Oxidative Transformations of 1-Nitropyrene under Simulated Environmental Conditions

Abstract

The oxidation of 1-nitropyrene (1-NP), adsorbed on silica gel, with dimethyldioxirane (DMD) leads to the formation of 1-nitropyrene 4,5-oxide and 1-nitropyrene 9,10-oxide in a ratio of 74/26 (4,5-oxide/9,10-oxide). When the adsorbed 1-NP is exposed to the products of the gas-phase reaction of tetramethylethylene (TME) with ozone at -40 degrees C, the same oxides are produced in a ratio of 72/28. The fact that the ratio of the oxides is essentially the same in these two different types of experiments is highly significant. We have speculated that the gas-phase ozonolysis of TME produces an energy-rich form of the carbonyl oxide, acetone oxide. Some of this carbonyl oxide may cyclize to the isomeric DMD which, we propose, is responsible for oxide formation in the TME/ozone experiment. This proposal is supported by the observation that using ozone alone to oxidize 1-NP does not lead to oxide formation. Thus the oxidant responsible for oxide formation in the TME/ozone experiment must be produced in the ozonolysis. We suggest that this oxidant is DMD.