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pK a Constant Determination of Two Triazole Pesticides: Tebuconazole and Penconazole |
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| Authors: | Eva Čadková Michael Komárek Jean Debord Loïc Della Puppa François Bordas Jean-Claude Bollinger |
| Institution: | 1. Department of Agro-Environmental Chemistry and Plant Nutrition, Czech University of Life Sciences Prague, Kamycká129, 165 21, Prague 6, Czech Republic 2. Czech Geological Survey, Geologická 6, 152 00, Prague 5, Czech Republic 3. Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamycká 129, 165 21, Prague 6, Czech Republic 4. Service de Pharmacologie-Toxicologie, H?pital Dupuytren, 2 Avenue Martin Luther King, 87042, Limoges, France 5. Groupement de Recherche Eau, Sol, Environnement (GRESE), Université de Limoges, 123 Avenue Albert Thomas, 87060, Limoges, France |
| Abstract: | We determined the acidity constants of tebuconazole and penconazole, two fungicides from the group of 1,2,4-triazoles. Potentiometric titrations were performed in a 20 % (v/v) acetonitrile/water mixture at 25 °C and at a fixed ionic strength (KNO3, 0.1 mol·dm?3). The pK a values (representing thermodynamic constants) were determined to be 5.0 ± 0.1 and 5.2 ± 0.1 for tebuconazole and penconazole, respectively. These values could be used in pure water solutions to consider the protonated or deprotonated forms when studying the field behavior of these fungicides. Molecular modeling calculations allowed identifying the N4 atom as the protonation site. |
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