γ-Valerolactone (GVL) is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

with the

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwee ...

C₅H₈O₂. This colourless liquid is one of the more common

lactone Lactones are cyclic carboxylic esters, containing a 1-oxacycloalkan-2-one structure (), or analogues having unsaturation or heteroatoms replacing one or more carbon atoms of the ring. Lactones are formed by intramolecular esterification of the co ...

s. GVL is chiral but is usually used as the

racemate In chemistry, a racemic mixture, or racemate (), is one that has equal amounts of left- and right-handed enantiomers of a chiral molecule or salt. Racemic mixtures are rare in nature, but many compounds are produced industrially as racemates. ...

. It is readily obtained from cellulosic biomass and is a potential fuel and

green solvent Green chemistry, also called sustainable chemistry, is an area of chemistry and chemical engineering focused on the design of products and processes that minimize or eliminate the use and generation of hazardous substances. While environmental che ...

. GVL behaves as a

prodrug A prodrug is a medication or compound that, after intake, is metabolized (i.e., converted within the body) into a pharmacologically active drug. Instead of administering a drug directly, a corresponding prodrug can be used to improve how the drug ...

to γ-hydroxyvaleric acid (GHV), a

drug A drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via insuffla ...

with similar effects to those of

γ-hydroxybutyric acid ''gamma''-Hydroxybutyric acid (or γ-hydroxybutyric acid (GHB), also known as 4-hydroxybutanoic acid) is a naturally occurring neurotransmitter and a depressant drug. It is a precursor to GABA, glutamate, and glycine in certain brain areas. ...

(GHB), albeit with less potency in comparison. Because GHB is controlled in many parts of the world, while GVL is not, GVL has gained popularity as a legal substitute for GHB.

Synthesis

GVL is produced from

levulinic acid Levulinic acid, or 4-oxopentanoic acid, is an organic compound with the formula CH3C(O)CH2CH2CO2H. It is classified as a keto acid. This white crystalline solid is soluble in water and polar organic solvents. It is derived from degradation of cell ...

, which is obtained from

hexose In chemistry, a hexose is a monosaccharide (simple sugar) with six carbon atoms. The chemical formula for all hexoses is C6H12O6, and their molecular weight is 180.156 g/mol. Hexoses exist in two forms, open-chain or cyclic, that easily convert ...

s. In a typical process, cellulosic

biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bi ...

es, such as corn stover, sawgrass, or wood, is hydrolysed into

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...

and other sugars using

acid catalyst In acid catalysis and base catalysis, a chemical reaction is catalyzed by an acid or a base. By Brønsted–Lowry acid–base theory, the acid is the proton (hydrogen ion, H+) donor and the base is the proton acceptor. Typical reactions catalyze ...

s. The resulting glucose can then be dehydrated via

hydroxymethylfurfural Hydroxymethylfurfural (HMF), also 5-(hydroxymethyl)furfural, is an organic compound formed by the dehydration of reducing sugars. It is a white low-melting solid (although commercial samples are often yellow) which is highly soluble in both water ...

to yield

formic acid Formic acid (), systematically named methanoic acid, is the simplest carboxylic acid, and has the chemical formula HCOOH and structure . It is an important intermediate in chemical synthesis and occurs naturally, most notably in some ants. Es ...

and

, which cyclises to intermediate unsaturated ring compounds, which can then be

hydrogenated Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic co ...

to ''gamma''-valerolactone, which has potential applications as a liquid fuel. :

Potential applications

GVL has been identified as a potential green solvent. Because of its herbal odor, it is used in the perfume and flavor industries. It is a structural isomer of δ-valerolactone.

Potential fuel

Since it is readily obtained from glucose, GVL has long been identified as a potential "green fuel." GVL retains 97% of the energy of glucose and can be blended by itself in gasoline where it performs comparably to

ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl ...

