The triplet mercury photosensitized decompositions of vinyl fluoride, 1,1-difluoroethylene, and cis- and trans-1,2-difluoroethylene proceed by molecular elimination of HF via an excited molecule mechanism producing the corresponding acetylene. Cis ⇋ trans isomerization occurs on deactivation, but structural isomerization is absent. Extended Hückel MO calculations have been carried out for ethylene, the haloethylenes, the corresponding acetylenes, and the intermediate carbenes implicated in the decomposition of these olefins. An attempt to correlate the decomposition mechanism with state energy levels, as calculated by the LCAO–MO method, is described.
ASJC Scopus subject areas
- Colloid and Surface Chemistry