Isanolic acid

{{Chembox <!-- Images --> | Name = Isanolic acid | ImageFile = Isanolic acid v2.svg | ImageSize = 250px | ImageAlt = <!-- Names --> | IUPACName = 8-hydroxyoctadec-17-en-9,11-diynoic acid | OtherNames = 8-OH-18:3-delta-9a,11a,17 | Section1 = {{Chembox Identifiers | CASNo = 64144-78-1 | CASNo_Ref = {{Cascite|changed|CAS}} | ChemSpiderID = 4472265 | DTXSID = DTXSID30415608 | EC_number = | ChEBI = 173157 | UNII = | PubChem = 5312840 | InChI = InChI=1S/C18H26O3/c1-2-3-4-5-6-7-8-11-14-17(19)15-12-9-10-13-16-18(20)21/h2,17,19H,1,3-6,9-10,12-13,15-16H2,(H,20,21) | InChIKey = KWLVIGJGNBJKPA-UHFFFAOYSA-N | SMILES = OC(CCCCCCC(=O)O)C#CC#CCCCCC=C }} | Section2 = {{Chembox Properties | H=26|O=3|C=18 | MolarMass = | Appearance = liquid | Density = | MeltingPtC = | BoilingPtC = | BoilingPt_ref = | Solubility = }} | Section3 = {{Chembox Hazards | GHSPictograms = | GHSSignalWord = | GHS_ref = | HPhrases = | PPhrases = | MainHazards = | FlashPt = | AutoignitionPt = }} }} '''Isanolic acid''' is a linear fatty acid composed of 18 carbon atoms, with two triple bonds in the positions 9≡10 and 11≡12, a double bond in the position 17=18, and a hydroxyl-OH in the position 8. The acid is one of the rare polyacetylenic acids with conjugated triple bonds.<ref>{{cite journal |last1=Riley |first1=J. P. |title=299. The seed oil of Onguekoa Gore engler. Part I. The position of the hydroxyl group in the unsaturated monohydroxy-C18 acid (or acids) |journal=Journal of the Chemical Society (Resumed) |date=1951|page=1346 |doi=10.1039/jr9510001346 |access-date=5 April 2025|url=https://pubs.rsc.org/en/content/articlelanding/1951/jr/jr9510001346|url-access=subscription }}</ref> The compound belongs to the family of diynes and enynes, as well as to the alkyne and alkenoic acids.

The related compounds are isanic and ketoisanic acids, both containing only one hydroxyl group. 250px|right|thumb|Seeds of ''Ongokea gore'' contain the acid

==Discovery== The acid was initially isolated in 1937 by researchers A. Steger and J. van Loon<ref>{{cite journal |last1=Steger |first1=A. |last2=van Loon |first2=J. |title=Das fette Oel der Samen von Onguekoa Gore Engler |journal=Fette und Seifen |date=January 1937 |volume=44 |issue=6 |pages=243–246 |doi=10.1002/lipi.19370440608|url=https://onlinelibrary.wiley.com/doi/10.1002/lipi.1937044060 |access-date=5 April 2025|url-access=subscription }}</ref> from the seed oilof the tree ''Ongokea gore'' or ''Ongokea klaineana'', a plant from equatorial Africa, called in the native language "boleka" or "isano"; a common name of isanolic acid comes from the latter.<ref>{{cite book |title=Ullmann's Food and Feed, 3 Volume Set |date=19 June 2017 |publisher=John Wiley & Sons |isbn=978-3-527-33990-7 |page=714 |url=https://books.google.com/books?id=Xwe3DQAAQBAJ&dq=%22Isanolic+acid%22&pg=PA714 |access-date=5 April 2025 |language=en}}</ref> They also discovered isanic acid. The oil seeds contain about 60% lipids.<ref>{{cite journal |last1=Black |first1=H. K. |last2=Weedon |first2=B. C. L. |title=368. Unsaturated fatty acids. Part I. The synthesis of erythrogenic (isanic) and other acetylenic acids |journal=Journal of the Chemical Society (Resumed) |date=1953 |pages=1785–1793 |doi=10.1039/JR9530001785 |url=https://pubs.rsc.org/en/content/articlelanding/1953/jr/jr9530001785|access-date=5 April 2025|url-access=subscription }}</ref> Since the compound is hard to isolate, various analyses have revealed non-homogeneous data on the concentration of isanolic acid in isano oil: from 3%<ref>{{cite journal |last1=Miller |first1=Roger W. |last2=Weisleder |first2=David |last3=Kleiman |first3=Robert |last4=Plattner |first4=Ronald D. |last5=Smith |first5=Cecil R. |title=Oxygenated fatty acids of isano oil |journal=Phytochemistry |date=January 1977 |volume=16 |issue=7 |pages=947–951 |doi=10.1016/s0031-9422(00)86701-1 |bibcode=1977PChem..16..947M |access-date=5 April 2025|url=https://www.sciencedirect.com/science/article/abs/pii/S0031942200867011|url-access=subscription }}</ref> to 44%<ref>{{cite journal |last1=Kaufmann |first1=H. P. |last2=Baltes |first2=J. |last3=Herminghaus |first3=H. |title=Über das Boleko-Öl I: Die Fettsäuren des Öles und ihre Trennung |journal=Fette und Seifen |date=January 1951 |volume=53 |issue=9 |pages=537–542 |doi=10.1002/lipi.19510530908 |access-date=5 April 2025|url=https://onlinelibrary.wiley.com/doi/10.1002/lipi.19510530908|url-access=subscription }}</ref> of the total fatty acids.

