Photolysis of cyclopentanone in the gas phase

Abstract

The photolysis of cyclopentanone has been carried out in the gas phase at 100°C using light of 206 and 193 nm. The major products of the decomposition were ethylene, cyclobutane and carbon monoxide; in addition various significant quantities of propene and various butenes were also produced. The product ratios have been determined as a function of pressure and wavelength. The relative quantum yields for the different modes of decomposition have been determined at various pressures of the pure ketone and with added nitrogen. The results are rationalised on the basis of a mechanism involving a vibrationally excited S₁ state of the ketone. The mechanism is simpler in some respects than that occurring when longer-wavelength radiation is employed.