View source for Geraniol

{{Short description|Monoterpenoid and alcohol that is the primary component of citronella oil}}
{{dist|Geranial}}
{{chembox
|Verifiedfields = changed
|Watchedfields = changed
|verifiedrevid = 443834400
|Reference = <ref>{{cite book|entry=Geraniol|title=The Merck Index|edition=12th|title-link=The Merck Index}}</ref>
|Name = Geraniol
|ImageFile = Geraniol structure.png
|ImageSize = 200px
|ImageName = Geraniol
|ImageFile2 = Geraniol-3D-balls-B.png
|ImageSize2 = 200px
|PIN = (2''E'')-3,7-Dimethylocta-2,6-dien-1-ol
|Section1 = {{Chembox Identifiers
 |IUPHAR_ligand = 2467
 |ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
 |ChemSpiderID = 13849989
 |InChI = 1/C10H18O/c1-9(2)5-4-6-10(3)7-8-11/h5,7,11H,4,6,8H2,1-3H3/b10-7+
 |InChIKey = GLZPCOQZEFWAFX-JXMROGBWBZ
 |StdInChI_Ref = {{stdinchicite|correct|chemspider}}
 |StdInChI = 1S/C10H18O/c1-9(2)5-4-6-10(3)7-8-11/h5,7,11H,4,6,8H2,1-3H3/b10-7+
 |StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
 |StdInChIKey = GLZPCOQZEFWAFX-JXMROGBWSA-N
 |CASNo_Ref = {{cascite|correct|CAS}}
 |PubChem = 637566
 |ChEMBL_Ref = {{ebicite|correct|EBI}}
 |ChEMBL = 25719
 |CASNo = 106-24-1
 |EINECS = 203-377-1
 |UNII_Ref = {{fdacite|correct|FDA}}
 |UNII = L837108USY
 |ChEBI_Ref = {{ebicite|correct|EBI}}
 |ChEBI = 17447
 |KEGG = C01500
 |DrugBank = DB14183
 |SMILES = CC(=CCC/C(=C/CO)/C)C
}}
|Section2 = {{Chembox Properties
 |C=10 |H=18 |O=1
 |Density = 0.889 g/cm<sup>3</sup>
 |MeltingPtC = -15
 |MeltingPt_ref = <ref name=GESTIS>{{GESTIS|ZVG = 491258}}</ref>
 |BoilingPtC = 230
 |BoilingPt_ref = <ref name=GESTIS/>
 |Solubility = 686 mg/L (20&nbsp;°C)<ref name=GESTIS/>
 |LogP =3.28<ref name="chemsrc">{{Cite web|url=https://www.chemsrc.com/en/cas/106-24-1_125147.html|title=Geraniol_msds}}</ref>
}}
|Section3 = {{Chembox Hazards
 |NFPA-H = 2
 |NFPA-F = 1
 |NFPA-R = 0
}}<ref>{{cite web|url=https://cameochemicals.noaa.gov/chemical/20432|title= GERANIOL - Cameo Chemicals - NOAA |access-date=26 June 2021}}</ref>
}}

'''Geraniol''' is a [[monoterpenoid]] and an [[Alcohol (chemistry)|alcohol]]. It is the primary component of [[citronella oil]] and is a primary component of [[rose oil]] and [[palmarosa]] 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. 

==Uses and occurrence==
Geraniol is used in medicine, perfumery, and food industry.<ref name="ullmannFF"/><ref name="perf">{{cite book |last1=Vom Ende |first1=Marc |last2=Sturm |first2=Wolfgang |last3=Peters |first3=Klaus |title=Ullmann's Encyclopedia of Industrial Chemistry |chapter=Perfumes |date=2017 |pages=1–7 |doi=10.1002/14356007.a19_171.pub2 |isbn=978-3-527-30673-2 }}</ref>

In addition to being found in [[rose oil]], [[palmarosa]] oil, and [[citronella oil]], it also occurs in small quantities in [[Pelargonium|geranium]], [[lemon]], and many other [[essential oil]]s. With a [[rose]]-like scent,<ref name="perf"/> it is commonly used in [[perfume]]s and in scents such as [[peach]], [[raspberry]], [[grapefruit]], [[apple|red apple]], [[plum]], [[lime (fruit)|lime]], [[Orange (fruit)|orange]], [[lemon]], [[watermelon]], [[pineapple]], and [[blueberry]].

