Citral

Citral[1]
Skeletal formula of geranial
Geranial
Ball-and-stick model of the geranial molecule
Skeletal formula of neral
Neral
Ball-and-stick model of the neral molecule
Names
IUPAC name
3,7-dimethylocta-2,6-dienal
Other names
citral
geranialdehyde
Identifiers
5392-40-5 YesY
ChEBI CHEBI:16980 YesY
ChEMBL ChEMBL1080997 YesY
ChemSpider 553578 YesY
6327
Jmol interactive 3D Image
Image
KEGG C01499 YesY
PubChem 638011
RTECS number RG5075000
UNII T7EU0O9VPP YesY
Properties
C10H16O
Molar mass 152.24 g/mol
Appearance Pale yellow liquid
Odor Lemon like
Density 0.893 g/cm3
Boiling point 229 °C (444 °F; 502 K)
Vapor pressure 0.22 mmHg (20 °C)
Hazards
R-phrases R36, R37, R38
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g., sodium chloride Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
1
0
0
Flash point 91 °C (196 °F; 364 K)
Related compounds
Related alkenals
 Citronellal

Methacrolein
trans-2-Methyl-2-butenal

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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.

Occurrence

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.[2][3][4]

Uses

Geranial has a strong lemon 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,[5] and pheromonal effects in insects.[6][7]

Citral is used in the synthesis of vitamin A, ionone, and methylionone, to mask the smell of smoke.

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.[8]

Compendial status

See also

References

  1. ↑ Citral, The Merck Index, 12th Edition.
  2. ↑ Fenaroli, G., Furia, T.E., Bellanca, N., Handbook of Flavor Ingredients, ISBN 0-87819-532-7
  3. ↑ Lawless, J., The Illustrated Encyclopedia of Essential Oils, ISBN 1-85230-661-0
  4. ↑ The Aromatic Plant Project
  5. ↑ 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.
  6. ↑ 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.
  7. ↑ 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.
  8. ↑ Survey and health assessment of chemical substances in massage oils
  9. ↑ The British Pharmacopoeia Secretariat (2009). "Index, BP 2009" (PDF). Retrieved 31 March 2010.

External links

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