Geraniol
Geraniol is a monoterpenoid and an alcohol. It is the primary component of rose oil, palmarosa oil, and citronella oil. It is a colorless oil, although commercial samples can appear yellow. It has low solubility in water, but it is soluble in common organic solvents. The functional group derived from geraniol (in essence, geraniol lacking the terminal −OH) is called geranyl.
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IUPAC name
(2E)-3,7-Dimethyl-2,6-octadien-1-ol | |
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ECHA InfoCard | 100.003.071 |
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Properties | |
C10H18O | |
Molar mass | 154.253 g·mol−1 |
Density | 0.889 g/cm3 |
Melting point | −15 °C (5 °F; 258 K)[2] |
Boiling point | 230 °C (446 °F; 503 K)[2] |
686 mg/L (20 °C)[2] | |
log P | 3.28[3] |
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NFPA 704 (fire diamond) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
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Uses and occurrence
In addition to rose oil, palmarosa oil, and citronella oil, it also occurs in small quantities in geranium, lemon, and many other essential oils. With a rose-like scent, it is commonly used in perfumes. It is used in flavors such as peach, raspberry, grapefruit, red apple, plum, lime, orange, lemon, watermelon, pineapple, and blueberry.
Geraniol is produced by the scent glands of honeybees to mark nectar-bearing flowers and locate the entrances to their hives.[4] It is also commonly used as an insect repellent, especially for mosquitoes.
It is a byproduct of the metabolism of sorbate and, thus, is a very unpleasant contaminant of wine if bacteria are allowed to grow in it.
Biochemistry
Geraniol is important in biosynthesis of other terpenes. For example, myrcene and ocimene are formed by dehydration and isomerization of geraniol.[5]
Reactions
In acidic solutions, geraniol is converted to the cyclic terpene α-terpineol. The alcohol group undergoes expected reactions. It can be converted to the chloride with thionyl chloride.[6] It can be hydrogenated.[7] It can be oxidized to the aldehyde geranial.[8]
Health and safety
Geraniol is classified as D2B (Toxic materials causing other effects) using the Workplace Hazardous Materials Information System (WHMIS).[9]
Related compounds
- Citral, the corresponding aldehyde
- Nerol, the double-bond isomer
- Rhodinol, a related terpene alcohol
- Geranyl pyrophosphate
- Geranylgeranyl pyrophosphate
- Linalool, the isomer derived from transposition of the allylic alcohol
- 8-Hydroxygeraniol, produced by action of geraniol 8-hydroxylase
See also
- Perfume allergy
References
- "Geraniol". The Merck Index (12th ed.).
- Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
- "Geraniol_msds".
- Danka, R. G.; Williams, J. L.; Rinderer, T. E. (1990). "A bait station for survey and detection of honey bees" (PDF). Apidologie. 21 (4): 287–292. doi:10.1051/apido:19900403.
- Eggersdorfer, M. "Terpenes". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a26_205.
- Stork, Gilbert; Grieco,, Paul A.; Gregson, Michael (1974). "Allylic Chlorides from Allylic Alcohols: Geranyl Chloride". Organic Syntheses. 54: 68. doi:10.15227/orgsyn.054.0068.CS1 maint: extra punctuation (link); Collective Volume, 6, p. 638
- Takaya, Hidemasa; Ohta, Tetsuo; Inoue, Shin-ichi; Tokunaga, Makoto; Kitamura, Masato; Noyori, Ryoji (1995). "Asymmetric Hydrogenation of Allylic Alcohols Using Binap-Ruthenium Complexes: (S)-(−)-citronellol". Organic Syntheses. 72: 74. doi:10.15227/orgsyn.072.0074.; Collective Volume, 9, p. 169
- Piancatelli, Giovanni; Leonelli, Francesca (2006). "Oxidation Of Nerol To Neral With Iodosobenzene and TEMPO". Organic Syntheses. 83: 18. doi:10.15227/orgsyn.083.0018.
- "MSDS – Geraniol". Sigma-Aldrich. Retrieved June 24, 2014.