Pulsed laser photolysis of bis(2-bromobenzoyl) peroxide. Structure of 2-bromobenzoyloxyl radicals and carbon-bromine bond cleavage

On pulsed laser photolysis of bis(2-bromobenzoyl) peroxide (2-BrBPO) a unique absorption band was observed around 400 nm as well as a broad band due to 2-BrC6H4CO2· radicals in the 500–800 nm region. The 400 nm band was also attributed to 2-BrC6H4CO2· on the basis of the similarity of both absorption in time profiles and behavior towards quenchers. Time-resolved EPR measurements provided clear evidence for some interaction between the CO2· radical center and the ortho-bromine atom in 2-BrC6H4CO2· and for the formation of ortho-substituted phenyl radicals, 2-XC6H4 by way of CBr bond cleavage in excited state 2-BrBPO.