Nitrite ion, a component of nitrogen oxide pollution, is an important source of free radicals in the environment. N02- absorbs ambient ultraviolet light to break into NO and 0-, and in environmental conditions, 0- is converted to hydroxyl radical, OH. Hydroxyl radical reacts with a wide variety of environmental pollutants, including hydrocarbons and nitrogen oxides, so its sources are of interest to environmental chemists. In order to investigate the processes of nitrite photochemistry, nitrite ion was photolyzed at 366 nm in 2-propanol/water solution. This mixed solvent system allows investigation of the effects of varying the solvent cage composition and scavenger concentration on the photolysis process and OH production in particular. A secondary goal was to follow nitrite ion and OH scavenging product concentrations simultaneously. OH radicals were scavenged by 2-propanol to form acetone, which was quantified by derivatization with 2,4-dinitrophenylhydrazine followed by HPLC detection. Acetone yields were compared to nitrite disappearance quantified by ultraviolet spectroscopy for nitrite ion photolyses in 96/4, 98/2, and 100/0 mass/mass 2-propanol/water solutions. Acetone was formed at a higher rate in the 100% 2-propanol solvent, suggesting a shift in mechanism at much lower water concentrations.



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