Thermal and photochemical decomposition of 9-arylxanthen-9-yl hydroperoxides and peroxides

Abstract

The thermolysis and photolysis of a series of 9-arylxanthenyl hydroperoxides and peroxides have been investigated by means of differential scanning calorimetry, electron paramagnetic spectroscopy and product studies. These relatively stable peroxidic compounds were found to rearrange smoothly on being heated at temperatures > 120°C and on photolysis, respectively, through concerted reaction pathways. Photolysis of 9-hydroperoxy-9-phenylxanthene and di(9-phenylxanthen-9-yl) peroxide, respectively, have been shown by EPR spectroscopy to generate 9-phenylxanthenyl radicals which dimerise at low temperatures and reform the free radicals at ambient temperature.