Photochemical reaction of biphenyl in water containing nitrite or nitrate ion

Abstract

Photochemical reaction of biphenyl with nitrate and nitrite in aqueous solution was investigated using two light sources, i.e., high-pressure mercury lamps fitted with a quartz glass filter (ML-Q) and a Pyrex glass filter (ML-P). Biphenyl was found to be photochemically hydroxylated and nitrated (produce nitrophenylphenols) in either nitrate and nitrite solutions, and the reaction was suppressed by excluding shorter wavelengths light than 300 nm (irradiation with ML-P) in aqueous nitrate solution. In aqueous nitrite solution, however, the reaction was easy to proceed even by irradiation with either light sources. The same tendency was also observed in the formation of mutagens which have been found to be dihydroxydinitrobiphenyls. Such wavelength characteristics for the photoreaction of biphenyl with nitrate and nitrite was correlated to the extent of the photolysis of nitrate and nitrite ions, that is, the photo-excitation of those and subsequent production of NO, NO 2 and OH radicals.