Chemiluminescent and Non‐Chemiluminescent Ozonations of Selected Electron‐Rich Alkynes in Halomethanes

Alkynes of sufficiently high nucleophilicity react with electrophilic O 3 under conversion of the alkyne function to a vicinal dicarbonyl function. Contrary to earlier investigations with alkylated or arylated acetylene, products of complete C−C cleavage were not found as primary products, and, beyond that, peroxidic reaction products were absent. Trimethylsilylated alkynes reacted with O 3 either by uptake of two or three O‐atoms, but again without C−C cleavage or formation of peroxides. Two particularly electron‐rich, symmetrically substituted alkynes revealed strong chemiluminescence during ozonation at low temperature, whereas this behavior was not observed with unsymmetrically substituted alkynes. The results are summarized in terms of a mechanistic discussion.