Citronellol

Not to be confused with Citronellal.

Citronellol, or dihydrogeraniol, is a natural acyclic monoterpenoid. Both enantiomers occur in nature. (+)-Citronellol, which is found in citronella oils, including Cymbopogon nardus (50%), is the more common isomer. (−)-Citronellol is widespread, but particularly abundant in the oils of rose (18–55%) and Pelargonium geraniums.^[1]

Citronellol

(+)-Citronellol (left) and (−)-citronellol (right)
R-(+)-Citronellol
S-(−)-Citronellol
Names
IUPAC name 3,7-Dimethyloct-6-en-1-ol
Other names (±)-β-Citronellol; Cephrol, Corol
Identifiers
CAS Number	106-22-9 Y 1117-61-9 (R) Y 7540-51-4 (S) Y
3D model (JSmol)	Interactive image Interactive image
Beilstein Reference	1362474
ChEBI	CHEBI:50462 Y
ChEMBL	ChEMBL395827 Y
ChemSpider	13850135 Y
ECHA InfoCard	100.003.069
EC Number	247-737-6
KEGG	C09849 Y
PubChem CID	8842
UNII	565OK72VNF Y P01OUT964K (R) Y 8RSY5Y5658 (S) Y
CompTox Dashboard (EPA)	DTXSID3026726
InChI InChI=1S/C10H20O/c1-9(2)5-4-6-10(3)7-8-11/h5,10-11H,4,6-8H2,1-3H3 Y Key: QMVPMAAFGQKVCJ-UHFFFAOYSA-N Y InChI=1/C10H20O/c1-9(2)5-4-6-10(3)7-8-11/h5,10-11H,4,6-8H2,1-3H3/t10-/m1/s1 Key: QMVPMAAFGQKVCJ-SNVBAGLBBU InChI=1/C10H20O/c1-9(2)5-4-6-10(3)7-8-11/h5,10-11H,4,6-8H2,1-3H3 Key: QMVPMAAFGQKVCJ-UHFFFAOYAO
SMILES OCC[C@@H](CC/C=C(/C)C)C C\C(C)=C\CCC(C)CCO
Properties
Chemical formula	C10H20O
Molar mass	156.269 g·mol−1
Density	0.855 g/cm3
Boiling point	225 °C (437 °F; 498 K)
Viscosity	11.1 mPa s
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H317, H319
Precautionary statements	P261, P264, P272, P273, P280, P302+P352, P305+P351+P338, P321, P332+P313, P333+P313, P337+P313, P362, P363, P391, P501
NFPA 704 (fire diamond)	1 2 0
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

Preparation

Several million kilograms of citronellol are produced annually. It is mainly obtained by partial hydrogenation of geraniol or nerol over copper chromite catalyst.^[2] Hydrogenation of both C=C bonds using a nickel catalyst gives tetrahydrogeraniol, yet another commercial fragrance.^[3]

Homogeneous catalysts have been investigated for the production of enantiomers.^[4][5]

Uses

Citronellol is used in perfumes and as a fragrance in cleaning products. In many applications, one of the enantiomers is preferred. It is a component of citronella oil, an insect repellant.^[2]

Citronellol is used as a raw material for the production of rose oxide.^[2][6] It is also a precursor to many commercial and potential fragrances such as citronellol acetate, citronellyl oxyacetaldehyde, citronellyl methyl acetal, and ethyl citronellyl oxalate.^[2]

Health and safety

The United States FDA considers citronellol as generally recognized as safe (GRAS) for food use.^[7] Citronellol is subject to restrictions on its use in perfumery,^[8] as some people may become sensitised to it, but the degree to which citronellol can cause an allergic reaction in humans is disputed.^[9][10]

In terms of dermal safety, citronellol has been evaluated as an insect repellent.^[11]

See also

• Citronellal
• Geraniol
• Rhodinol
• Pelargonium graveolens
• Perfume intolerance (allergy)