Citral

Not to be confused with Geraniol.

Citral

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
CAS Number	5392-40-5 checkY
3D model (JSmol)	Interactive image Interactive image
ChEBI	CHEBI:16980 checkY
ChEMBL	ChEMBL1080997 checkY
ChemSpider	553578 checkY
ECHA InfoCard
EC Number	226-394-6
E number
IUPHAR/BPS	6327
KEGG	C01499 checkY
PubChem CID	638011
RTECS number	RG5075000
UNII	T7EU0O9VPP checkY
UN number	2810
CompTox Dashboard (EPA)	{{#property:P3117}}
InChI InChI=1S/C10H16O/c1-9(2)5-4-6-10(3)7-8-11/h5,7-8H,4,6H2,1-3H3/b10-7+ checkY Key: WTEVQBCEXWBHNA-JXMROGBWSA-N checkY 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	GHS07: Exclamation mark
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). checkY verify (what is checkYN ?) 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. (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.

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.

See also

• Citronellal
• Geraniol
• Limonene
• Nerol
• Vaporizer

External links

• MSDS Archived 18 August 2007 at the Wayback Machine