Citral

Citral^[1]
	; Geranial
	; Neral
Names
	IUPAC name 3,7-dimethylocta-2,6-dienal
	Other names citral; geranialdehyde
Identifiers
CAS Number	5392-40-5 ;
3D model (JSmol)	Interactive image; Interactive image;
3DMet	B00306;
ChEBI	CHEBI:16980 ;
ChEMBL	ChEMBL1080997 ;
ChemSpider	553578 ;
ECHA InfoCard	100.023.994
EC Number	226-394-6;
IUPHAR/BPS	6327;
KEGG	C01499 ;
PubChem CID	638011;
RTECS number	RG5075000;
UNII	T7EU0O9VPP ;
UN number	2810
CompTox Dashboard (EPA)	DTXSID6024836 ;
	InChI InChI=1S/C10H16O/c1-9(2)5-4-6-10(3)7-8-11/h5,7-8H,4,6H2,1-3H3/b10-7+ Key: WTEVQBCEXWBHNA-JXMROGBWSA-N ; InChI=1/C10H16O/c1-9(2)5-4-6-10(3)7-8-11/h5,7-8H,4,6H2,1-3H3/b10-7+ Key: WTEVQBCEXWBHNA-JXMROGBWBB;
	SMILES O=CC=C(C)CCC=C(C)C; O=C/C=C(/CC/C=C(/C)C)C;
Properties
Chemical formula	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)
Magnetic susceptibility (χ)	−98.9×10−6 cm3/mol
Hazards
GHS pictograms
GHS Signal word	Warning
GHS hazard statements	H315, H317
GHS precautionary statements	P261, P264, P272, P280, P302+352, P321, P332+313, P333+313, P362, P363, P501
NFPA 704 (fire 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).

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 geometric 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

Citral has a strong lemon (citrus) odor and is used as an aroma compound in perfumery. (Nerol, another perfumery compound, has a less intense but sweeter lemon odor.) In addition, Citral is used as a flavor and for fortifying lemon oil. It also has strong antimicrobial qualities,^[5] and pheromonal effects in acari and insects.^[6]^[7]

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

Health and safety information

Two studies showed 1–1.7% of people to be allergic to citral, with allergies 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, with no known genotoxicity or carcinogenic effect.^[8]

References

^ 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. Microbiol. 9 (3): 105–108. doi:10.1111/j.1472-765X.1989.tb00301.x.
^ Kuwahara, Yasumasa; Suzuki, Hiroshi; Matsumoto, Katsuhiko; Wada, Yoshitake (1983). "Pheromone study on acarid mites. XI. Function of mite body as geometrical isomerization and reduction of citral (the alarm pheromone)". Applied Entomology and Zoology. 18 (1): 30–39. doi:10.1303/aez.18.30.
^ 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 Archived 28 June 2007 at the Wayback Machine

External links

MSDS

[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. Microbiol. 9 (3): 105–108. doi:10.1111/j.1472-765X.1989.tb00301.x.

[6] Kuwahara, Yasumasa; Suzuki, Hiroshi; Matsumoto, Katsuhiko; Wada, Yoshitake (1983). "Pheromone study on acarid mites. XI. Function of mite body as geometrical isomerization and reduction of citral (the alarm pheromone)". Applied Entomology and Zoology. 18 (1): 30–39. doi:10.1303/aez.18.30.

[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.

[summary-8] Survey and health assessment of chemical substances in massage oils Archived 28 June 2007 at the Wayback Machine

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