscopic colorless liquid with a weak characteristic odor. Soluble in water, GBL is a common solvent and reagent in chemistry as well as being used as a flavouring, as a cleaning solvent, as a superglue remover, and as a solvent in some wet aluminium electrolytic capacitors. In humans it acts as a prodrug for γ-hydroxybutyric acid (GHB), and it is used as a recreational intoxicant with effects similar to alcohol.

GBL 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.

GBL is produced industrially by dehydrogenation of 1,4-butanediol. This route proceeds via dehydration of GHB.

In the laboratory, it may also be obtained via the oxidation of tetrahydrofuran (THF), for example with aqueous sodium bromate.

As a lactone, GBL 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). 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.


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