Gamma-Butyrolactone

Chembox new
Name = "gamma"-Butyrolactone
ImageFile1 = GBL chemical structure.png ImageName1 =
ImageFile2 = GBL-from-xtal-3D-balls.png ImageSize2 = 200px
IUPACName = Dihydrofuran-2(3H)-one
OtherNames = GBL, butyrolactone, 1,4-lactone, 4-butyrolactone, 4-hydroxybutyric acid lactone, and gamma-hydroxybutyric acid lactone
Section1 = Chembox Identifiers
SMILES = O=C1CCCO1
CASNo = 96-48-0
RTECS = LU3500000
Section2 = Chembox Properties
Formula = C₄H₆O₂
MolarMass = 86.089 g/mol
Appearance = Colorless liquid
Density = 1.144 g/mL
Solubility = Hygroscopic
MeltingPt = -45 °C
BoilingPt = 204 - 205 °C
pKa =
Viscosity =
Section3 = Chembox Structure
Dipole =
Section7 = Chembox Hazards
ExternalMSDS = [http://www.physchem.ox.ac.uk/MSDS/BU/gamma-butyrolactone.html External MSDS]
MainHazards = Harmful
FlashPt = 98 °C (closed cup)
RPhrases = R22 R36
SPhrases = S26 S36
Section8 = Chembox Related
OtherCpds =

"gamma"-Butyrolactone (γ-butyrolactone or GBL) is a hygroscopic colorless oily liquid with a weak characteristic odor and is soluble in water. GBL is a common solvent and reagent in chemistry and is used as an aroma compound, as a stain remover, as a superglue remover, as a paint stripper, and as a solvent in some wet aluminium electrolytic capacitors.

Occurrence

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.

Preparation

GBL can be synthesized from "gamma"-hydroxybutyric acid (GHB) by removal of water or by distillation from such a mixture. It may also be obtained via oxidation of tetrahydrofuran (THF). One such process, which affords GBL in yields of up to 80%, utilises bromine generated "in situ" from an aqueous solution of sodium bromate and potassium hydrogen sulfate. [Metsger, L.; Bittner, S. Autocatalytic Oxidation of Ethers with Sodium Bromate, "Tetrahedron" 2000, 56, 1905-1910]

Chemistry

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.

Pharmacology

GBL is not active in its own right, its mechanism of action stems from its identity as a prodrug of 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. [Citation
last = Sassenbroek
first = Van
title = Characterization of the pharmacokinetic and pharmacodynamic interaction between gamma-hydroxybutyrate and ethanol in the rat.
journal = Toxicological Sciences
date = Jun
year = 2007
pmid = 12700396 ]

Pharmacokinetics

GBL is rapidly converted into GHB by lactamase enzymes found in the blood. GBL is more lipophilic (fat soluble) than GHB, and so is absorbed faster and has higher bioavailability; the paradox is that this can mean that GBL has a faster onset of effects than GHB itself, even though it is a prodrug. The levels of lactamase enzyme can vary between individuals, and GBL is not active in its own right, so people who have never tried GBL before may have delayed or fewer effects than expected; however, once someone has taken GBL a few times, the production of lactamase enzymes is increased and he/she will feel the effects like normal.

Because of these pharmacokinetic differences, GBL tends to be more potent and faster-acting than GHB, but has a shorter duration; whereas the related compound 1,4-butanediol (1,4-B) tends to be slightly less potent, slower to take effect but longer-acting than GHB.

Recreational use

GBL is a prodrug of GHB. To bypass GHB restriction laws, home synthesis kits were introduced to transform GBL and/or 1,4-B into GHB. GBL can also be used as a recreational drug by itself. [ cite book
last = Meyer
first = Jerrold
coauthors = Linda F. Quenzer
title = Psychopharmacology: Drugs, the Brain and Behavior
publisher = Sinauer
date = 2005
pages = pp. 370
isbn = 0-87893-534-7 ]

GBL overdose can cause severe sickness, coma and death.

Metabolism takes place in stomach and blood plasma. GBL is longer acting and has a shorter onset than GHB. Otherwise, effects are similar to GHB, although weight for weight it is significantly more powerful, meaning dosage must be lowered accordingly. If ingested undiluted through orally, GBL can cause esophogeal and gastro-intestinal irritation. It is possible for oral ingestion of GBL to cause nausea and other similar problems, possibly more so than with GHB.

Dose

A milliliter of pure GBL metabolizes to roughly 1.6g of GHB, so doses are measured in the single milliliter range, either taken all at once or sipped over the course of a night.

Legal Status of GBL

Canada: GBL is a Controlled Substance under Schedule VI of the "Controlled Drugs and Substances Act" in Canada.

United Kingdom: Although GBL is an unclassified drug in the United Kingdom, risk to life is being recognised on the London Gay Scene, where use is more prevalent than other parts of the countryFact|date=October 2007. At the end of 2006, a campaign began to reduce the number of people using GBL in the areaFact|date=October 2007. The effects of this campaign are yet to be seen.

Sweden: GBL is not classified as a drug but as a health dangering substance. [ [http://sv.wikipedia.org/wiki/GBL GBL] ]

ee also

* "gamma"-Hydroxybutyrate (GHB)
* 1,4-Butanediol (1,4-B)

References

External links

* [http://www.erowid.org/chemicals/ghb/gbl_info1.shtml Erowid on GBL]
* [http://www.drugs-forum.co.uk/forum/showthread.php?p=253643 Forum on GBL's Legal Status]
* BBC News story: [http://news.bbc.co.uk/2/hi/uk_news/magazine/4261788.stm The paint stripper drug that kills] , October 7, 2005.
* [http://www.nida.nih.gov/whatsnew/meetings/GHB/default.html “All About GHB,"] a NIDA Neuroscience Consortium and OSPC “Cutting Edge” colloquium (27 June 2000 at the Doubletree hotel, Rockville, MD) Organized by Drs. Jerry Frankenheim and Minda Lynch in response to the rapid ascent of GHB and its precursors, GBL and 1,4-butanediol, as public health concerns.