{{chembox | Section7 = {{Chembox Hazards | GHSPictograms = {{GHS05}}{{GHS07}} | GHSSignalWord = Danger | HPhrases = {{H-phrases|H302|H315|H317|H318|H319}} | PPhrases = {{P-phrases|P261|P264|P264+P265|P270|P272|P280|P301+P317|P302+P352|P305+P351+P338|P305+P354+P338|P317|P321|P330|P332+P317|P333+P317|P337+P317|P362+P364|P501}} | LD50 = 1850&nbsp;mg/kg<ref name=Ullmann/> }} | Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 462091509 | Name = Levulinic acid | Reference = <ref>''The Merck Index'', '''15th Ed.''' (2013), p. 1018, Monograph '''5526''', O'Neil: The Royal Society of Chemistry. Available online at: http://www.rsc.org/Merck-Index/monograph/mono1500005526</ref> | ImageFile = Levulinic Acid Structural Formulae.svg | ImageClass = skin-invert-image | ImageSize = 180px | ImageName = Skeletal formula | ImageFile1 = Levulinic-acid-3D-balls.png | ImageClass1 = bg-transparent | ImageName1 = Ball-and-stick model | PIN = 4-Oxopentanoic acid | OtherNames = Levulinic acid, β-Acetylpropionic acid, 3-Acetopropionic acid, β-acetylpropionic acid, γ-ketovaleric acid | Section1 = {{Chembox Identifiers | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 11091 | ChEMBL_Ref = {{ebicite|changed|EBI}} | ChEMBL = 1235931 | PubChem = 11579 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = RYX5QG61EI | InChI = 1/C5H8O3/c1-4(6)2-3-5(7)8/h2-3H2,1H3,(H,7,8) | InChIKey = JOOXCMJARBKPKM-UHFFFAOYAR | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C5H8O3/c1-4(6)2-3-5(7)8/h2-3H2,1H3,(H,7,8) | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = JOOXCMJARBKPKM-UHFFFAOYSA-N | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 123-76-2 | DrugBank_Ref = {{drugbankcite|correct|drugbank}} | DrugBank = DB02239 | ChEBI_Ref = {{ebicite|correct|EBI}} | ChEBI = 45630 | SMILES = CC(=O)CCC(=O)O }} | Section2 = {{Chembox Properties | Formula = C<sub>5</sub>H<sub>8</sub>O<sub>3</sub> | MolarMass = 116.11 g/mol | Density = 1.1447 g/cm<sup>3</sup> | MeltingPtC = 33 to 35 | MeltingPt_notes = | BoilingPtC = 245 to 246 }} }}

'''Levulinic acid''', or 4-oxopentanoic acid, is an organic compound with the formula CH<sub>3</sub>C(O)CH<sub>2</sub>CH<sub>2</sub>CO<sub>2</sub>H. 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 cellulose and is a potential precursor to biofuels,<ref>Biorefineries – Industrial Processes and Products. Status Quo and Future Directions. Vol. 1, Edited by Birgit Kamm, Patrick R. Gruber, Michael Kamm. 2006, WILEY-VCH, Weinheim. {{ISBN|3-527-31027-4}}</ref> such as ethyl levulinate.<ref>{{Cite journal|last1=Leal Silva|first1=Jean Felipe|last2=Grekin|first2=Rebecca|last3=Mariano|first3=Adriano Pinto|last4=Maciel Filho|first4=Rubens|title=Making Levulinic Acid and Ethyl Levulinate Economically Viable: A Worldwide Technoeconomic and Environmental Assessment of Possible Routes|journal=Energy Technology|volume=6|issue=4|language=en|pages=613–639|doi=10.1002/ente.201700594|issn=2194-4296|year=2018}}</ref>

