Pavel Lederer

Methylene-blue-sensitized photochemical hydroxylation of 2-hydroxybenzoic acid by hydrogen peroxide: photocatalytic effect of ferric chloride

Abstract The methylene-blue-sensitized hydroxylation of 2-hydroxybenzoic acid by hydrogen peroxide initiated by visible radiation and catalysed by ferric chloride has been investigated. The major reaction product is 2,3-dihydroxy-benzoic acid. In the absence of iron(III), the reaction occurs extremely slowly. Iron(III) is observed to have an appreciable catalytic effect on the photosensitized reaction at concentrations as low as 10 −8 M. The first step of the reaction is the photochemical reduction of iron(III) to iron(II), i.e. the generation of Fentons reagent.

Photocatalytic effects of Fe(III) compounds on the hydroxylation of benzoic acid by hydrogen peroxide initiated by UV-radiation

The addition of FeCl3 and Na2[Fe(CN)5NO] increases the quantum yields of photochemical hydroxylation of benzoic acid by hydrogen peroxide. The photocatalytic effects operate especially when the radiation is absorbed by benzoic acid. When hydrogen peroxide is excited, the catalytic effects in the hydroxylation are small.AbstractДобавки FeCl3 и Na2[Fe(CN)5NO] повышают квантовые выходы фотохимического гидроксилирования бензойной, кислоты перекисью водорода. Фотокаталитические эффекты проявляются особенно тогда, когда радиация абсорбируется бензойной кислотой. Нри возбуждении перекисн водорода каталитический эффект гидроксииирования мал.

Photocatalytic effects of Fe(III) compounds on the hydroxylation of benzoic acid by hydrogen peroxide initiated by 589 nm radiation and sensitized by methylene blue

Abstract The hydroxylation of benzoic acid by hydrogen peroxide initiated by 589 nm radiation is catalyzed by the following Fe(III) compounds: FeCl3, K3[Fe(C2O4)3], Na2[Fe(CN)5NO], and K3[Fe(CN)6]. This photochemical reaction can be effectively sensitized by methylene blue.

Photocatalytic effects of halogenpentaamminecobalt(III) complexes on hydrogen peroxide photolysis

Abstract The effects of [Co III (NH 3 ) 5 L]A n compounds (LNH 3 , H 2 O, F − , Cl − , Br − , I − , CO 3 2− ; ACl − , Br − , I − , NO 3 − ; n = 1–3) on the thermal decomposition and photolysis of hydrogen peroxide (λ irr =365 nm) were studied. Complexes containing the fluoride anion are almost inactive in terms of their catalytic/photocatalytic effects, whereas those containing the iodide anion catalyse the thermal reaction effectively. The [Co(NH 3 ) 5 Cl]Cl 2 and [Co(NH 3 ) 5 Br]Br 2 complexes show significant photocatalytic effects including an autocatalytic reaction and a marked post-irradiation effect. The photocatalytic activity is explained by the photochemical reduction of the central ion and the subsequent formation of the peroxo complexes of the [Co II (NH 3 ) 5 O 2 Co II (NH 3 ) 5 ] 4+ type.

Solvent effects in the photolysis of 1,2,3,4-tetrahydro-1-naphthylhydroperoxide. Photocatalytic effect of Co(III) 2,4-pentanedionate

The effect of various solvents on the photoinitiated decomposition of 1,2,3,4-tetrahydro-1-naphthylhydroperoxide (THP) with and without added Co(III) 2,4-pentanedionate has been studied. The conversion of THP, formation of major products and change in the oxidation state of the metal ion have been investigated in different solvents.AbstractИсследовали влияние различных растворителей на фотоинициированное разложение 1, 2, 3, 4-тетрагидро-1-нафтилгидропероксида (ТГП) с добавкой и без добавки Co(III) 2,4-пентандионата. Превращение ТГП, образование главных продуктов и изменение окисленного состояния металлического иона исследовали в различных растворителях.