Photolysis of 2-methylcyclopentanone

Abstract

The photolysis of 2-methylcyclopentanone has been studied in the gas phase, mainly at 313 nm and at 100 °C. The major photolytic products are ethylene, propene, methylcyclobutane, cis- and trans-hex-4-enal, 2-methylpent-4-enal, and carbon monoxide. Product quantum yields were determined over a pressure range of 0·69 to 4·62 kN m^–2 of pure ketone, and also with added nitrogen up to a total nitrogen pressure of 78·1 kN m^–2. These results suggested that the hydrocarbon products were formed by a higher energy pathway than the aldehydes and this was confirmed by carrying out photolyses at shorter wavelengths and at higher temperatures. A mechanism involving decomposition through a triplet state is discussed.