PHOTOOXYGENATION OF BENZENE IN SUPERCRITICAL CO2

Benzene photo-oxygenation reactions have been studied under CO2 pressu rized conditions with the irradiation of KrF excimer laser light at 24 8 nm. The absorption measurements of the relevant mixtures indicate th at the main photo-absorber is benzene. The identified principal produc t is phenol with smaller amounts of dihydroxybenzenes, whose quantum y ield is 0.004 under a typical reaction condition in the neighbourhood of the critical point. The pulse energy dependence of the quantum yiel d indicates that the reaction is induced by one-photon absorption. A r elatively flat quantum yield dependence on the total pressure has been found. The subsequent reaction progress is discussed on the basis of the quantum yield dependence on benzene and O-2 concentrations. (C) 19 98 Elsevier Science B.V.