In organic chemistry, the term ethynyl designates a functional group with a double bond with 2 carbon atoms both with sp hybridisation and a triple bond (1 sigma and 2 pi bonds). It is a species similar to acetylene (or in IUPAC ethyne ) with a less H atom thus joined to root chain. An ethynyl group (HC≡C–), also designated as acetylenic group (from acetylene), and referred to in IUPAC chemical nomenclature as -yne suffix. Also sometimes designed as ethinyl in compounds (ethinylestradiol, ethisterone (ethinyltestosterone)). See main page alkynes. The ethynyl radical (HC≡C·), the compound found in interstellar medium, and transiently on earth during chemical reactions.
Jérôme Waser, Romain Gaëtan Tessier, Charlotte Marie Sornay, Raj Kumar Nandi