Cinnamic acid
IUPAC name	(E)-3-phenylprop-2-enoic acid
Other names	Cinnamic Acid, trans-Cinnamic Acid
Identifiers
CAS number	[140-10-3]
Properties
Molecular formula	C9H8O2 / C6H5CHCHCOOH
Molar mass	148.17 g/mol
Appearance	monoclinic crystals
Density	1.2475 g/cm3
Melting point	133 °C
Boiling point	300 °C
Solubility in water	0.4 g/L
Acidity (pKa)	4.44
Hazards
EU classification	Irritant (Xi)
R-phrases	R36
S-phrases	S25
Flash point	>110 °C
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

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.

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-lyase (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.

Source: adapted by the editor from Wikipedia, the free encyclopedia; from the article "Cinnamic acid". Image Credit.

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