Ag+/S2O8 2– system for the degradation of aqueous flutriafol

Abstract

The degradation of flutriafol in aqueous persulfate (S2O8 2-) system in the presence of selected transition metal ions was investigated. In the presence of Ag + or Fe 2+ , flutriafol degradation occurs, whereas in the presence of Mn 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ and Bi 3+ ions, the degradation is less than 15%. The Ag + /S2O8 2aqueous system being the most effective was adopted for experimental and theoretical investigations. It was confirmed that pH of 3.0 is the most suitable, and that both • SO4 and • OH radicals are the main active species to afford flutriafol degradation, with the former contributes more than the latter. To elucidate degradation mechanism, molecular orbital calculations were performed and reaction intermediates identified by GC/MS and HPLC/MS/MS analyses. Three degradation pathways are proposed that involve the cleavage of C-N and CC bonds as a result of • SO4 attack, as well as the formation of hydroxylated products due to • OH radicals.

Parallel Minisci Reaction of gem-Difluorocycloalkyl Building Blocks

“…Comparison of the obtained oxidation potentials with those for the oxidative species (i.e., E(Ag 2+ /Ag + ) and E(SO4 -/SO4 2-)) 69,84,85 shows that in the case of non-fluorinated trifluoroborates 2{1}, 2{3}, 2{5}, and 2{7}, both Ag 2+ and SO4 can participate in the radical generation. On the contrary, for most gemdiflurinated trifluroborates studied, E(Ag 2+ /Ag + ) is not sufficient for the reaction, so that SO4 is the likely oxidant.…”

Parallel Minisci Reaction of gem-Difluorocycloalkyl Building Blocks

“…Comparison of the obtained oxidation potentials with those for the oxidative species [i.e., E (Ag 2+ /Ag + ) and E (SO 4 •– /SO 4 2– )] ,, shows that in the case of nonfluorinated trifluoroborates 2 {1}, 2 {3}, 2 {5}, and 2 {7}, both Ag 2+ and SO 4 •– can participate in the radical generation. On the contrary, for most gem -difluorinated trifluoroborates studied, E (Ag 2+ /Ag + ) is not sufficient for the reaction, so that SO 4 •– is the likely oxidant.…”

“…•− / SO 4 2− )] 70,83,84 shows that in the case of nonfluorinated trifluoroborates 2{1}, 2{3}, 2{5}, and 2{7}, both Ag 2+ and SO 4…”

“…78,79 This effect might be partially responsible for the lower efficiency of some gem-difluorinated cycloalkyl building blocks as the radical sources in the Minisci reaction. Nevertheless, other factors (e.g., radical nucleophilicity •− / SO 4 2− )] 70,83,84 shows that in the case of nonfluorinated trifluoroborates 2{1}, 2{3}, 2{5}, and 2{7}, both Ag 2+ and SO 4…”