Cinnamic acid

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Cinnamic acid
Skeletal formula of the trans form
Ball-and-stick model of the trans form
IUPAC name
(E)-3-phenylprop-2-enoic acid
Other names
Cinnamic Acid
trans-Cinnamic Acid
Phenylacrylic acid
Cinnamylic acid
3-Phenylacrylic acid
(E)-Cinnamic acid
Benzenepropenoic acid
Isocinnamic acid
3D model (JSmol)
ECHA InfoCard 100.004.908
Molar mass 148.16 g·mol−1
Appearance White monoclinic crystals
Density 1.2475 g/cm3[1]
Melting point 133 °C (271 °F; 406 K)
Boiling point 300 °C (572 °F; 573 K)
500 mg/L[1]
Acidity (pKa) 4.44
Irritant (Xi)
R-phrases (outdated) R36
S-phrases (outdated) S25
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oilHealth code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
Flash point >100 °C (212 °F)[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Cinnamic acid is a white crystalline organic acid, which is slightly soluble in water.

It is obtained from oil of cinnamon, or from balsams such as storax.[2] It is also found in shea butter and is the best indication of its environmental history and post-extraction conditions. It can also be made synthetically.

Cinnamic acid is used in flavors, synthetic indigo, and certain pharmaceuticals, though its primary use is in the manufacturing of the methyl, ethyl, and benzyl esters for the perfume industry.[2] Cinnamic acid has a honey-like odor;[3] 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. Cinnamic acid is also part of the biosynthetic shikimate and phenylpropanoid pathways. Its biosynthesis is performed by action of the enzyme phenylalanine ammonia-lyase (PAL) on phenylalanine.

Cinnamic acid is freely soluble in benzene, diethyl ether, acetone, and it is insoluble in hexane.[4]

Cinnamic acid is also a kind of self-inhibitor produced by fungal spore to prevent germination.

Chemical synthesis

Rainer Ludwig Claisen (1851–1930), German chemist, described for the first time in 1890 the synthesis of cinnamates by reacting aromatic aldehydes with esters. The reaction is known as the Claisen reaction.


  1. ^ a b c d e Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  2. ^ a b Budavari, Susan, ed. (1996), The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (12th ed.), Merck, ISBN 0911910123
  3. ^ Cinnamic acid,
  4. ^ [ ONSC: Solubility of trans-cinnamic acid. ] doi:10.1038/npre.2010.4243.3