Cinnamaldehyde

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 98% cinnamaldehyde.

Structure and synthesis

Cinnamaldehyde was isolated from cinnamon essential oil in 1834 by Dumas and Péligot and synthesized in the laboratory by Chiozza in 1854.

The natural product is trans-cinnamaldehyde. The molecule consists of a benzene ring 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.

Synthesis

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.