Chemiluminescence of organic peroxides. Thermal generation of an o-xylylene peroxide

: Thermolysis of 1,4-diphenyl-1,4-dioxa-2,3-benzopyrone (endoperoxide 1) in p-xylene solution generates chemiluminescence. Two intermediate products are formed from thermolysis of 1. The major product, trapped in 70% yield by added maleic anhydride, is 1,4-diphenyl-2,3-benzodioxin (o-xylylene peroxide 7). This peroxide becomes eventually o-dibenzoylbenzene 3 which is isolated from the reaction in 85% yield. The second intermediate is unidentified. It is formed in ca. 3% yield and apparently becomes eventually the other isolated product of the reaction phenyl-(o-benzoyl) benzoate (4). The chemiluminescence results from interaction of 7 with an added fluorescent activator or with the minor intermediate according to the chemically initiated electron-exchange luminescence (CIEEL) mechanism. (Author)