Photodecomposition of metalaxyl in an aqueous solution

• Published in: Journal of agricultural and food chemistry Vol. 37; no. 6; pp. 1518 - 1523
• Main Authors: Yao, Jian Ren, Liu, Shu Yen, Freyer, Alan J., Minard, Robert D., Bollag, Jean Marc
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-11-1989
• Subjects: Chemistry; Exact sciences and technology; fongicide; fungicidas; fungicides; General and physical chemistry; Photochemistry; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); radiacion ultravioleta; rayon ultraviolet; ultraviolet radiation; Aminoester; Overhauser effect; Enzyme inhibitor; Carboxamide; Benzenic compound; NMR spectrometry; Kinetics; Aqueous solution; Fungicide; Ultraviolet photolysis
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf00090a015

Metalaxyl, the active ingredient of the fungicide Ridomil, was irradiated with a 30 w UV lamp for 1-5 d at 30C in the presence and absence of one of the photosensitizers, riboflavin, methylene blue, acetone or benzophenone. Seventy per cent substrate transformation was achieved after 5 d with two major products being identified. These two compounds were isolated by thin layer chromatography (TLC) and identified by mass and NMR spectroscopy. Transformation rates were dependent upon irradiation time, pH and substrate concentration. Acetone (1 per cent) accelerated photodecomposition while the other photosensitizers had no effect. Mechanisms of photolytic degradation are proposed.