Reaction of oxygen atoms with alkynes. Part 1.—The butyne-2 reaction

Abstract

The reaction between butyne-2 and ground-state oxygen atoms produced by the Hg6(³P₁) photosensitized decomposition of N₂O has been studied under static conditions at room temperature. The major products were CO, propylene, ethane, methyl vinyl ketone and a polymer. The results suggest that the initial step involves the formation of a biradical intermediate, which rapidly rearranges into an unsaturated carbonyl compound. Rearrangements involving the internal migration of H atoms and CH₃ radicals, and the splitting-off of CH₃ radicals occur. The addition product is formed “hot” and undergoes decomposition if not stabilized by collisions. The pressure dependence of the formation of the products enables the lifetime of the initially formed “hot” molecule to be determined.