Citronellol, or dihydrogeraniol, is a natural acyclic monoterpenoid. Both occur in nature. (+)-Citronellol, which is found in , 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.
Preparation
Several million kilograms of citronellol are produced annually. It is mainly obtained by partial
hydrogenation of
geraniol or
nerol over
copper chromite catalyst.
Hydrogenation of both C=C bonds using a nickel catalyst gives tetrahydro
geraniol, yet another commercial fragrance.
Homogeneous catalysts have been investigated for the production of .
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.
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Citronellol is used as a raw material for the production of rose oxide. It is also a precursor to many commercial and potential fragrances such as citronellol acetate, citronellyl oxyacetaldehyde, citronellyl methyl acetal, and ethyl citronellyl oxalate.[
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Health and safety
The United States FDA considers citronellol as generally recognized as safe (GRAS) for food use. Citronellol is subject to restrictions on its use in perfumery, as some people may become sensitised to it, but the degree to which citronellol can cause an allergic reaction in humans is disputed.[ Survey and health assessment of chemical substances in massage oils ]
In terms of dermal safety, citronellol has been evaluated as an insect repellent.
See also