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It is obtained from oil of [[cinnamon]], or from [[balsam]]s such as [[storax]].<ref name=Merck>{{Merck12th}}</ref> It is also found in [[shea butter]]. Cinnamic acid has a [[honey]]-like odor;<ref>{{cite web|url=http://www.flavornet.org/info/140-10-3.html|title=Cinnamic acid|website=flavornet.org}}</ref> it and its more volatile ethyl ester ([[ethyl cinnamate]]) are flavor components in the essential oil of [[cinnamon]], in which related [[cinnamaldehyde]] is the major constituent.
It is obtained from oil of [[cinnamon]], or from [[balsam]]s such as [[storax]].<ref name=Merck>{{Merck12th}}</ref> It is also found in [[shea butter]]. Cinnamic acid has a [[honey]]-like odor;<ref>{{cite web|url=http://www.flavornet.org/info/140-10-3.html|title=Cinnamic acid|website=flavornet.org}}</ref> it and its more volatile ethyl ester ([[ethyl cinnamate]]) are flavor components in the essential oil of [[cinnamon]], in which related [[cinnamaldehyde]] is the major constituent.


===Production===
===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=Ullmann>{{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|page=976–978}}</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 industrial route to cinnamic acid involves the [[Perkin reaction]]:<ref name=Ullmann/>
The oldest {{cn|date=September 2019}}<!-- previous versions of this article says Claisen's was first --><!-- maybe the difference between first documented and oldest industrial synthesis --> synthesis of cinnamic acid involves the [[Perkin reaction]], which entails the base-catalysed [[aldol condensation]] reaction between [[acetic anhydride]] and [[benzaldehyde]], with accompanying [[hydrolysis]] of the [[acid anhydride]] product<ref name=Ullmann>{{Ullmann|first=Dorothea|last=Garbe|title=Cinnamic Acid|doi=10.1002/14356007.a07_099}}</ref>
:[[File:Zimtsäure nach Perkin.svg|450px|center|thumb|Synthesis of cinnamic acid via the [[Perkin reaction]]]]:
:[[File:Zimtsäure nach Perkin.svg|450px|center|thumb|Synthesis of cinnamic acid via the [[Perkin reaction]].]]


In 1890, [[Rainer Ludwig Claisen]] described the synthesis of [[ethyl cinnamate]] by the reaction of [[ethyl acetate]] with benzaldehyde using [[sodium]] to form the [[enolate]] of the ethyl acetate, the hydrolysis of which gives the acid.<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|page=976–978}}</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<!-- what other reagents are involved, and what type of reaction is it--is this a [[Cannizzaro reaction]]-like disproportionation followed by hydrolysis? --> also be prepared from [[cinnamaldehyde]] and [[benzal chloride]].<ref name=Ullmann></ref>{{clarify|date=September 2019}}


==Uses==
==Uses==

Revision as of 17:16, 16 September 2019

Cinnamic acid
Skeletal formula of cinnamic acid
Ball-and-stick model of the cinnamic acid molecule
Sample of compound
Names
Preferred IUPAC name
(2E)-3-Phenylprop-2-enoic acid
Other names
Cinnamic acid
trans-Cinnamic acid
Phenylacrylic acid[1]
Cinnamylic acid
3-Phenylacrylic acid
(E)-Cinnamic acid
Benzenepropenoic acid
Isocinnamic acid
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.004.908 Edit this at Wikidata
KEGG
UNII
  • InChI=1S/C9H8O2/c10-9(11)7-6-8-4-2-1-3-5-8/h1-7H,(H,10,11)/b7-6+ checkY
    Key: WBYWAXJHAXSJNI-VOTSOKGWSA-N checkY
  • InChI=1/C9H8O2/c10-9(11)7-6-8-4-2-1-3-5-8/h1-7H,(H,10,11)/b7-6+
    Key: WBYWAXJHAXSJNI-VOTSOKGWBT
  • O=C(O)\C=C\c1ccccc1
Properties
C9H8O2
Molar mass 148.161 g·mol−1
Appearance White monoclinic crystals
Density 1.2475 g/cm3[2]
Melting point 133 °C (271 °F; 406 K)[2]
Boiling point 300 °C (572 °F; 573 K)[2]
500 mg/L[2]
Acidity (pKa) 4.44
−7.836×10−5 cm3/mol
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
1
0
Flash point > 100 °C (212 °F; 373 K)[2]
Related compounds
Related compounds
 Benzoic acid, Phenylacetic acid, Phenylpropanoic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Cinnamic acid is an organic compound with the formula C6H5CH=CHCOOH. It is a white crystalline compound that is slightly soluble in water, and freely soluble in many organic solvents.[3] Classified as an unsaturated carboxylic acid, it occurs naturally in a number of plants. It exists as both a cis and a trans isomer, although the latter is more common.[4]

