INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
Reaction kinetics and mechanisms of neonicotinoid pesticides with sulfate radicals
MARIA L. DELL;ARCIPRETE; CARLOS J. COBOS; DANIEL O. MARTIRE; JORGE P. FURLONG; MONICA C. GONZALEZ
NEW JOURNAL OF CHEMISTRY
ROYAL SOC CHEMISTRY
Lugar: CAMBRIDGE; Año: 2011 vol. 35 p. 672 - 672
The reaction kinetics and mechanisms of three neonicotinoid insecticides, imidacloprid (IMD), thiacloprid(THIA) and acetamiprid (ACT) with sulfate radicals were studied by flash-photolysis of peroxodisulfate,S2O82-. The absolute rate constants (3 1) 108, (1.1 0.6) 109, and (3 1) 109 M1 s1 were determined for IMD, ACT, and THIA, respectively. The reactivity and absorption spectra of the observed organic intermediates are in line with those reported for a-aminoalkyl radicals, and their absorption spectra agree very well with those estimated employing the time-dependent density functional theory with explicit account for bulk solvent effects. The mono- and di-hydroxylated oxidation products of the insecticides were identified as primary degradation products. The proposed reaction mechanism supports an initial charge transfer from the amidine nitrogen of the insecticides to the sulfate radicals. The pyridine moiety of the insecticides remains unaffected even after long irradiation times, until nicotinic acid is formed.