/gasoline mixtures. However, due to blending limits for use in conventional combustion engines, it may be more efficient to convert GVL into liquid

alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...

s (or

alkane In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which ...

s). The first step in this process is the ring-opening of GVL to yield a mixture of

pentenoic acid Pentenoic acid is any of five mono-carboxylic acids whose molecule has an unbranched chain of five carbons connected by three single bonds and one double bond. That is, any compound with one of the formulas (2-pentenoic), (3-pentenoic), or ( ...

s. These acids can then be

decarboxylated Decarboxylation is a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO2). Usually, decarboxylation refers to a reaction of carboxylic acids, removing a carbon atom from a carbon chain. The reverse process, which is t ...

to produce

butene Butene, also known as butylene, is an alkene with the formula . The word ''butene'' may refer to any of the individual compounds. They are colourless gases that are present in crude oil as a minor constituent in quantities that are too small for ...

and CO₂. These conversions can be performed with

zeolite Zeolites are microporous, crystalline aluminosilicate materials commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, oxygen, and have the general formula ･y where is either a metal ion or H+. These pos ...

catalysts. After this stream is dehydrated, the products can be

oligomer In chemistry and biochemistry, an oligomer () is a molecule that consists of a few repeating units which could be derived, actually or conceptually, from smaller molecules, monomers.Quote: ''Oligomer molecule: A molecule of intermediate relativ ...

ized at elevated pressures in the presence of a common acid-catalyst to yield alkenes with higher

molecular weights The molecular mass (''m'') is the mass of a given molecule: it is measured in daltons (Da or u). Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element. The related quanti ...

, targeted for gasoline and other fuel applications. One of the main advantages that allows GVL to be a practical

biofuel Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels, such as oil. According to the United States Energy Information Administration (E ...

is that it is relatively inexpensive to produce. Using a cheap

feedstock A raw material, also known as a feedstock, unprocessed material, or primary commodity, is a basic material that is used to produce goods, finished goods, energy, or intermediate materials that are feedstock for future finished products. As feedst ...

, this biofuel can be produced at prices between 2-3 US$/gallon. The conversion of GVL to transportation fuel capable alkenes only requires a system containing two flow reactors, two phase separators, and a simple pumping arrangement for the delivery of an aqueous GVL feed. Since the use of

precious metal Precious metals are rare, naturally occurring metallic chemical elements of high economic value. Chemically, the precious metals tend to be less reactive than most elements (see noble metal). They are usually ductile and have a high lustre. ...

catalysts is not required, this also decreases the total price of fuel production.

Potential production of biomass-derived fuels

Apart from its value as a potential fuel in its own right, gamma-valerolactone has shown promise in laboratory-scale thermocatalytic production of soluble carbohydrates from corn

stover Stover are the leaves and stalks of field crops, such as corn (maize), sorghum or soybean that are commonly left in a field after harvesting the grain. It is similar to straw, the residue left after any cereal grain or grass has been harvested a ...

and wood at high yields. The biomass reacts in a solvent mixture of water, dilute sulfuric acid, and gamma-valerolactone, itself derived from biomass. The gamma-valerolactone promotes thermocatalytic hydrolysis into monosaccharides by complete solubilization of the raw material, including lignins. The saccharide products can be recovered from the lactone into water solution by antisolvent addition of salt or liquid carbon dioxide. The product can be used as feedstock for producing furans or ethanol at high yield, while the gamma-valerolactone is returned to the catalytic cycle.

Membrane Fabrication

Gamma-Valerolactone has been studied and shown the potential to prepare dope solutions for the fabrication of polymeric membranes. Due to the toxicity of the traditional solvents, green solvents were investigated in recent years. Due to its environmentally friendly profile, Gamma-Valerolactone showed the potential to fabricate polysulfone membranes as a co-solvent.

References

External links

; General Safety Information
gamma-Valerolactone MSDS by Sciencelab.com
{{DEFAULTSORT:Valerolactone, gamma- Gamma-lactones GABAB receptor agonists GHB receptor agonists Designer drugs Hypnotics Prodrugs Solvents