View source for Linalool

{{Short description|Chemical compound with a floral aroma}}
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 470609278
| ImageFile = Linalool skeletal.svg
| ImageSize = 240
| ImageAlt = Skeletal formula
| ImageFile1 = (S)-Linalool molecule ball.png
| ImageSize1 = 240
| ImageAlt1 = Ball-and-stick model
| PIN = 3,7-Dimethylocta-1,6-dien-3-ol
| OtherNames = 3,7-Dimethyl-1,6-octadien-3-ol, β-linalool, linalyl alcohol, linaloyl oxide, allo-ocimenol, coriandrol, Licareol
|Section1={{Chembox Identifiers
| index_label = 
| index1_label = (''R'')
| index2_label = (''S'')
| index_comment = (±)-linalool
| index1_comment = (−)-linalool
| index2_comment = (+)-linalool
| testQID = Q410932
| QID1 = Q27105200
| QID2 = Q27105233
| IUPHAR_ligand = 2469
| CASNo = 78-70-6
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo1 = 126-91-0
| CASNo1_Ref = {{cascite|correct|CAS}}
| CASNo2 = 126-90-9
| CASNo2_Ref = {{cascite|correct|CAS}}
| PubChem = 6549
| PubChem1 = 443158
| PubChem2 = 67179
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 25306
| ChEMBL2 = 235672 
| KEGG1 = C11388
| KEGG2 = C11389
| 3DMet = B05103
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = D81QY6I88E
| UNII1_Ref = {{fdacite|correct|FDA}}
| UNII1 = 3U21E3V8I2
| UNII2_Ref = {{fdacite|correct|FDA}}
| UNII2 = F4VNO44C09
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 13849981
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 17580
| ChEBI1 = 28
| ChEBI2 = 98
| InChI = 1/C10H18O/c1-5-10(4,11)8-6-7-9(2)3/h5,7,11H,1,6,8H2,2-4H3
| InChIKey = CDOSHBSSFJOMGT-UHFFFAOYAV
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C10H18O/c1-5-10(4,11)8-6-7-9(2)3/h5,7,11H,1,6,8H2,2-4H3
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = CDOSHBSSFJOMGT-UHFFFAOYSA-N
| SMILES = CC(O)(C=C)CCC=C(C)C
  }}
|Section2={{Chembox Properties
| C=10|H=18|O=1
| Appearance = Colorless oil
| Density = 0.858 to 0.868 g/cm<sup>3</sup>
| MeltingPt= <
| MeltingPtC = −20
| BoilingPtC = 198 to 199
| BoilingPt_notes = 
| Solubility = 1.589 g/l
  }}
|Section3={{Chembox Hazards
| NFPA-H = 1
| NFPA-F = 2
| NFPA-R = 0
| MainHazards =
| FlashPtC = 55
| AutoignitionPtC = 
 }}
}}

'''Linalool''' ({{IPAc-en|l|ᵻ|ˈ|n|æ|l|oʊ|ɒ|l|,_|l|aɪ|-|,_|-|l|oʊ|oʊ|l|,_|-|ˈ|l|uː|l}}) refers to two [[enantiomer]]s of a naturally occurring [[terpene]] [[Alcohol (chemistry)|alcohol]] found in many [[flower]]s and [[spice]] plants.<ref name="pubchem">{{cite web |title=Linalool |url=https://pubchem.ncbi.nlm.nih.gov/compound/6549 |publisher=PubChem, US National Library of Medicine |access-date=17 October 2021 |date=16 October 2021}}</ref> Together with [[geraniol]], [[nerol]], and [[citronellol]], linalool is one of the '''rose alcohols'''.<ref name=KO/> Linalool has multiple commercial applications, the majority of which are based on its pleasant scent (floral, with a touch of spiciness).<ref name="Ullmann">{{Ullmann |doi=10.1002/14356007.a26_205|title=Terpenes|year= 2000|last1=Eggersdorfer|first1=Manfred}}</ref><ref>{{cite journal |doi=10.1016/S0278-6915(03)00015-2|title=Fragrance material review on linalool|year=2003|last1=Letizia|first1=C.S|last2=Cocchiara|first2=J.|last3=Lalko|first3=J.|last4=Api|first4=A.M|journal=Food and Chemical Toxicology|volume=41|issue=7|pages=943–964|pmid=12804650}}</ref> 

