Editing Cinnamic acid

{{Chembox
|Verifiedfields = changed
|Watchedfields = changed
|verifiedrevid = 476994181
|Name = Cinnamic acid
|ImageFile = Zimtsäure - Cinnamic acid.svg
|ImageName = Skeletal formula of trans-cinnamic acid
|ImageFile1 = Cinnamic acid 3D ball.png
|ImageName1 = Ball-and-stick model of the trans-cinnamic acid molecule
|ImageFile2 = Cinnamic acid.jpg
|ImageName2 = Sample of the compound cinnamic acid in powder form
|PIN = (2''E'')-3-Phenylprop-2-enoic acid
|SystematicName = Cinnamic acid
|OtherNames = ''trans''-Cinnamic acid<br>Phenylacrylic acid<ref>{{cite EB1911|wstitle=Cinnamic Acid|volume=6|page=376|short=1}}</ref><br>Cinnamylic acid<br>3-Phenylacrylic acid<br />(''E'')-Cinnamic acid<br>Benzenepropenoic acid<br>Isocinnamic acid
|Section1={{Chembox Identifiers
|IUPHAR_ligand = 3203
|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|ChemSpiderID = 392447
|ChEMBL_Ref = {{ebicite|correct|EBI}}
|ChEMBL = 27246
|InChI = 1/C9H8O2/c10-9(11)7-6-8-4-2-1-3-5-8/h1-7H,(H,10,11)/b7-6+
|ChEBI_Ref = {{ebicite|correct|EBI}}
|ChEBI = 35697
|SMILES = O=C(O)\C=C\c1ccccc1
|InChIKey = WBYWAXJHAXSJNI-VOTSOKGWBT
|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
|StdInChI = 1S/C9H8O2/c10-9(11)7-6-8-4-2-1-3-5-8/h1-7H,(H,10,11)/b7-6+
|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
|StdInChIKey = WBYWAXJHAXSJNI-VOTSOKGWSA-N
|CASNo_Ref = {{cascite|correct|CAS}}
|CASNo = 140-10-3
|UNII_Ref = {{fdacite|changed|FDA}}
|UNII = U14A832J8D
|PubChem = 444539
|KEGG_Ref = {{keggcite|correct|kegg}}
|KEGG = C00423
|Gmelin = 3731
|Beilstein = 1905952
|EINECS = 205-398-1
|3DMet = B00108
}}
|Section2={{Chembox Properties
|C=9 | H=8 | O=2
|Appearance = White monoclinic crystals
|Odor = Honey-like<ref name="flavornet.org">{{cite web|url=http://www.flavornet.org/info/140-10-3.html|title=Cinnamic acid|website=flavornet.org}}</ref>
|Solubility = 500 mg/L<ref name="GESTIS-IOSH">{{GESTIS|ZVG=25910}}</ref>
|Density = 1.2475 g/cm<sup>3</sup><ref name="GESTIS-IOSH"/>
|MeltingPtC = 133
|MeltingPt_ref = <ref name="GESTIS-IOSH"/>
|BoilingPtC = 300
|BoilingPt_ref = <ref name="GESTIS-IOSH"/>
|pKa = 4.44
|MagSus = {{val|-7.836e-5|u=cm<sup>3</sup>/mol}}
}}
|Section3={{Chembox Hazards
|NFPA-H = 1
|NFPA-F = 1
|NFPA-R = 0
|GHSPictograms = {{GHS07}}
|GHSSignalWord = Warning
|HPhrases = {{H-phrases|315|319|335}}
|PPhrases = {{P-phrases|261|264|271|280|302+352|304+340|305+351+338|312|321|332+313|337+313|362|403+233|405|501}}
|FlashPt = >
|FlashPtC = 100
|FlashPt_ref = <ref name="GESTIS-IOSH"/>
}}
|Section4={{Chembox Related
|OtherCompounds = [[Benzoic acid]], [[Phenylacetic acid]], [[Phenylpropanoic acid]]
}}
}}

'''Cinnamic acid''' is an [[organic compound]] with the formula [[phenyl|C<sub>6</sub>H<sub>5</sub>]]-CH=CH-[[Carboxylic acid|COOH]]. It is a white crystalline compound that is slightly [[soluble]] in water, and freely soluble in many organic solvents.<ref name="Merck-1996"/> Classified as an unsaturated [[carboxylic acid]], it occurs naturally in a number of plants. It exists as both a [[Cis–trans isomerism|''cis'' and a ''trans'' isomer]], although the latter is more common.<ref name="Garbe-2012"/>

==Occurrence and production==
===Biosynthesis===
Cinnamic acid is a central intermediate in the biosynthesis of a myriad of natural products including lignols (precursors to [[lignin]] and [[lignocellulose]]), [[flavonoids]], [[isoflavonoids]], [[coumarin]]s, [[aurones]], [[stilbenes]], [[catechin]], and [[phenylpropanoid]]s. Its [[biosynthesis]] involves the action of the [[enzyme]] [[phenylalanine ammonia-lyase]] (PAL) on [[phenylalanine]].<ref>{{cite journal|journal=Molecular Plant|year=2010|volume=3|issue=1|pages=2–20|doi=10.1093/mp/ssp106|title=Phenylpropanoid Biosynthesis|last=Vogt|first=T.|pmid=20035037|doi-access=free}}</ref>

