Photolysis of cyflufenamid in liquid media.

ABSTRACT

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.