Citral
[1]
Geranial
Neral
Names
IUPAC name
3,7-dimethylocta-2,6-dienal
Other names
citral geranialdehyde
Identifiers
3DMet
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard
100.023.994
EC Number
KEGG
RTECS number
UNII
UN number
2810
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
O=CC=C(C)CCC=C(C)C
O=C/C=C(/CC/C=C(/C)C)C
Properties
C10 H16 O
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)
−98.9× 10−6 cm3 /mol
Hazards
GHS labelling :
Warning
H315 ,
H317
P261 ,
P264 ,
P272 ,
P280 ,
P302+P352 ,
P321 ,
P332+P313 ,
P333+P313 ,
P362 ,
P363 ,
P501
NFPA 704 (fire diamond)
Flash point
91 °C (196 °F; 364 K)
Related compounds
Related alkenals
Except where otherwise noted, data are given for materials in their
standard state (at 25 °C [77 °F], 100 kPa).
Chemical compound
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]
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 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]
Citral is used in the synthesis of
vitamin A ,
lycopene ,
ionone and
methylionone , and to mask the smell of smoke.
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]
Medical exploration
In a report (1997), citral is mentioned as cytotoxic to P(388) mouse leukaemia cells.
[10] It has strong
antimicrobial qualities.
[13]
Adverse effects
A number of studies have shown allergic reactions to Citral.
[14] The
International Fragrance Association gives a
no-observed-adverse-effect level of 1400
micrograms .
[15] Citral has been extensively tested, with no known genotoxicity or
carcinogenic effect.
[16]
See also
References
^ Citral ,
The Merck Index , 12th Edition.
^
a
b 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 .
^
a
b Zachariah, T. J.; Parthasarathy, V. A.; Chempakam, B. (2008). Chemistry of spices . Wallingford: CABI. p. 76.
ISBN
9781845934057 .
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 .
^
a
b 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 .
^ 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 .
^
a
b 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 .
^ Onawunmi, Grace O. (September 1989). "Evaluation of the antimicrobial activity of citral". Letters in Applied Microbiology . 9 (3): 105–108.
doi :
10.1111/j.1472-765X.1989.tb00301.x .
S2CID
84751250 .
^ Hagvall, L.; Bruze, M.; Engfeldt, M.; Isaksson, M.; Lindberg, M.; Ryberg, K.; Stenberg, B.; Svedman, C.; Karlberg, A. T.; Bråred Christensson, J. (2020). "Contact allergy to citral and its constituents geranial and neral, coupled with reactions to the prehapten and prohapten geraniol". Contact Dermatitis . 82 (1): 31–38.
doi :
10.1111/cod.13404 .
PMID
31566752 .
^
"IRFA Standards, 47th Amendment: Citral" (PDF) . International Fragrance Association.
^ Andersen, Dorthe N.; Holmberg, Rikke D.; Larsen, Jette R.; Søborg, Inge; Cohr, Karl-Heinz (2006).
Survey and health assessment of chemical substances in massage oils (PDF) . Survey of Chemical Substances in Consumer Products, No. 78. Danish Toxicology Centre.
External links