Josef Vepřek-Šiška

Photochemical hydroxylation of salicylic acid by hydrogen peroxide. Photocatalytic effect of Fe(III)

The rate and quantum yields of photoinitiated hydroxylation of salicylic acid by hydrogen peroxide can be increased substantially by adding Fe(III) compounds to the reaction mixture. The UV radiation reduces the catalytically inactive Fe(III) to catalytically active Fe(II) during the reaction, thereby continuously producing the Fenton reagent.AbstractСкорость и квантовые выходы фотоинициированного гидроксилирования салициловой кислоты с помощью перекиси водорода могут быть значительно повышены добавлением соединений Fe(III) к реакционной смеси. У Ф облучение восстанавливает каталитически неактивное Fe(III) до каталитически активного Fe(II) в ходе реакции, тем самым неапрерывно вырабатывая раегент фентона.

The fate of the inhibitor in inhibited oxidation of organic substrate by dioxygen

Abstract The reaction of benzaldehyde with dioxygen catalyzed by Fe(III)-pentanedionate and inhibited by 2-propanol was employed to study the conditions of the inhibitor oxidation. Though the inhibitor affects the reaction in a manner ascribed to chain-breaking inhibitors, it is not oxidized during the induction period. Its partial oxidation (20–50%) only occurs in a parallel reaction coupled with benzaldehyde oxidation. The relative amount of the inhibitor oxidized decreases with its initial concentration.

Notizen: Oxidation of Tetraline by Dioxygen. Effect of Fe(acac)3 on the Thermal and Photoinitiated Reactions

Abstract The photochemical oxidation of tetraline by dioxygen is catalyzed by ferric acetylacetonate (iron(III) 2,4-pentadionate), the reaction rate increasing markedly with temperature. The rate-determining step of the photochemical oxidation is presumably a catalyzed thermal reaction.

Could Hydrogen Peroxide Photolysis Occur in the Absence of Transition Metals

Quantum yields of hydrogen peroxide photolysis increase with the square root of concentration of added Cu(II). The cupric ions are photo-catalytically active already at trace concentrations (10-7), i.e., at the concentrations present in any real reaction system. Hydrogen peroxide photolysis is completely suppressed on addition of complexing agents such as EDTA. It is believed that no hydrogen peroxide photolysis would occur in complete absence of photo-catalytically active transition metal ions

Notizen: Catalytic Effect of Ferric Ions on the Photoinitiated Antoxidation of Sulfite

The rate of the photoinitiated autoxidation of sulfite is considerably influenced by ferric ions in trace concentrations.