Photolysis of cyflufenamid in liquid media

The photolysis of cyflufenamid (CFA) in different organic solvents and water under ultraviolet irradiation was investigated. The photolytic rate constant and photolytic half-life were measured for the different solutions. Factors influencing the photolysis of CFA were investigated, including initial concentration, types of solvent, pH, occurrence of catalyst (TiO₂), and environmental substances (Fe³⁺, Fe²⁺, NO₃ ^-, NO₂ ^-). Photolysis of CFA followed first-order kinetics in various systems, and the photolytic rate of CFA decreased with increased initial concentration. Photolytic rates of CFA in different solvents were as follows: n-hexane > methanol > acetonitrile > ultrapure water > ethyl acetate. The pH had a significant effect on the photolysis of CFA, and the photolysis rate reached its peak at pH 9.0. NO₂ ^- and TiO₂ had positive effects on the photolysis of CFA, while Fe²⁺ had an adverse effect. NO₃ ^- in aqueous solution had no effect on the photolysis of CFA. In addition, the rates of photolysis were accelerated at lower concentrations of Fe³⁺ (0.5-5 mmol L^-1) and decreased at higher concentrations (10 mmol L^-1). Moreover, a main photolytic product of CFA was confirmed to be N-cyclopropoxy-2,3-difluoro-6-(trifluoromethyl)benzamide, and cleavage of the amido bond was proposed to be the predicted photolysis pathway in n-hexane.