===Natural occurrence===
It is obtained from oil of [[cinnamon]], or from [[balsam]]s such as [[storax]].<ref name="Merck-1996">{{Merck12th}}</ref> It is also found in [[shea butter]].{{cn|date=June 2023}} Cinnamic acid has a [[honey]]-like odor;<ref name="flavornet.org">{{cite web|url=http://www.flavornet.org/info/140-10-3.html|title=Cinnamic acid|website=flavornet.org}}</ref> and its more volatile ethyl ester, [[ethyl cinnamate]], is a flavor component in the essential oil of [[cinnamon]], in which related [[cinnamaldehyde]] is the major constituent. It is also found in wood from many diverse tree species.<ref>{{cite web |last1=Oldach |first1=Laurel |title=Forensic researchers use mass spectrometry to identify smuggled wood |url=https://cen.acs.org/analytical-chemistry/mass-spectrometry/Forensic-researchers-use-mass-spectrometry-to-identify-smuggled-wood/101/i7 |website=Chemical and Engineering News |publisher=American Chemical Society |date=February 22, 2023}}</ref>

===Synthesis===
Cinnamic acid was first synthesized by the base-catalysed condensation of [[acetyl chloride]] and [[benzaldehyde]], followed by [[hydrolysis]] of the [[acid chloride]] product.<ref name="Garbe-2012">{{Ullmann|first=Dorothea|last=Garbe|title=Cinnamic Acid|doi=10.1002/14356007.a07_099|year=2012}}</ref> In 1890, [[Rainer Ludwig Claisen]] described the synthesis of [[ethyl cinnamate]] via the reaction of [[ethyl acetate]] with benzaldehyde in the presence of [[sodium]] as base.<ref>{{cite journal|last=Claisen|first=L.|date=1890|url=https://babel.hathitrust.org/cgi/pt?id=uc1.b3481786;view=1up;seq=992|title=Zur Darstellung der Zimmtsäure und ihrer Homologen|trans-title=On the preparation of cinnamic acid and its homologues|journal=Berichte der Deutschen Chemischen Gesellschaft|volume=23|pages=976–978|doi=10.1002/cber.189002301156}}</ref> Another way of preparing cinnamic acid is by the [[Knoevenagel condensation]] reaction.<ref>{{cite book|first=L.|last=Tieze|title=Reactions and Synthesis in the Organic Chemistry Laboratory|location=Mill Vall, CA|date=1988|page=1988}}</ref> The reactants for this are benzaldehyde and [[malonic acid]] in the presence of a weak base, followed by acid-catalyzed [[decarboxylation]].  It can also be prepared by oxidation of [[cinnamaldehyde]], condensation of [[benzal chloride]] and sodium acetate (followed by acid hydrolysis), and the [[Perkin reaction]]. The oldest commercially used route to cinnamic acid involves the [[Perkin reaction]], which is given in the following scheme<ref name="Garbe-2012"/>
:[[File:Zimtsäure nach Perkin.svg|450px|center|thumb|Synthesis of cinnamic acid via the [[Perkin reaction]].<ref>{{cite journal |doi=10.15227/orgsyn.005.0083|author=F. K. Thayer|title=m-Nitrocinnamic Acid|journal=Organic Syntheses|year=1925|volume=5|page=83}}</ref>]]

==Metabolism==
Cinnamic acid, obtained from autoxidation of [[cinnamaldehyde]], is metabolized into [[sodium benzoate]] in the liver.<ref name="Jana-2013">{{cite journal | vauthors = Jana A, Modi KK, Roy A, Anderson JA, van Breemen RB, Pahan K | title = Up-regulation of neurotrophic factors by cinnamon and its metabolite sodium benzoate: therapeutic implications for neurodegenerative disorders | journal = [[Journal of Neuroimmune Pharmacology]] | volume = 8 | issue = 3 | pages = 739–55 | date = June 2013 | pmid = 23475543 | pmc = 3663914 | doi = 10.1007/s11481-013-9447-7 | url = | issn = }}</ref>

==Uses==
Cinnamic acid is used in flavorings, [[Indigo dye#Chemical synthesis|synthetic indigo]], and certain [[pharmaceutical]]s. A major use is as a precursor to produce [[methyl cinnamate]], [[ethyl cinnamate]], and [[benzyl cinnamate]] for the perfume industry.<ref name="Merck-1996"/>  Cinnamic acid is a precursor to the sweetener [[aspartame]] via enzyme-catalysed amination with [[phenylalanine]].<ref name="Garbe-2012"/> Cinnamic acid can [[Dimer (chemistry)|dimerize]] in non-polar solvents resulting in different [[Free-energy relationship|linear free energy relationships]].<ref>{{cite journal | doi = 10.1186/s13065-015-0080-9 | pmid = 25798191 | pmc = 4369286 | title = Determination of Abraham model solute descriptors for the monomeric and dimeric forms of ''trans''-cinnamic acid using measured solubilities from the Open Notebook Science Challenge | journal = Chemistry Central Journal | volume = 9 | pages = 11 | year = 2015 | last1 = Bradley | first1 = J.-C. | last2 = Abraham | first2 = M. H. | last3 = Acree | first3 = W. E. | last4 = Lang | first4 = A. | last5 = Beck | first5 = S. N. | last6 = Bulger | first6 = D. A. | last7 = Clark | first7 = E. A. | last8 = Condron | first8 = L. N. | last9 = Costa | first9 = S. T. | last10 = Curtin | first10 = E. M. | last11 = Kurtu | first11 = S. B. | last12 = Mangir | first12 = M. I. | last13 = McBride | first13 = M. J. | doi-access = free }}</ref>

==References==
{{Reflist|30em}}

{{Hydroxycinnamic acid}}

{{Authority control}}

[[Category:Flavors]]
[[Category:Enoic acids]]
[[Category:Phenylpropanoids]]