Theoretical and organic chemical approaches to environmental behavior and metabolism of pesticides

Abstract

Investigation of the dissipation and transformation of pesticide through laboratory experiments, conducted in accordance with standard and newly developed designs, gives us valuable information to understand their environmental behavior. We have also been investigating the mechanisms of partition and transformation reactions of pesticides, not only through kinetic analyses, but also through theoretical approaches based on their molecular properties estimated using various spectroscopies and molecular orbital calculations. Furthermore, synthetic iron porphyrin with a peroxide was shown to be a good model to simulate the P450catalyzed oxidation in the metabolism of pesticides. Through these investigations, the knowledge of surface water, soil, sediment, and plants, such as their properties and constituents, was found indispensable to a deep understanding of the mechanism in the hydrolysis, photolysis, and metabolism of pesticides.

Degradation of the strobilurin fungicide mandestrobin in illuminated water–sediment systems

“…Photodegradation is one of the important routes for transformation of pesticides in the natural environment. [1][2][3] Pesticides applied to agricultural fields show various degradation profiles by sunlight irradiation in natural water and on soil and plant surfaces. [4][5][6][7] In order to understand the fundamental behavior of pesticides in the aqueous environments, simulation studies of degradative processes such as hydrolysis, aqueous photolysis, and biodegradation in water-sediment systems in darkness are mandatory for registration of pesticides in the European Union (EU) in accordance with Organization for Economic Co-operation and Development (OECD) Guidelines 111, 316, and 308, respectively.…”

Combined Experimental and Computational Study on the Transformation of a Novel 1,3,4-Oxadiazole Thioether Nematicide in Aqueous Solutions

“…The combination of experimental and computational methods may provide an effective strategy to predict or interpret experimental results and identify the degradation mechanisms and pathways of agrochemicals. 25,26 In this study, a detailed experimental and theoretical analysis of the hydrolytic and photolytic fate of EXLYM in aqueous solutions was conducted with the aim of understanding the persistence and degradation characteristics of this novel nematicide. First, the transformation kinetics of EXLYM in aqueous solutions were investigated in laboratory-scale experiments, with and without simulated sunlight irradiation.…”

“…The lowest ALIE value indicates the site with electrons that are bound least tightly. , Furthermore, the course of a chemical reaction can be elucidated based on quantum theoretical calculations. The combination of experimental and computational methods may provide an effective strategy to predict or interpret experimental results and identify the degradation mechanisms and pathways of agrochemicals. , …”