A colorless oil, linalool is classified as an acyclic [[monoterpenoid]].<ref name=pubchem/> In plants, it is a [[metabolite]], a [[Essential oil|volatile oil]] component, an [[antimicrobial]] agent, and an [[aroma compound]].<ref name=pubchem/> Linalool has uses in manufacturing of soaps, fragrances, [[food additive]]s as flavors, household products, and [[insecticide]]s.<ref name=pubchem/>  [[Ester]]s of linalool are referred to as '''linalyl''', e.g. linalyl [[pyrophosphate]], an isomer of [[geranyl pyrophosphate]].<ref name=Crot>{{cite journal |pmid=3392006|year=1988|last1=Croteau|first1=R.|last2=Satterwhite|first2=D. M.|last3=Cane|first3=D. E.|last4=Chang|first4=C. C.|title=Biosynthesis of Monoterpenes. Enantioselectivity in the Enzymatic Cyclization of (+)- and (-)-Linalyl Pyrophosphate to (+)- and (-)-Pinene and (+)- and (-)-Camphene|journal=The Journal of Biological Chemistry|volume=263|issue=21|pages=10063–71|doi=10.1016/S0021-9258(19)81477-1 |doi-access=free }}</ref>

The word ''linalool'' is based on ''[[linaloe]]'' (a type of wood) and the suffix ''{{linktext|-ol}}''.<ref>{{Merriam-Webster|Linalool}}: "International Scientific Vocabulary, from Mexican Spanish lináloe"</ref> In food manufacturing, it may be called ''coriandrol''.<ref name=pubchem/>

==Occurrence==
[[File:Linalool Enantiomers Structural Formulae.png|260px|thumb|left|(''S'')-(+)-linalool (left) and (''R'')-(–)-linalool (right)]]
Both [[enantiomer]]ic forms are found in nature: (''S'')-linalool is found, for example, as a major constituent of the essential oils of [[coriander]] (''[[Coriandrum sativum]]'' L.), [[cymbopogon]] (''[[Cymbopogon martini]]'' var. ''martinii''), and [[sweet orange]] (''[[Citrus sinensis]]'') flowers. (''R'')-linalool is present in [[lavender]] (''[[Lavandula officinalis]]''), [[bay laurel]] (''Laurus nobilis''), and [[sweet basil]] (''Ocimum basilicum''), among others.

Each enantiomer evokes distinct neural responses in humans, so each is classified as possessing distinct [[scent]]s. (''S'')-(+)-Linalool is perceived as sweet, floral, [[petitgrain]]-like (odor threshold 7.4&nbsp;[[parts per billion|ppb]]) and the (''R'')-form as more woody and [[lavender]]-like (odor threshold 0.8&nbsp;[[parts per billion|ppb]]).

Over 200 species of plants produce linalool, notably from the families [[Lamiaceae]] ([[Mentha|mint]] and other herbs), [[Lauraceae]] ([[laurels]], [[cinnamon]], [[Aniba rosaeodora|rosewood]]), and [[Rutaceae]] ([[citrus fruits]]), but also [[birch trees]] and other plants, from [[tropical]] to [[boreal climate]] zones.