Occurrence and production

Biosynthesis

Cinnamic acid is a central intermediate in the biosynthesis of myriad natural products include lignols (precursors to lignin and lignocellulose), flavonoids, isoflavonoids, coumarins, aurones, stilbenes, catechin, and phenylpropanoids. Its biosynthesis is performed by action of the enzyme phenylalanine ammonia-lyase (PAL) on phenylalanine.[5]

Natural occurrence

It is obtained from oil of cinnamon, or from balsams such as storax.[3] It is also found in shea butter. Cinnamic acid has a honey-like odor;[6] it and its more volatile ethyl ester (ethyl cinnamate) are flavor components in the essential oil of cinnamon, in which related cinnamaldehyde is the major constituent.

Synthesis

Cinnamic acid was first synthesized by the base-catalysed condensation of acetyl chloride and benzaldehyde, followed by hydrolysis of the acid chloride product.[4] 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.[7]Another way of preparing cinnamic acid is by the Knoevenagel condensation reaction.[8] 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 industrial route to cinnamic acid involves the Perkin reaction:[4]

Synthesis of cinnamic acid via the Perkin reaction.

Uses

Cinnamic acid is used in flavorings, synthetic indigo, and certain pharmaceuticals. A major use is as a precursor to produce methyl cinnamate, ethyl cinnamate, and benzyl cinnamate for the perfume industry.[3] Cinnamic acid is a precursor to the sweetener aspartame via enzyme-catalysed amination to give phenylalanine.[4] Cinnamic acid can dimerize in non-polar solvents resulting in different linear free energy relationships.[9]

References

  1. ^ "Cinnamic Acid" . Encyclopædia Britannica. Vol. 6 (11th ed.). 1911. p. 376.
  2. ^ a b c d e Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  3. ^ a b c Budavari, Susan, ed. (1996), The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (12th ed.), Merck, ISBN 0911910123
  4. ^ a b c d Garbe, Dorothea (2012). "Cinnamic Acid". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a07_099. ISBN 978-3527306732.
  5. ^ Vogt, T. (2010). "Phenylpropanoid Biosynthesis". Molecular Plant. 3 (1): 2–20. doi:10.1093/mp/ssp106. {{cite journal}}: Cite has empty unknown parameter: |1= (help)
  6. ^ "Cinnamic acid". flavornet.org.
  7. ^ Claisen, L. (1890). "Zur Darstellung der Zimmtsäure und ihrer Homologen" [On the preparation of cinnamic acid and its homologues]. Berichte der deutschen chemischen Gesellschaft. 23: 976–978.
  8. ^ Tieze, L. (1988). Reactions and Synthesis in the Organic Chemistry Laboratory. Mill Vall, CA. p. 1988.{{cite book}}: CS1 maint: location missing publisher (link)
  9. ^ Bradley, J.-C.; Abraham, M. H.; Acree, W. E.; Lang, A.; Beck, S. N.; Bulger, D. A.; Clark, E. A.; Condron, L. N.; Costa, S. T.; Curtin, E. M.; Kurtu, S. B.; Mangir, M. I.; McBride, M. J. (2015). "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". Chemistry Central Journal. 9: 11. doi:10.1186/s13065-015-0080-9. PMC 4369286. PMID 25798191.{{cite journal}}: CS1 maint: unflagged free DOI (link)
source: https://en.wikipedia.org/w/index.php?title=Cinnamic_acid&diff=prev&oldid=916038713

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