Geraniol is produced by the [[Nasonov's gland|scent glands]] of [[honeybee]]s to mark nectar-bearing flowers and locate the entrances to their hives.<ref>{{cite journal |first1=R. G. |last1=Danka |first2=J. L. |last2=Williams |first3=T. E. |last3=Rinderer | title = A bait station for survey and detection of honey bees | journal = Apidologie | volume = 21 | issue = 4 | pages = 287–292 | year = 1990 | doi = 10.1051/apido:19900403| url = https://hal.archives-ouvertes.fr/hal-00890837/file/hal-00890837.pdf | doi-access = free }}</ref>  It is also commonly used as an insect repellent, especially for mosquitoes.<ref>{{Cite journal|last1=Müller|first1=Günter C.|last2=Junnila|first2=Amy|last3=Kravchenko|first3=Vasiliy D.|last4=Revay|first4=Edita E.|last5=Butler|first5=Jerry|last6=Orlova|first6=Olga B.|last7=Weiss|first7=Robert W.|last8=Schlein|first8=Yosef|date=March 2008|title=Ability of essential oil candles to repel biting insects in high and low biting pressure environments|journal=Journal of the American Mosquito Control Association|volume=24|issue=1|pages=154–160|doi=10.2987/8756-971X(2008)24[154:AOEOCT]2.0.CO;2|issn=8756-971X|pmid=18437832|s2cid=41927381}}</ref>

The scent of geraniol is reminiscent of, but chemically unrelated to, 2-ethoxy-3,5-hexadiene, also known as [[Wine fault#Geranium taint|geranium taint]], a wine fault resulting from fermentation of [[sorbic acid]] by [[lactic acid bacteria]].<ref>Holcombe, Luke (9 January 2018) [https://aggie-horticulture.tamu.edu/vitwine/files/2018/03/Wine-Faults.pdf "Wine faults"] {{Webarchive|url=https://web.archive.org/web/20210916114943/https://aggie-horticulture.tamu.edu/vitwine/files/2018/03/Wine-Faults.pdf |date=2021-09-16}}, p. 11.</ref>

==Reactions==
[[Geranyl pyrophosphate]] is an intermediate in the [[biosynthesis]] of other [[terpene]]s such as [[myrcene]] and [[ocimene]].<ref name=UllmannEgg>{{Ullmann|first=M.|last=Eggersdorfer|title=Terpenes|doi=10.1002/14356007.a26_205}}</ref> It also participates in the [[biosynthesis]] of many [[cannabinoids]] in the form of [[Cannabigerolic acid|CBGA]].<ref name="pmid9607329">{{cite journal | vauthors = Fellermeier M, Zenk MH | title = Prenylation of olivetolate by a hemp transferase yields cannabigerolic acid, the precursor of tetrahydrocannabinol | journal = FEBS Letters | volume = 427 | issue = 2 | pages = 283–85 | date = May 1998 | pmid = 9607329 | doi = 10.1016/S0014-5793(98)00450-5 | doi-access = free | bibcode = 1998FEBSL.427..283F}}</ref>

Geraniol undergoes a variety of reactions to give useful derivatives. it can be converted to the [[tosylate]], which is a precursor to the chloride.  Geranyl chloride also arises by the [[Appel reaction]] by treating geraniol with triphenylphosphine and carbon tetrachloride.<ref>{{OrgSynth|title=Allylic Chlorides from Allylic Alcohols: Geranyl Chloride|first1=Gilbert |last1=Stork |first2=Paul A. |last2=Grieco |first3=Michael |last3=Gregson |year=1974|volume=54|page=68|doi=10.15227/orgsyn.054.0068}}</ref><ref>{{OrgSynth | author = Jose G. Calzada and John Hooz | title = Geranyl chloride| volume = 54 | pages = 63 | year=1974|doi = 10.15227/orgsyn.054.0063}}</ref> It can be oxidized to the aldehyde [[Citral|geranial]].<ref>{{OrgSynth|title=Oxidation of Nerol to Neral With Iodosobenzene and TEMPO |first1=Giovanni |last1=Piancatelli |first2=Francesca |last2=Leonelli |year=2006|volume=83|page=18|doi=10.15227/orgsyn.083.0018}}</ref>  Hydrogenation of the two C=C bonds over a nickel catalyst gives tetrahydrogeraniol.<ref>{{OrgSynth|title=Asymmetric Hydrogenation of Allylic Alcohols Using BINAP–Ruthenium Complexes: (''S'')-(−)-citronellol|first1=Hidemasa |last1=Takaya |first2=Tetsuo |last2=Ohta |first3=Shin-ichi |last3=Inoue |first4=Makoto |last4=Tokunaga |first5=Masato |last5=Kitamura |author6-link=Ryoji Noyori |first6=Ryoji |last6=Noyori |year=1995|volume=72|page=74|collvol=9|collvolpages=169|doi=10.15227/orgsyn.072.0074}}</ref><ref name="ullmannFF">{{cite book |doi=10.1002/14356007.t11_t01 |chapter=Flavors and Fragrances, 2. Aliphatic Compounds |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2015 |last1=Panten |first1=Johannes |last2=Surburg |first2=Horst |pages=1–55 |isbn=978-3-527-30673-2 }}</ref> In [[acidic]] solutions, geraniol is converted to the cyclic terpene [[terpineol|α-terpineol]].

