Citral

Citral
	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;
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 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). verify (what is ?) Infobox references

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) or citral A. The Z-isomer is named neral (cis-citral; β-citral) 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.

Natural Occurrence

Citral is present in the volatile oils of several plants:

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%)
orange

Of the many sources of citral, the Australian tree Backhousia citriodora (family Myrtaceae) is considered superior.

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 presenting as sharp, lemon, sweet, fresh, juicy, lemon peel, tart, and green. (Neral, the (Z)-isomer, has a less sweet citrus, lemon, lemon peel note, whilst Geranial, the (E)-isomer is described as citrus, lemon.) The aldehydes citronellal and citral are considered key components responsible for the lemon note with citral preferred.

It also has pheromonal effects in acari and insects.

The herb Cymbopogon citratus has shown promising insecticidal and antifungal activity against storage pests.

Food additive

Citral is commonly used as a food additive ingredient.

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

References

↑ Citral, The Merck Index, 12th Edition.
1 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.
↑ Zachariah, T. J.; Parthasarathy, V. A.; Chempakam, B. (2008). Chemistry of spices. Wallingford: CABI. p. 76. ISBN 978-1-84593-405-7. OCLC 1120264204.
↑ Fenaroli, G.; Furia, T.E.; Bellanca, N. Handbook of Flavor Ingredients. ISBN 0-87819-532-7.
↑ Lawless, J. (2 November 1995). The Illustrated Encyclopedia of Essential Oils. Element. ISBN 1-85230-661-0.
↑ "The Aromatic Plant Project". Archived from the original on 24 November 2019. Retrieved 1 June 2008.
1 2 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.
↑ "Citral". Scents and Flavors. Scents and Flavors. Retrieved 25 March 2026.
↑ "(Z)-Citral". Scents and Flavors. Scents and Flavors. Retrieved 25 March 2026.
↑ "(E)-Citral". Scents and Flavors. Scents and Flavors. Retrieved 25 March 2026.
↑ 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". Journal of Chemical Ecology. 3 (5): 563–577. doi:10.1007/BF00989077. S2CID 11568355.
↑ 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.
↑ 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.
↑ 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

[1] Citral, The Merck Index, 12th Edition.

[Waghulde2020-2] 1 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.

[Zachariah-3] Zachariah, T. J.; Parthasarathy, V. A.; Chempakam, B. (2008). Chemistry of spices. Wallingford: CABI. p. 76. ISBN 978-1-84593-405-7. 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.

[Southwell2021-7] 1 2 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] "Citral". Scents and Flavors. Scents and Flavors. Retrieved 25 March 2026.

[9] "(Z)-Citral". Scents and Flavors. Scents and Flavors. Retrieved 25 March 2026.

[10] "(E)-Citral". Scents and Flavors. Scents and Flavors. Retrieved 25 March 2026.

[11] 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.

[12] 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.

[Dubey_et_al_1997-13] 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.

[14] 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.

[15] 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.