pKa constant determination of two triazole herbicides : Tebuconazole and Penconazole

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 pKa values (representing thermod...

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Bibliographic Details
Published in:Journal of solution chemistry 2013-05, Vol.42, p.1075-1082
Main Authors: Čadková, Eva, Komárek, Michael, Debord, Jean, Puppa Loïc, Della, Bordas, François, Bollinger, Jean-Claude
Format: Article
Language:English
Subjects:
Analytical chemistry
Chemical Sciences
Environmental Sciences
Online Access:Get full text
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Summary: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 pKa 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.
ISSN:0095-9782
1572-8927
DOI:10.1007/s10953-013-0012-z