Detection and trapping of a chemiluminescent o-xylylene peroxide. Chemical light formation along two separate paths

: Thermolysis of pyranone exdoperoxide (1) (prepared by singlet oxygenation of 1,4-diphenyl-2-benzopyran-3-one) in benzene solution leads to o-xylylene peroxide (2). Peroxide (2) is trapped in a Diels-Alder reaction with maleic anhydride to yield an adduct (6). It was observed that the chemiluminescence that resulted from the thermal reaction of peroxide (2) occurred by two distinct paths. The first occurred in the absence of easily oxidized aromatic hydrocarbons and was the result of the unimolecular rearrangement of (2) to electronically excited o-dibenzoylbenzene (4). In this case chemiluminescence was detected by energy transfer from excited (4) to suitable acceptors. The second occurred when any one of several easily oxidized aromatic hydrocarbons was included in the reaction solution. In this case light generation is apparently the result of chemically initiated electron exchange luminescence.