Nitrogen containing compounds contribute to many environmental problems such as acid rain, air pollution, groundwater contamination, and smog formation. For example, when the atmosphere is heavily polluted with nitrites and aromatic hydrocarbons, nitrogen compounds can undergo photochemical reactions to produce harmful compounds that can adversely affect the environment. This project studied the photochemistry of the nitrite ion in aqueous basic solution. Both ·OH and NO· radicals are produced during photolysis, but the two radicals recombine in the presence of pure water causing no net reaction. Aromatic compounds present in the solution being photolyzed can act as scavengers reacting with either one or both radicals to produce different compounds. Two scavengers, benzene and phenol, were studied in the basic nitrite solution. Photolysis for 24 hours at 366 nm caused both solutions to darken considerably. The benzene solution changed from clear to brown/orange, and the phenol solution changed from yellow to dark brown. Thermal reactions for the same amount of time yielded no such results. Methylene chloride preceded by acidification of the aqueous solution was used to extract the photolysate, although some question of this method does exist. The attempt at separation of products contained in the photolysate included the following techniques: TLC, HPLC, and column chromatrography. UV-vis spectroscopy, FTIR, and HPLC were used in the attempt to characterize the products formed. Products that are most likely to be present include p-nitrosophenol and phenol (from the benzene photolysate).
Wilson '95, Laura J., "Photochemistry of the Nitrite Ion" (1995). Honors Projects. 16.