What Is Cinnamic Acid?
Cinnamic acid is an organic compound with the chemical formula C6H5CH=CHCOOH. It consists of a benzene ring substituted with an ethylene carboxyl group, classifying it as an aromatic unsaturated carboxylic acid.
While both cis-trans isomers are sometimes referred to as cinnamic acid, strictly speaking, the E-isomer is cinnamic acid, and the Z-isomer is allocinnamic acid. Allocinnamic acid is unstable and easily isomerizes to the E-isomer. Their CAS registry numbers are 621-82-9 (mixture), 140-10-3 (E form), and 102-94-3 (Z form).
Uses of Cinnamic Acid
Cinnamic acid is used as a herbicide, plant growth inhibitor, fungicide, and preservative. Its ester derivatives serve as raw materials in the production of fragrances, food additives, cosmetics, and agricultural chemicals. For instance, methyl cinnamate and ethyl cinnamate are primarily used in food additives for flavoring. Additionally, in pharmaceutical applications, cinnamic acid is used as a local anesthetic, disinfectant, hemostatic agent, and redness agent.
Other derivatives, such as ethylhexyl methoxycinnamate and methyl diisopropyl cinnamate, are known for their high UV absorption capabilities and are used in cosmetics as anti-fading agents, UV absorbers, and scattering agents.