Citral

Not to be confused with Geraniol.

Citral is an acyclic monoterpene aldehyde. Being a monoterpene, it is made of two isoprene units. Citral is a collective term which covers two geometric isomers that have their own separate names; the E-isomer is named geranial (trans-citral; α-citral^[2]) or citral A. The Z-isomer is named neral (cis-citral; β-citral^[2]) or citral B. These stereoisomers occur as a mixture, often not in equal proportions; e.g. in essential oil of Australian ginger, the neral to geranial ratio is 0.61.^[3]

Citral^[1]

Geranial
Neral
Names
IUPAC name 3,7-dimethylocta-2,6-dienal
Other names citral geranialdehyde
Identifiers
CAS Number	5392-40-5 Y
3D model (JSmol)	Interactive image Interactive image
3DMet	B00306
ChEBI	CHEBI:16980 Y
ChEMBL	ChEMBL1080997 Y
ChemSpider	553578 Y
ECHA InfoCard	100.023.994
EC Number	226-394-6
IUPHAR/BPS	6327
KEGG	C01499 Y
PubChem CID	638011
RTECS number	RG5075000
UNII	T7EU0O9VPP Y
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+ Y Key: WTEVQBCEXWBHNA-JXMROGBWSA-N Y 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 labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H317
Precautionary statements	P261, P264, P272, P280, P302+P352, P321, P332+P313, P333+P313, P362, P363, P501
NFPA 704 (fire diamond)	0 1 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). Y verify (what is YN ?) Infobox references

Occurrence

Citral is present in the volatile 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.^[4][5][6] Further, in the lipid fraction (essential oil) of Australian ginger (51–71%)^[3] Of the many sources of citral, the Australian myrtaceous tree, lemon myrtle, Backhousia citriodora F. Muell. (of the family Myrtaceae), is considered superior.^[7]

Uses

Citral is a precursor in the industrial production of vitamin A, vitamin E, vitamin K.

Citral is also precursor to lycopene, ionone and methylionone.

Fragrances

Citral has a strong lemon (citrus) scent and is used as an aroma compound in perfumery. It is used to fortify lemon oil. (Nerol, another perfumery compound, has a less intense but sweeter lemon note.) The aldehydes citronellal and citral are considered key components responsible for the lemon note with citral preferred.^[7]

It also has pheromonal effects in acari and insects.^[8][9]

The herb Cymbopogon citratus has shown promising insecticidal and antifungal activity against storage pests.^[10]

Food additive

Citral is commonly used as a food additive ingredient.^[11]

It has been tested (2016) in vitro against the food-borne pathogen Cronobacter sakazakii.^[12]

See also

• Citronellal
• Geraniol
• Limonene
• Nerol
• Vaporizer

References

1. Citral, The Merck Index, 12th Edition.
2. Waghulde, S.; Parmar, P.; Mule, J.; Pashte, D.; Patil, B.; Modhale, N.; Gorde, N.; Kharche, A.; Kale, M. (2020). "Lead Finding from Plant Cymbopogon Citratus with Immunomodulator Potentials through in Silico Methods". Chemistry Proceedings. 3 (1): 77. doi:10.3390/ecsoc-24-08302. ISSN 2673-4583.
3. Zachariah, T. J.; Parthasarathy, V. A.; Chempakam, B. (2008). Chemistry of spices. Wallingford: CABI. p. 76. ISBN 9781845934057. OCLC 1120264204.
4. Fenaroli, G.; Furia, T.E.; Bellanca, N. Handbook of Flavor Ingredients. ISBN 0-87819-532-7.
5. Lawless, J. (2 November 1995). The Illustrated Encyclopedia of Essential Oils. Element. ISBN 1-85230-661-0.
6. "The Aromatic Plant Project". Archived from the original on 24 November 2019. Retrieved 1 June 2008.
7. Southwell, Ian (9 July 2021). "Backhousia citriodora F. Muell. (Lemon Myrtle), an Unrivalled Source of Citral". Foods. 10 (7): 1596. doi:10.3390/foods10071596. PMC 8305781. PMID 34359465.
8. 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.
9. Robacker, D.C.; Hendry, L.B. (1977). "Neral and geranial: components of the sex pheromone of the parasitic wasp, Itoplectis conquisitor". Journal of Chemical Ecology. 3 (5): 563–577. doi:10.1007/BF00989077. S2CID 11568355.
10. Dubey, N. K.; Takeya, Koichi; Itokawa, Hideji (1997). "Citral: A cytotoxic principle isolated from the essential oil of Cymbopogon citratus against P388 leukaemia cells". Current Science. 73 (1): 22–24. JSTOR 24098141.
11. Liao, Pei-Chun; Yang, Tsung-Shi; Chou, Ju-Ching; Chen, Jie; Lee, Shu-Ching; Kuo, Yueh-Hsiung; Ho, Chen-Lung; Chao, Louis Kuo-Ping (1 December 2015). "Anti-inflammatory activity of neral and geranial isolated from fruits of Litsea cubeba Lour". Journal of Functional Foods. 19: 248–258. doi:10.1016/j.jff.2015.09.034.
12. Shi, Chao; Song, Kaikuo; Zhang, Xiaorong; Sun, Yi; Sui, Yue; Chen, Yifei; Jia, Zhenyu; Sun, Huihui; Sun, Zheng; Xia, Xiaodong (14 July 2016). "Antimicrobial Activity and Possible Mechanism of Action of Citral against Cronobacter sakazakii". PLOS ONE. 11 (7): e0159006. Bibcode:2016PLoSO..1159006S. doi:10.1371/journal.pone.0159006. PMC 4945043. PMID 27415761.

External links

• MSDS Archived 18 August 2007 at the Wayback Machine