* ''[[Aniba rosaeodora]]''
* ''[[Lavandula]]''<ref>{{cite journal | vauthors = Kasper S, Gastpar M, Müller WE, Volz HP, Möller HJ, Dienel A, Schläfke S | title = Silexan, an orally administered Lavandula oil preparation, is effective in the treatment of 'subsyndromal' anxiety disorder: a randomized, double-blind, placebo controlled trial | journal = International Clinical Psychopharmacology | volume = 25 | issue = 5 | pages = 277–87 | date = September 2010 | pmid = 20512042 | doi = 10.1097/YIC.0b013e32833b3242 | s2cid = 46290020 }}</ref>
* ''[[Cinnamomum tamala]]''<ref name=eocs>{{cite journal | vauthors = Ahmed A, Choudhary MI, Farooq A, Demirci B, Demirci F, Can Başer KH | title = Essential oil constituents of the spice ''Cinnamomum tamala'' (Ham.) Nees & Eberm. | journal = Flavour and Fragrance Journal | volume = 15 | issue = 6 | pages = 388–390 | year = 2000 | doi = 10.1002/1099-1026(200011/12)15:6<388::AID-FFJ928>3.0.CO;2-F | doi-access = free }}</ref>
* ''[[Cannabis sativa]]''<ref name="Ibrahim">{{cite journal | vauthors = Ibrahim EA, Wang M, Radwan MM, Wanas AS, Majumdar CG, Avula B, Wang YH, Khan IA, Chandra S, Lata H, Hadad GM, Abdel Salam RA, Ibrahim AK, Ahmed SA, ElSohly MA | display-authors = 6 | title = Analysis of Terpenes in Cannabis sativa L. Using GC/MS: Method Development, Validation, and Application | journal = Planta Medica | volume = 85 | issue = 5 | pages = 431–438 | date = March 2019 | pmid = 30646402 | doi = 10.1055/a-0828-8387 | bibcode = 2019PlMed..85..431I | s2cid = 58668648 }}</ref>
* ''[[Basil]]''<ref name=apfb>{{cite journal | vauthors = Klimankova E, Holadová K, Hajšlová J, Čajka T, Poustka J, Koudela M | title = Aroma profiles of five basil (''Ocimum basilicum'' L.) cultivars grown under conventional and organic conditions | journal = Food Chemistry | volume = 107 | issue = 1 | pages = 464–472 | year = 2008 | doi = 10.1016/j.foodchem.2007.07.062 }}</ref>
* ''[[Solidago]]'' (goldenrod)<ref>{{cite journal | vauthors = Vila R, Mundina M, Tomi F, Furlán R, Zacchino S, Casanova J, Cañigueral S | title = Composition and antifungal activity of the essential oil of Solidago chilensis | journal = Planta Medica | volume = 68 | issue = 2 | pages = 164–7 | date = February 2002 | pmid = 11859470 | doi = 10.1055/s-2002-20253 | bibcode = 2002PlMed..68..164V | s2cid = 260283973 }}</ref>
* ''[[Artemisia vulgaris]]'' (mugwort)
* ''[[Humulus lupulus]]'' (hop)

It was first synthesized in the laboratory of [[Leopold Ružička]] in 1919.<ref name=em90>Albert Eschenmoser: "Leopold Ruzicka - From the Isoprene Rule to the Question of Life's Origin" CHIMIA 44 (1990)</ref>

==Production==
Linalool is produced commercially from several terpenes and terpenoid precursors, which are often components of [[terpentine]].  2-Pinanol, derived from [[pinene]], gives [[linalool]] upon pyrolysis.<ref>{{Ullmann |doi=10.1002/14356007.a26_205|title=Terpenes |year=2000 |last1=Eggersdorfer |first1=Manfred |isbn=3527306730 }}</ref>

===Biosynthesis===
In [[Vascular plant|higher plants]] linalool is formed by rearrangement of [[geranyl pyrophosphate]] (GPP).<ref name="Planta Medica">{{cite journal | vauthors = Woronuk G, Demissie Z, Rheault M, Mahmoud S | title = Biosynthesis and therapeutic properties of Lavandula essential oil constituents | journal = Planta Medica | volume = 77 | issue = 1 | pages = 7–15 | date = January 2011 | pmid = 20665367 | doi = 10.1055/s-0030-1250136 | doi-access = free | bibcode = 2011PlMed..77....7W }}</ref> With the aid of [[linalool synthase (disambiguation)|linalool synthase]] (LIS), water attacks to form the chiral center.<ref>{{cite book |last1=Dewick |first1=Paul M | name-list-style = vanc |title=Medicinal Natural Products: A Biosynthetic Approach |date=2009 |publisher=John Wiley & Sons |isbn=978-0-470-74168-9 |edition=3rd}}</ref><ref name="Planta Medica"/> LIS appears to show a [[limonene synthase (disambiguation)|limonene synthase]]-type catalysis through a simplified "metal-cofactor-binding domain [where the majority] of the residues involved in substrate...binding [are] in the C-terminal part of the protein" suggesting [[stereoselectivity]] and the reasoning behind why some plants have varying levels of each enantiomer.<ref name="Molecular Biology and Evolution">{{cite journal | vauthors = Cseke L, Dudareva N, Pichersky E | title = Structure and evolution of linalool synthase | journal = Molecular Biology and Evolution | volume = 15 | issue = 11 | pages = 1491–8 | date = November 1998 | pmid = 12572612 | doi = 10.1093/oxfordjournals.molbev.a025876 | doi-access = free }}</ref><ref name="Plant Physiol">{{cite journal | vauthors = Iijima Y, Davidovich-Rikanati R, Fridman E, Gang DR, Bar E, Lewinsohn E, Pichersky E | title = The biochemical and molecular basis for the divergent patterns in the biosynthesis of terpenes and phenylpropenes in the peltate glands of three cultivars of basil | journal = Plant Physiology | volume = 136 | issue = 3 | pages = 3724–36 | date = November 2004 | pmid = 15516500 | pmc = 527170 | doi = 10.1104/pp.104.051318 | doi-access = free }}</ref>
[[File:Linalool_Biosynthesis.png|alt=|center|thumb|Linalool [[biosynthesis]] [[metabolic pathway|pathway]]. Abbreviations used: geranyl diphosphate synthase (GDS), pyrophosphate ester (OPP), [[isopentenyl pyrophosphate]] (IPP), [[dimethylallyl pyrophosphate]] (DMAPP), geranyl pyrophosphate (GPP). Stereogenic centers are indicated by an asterisk.|654x654px]]

