Chemistry:Citronellol

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Short description: Pair of enantiomers


Citronellol
Skeletal formula of (+)-citronellol and (−)-citronellol
(+)-Citronellol (left) and (−)-citronellol (right)
Ball-and-stick model of the (+)-citronellol molecule
R-(+)-Citronellol
Ball-and-stick model of the (−)-citronellol molecule
S-(−)-Citronellol
Names
IUPAC name
3,7-Dimethyloct-6-en-1-ol
Other names
(±)-β-Citronellol; Cephrol, Corol
Identifiers
3D model (JSmol)
1362474
ChEBI
ChEMBL
ChemSpider
EC Number
  • 247-737-6
KEGG
UNII
Properties
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 pictograms GHS07: HarmfulGHS09: Environmental hazard
GHS Signal word Warning
H315, H317, H319
P261, P264, P272, P273, P280, P302+352, P305+351+338, P321, P332+313, P333+313, P337+313, P362, P363, P391, P501
NFPA 704 (fire diamond)
Flammability code 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
2
1
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
Tracking categories (test):

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]

Preparation

Several million kilograms of citronellol are produced annually. It is mainly obtained by hydrogenation of geraniol or nerol over copper chromite catalyst.[2] Homogeneous catalysts are used for the production of enantiomers.[3][4]

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][5] 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.[6] Citronellol is subject to restrictions on its use in perfumery,[7] as some people may become sensitised to it, but the degree to which citronellol can cause an allergic reaction in humans is disputed.[8][9]

In terms of dermal safety, citronellol has been evaluated as an insect repellent.[10]

See also

References

  1. Lawless, J. (1995). The Illustrated Encyclopedia of Essential Oils. ISBN 978-1-85230-661-8. 
  2. 2.0 2.1 2.2 2.3 Sell, Charles S. (2006). "Terpenoids". Kirk-Othmer Encyclopedia of Chemical Technology. doi:10.1002/0471238961.2005181602120504.a01.pub2. ISBN 0471238961. 
  3. Morris, Robert H. (2007). "Ruthenium and Osmium". in De Vries, J. G.; Elsevier, C. J.. The Handbook of Homogeneous Hydrogenation. Weinheim: Wiley-VCH. ISBN 978-3-527-31161-3. 
  4. Ait Ali, M.; Allaoud, S.; Karim, A.; Roucoux, A.; Mortreux, A. (1995). "Catalytic Synthesis of (R)- and (S)-citronellol by homogeneous hydrogenation over amidophosphinephosphinite and diaminodiphosphine rhodium complexes". Tetrahedron: Asymmetry 6 (2): 369. doi:10.1016/0957-4166(95)00015-H. 
  5. Alsters, Paul L.; Jary, Walther; Aubry, Jean-Marie (2010). ""Dark" Singlet Oxygenation of β-Citronellol: A Key Step in the Manufacture of Rose Oxide". Organic Process Research & Development 14: 259–262. doi:10.1021/op900076g. 
  6. "Redirect". epa.gov. http://www.epa.gov/pesticides/biopesticides/ingredients/factsheets/factsheet_167004.htm. Retrieved 29 July 2015. 
  7. "Standards Restricted - IFRA International Fragrance Association". Archived from the original on 6 January 2012. https://web.archive.org/web/20120106222844/http://www.ifraorg.org/en-us/standards_restricted/s3/p3. Retrieved 19 July 2012. 
  8. "Cropwatch Report April 2008". http://www.leffingwell.com/Cropwatch%20Claims%20Victory%20Over%2026%20Allergens.pdf. 
  9. Survey and health assessment of chemical substances in massage oils
  10. Taylor, W. G.; Schreck, C. E. (1985). "Chiral-phase capillary gas chromatography and mosquito repellent activity of some oxazolidine derivatives of (+)- and (−)-citronellol". Journal of Pharmaceutical Sciences 74 (5): 534–539. doi:10.1002/jps.2600740508. PMID 2862274. https://zenodo.org/record/1229253.