Cinnamic acid

Cinnamic acid has the formula C₆H₅CHCHCOOH and is a white crystalline acid, which is slightly soluble in water. It has a melting point of 133°C and a boiling point of 300°C.

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It is obtained from oil of cinnamon, or from balsams such as storax. 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 flavours, synthetic indigo, and certain pharmaceuticals, though its primary use is in the manufacturing of the methyl, ethyl, and benzyl esters for the perfume industry. Cinnamic acid has a "honey, floral odor" (Merck Index); it and its more volatile ethyl ester (ethyl cinnamate) are flavour 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 lysase (PAL) on phenylalanine.

Cinnamic acid is soluble in diethyl ether, insoluble in hexane.

References

• Flavornet.org
• CRC Handbook
• Chemfinder
• Katzer, G. Gernot Katzer's Spice Pages, accessed August 17, 2006.
• Budavari, Susan (Ed.) The Merck Index, 13 Ed. Merck & Co., Inc, Whitehouse Station, NJ, USA, 2001.