{{Chembox <!-- Images --> | Name = Isanic acid | ImageFile = Isanic acid.png | ImageSize = 250px | ImageAlt = <!-- Names --> | IUPACName = octadec-17-en-9,11-diynoic acid | OtherNames = Erythrogenic acid | Section1 = {{Chembox Identifiers | CASNo = 506-25-2 | CASNo_Ref = {{Cascite|changed|CAS}} | ChemSpiderID = 4472111 | DTXSID = DTXSID701304957 | EC_number = | ChEBI = 197116 | UNII = JEO6512256 | PubChem = 5312686 | InChI = InChI=1S/C18H26O2/c1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-18(19)20/h2H,1,3-6,11-17H2,(H,19,20) | InChIKey = OASRDXXKKGHDJZ-UHFFFAOYSA-N | SMILES = OC(=O)CCCCCCCC#CC#CCCCCC=C }} | Section2 = {{Chembox Properties | H=26|O=2|C=18 | MolarMass = | Appearance = crystalline platelets or prisms, light-sensitive; turns red | Density = | MeltingPtC = | BoilingPtC = | BoilingPt_ref = | Solubility = }} | Section3 = {{Chembox Hazards | GHSPictograms = | GHSSignalWord = | GHS_ref = | HPhrases = | PPhrases = | MainHazards = | FlashPt = | AutoignitionPt = }} }} '''Isanic acid''' or erythrogenic acid is a linear fatty acid composed of 18 carbon atoms, with two triple bonds in the positions 9≡10 and 11≡12 and a double bond in the position 17=18. This is one of the rare polyacetylenic acids with conjugated triple bonds. Its delta notation is 18:3Δ9a,11a,17. Its structural formula is CH<sub>2</sub>=CH-(CH<sub>2</sub>)<sub>4</sub>–C≡C–C≡C–(CH<sub>2</sub>)<sub>7</sub>–COOH.<ref>{{cite web |title=NCATS Inxight Drugs — ISANIC ACID |url=https://drugs.ncats.io/drug/JEO6512256 |publisher=drugs.ncats.io |access-date=10 April 2025 |language=en}}</ref>
Exocarpic acid is isomeric to isanic acid. The related isanolic acid, unlike isanic acid, contains an additional hydroxyl group. The oxygenated isanic acid is called ketoisanic acid.
==Discovery== Isanic 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=1937 |volume=44 |issue=6 |pages=243–246 |doi=10.1002/lipi.19370440608 |url=https://onlinelibrary.wiley.com/doi/10.1002/lipi.19370440608 |access-date=10 April 2025 |language=en |issn=1521-4133|url-access=subscription }}</ref> in the oil of the seeds of ''Ongokea gore'' or ''Ongokea klaineana'', a plant from equatorial Africa, called in the native language "boleka" or "isane", hence the common name of isanic acid.<ref>{{cite book |title=Vegetable oils |date=2007 |publisher=PROTA |isbn=978-90-5782-191-2 |page=128 |url=https://books.google.com/books?id=YW-ZbQnWQYsC&dq=Isanic+acid&pg=PA128 |access-date=25 April 2025 |language=en}}</ref><ref>{{cite book |first1=Oil and Colour Chemists Association of Australia|last1=St |title=Surface Coatings: Vol I-Raw Materials and Their Usage |date=9 March 2013 |publisher=Springer Science & Business Media |isbn=978-94-011-6940-0 |page=24 |url=https://books.google.com/books?id=P0fqCAAAQBAJ&dq=Isanic+acid&pg=PA24 |access-date=25 April 2025 |language=en}}</ref> The oil seeds contain about 60% lipids.<ref name="Black"/> Various analyses have revealed the concentration of isanic acid in isane oil from 32% to 51%.
==Synthesis== The synthesis of isanic acid is possible starting from 10-undecynoic acid.<ref name="Black">{{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=1 January 1953 |pages=1785–1793 |doi=10.1039/JR9530001785 |url=https://pubs.rsc.org/en/content/articlelanding/1953/jr/jr9530001785 |access-date=10 April 2025 |language=en |issn=0368-1769|url-access=subscription }}</ref>
==Physical properties== Isanic acid can be detected together with its isomers with the double bond in position 13=14: boletic acid and exocarpic acid, and hydroxylated fatty acids, such as isanolic acid.{{cn|date=February 2026}}{{clarify|date=February 2026}}
The high degree of unsaturation suggests that oils with a high content of these conjugated acetylenic fatty acids are drying. Isanic acid polymerizes easily,<ref>{{cite book |title=Surface Coatings: Vol I-Raw Materials and Their Usage |date=9 March 2013 |publisher=Springer Science & Business Media |isbn=978-94-011-6940-0 |page=24 |url=https://books.google.com/books?id=P0fqCAAAQBAJ&dq=Isanic+acid&pg=PA24 |access-date=10 April 2025 |language=en}}</ref> turning a bright red color when exposed to light. Because of this characteristic the alternative name of erythrogenic acid was proposed by Castille in 1940.<ref name="Black"/>
Insoluble in ether.<ref>{{cite book |title=Journal of the Chemical Society |date=1896 |publisher=Chemical Society |page=638 |url=https://books.google.com/books?id=8704AQAAMAAJ&dq=Isanic+acid&pg=PA638 |access-date=10 April 2025 |language=en}}</ref>
== References == <references/>
{{Fatty acids}}
Category:Alkenoic acids Category:Fatty acids Category:Conjugated diynes