==Odor and flavor==
Linalool has complex odor and flavor properties. Its odor is similar to floral, spicy wood, somewhat resembling [[French lavender]] plants, [[bergamot oil]] or [[lily of the valley]].<ref name=pubchem/> It has a light, citrus-like flavor, sweet with a spicy tropical accent.<ref name=pubchem/>  Linalool is used as a scent in  [[perfume]]d hygiene products and cleaning agents, including [[soap]]s, [[detergent]]s, [[shampoo]]s, and lotions.<ref name=pubchem/><ref name="Ullmann"/> It exhibits antimicrobial and antifungal properties.<ref name=pubchem/><ref>{{cite journal |doi=10.1016/j.foodchem.2007.12.010|title=Chemical composition, antioxidant and antimicrobial activities of basil (Ocimum basilicum) essential oils depends on seasonal variations|year=2008|last1=Hussain|first1=Abdullah Ijaz|last2=Anwar|first2=Farooq|last3=Hussain Sherazi|first3=Syed Tufail|last4=Przybylski|first4=Roman|journal=Food Chemistry|volume=108|issue=3|pages=986–995|pmid=26065762}}</ref>

==Chemical derivatives==
Linalool is hydrogenated to give dihydro- and tetrahydrolinalool, which are fragrances that are more resilient toward oxidants, as might be found in household cleaning products.  [[Linalyl acetate]], a popular scent, is produced by esterification of linalool (as well as occurring naturally).  Isomerization of linalool gives [[geraniol]] and [[nerol]].<ref name=KO>{{cite book |doi=10.1002/0471238961.2005181602120504.a01.pub2|chapter=Terpenoids |title=Kirk-Othmer Encyclopedia of Chemical Technology |year=2006 |last1=Sell |first1=Charles S. |isbn=0471238961 }}</ref>

==Safety==
Linalool can be absorbed by inhalation of its [[aerosol]] and by oral intake or skin absorption, potentially causing irritation, pain and [[allergy|allergic]] reactions.<ref name="Ullmann" /><ref>{{cite web |title=Linalool |url=https://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@term+@DOCNO+645 | archive-url = https://web.archive.org/web/20190228004550/https://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@term+@DOCNO+645 | archive-date = 28 February 2019 |publisher=Toxnet, National Library of Medicine, US National Institutes of Health |access-date=21 May 2019 |date=14 January 2016}}</ref> Some 7% of people undergoing [[patch test]]ing in Europe were found to be allergic to the [[Redox|oxidized form]] of linalool.<ref>{{cite journal | vauthors = Ung CY, White JM, White IR, Banerjee P, McFadden JP | title = Patch testing with the European baseline series fragrance markers: a 2016 update | journal = The British Journal of Dermatology | volume = 178 | issue = 3 | pages = 776–780 | date = March 2018 | pmid = 28960261 | doi = 10.1111/bjd.15949 | s2cid = 4434234 }}</ref>

The US Food and Drug Administration (FDA) lists linalool in the Code of Federal Regulations under substances generally recognized as safe, synthetic flavoring substances and adjuvants.<ref name="21CFR182.60">{{cite web | title=eCFR :: 21 CFR 182.60 -- Synthetic flavoring substances and adjuvants. | website=eCFR | date=2021-10-27 | url=https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-182/subpart-A/section-182.60 | access-date=2021-10-29}}</ref>

== See also ==
* [[Lavender oil]]

== References ==
{{reflist}}

== External links ==
* [https://web.archive.org/web/20131007220230/http://www.inchem.org/documents/sids/sids/78706.pdf Comprehensive data sheet]
* {{CPID|id=2771}}

{{Transient receptor potential channel modulators}}

[[Category:Flavors]]
[[Category:Tertiary alcohols]]
[[Category:Plant toxin insecticides]]
[[Category:Alkene derivatives]]
[[Category:Monoterpenes]]
[[Category:Perfume ingredients]]