Cinnamic Acid

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cinnamic acid

[sə′nam·ik ′as·əd]
(organic chemistry)
C6H5CHCHCOOH Colorless, monoclinic acid; forms scales, slightly soluble in water; found in natural balsams.

Cinnamic Acid


(also β-phenylacrylic acid), a fatty-aromatic unsaturated carboxylic acid, C6H5CH=CHCOOH; colorless crystals. Two geometric isomers of cinnamic acid are known—the trans-isomer and cis-isomer. The trans-isomer is more stable and has a melting point of 133°C, and a boiling point of 300°C. The cis-isomer forms three polymorphic forms with melting points of 68°, 58°, and 42°C, respectively; the first form, allocinnamic acid, exhibits the highest degree of stability.

Cinnamic acid is contained in Peru balsam and Tolu balsam (mainly in the form of esters), as well as in certain essential oils. In industry trans-cinnamic acid is usually prepared by condensation of acetone with benzaldehyde followed by oxidation of the product benzylidene acetone, C6H5CH = CHCOCH3, with hypochlorous acid. The cis-form is obtained from the byproducts of the cocaine industry. Esters of cinnamic acid serve as aromatic substances in perfumes and cosmetics.

References in periodicals archive ?
The strong hydrophobic interaction of the cinnamates side chains promotes the formation of spherical structure.
The range contains broad UVA and UVB filters such as cinnamates and titanium dioxide to block out UV light.
The cinnamates, salicylates and benzophenones are small molecules that penetrate the skin and do not adequately protect against UVA.
This is evident in liquid crystalline polymers that contain aryl cinnamates as the mesogenic group.
Polyphenols, such as flavonoids and cinnamates play their role in the prevention of many degenerative diseases (Manach et al.
Several compounds were synthesized to model the aggregation properties of liquid crystalline polymers in which aryl cinnamates act as both chromophores and mesogens.
Ingredients that block UVB rays include the cinnamates, octinoxate or octyl methoxycinnamate, which are the most effective UVB absorbers, according to Graf.
It has been estimated that coffee drinkers might ingest as much as 1 g per day of cinnamate esters (mostly chlorogenic acid) and 500 mg per day of cinnamates (mostly caffeic acid).
From a technical perspective, ultraviolet filters have been transformed from low molecular weight, narrow band spectrum filters (predominantly PABA and its esters, cinnamates, benzophenones and salicylates) to filters designed according to the Dalton 500 rule with multiple chromophores offering both broad-spectrum as well as UVA and UVB protection.
They show perturbed UV-Vis spectra but these spectra are unlike those seen in the LC polymers possibly reflecting significant perturbation of the cinnamate absorption spectrum by the polar effect of the OC[H.
The first step in the phenylpropanoid pathway involves the deamination of phenylalanine to cinnamate via the enzyme phenylalanine ammonia lyase (PAL).