Octatetraynyl radical (C8H) is an organic free radical with eight carbon atoms linked in a linear chain with alternating single bonds and triple bonds (H−C≡C−C≡C−C≡C−C≡C•).
In 2007 negatively charged octatetraynyl was detected in Galactic molecular source TMC-1, making it the second type of anion to be found in the interstellar medium (after hexatriynyl radical) and the largest such molecule detected to date.
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![111052381_9,12,15Octadecatrienoic acid, 2[1,1'biphenyl]4yl2](https://scimg.chem960.com/cas/0/111052-38-1.png)
