Vacuum-ultraviolet (147.0 nm and 123.6 nm) photolysis of 1,1-dimethylcyclopropane

The gas-phase photolysis of 1,1-dimethylcyclopropane has been investigated using xenon (147.0 nm) and krypton (123.6 nm) resonance radiation. Major products observed in order of decreasing importance were isobutene, ethylene, hydrogen, 1,3-butadiene 2-methyl-1,3-butadiene, propylene, allene, methylacetylene, and acetylene. Radical scavengers, NO and O 2 , and radical interceptors, H 2 S/D 2 S and HI, were used to determine the relative importance of radical and molecular processes. CH 3 , C 2 H 3 , C 3 H 5 , and C 4 H 7 radical species were identified and quantified. Ten primary reaction channels were postulated, of which the elimination of methylene was the most predominant, accounting for 34% of the photo-decomposition at 147.0 nm and 39% at 123.6 nm. Although ionization was established at 123.6 nm (η = 0.10) the nature of a charge transfer or other ion-molecule reaction channel leading to the formation of 2-methyl-1-butene and 2-methyl-2-butene could not be determined.