Effect of NO2 Concentration on Product Yields of the Gas-Phase NO3 Radical-Initiated Reaction of Ethyl- and Dimethyl-naphthalenes

Alkylnaphthalenes are minor constituents of vehicle fuels and are emitted into the atmosphere in vehicle exhaust and other sources of incomplete combustion. In the lower atmosphere, alkylnaphthalenes react with OH radicals during daylight hours and with NO3 radicals during evening and nighttime, and both radical-initiated reactions have been postulated to explain ambient alkylnftronaphthalene profiles. To obtain insight into the NO3 radical reaction mechanism, we have investigated the formation of potentially genotoxic ethyl- and dimethyl-nitronaphtfialenes and quinones, as well as aromatic carbonyls, from the NO3 radical-initiated reactions of ethylnaphthalenes (ENS) and dimethylnaphthalenes (DMNs) over the NO2 concentration range similar to 0.2-2 ppmV. Our results for the formation of alkylnitronaphthalenes are consistent with gas-phase NO3 radical-initiated reactions being a source of alkylnitronaphthalenes in ambient air, and it appears that quinone formation from the gas-phase nighttime reactions of NO3 radicals with 2,6- and 2,7-DMN may be important in the atmosphere and warrants further investigation.