Photochemical reaction of superoxide radicals with 1-naphthol

The photochemical reactions between 1-naphthol (1-NP) and the superoxide anion radical (O₂^·–) were investigated in detail by using 365 nm UV irradiation. The results showed that the conversion rate of 1-NP decreased with the increase of the initial concentration of 1-NP, whereas by increasing the pH and riboflavin concentration, the photochemical reaction was accelerated. The second-order reaction rate constant was estimated to be (3.64 ±6 0.17) 10⁸ L mol^-1 s^-1 . The major photolysis products identified by using gas chromatography – mass spectrometry (GC–MS) were 1,4-naphquinone and 2,3- epoxyresin-2,3-dihydro-1,4-naphquinone, and their reaction pathways were also discussed. An atmospheric model showed that both the bulk water reaction and the heterogeneous surface reaction deserve attention in atmospheric aqueous chemistry. (author)