==Chemical properties== The compound can be detected in isane oil together with other hydroxylated acetylenic fatty acids, all with the hydroxyl in position 8.<ref>{{cite journal |last1=Gunstone |first1=F. D. |last2=Sealy |first2=A. J. |title=1101. Fatty acids. Part XII. The acetylenic acids of isano (boleko) oil |journal=Journal of the Chemical Society (Resumed) |date=1963 |pages=5772 |doi=10.1039/jr9630005772 |access-date=5 April 2025|url=https://pubs.rsc.org/en/content/articlelanding/1963/jr/jr9630005772|url-access=subscription }}</ref><ref>{{cite journal |last1=Morris |first1=L. J. |title=1102. The oxygenated acids of isano (boleko) oil |journal=Journal of the Chemical Society (Resumed) |date=1963 |pages=5779 |doi=10.1039/jr9630005779 |access-date=5 April 2025|url=https://pubs.rsc.org/en/content/articlelanding/1963/jr/jr9630005779|url-access=subscription }}</ref>

The high degree of unsaturation suggests that oils with a high content of these conjugated acetylenic fatty acids are drying; the presence of hydroxylated fatty acids implies the possibility of forming atypical glycerides, such as triglycerides containing more than three acyl groups.<ref>{{cite journal |last1=Payne-Wahl |first1=Kathleen |last2=Plattner |first2=Ronald D. |last3=Spencer |first3=Gayland F. |last4=Kleiman |first4=Robert |title=Separation of tetra-, penta-, and hexaacyl triglycerides by high performance liquid chromatography |journal=Lipids |date=July 1979 |volume=14 |issue=7 |pages=601–605 |doi=10.1007/bf02533443 |access-date=5 April 2025|url=https://aocs.onlinelibrary.wiley.com/doi/10.1007/BF02533443|url-access=subscription }}</ref>

Depending on the reaction conditions, isanolic acid reacts with phenol to form enol ethers or vinyl aromatics.<ref>{{cite journal |last1=Ravve |first1=A. |last2=Fitko |first2=C. |title=A study on alkylation of phenol with isano oil |journal=Journal of the American Oil Chemists' Society |date=1969 |volume=46 |issue=6 |pages=315–319 |doi=10.1007/BF02545012 |url=https://aocs.onlinelibrary.wiley.com/doi/10.1007/BF02545012 |access-date=5 April 2025 |language=en |issn=1558-9331|url-access=subscription }}</ref>

== References == <references/>

{{Fatty acids}}

Category:Alkenoic acids Category:Fatty acids Category:Conjugated diynes Category:Alkynoic acids