Photochemistry of the Mixed Aqueous Solution of Nitrobenzene and Hydrogen Peroxide Initiated with 266 nm UV Light.

The reaction microscopic mechanism of mixed aqueous solutions of nitrobenzene and hydrogen peroxide under different conditions was studied by the laser flash photolysis technique (266 nm). The main characteristic peaks in these transient absorption spectra were attributed and the build-up/decay trends of several transient species were investigated. The transient absorption peaks of 285 nm and 305 nm were attributed to when nitrobenzene aqueous solutions were irradiated by 266 nm UV light and the decay rate constant was k 285 nm = 1.22 × 104 s−1 and k 305 nm = 1.05 × 104 s−1 in the presence of N2. k 285 nm and k 305 nm increased to 1.32 × 104 s−1 and 2.05 × 104 s−1, respectively, in the presence of O2. OH radical can be produced through the 266 nm laser flash photolysis of hydrogen peroxide in aqueous solutions. The rate constant of the reaction between OH radical and nitrobenzene was measured to be (3.6–6.0) × 109 (L · mol−1 · s−1). The intermediate of the C6H5NO2-OH adduct can undergo secondary self-decay with a reaction rate of 2k/ϵl = 1.82 × 106 s−1. The C6H5NO2-OH adduct is able to react with O2 to form C6H5NO2-OHO2 with a rate constant of (6.6 ± 0.56) × 107 (L · mol−1 · s−1). [ABSTRACT FROM PUBLISHER]