Triplet-Triplet Energy Transfer Reaction of 5-Methylthiazole and Benzophenone: Mechanism and Kinetics

摘要

The photosensitized reaction of 5–Methylthiazole (5MT) with benzophenone (BP) in aqueous alkaline medium using visiblelight has been studied to mineralize 5MT to less toxic ions. 5MT shows the λmax at 240 nm in the pH range of 2-12. Thetriplet–triplet energy transfer from the triplet excited state of the aromatic ketone BP to the substrate molecule takesplace during the photosensitized reaction. The triplet excited 5MT breaks down on further exposure and photoproductformation takes place. The reaction shows the participation of singlet oxygen during the photoreaction. The sulfate hasbeen observed as photoproduct. The apparent rate of the reaction has been calculated and the effect of pH, concentrationof the sensitizer, the light intensity on the apparent rate of the reaction has been studied. The quantum efficiency of thephotochemical reaction is calculated using potassium ferri oxalate actinometer and the effect of the concentration of thesubstrate on the quantum efficiency is calculated. The reaction mechanism and the excited states involved have beensuggested.