Levulinic acid, or 4-oxopentanoic acid, 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. Th ...

with the formula CH₃C(O)CH₂CH₂CO₂H. It is classified as a

keto acid In organic chemistry, keto acids or ketoacids (also called oxo acids or oxoacids) are organic compounds that contain a carboxylic acid group () and a ketone group ().Franz Dietrich Klingler, Wolfgang Ebertz "Oxocarboxylic Acids" in Ullmann's En ...

. This white crystalline solid is soluble in water and polar organic solvents. It is derived from degradation of

cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...

and is a potential precursor to biofuels, such as ethyl levulinate.

Synthesis

Levulinic acid was first prepared in 1840 by Dutch chemist Gerardus Johannes Mulder by heating

fructose Fructose, or fruit sugar, is a ketonic simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorb ...

with hydrochloric acid. The first commercial production of levulinic acid began as a batchwise process in an autoclave by

starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...

manufacturer

A. E. Staley Primary Products Ingredients Americas LLC (founded as A. E. Staley Manufacturing Company), also formerly known as Tate & Lyle Primary Products, is an American subsidiary of Tate & Lyle PLC and produces a range of starch products for the food, p ...

in the 1940s. In 1953 Quaker Oats developed a continuous process for the production of levulinic acid. In 1956 it was identified as a platform chemical with high potential. and in 2004 the US Department of Energy (U.S. DoE) identified levulinic acid as one of the 12 potential platform chemicals in the biorefinery concept. The synthesis of levulinic acid from hexoses (

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, usi ...

) or starch in dilute

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the dig ...

or sulfuric acid. In addition to

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. Est ...

further, partly insoluble, by-products are produced. These are deeply colored and their complete removal is a challenge for most technologies. Synthesis levulinic acid

Many concepts for the commercial production of levulinic acid are based on a strong acid technology. The processes are conducted in a continuous manner at high pressures and temperatures. Lignocellulose is an inexpensive starting material. Levulinic acid is separated from the mineral acid

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

extraction Extraction may refer to: Science and technology Biology and medicine * Comedo extraction, a method of acne treatment * Dental extraction, the surgical removal of a tooth from the mouth Computing and information science * Data extraction, the pro ...

. Levulinic acid is purified by

distillation Distillation, or classical distillation, is the process of separating the components or substances from a liquid mixture by using selective boiling and condensation, usually inside an apparatus known as a still. Dry distillation is the he ...

Reactions and applications

Levulinic acid is used as a precursor for pharmaceuticals, plasticizers, and various other additives.Franz Dietrich Klingler, Wolfgang Ebertz "Oxocarboxylic Acids" in ''Ullmann's Encyclopedia of Industrial Chemistry'', 2005, Wiley-VCH, Weinheim. The largest application of levulinic acid is its use in the production of aminolevulinic acid, a biodegradable herbicide used in South Asia. Another key application is the use of levulinic acid in cosmetics. Ethyl levulinate, a primary derivative of levulinic acid, is extensively used in fragrances and perfumes. Levulinic acid is a chemical building block or starting material for a wide variety of other compounds including γ-valerolactone and 2-methyl-THF. Levulinic acid family

Other occurrence and niche uses

Levulinic acid is used in cigarettes to increase nicotine delivery in smoke and binding of nicotine to neural receptors.Doris Cullen et al., ''A Guide to Deciphering the Internal Codes Used by the Tobacco Industry'', Report No. 03-05, Harvard School of Public Health, Division of Public Health Practice, Tobacco Research Program, August 2005, http://legacy.library.ucsf.edu/resources/harvard_monograph.pdf

Etymology

The former term “levulose” for fructose gave levulinic acid its name.

Safety

Levulinic acid is relatively nontoxic, with an of 1850 mg/kg.

References

* {{cite EB1911 , wstitle=Rubber , volume=23 , page=802 , first=Wyndham Rowland , last=Dunstan Keto acids