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

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 freely soluble in benzene, diethyl ether, acetone, and acetic acid; it is insoluble in hexane.

Synonyms: Cinnamic Acid, trans-Cinnamic Acid, Phenylacrylic acid, Cinnamylic acid, 3-Phenylacrylic acid, (E)-Cinnamic acid, Benzenepropenoic acid, Isocinnamic acid.

Molecular formula C₉H₈O₂

Molar mass 148.16 g mol−1

Exact mass 148.05243

Appearance White monoclinic crystals

Density 1.2475 g/cm^3­

Melting point 133 °C

Flash point > 110 C

Boiling point 300 °C

Solubility in water 500 mg/L

Flash point: >100 °C

CAS number 140-10-3

PubChem 444539

ChemSpider 392447

KEGG C00423

ChEBI CHEBI:35697

ChEMBL CHEMBL27246

Acidity (pKa) 4.44

Hazards symbol: Irritant (Xi)

Risk Code: R36

Safety Code: S25

Cinnamic acid primary use is in the manufacturing of the methyl, ethyl, and benzyl esters for the perfume industry. Cinnamic acid has a honey-like odor; 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 widly used as deodorant, perfume fixative ; food additives, food flavorant; food preservative. It also wildly used in medical and cosmetic industries; pesticide; organic synthesis; PVC heat stabilizer. Cinnamic acid is also major raw material of Aspartme and Negative photosensitive resin. It is also a kind of self-inhibitor produced by fungal spore to prevent germination.