Alkynecontaining

Alkyne-containing compounds are organic molecules that include one or more carbon–carbon triple bonds (C≡C). They may be terminal, with a hydrogen on one end of the triple bond, or internal, with substituents on both ends. For acyclic alkynes, the formula is commonly CnH2n−2 and the triple bond is linear due to sp hybridization.

Terminal alkynes possess an acidic hydrogen (pKa around 25) that can be deprotonated to form acetylide ions, enabling nucleophilic transformations. Alkyne groups participate in a wide range of reactions, including hydrohalogenation, hydration, and various cross-couplings, as well as cycloadditions and click chemistry. Hydration of terminal and internal alkynes, under mercuric or other catalysts, yields ketones or aldehydes after tautomerization; hydroboration-oxidation of terminal alkynes gives aldehydes (anti-Markovnikov).

Common examples include acetylene (ethyne) and phenylacetylene, as well as longer-chain and aryl–alkyl alkynes. Diynes contain two triple bonds, as in butadiyne.

Synthesis strategies include elimination of vicinal dihalides with strong bases to form alkynes, and coupling methods such as the Sonogashira reaction to form C–C bonds between alkynes and aryl or vinyl halides. Alkynes are valuable building blocks in organic synthesis, polymer chemistry, and materials science, especially in click chemistry to form 1,2,3-triazoles.

Safety and handling depend on the specific compound. Many alkynes are flammable; terminal alkynes can be reactive and require careful handling, and some gaseous alkynes are stored under pressure due to flammability and hazards with air or oxygen.