NEW INTERMEDIATES IN THE REACTION OF BENZOPHENONE PHOTOREDUCTION BY HYDROGEN DONORS

The influence of various factors on the photoreduction of benzophenone by benzhydrol and triethylamine was studied using flash photolysis and steady state spectroscopic techniques. As a result of the investigations conducted, it has been shown that one of the intermediates formed in the reaction is a ketyl radical complex. The second component of the complex is a hydrogen-donor radical. A benzophenone-triethylamine ground state complex is also produced. This affects the properties of the detected radical complex. The spectral and kinetic characteristics of the observed intermediates are presented and the mechanism of the photoreduction is proposed. The mechanism includes the formation of a long-lived exciplex and its decay in two competitive processes: photochemical reaction of the triplet exciplex leads to a ketyl radical and thermal reaction of the exciplex leads to a ketyl radical complex.