==Health and safety==
Geraniol is classified as D2B (Toxic materials causing other effects) using the [[Workplace Hazardous Materials Information System]] (WHMIS).<ref>{{cite web|url=https://www.sigmaaldrich.com/US/en/product/aldrich/163333 |title=MSDS – Geraniol |publisher=Sigma-Aldrich |access-date= Feb 15, 2022}}</ref>

== History ==
Geraniol was first isolated in pure form in 1871 by the German chemist [[:de:Oscar Jacobsen|Oscar Jacobsen]] (1840–1889).<ref>{{cite journal |last1=Jacobsen |first1=Oscar |title=Untersuchung der indischen Geraniumöls |journal=Annalen der Chemie und Pharmacie |date=1871 |volume=157 |pages=232–239 |url=https://babel.hathitrust.org/cgi/pt?id=uva.x002457983&view=1up&seq=244 |trans-title=InvestIgation of Indian oil from geranium [grass] |language=German}} Jacobsen named geraniol on p. 234: ''"Danach ist dieser Körper, das Geraniol, isomer mit dem Borneol … "'' (Accordingly this body [i.e., substance], geraniol, is isomeric with borneol … )</ref><ref>{{cite book |last1=Semmler |first1=F.W. |title=Die ätherischen Öle |trans-title=The Volatile Oils |date=1906 |publisher=Von Veit & Co. |location=Leipzig, Germany |volume=1  |page=292 |url=https://archive.org/details/b28089595_0001/page/292/mode/2up |language=German}}  From p. 292:  ''"Von dem Geraniol ist zu erwähnen, daß … erst Jacobsen (A. '''157''', 232) brachte im Jahre 1870 über den Alkohol, den er Geraniol nannte, nähere Angaben, er stellte die Formel C<sub>10</sub>H<sub>18</sub>O auf, ohne weitere Konstitionsangaben zu machen."'' (It should be mentioned about geraniol that … Jacobsen (A. '''157''', 232) first gathered in 1870 more detailed data about the alcohol, which he named geraniol ; he established its [empirical] formula C<sub>10</sub>H<sub>18</sub>O, without providing further data about its chemical structure.) See also:  § ''49. Geraniol C<sub>10</sub>H<sub>18</sub>O'', pp. 439-493.  On p. 439, two hypothetical structures of geraniol are proposed.</ref>  Using [[distillation]], Jacobsen obtained geraniol from an essential oil produced in India which was obtained from the so-called [[geranium grass]].<ref>(Semmler, 1906), p. 491.</ref> This essence, after which the compound was named, was a 50% cheaper substitute for the essence of the proper [[geranium]] flower with a similar, although less delicate, odor.<ref>{{Cite book |last=Askinson |first=George William |url=https://books.google.com/books?id=ToXYI1IIcN4C&pg=PA154 |title=Perfumes and Their Preparation |date=1892 |publisher=N.W. Henley |pages=123–124, 154 |language=en}}</ref>

The chemical structure of geraniol was determined in 1919 by the French chemist [[Albert Verley]] (1867–1959).<ref>{{cite journal |last1=Verley |first1=Albert |title=Sur la constitution du géraniol, du linalool et du nérol |journal=Bulletin de la Société Chimique de France |date=1919 |volume=25 |pages=68–80 |url=https://babel.hathitrust.org/cgi/pt?id=iau.31858002467680&view=1up&seq=78 |series=4th series |trans-title=On the chemical structure of geraniol, linalool, and nerol |language=French}} The chemical structure of geraniol appears on p. 70.</ref>

==See also==
*[[Citronellol]]
*[[Citral]]
*[[Nerol]]
*[[Rhodinol]]
*[[Geranyl pyrophosphate]]
*[[Geranylgeranyl pyrophosphate]]
*[[Linalool]]
*[[8-Hydroxygeraniol]]
*[[Geraniol 8-hydroxylase]]
*[[Bergamottin]]
*[[Perfume allergy]]

==References==
{{reflist}}

==External links==
*[http://gmd.mpimp-golm.mpg.de/Spectrums/3a24b562-4124-4405-af12-a5ab43c97740.aspx Geraniol MS Spectrum]
*[http://www.thegoodscentscompany.com/data/rw1006991.html Geraniol properties, animations, links]

{{Transient receptor potential channel modulators}}
{{Authority control}}

[[Category:Perfume ingredients]]
[[Category:Monoterpenes]]
[[Category:Primary alcohols]]
[[Category:Alkene derivatives]]
[[Category:Flavors]]
[[Category:Insect repellents]]