Citral

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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 3D model Interactive image
Interactive 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
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[edit]

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[edit]

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[edit]

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[edit]

See also[edit]

References[edit]

  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[edit]