3D model (JSmol)
|Molar mass||152.24 g/mol|
|Appearance||Pale yellow liquid|
|Boiling point||229 °C (444 °F; 502 K)|
|Vapor pressure||0.22 mmHg (20 °C)|
|R-phrases (outdated)||R36, R37, R38|
|Flash point||91 °C (196 °F; 364 K)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Citral, or 3,7-dimethyl-2,6-octadienal or lemonal, is either a pair, or a mixture of terpenoids with the molecular formula C10H16O. The two compounds are double bond isomers. The E-isomer is known as geranial or citral A. The Z-isomer is known as neral or citral B.
Citral is present in the oils of several plants, including lemon myrtle (90–98%), Litsea citrata (90%), Litsea cubeba (70–85%), lemongrass (65–85%), lemon tea-tree (70–80%), Ocimum gratissimum (66.5%), Lindera citriodora (about 65%), Calypranthes parriculata (about 62%), petitgrain (36%), lemon verbena (30–35%), lemon ironbark (26%), lemon balm (11%), lime (6–9%), lemon (2–5%), and orange.
Geranial has a strong lemon (citrus) odor. Neral's lemon odor is less intense, but sweeter. Citral is therefore an aroma compound used in perfumery for its citrus effect. Citral is also used as a flavor and for fortifying lemon oil. It also has strong antimicrobial qualities, and pheromonal effects in insects.
Health and safety information
Two studies have shown 1–1.7% of people to be allergic to citral, and allergies are frequently reported. Citral on its own is strongly sensitizing to allergies; the International Fragrance Association recommends that citral only be used in association with substances that prevent a sensitizing effect. Citral has been extensively tested and has no known genotoxicity, and no known carcinogenic effect, but animal tests show dose-dependent effects on the kidneys.
- Citral, The Merck Index, 12th Edition.
- Fenaroli, G., Furia, T.E., Bellanca, N., Handbook of Flavor Ingredients, ISBN 0-87819-532-7
- Lawless, J., The Illustrated Encyclopedia of Essential Oils, ISBN 1-85230-661-0
- The Aromatic Plant Project
- Onawunmi, G.O. (1989). "Evaluation of the antimicrobial activity of citral". Lett. Appl. Microbial. 9 (3): 105–108. doi:10.1111/j.1472-765X.1989.tb00301.x.
- Kuwahara, Y., Suzuki, H., Matsumoto, K. & Wada, Y. (1983). "Pheromone study on acarid mites. XI. Function of mite body as geometrical isomerization and reduction of citral (the alarm pheromone) Carpoglyphus lactis". Appl. Entomol. Zool. 18: 30–39.
- Robacker, D.C.; Hendry, L.B. (1977). "Neral and geranial: components of the sex pheromone of the parasitic wasp, Itoplectis conquisitor". J. Chem. Ecol. 3 (5): 563–577. doi:10.1007/BF00989077.
- Survey and health assessment of chemical substances in massage oils