Alkyne

Alkynes are hydrocarbons that have at least one triple bond between two carbon atoms. The alkynes are traditionally known as acetylenes, though the name acetylene is also used to refer specifically to the simplest member of the series, known officially as ethyne.

Reactions

Alkynes are involved in many organic reactions.

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• electrophilic addition reactions
• addition of hydrogen to the alkene or the alkane
• addition of halogens to the vinyl halides or alkyl halides
• addition of hydrogen halides to the corresponding vinyl halides or alkyl halides
• addition of water to the carbonyl compound (through the enol intermediate)
• Cycloadditions
• Diels-Alder reaction with 2-pyrone to an aromatic compound after elimination of carbon dioxide
• Azide alkyne Huisgen cycloaddition to triazoles
• Bergman cyclization of enediynes to an aromatic compound
• Alkyne trimerisation to aromatic compounds
• scrambling of alkynes in alkyne metathesis to new alkyne compounds
• cycloaddition of an alkyne, alkene and carbon monoxide in the Pauson?Khand reaction
• nucleophilic substitution reactions of metal acetylides
• new carbon-carbon bond formation with alkyl halides
• nucleophilic addition reactions of metal acetylides
• reaction with carbonyl compounds to an intermediate alkoxide and then to the hydroxyalkyne after acidic workup.
• hydroboration reaction of alkynes with organoboranes to vinylic boranes
• followed by reduction by hydrogen peroxide to the corresponding aldehyde or ketone
• oxidative cleavage with potassium permanganate to the carboxylic acids