== Synthesis == Levulinic acid was first prepared in 1840 by Dutch chemist Gerardus Johannes Mulder by heating fructose with hydrochloric acid.<ref name=":0">{{Cite journal|title = Untersuchungen über die Humussubstanzen|language = German|trans-title=Investigations on humic substances|last = Mulder|first = G. J.|author-link = Gerardus Johannes Mulder|journal = J. Prakt. Chem.|doi = 10.1002/prac.18400210121|year = 1840|volume = 21|issue = 1|pages = 203–240| url=https://zenodo.org/record/1427786 }}</ref> The first commercial production of levulinic acid began as a batchwise process in an autoclave by starch manufacturer A. E. Staley in the 1940s.<ref>A. E. Staley, Mfg. Co. (Decatur, Ill.); Levulinic Acid 1942 [C.A. 36, 1612]</ref> In 1953 Quaker Oats developed a continuous process for the production of levulinic acid.<ref>{{US patent|2813900}}</ref> In 1956 it was identified as a platform chemical with high potential.<ref>R. H. Leonard, Ind. Eng. Chem. 1331, (1956).</ref> 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.<ref name=":1">{{Cite web|url = http://www.nrel.gov/docs/fy04osti/35523.pdf|work = Top Value Added Chemicals from Biomass |title=Volume I-Results of Screening for Potential Candidates from Sugars and Synthesis Gas |date =Aug 2004 |author=The Pacific Northwest National Laboratory and The National Renewable Energy Laboratory |publisher=U.S. Department of Energy }}</ref>

The synthesis of levulinic acid from hexoses (glucose, fructose) or starch in dilute hydrochloric acid or sulfuric acid.<ref name=":0" /><ref>A. Freiherrn, V. Grote, B. Tollens, "Untersuchungen über Kohlenhydrate. I. Ueber die bei Einwirkung von Schwefelsäure auf Zucker entstehende Säure (Levulinsäure)" Justus Liebigs Annalen der Chemie volume 175, pp. 181-204 (1875). {{doi| 10.1002/jlac.18751750113}}</ref><ref>{{OrgSynth |author = B. F. McKenzie|title = Levulinic acid|collvol = 1|collvolpages = 335|year = 1941|prep = cv1p0335}}</ref><ref>S.L. Suib, New and Future Developments in Catalysis – Catalytic Biomass Conversion, Elsevier, (2013). {{ISBN|978-0-444-53878-9}}</ref> In addition to formic acid further, partly insoluble, by-products are produced. These are deeply colored and their complete removal is a challenge for most technologies. centre|thumb|497x497px 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 by extraction. Levulinic acid is purified by distillation.<ref>{{US patent|5608105}}</ref>

==Reactions and applications== Levulinic acid is used as a precursor for pharmaceuticals, plasticizers, and various other additives.<ref name=Ullmann>Franz Dietrich Klingler, Wolfgang Ebertz "Oxocarboxylic Acids" in ''Ullmann's Encyclopedia of Industrial Chemistry'', 2005, Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a18_313}}</ref> 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<ref>{{Cite journal|title = Technology development for the production of biobased products from biorefinery carbohydrates—the US Department of Energy's "Top 10" revisited|journal = Green Chemistry|volume = 12|issue = 4|pages = 539–554|doi = 10.1039/b922014c|first1 = Joseph J.|last1 = Bozell|first2 = Gene R.|last2 = Petersen|date = 2010-04-06}}</ref> including γ-valerolactone and 2-methyl-THF.<ref name=":1" />

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===Other occurrence and niche uses=== Levulinic acid is used in cigarettes to increase nicotine delivery in smoke and binding of nicotine to neural receptors.<ref>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</ref>

Levulinic acid, in its cyclic alternate structure, was the first pseudoacid to be described as such.

== Etymology == The former term "levulose" for fructose gave levulinic acid its name.

== References == {{reflist}} * {{cite EB1911 |wstitle=Rubber |volume=23 |page=802 |first=Wyndham Rowland |last=Dunstan |author-link=Wyndham Dunstan}}

Category:Keto acids Category:Substances discovered in the 19th century