Cinnamic aldehyde; trans-cinnamaldehyde
|Molar mass||132.16 g/mol|
|Melting point||−7.5 °C (18.5 °F; 265.6 K)|
|Boiling point||248 °C (478 °F; 521 K)|
|Solubility||soluble in ether, chloroform
insoluble in petroleum ether
miscible with alcohol, oils
Refractive index (nD)
|R-phrases||R36 R37 R38|
|Flash point||71 °C (160 °F; 344 K)|
LD50 (Lethal dose)
|3400 mg/kg (rat, oral)|
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
Cinnamaldehyde is the organic compound that gives cinnamon its flavor and odor. This pale yellow, viscous liquid occurs naturally in the bark of cinnamon trees and other species of the genus Cinnamomum. The essential oil of cinnamon bark is about 90% cinnamaldehyde.
Structure and synthesis
The natural product is trans-cinnamaldehyde. The molecule consists of a phenyl group attached to an unsaturated aldehyde. As such, the molecule can be viewed as a derivative of acrolein. Its color is due to the π → π* transition: increased conjugation in comparison with acrolein shifts this band towards the visible.
Several methods of laboratory synthesis exist, but cinnamaldehyde is most economically obtained from the steam distillation of the oil of cinnamon bark. The compound can be prepared from related compounds such as cinnamyl alcohol, (the alcohol form of cinnamaldehyde), but the first synthesis from unrelated compounds was the aldol condensation of benzaldehyde and acetaldehyde.
As a flavorant
The most obvious application for cinnamaldehyde is as flavoring in chewing gum, ice cream, candy, and beverages; use levels range from 9 to 4900 parts per million (ppm) (that is, less than 0.5%). It is also used in some perfumes of natural, sweet, or fruity scents. Almond, apricot, butterscotch, and other aromas may partially employ the compound for their pleasant smells. Cinnamaldehyde can be used as a food adulterant; powdered beechnut husk aromatized with cinnamaldehyde can be marketed as powdered cinnamon.
As an agrichemical
Cinnamaldehyde is also used as a fungicide. Proven effective on over 40 different crops, cinnamaldehyde is typically applied to the root systems of plants. Its low toxicity and well-known properties make it ideal for agriculture. Cinnamaldehyde is an effective insecticide, and its scent is also known to repel animals, such as cats and dogs. It has recently been recognized as an effective insecticide for mosquito larvae. A concentration of 29 ppm of cinnamaldehyde kills half of Aedes aegypti mosquito larvae in 24 hours.
Cinnamaldehyde is also known as a corrosion inhibitor for steel and other ferrous alloys in corrosive fluids. It can be used in combination with additional components such as dispersing agents, solvents and other surfactants. Its high refractive index of 1.6220 makes it a fairly safe and useful fluid for examining gemstone rough for inclusions.
Derivatives of cinnamaldehyde
Numerous derivatives of cinnamaldehyde are commercially useful. Dihydrocinnamyl alcohol, which occurs naturally but is produced by double hydrogenation of cinnamaldehyde, is used to confer the fragrances of hyacinth and lilac. Cinnamyl alcohol similarly occurs naturally and has the odor of lilac. Dihydrocinnamaldehyde is produced by the selective hydrogenation of the alkene subunit. α-Amyl- and α-hexylcinnamaldehyde are important commercial fragrances, but they are not prepared from cinnamaldehyde.
Cinnamaldehyde is used in agriculture because of its low toxicity, but it is a skin irritant.
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