Phototransformation of napropamide [N,N-diethyl-2-(1-naphthyloxy)propionamide] in aqueous solution: Influence on the toxicity of solutions

The main photoproducts formed in an aqueous solution of napropamide irradiated in UV light are N,N-diethyl-2-(1-hydroxynaphthalen-2-yl)propionamide, N,N-diethyl-2-(4-hydroxynaphthalen-1-yl)propionamide and 1-naphthol. These account for c.60%, 15% and 10% of napropamide converted respectively. No influence of the irradiation wavelength or of oxygen was observed. The same products were obtained by irradiation of methanolic solutions. The three identified products result from the cleavage of naphthoxy-carbon bond. The first two products imply a photo-Fries rearrangement. The influence of irradiation on the toxicity of the solutions was studied by the Microtox(R) test. The significant increase observed may be attributed partly to the formation of 1-naphthol. (C) 1998 Society of Chemical Industry.