The photolysis of Cyclopropanecarbaldehyde at 313 nm and 254 nm in the presence of CIS-Butene

Cyclopropanecarbaldehyde has been photolyzed in the gas phase with light of 313 nm and 254 nm in the presence of cis-2-butene. With increasing total pressure the quantum yields of the gaseous products, carbon monoxide, ethene, propene and cyclopropane, decrease. The photolysis is accompanied by isomerization of cis-2-butene to trans-2-butene, due to the transfer of triplet energy from the aldehyde to the olefin. The quantum yield of the 2-butene triplet, OBT, increases with increasing concentration of added cis-2-butene. At a temperature of 50°, OBT is about proportional to the concentration of cis-2-butene. At a temperature of 150°, however, OBT very quickly reaches a constant value which is much lower for the photolysis with light of 313 nm (OBT ∼ 0.05) than for that with light of 254 nm (OBT ∼ 0.25).