Remarkable efficiency of iron(III) versus manganese(III) tetraphenylporphyrins as catalysts for fast and quantitative oxidation of sulfides into sulfones by hydrogen peroxide

1998 ◽  
Vol 76 (6) ◽  
pp. 770-775 ◽  
Author(s):  
Antonio Marques ◽  
Massimo di Matteo ◽  
Marie-Françoise Ruasse
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Radical Cation ◽  
Oxygen Transfer ◽  
Sulfide Oxidation ◽  
Oxidation Of Sulfides ◽  
Active Intermediate

The efficiency of various metallo-phtalocyanines (Pht) and -tetraphenylporphyrins (TPP) as catalysts for the H2O2 oxidations of dibenzylsulfide, phenylchloroethylsulfide, and thioanisole is investigated in ethanol and acetonitrile, using imidazole as a cocatalyst. Neither PhtNiII nor TPPCoII exhibits any catalytic activity. PhtMnII and TPPMnIIICl accelerate markedly these reactions but do not promote quantitative oxidations, at most 70% of the sulfides being transformed into sulfoxides. In contrast, with PhtFeII sulfoxides are obtained with a 100% yield from sulfides. Finally, the only catalyst able to oxidize sulfides rapidly (<5 min), completely and quantitatively (100% sulfone) is TPPFeIIICl in EtOH. The absence of any by-product, disulfide in particular, suggests that a free sulfenium radical cation is not an active intermediate in these reactions. The marked differences in the behaviour of TPPMnIIICl and TPPFeIII Cl are analyzed by comparing the rates of the catalyst decomposition, of the sulfoxide and sulfone formation as a function of the hydrogen peroxide concentration. The results are discussed in terms of a competition between the several oxidative pathways and a possible mechanism for the oxygen transfer to sulfides.Key words: sulfide, oxidation, H2O2, manganese(III) or iron(III) tetraphenylporphyrin.

The oxidation of sulfides by chromium(V)

2003 ◽  
Vol 81 (1) ◽  
pp. 75-80 ◽  
Author(s):  
Carmela R Jackson Lepage ◽  
Lynn Mihichuk ◽  
Donald G Lee
Keyword(s):  
Electron Transfer ◽  
Molecular Orbital ◽  
Radical Cation ◽  
Oxygen Transfer ◽  
Single Electron ◽  
Frontier Molecular Orbital ◽  
Molecular Orbital Calculations ◽  
Single Electron Transfer ◽  
Oxidation Of Sulfides

The mechanism for the oxidation of sulfides by [(me4-salen)CrV(O)(pyO)]CF3SO3, where me4-salen is 8,8,8',8'-tetramethylsalen and pyO is pyridine N-oxide, has been investigated. Results from Hammett correlations on the rates of oxidation of substituted thioanisoles, frontier molecular orbital calculations, and product studies are consistent with a mechanism that is initiated by a single electron transfer to give a radical cation intermediate.Key words: oxidation, chromium(V), sulfides, radical cation, oxygen transfer.

scholarly journals Efficient and selective hydrogen peroxide-mediated oxidation of sulfides in batch and segmented and continuous flow using a peroxometalate-based polymer immobilised ionic liquid phase catalyst

2015 ◽  
Vol 17 (3) ◽  
pp. 1559-1571 ◽  
Author(s):  
S. Doherty ◽  
J. G. Knight ◽  
M. A. Carroll ◽  
J. R. Ellison ◽  
S. J. Hobson ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Ionic Liquid ◽  
Liquid Phase ◽  
Continuous Flow ◽  
Sulfide Oxidation ◽  
Oxidation Of Sulfides ◽  
Highly Efficient ◽  
Mediated Oxidation

Highly efficient sulfide oxidation has been achieved under segmented and continuous flow using a peroxometalate-based polymer immobilised ionic liquid phase catalyst.

Non-peripherally alkyl substituted ruthenium phthalocyanines as catalysts in the epoxidation of alkenes

2015 ◽  
Vol 19 (04) ◽  
pp. 582-594 ◽  
Author(s):  
Charles A. Enow ◽  
Charlene Marais ◽  
Barend C.B. Bezuidenhoudt
Keyword(s):  
Catalytic Activity ◽  
Oxygen Transfer ◽  
Catalytic Systems ◽  
Highly Active ◽  
Trans Stilbene ◽  
Active Intermediate ◽  
High Valent ◽  
Epoxidation Of Alkenes

Non-peripherally alkyl substituted ruthenium phthalocyanines were demonstrated to be highly active epoxidation catalysts. It is compatible with pyridine N-oxides, and especially 2,6-dichloropyridine N-oxide. The catalytic activity towards a variety of alkenes was comparable to that published for other catalytic systems, but superior in the cases of 1,2-dihydronaphthalene and trans-stilbene. Linear substituents on the non-peripheral sites of the phthalocyanine were able to reduce aggregation and increase the solubility of the catalyst without compromising its activity by steric congestion as all substituted catalysts were more reactive than the unsubstituted phthalocyanine, whereas the bulky isopentyl and cyclohexyl substituted catalysts were less active than those with linear substituents. Although the epoxidation mechanism and the exact active intermediate is still ambigious, it likely involves the coordination of the N-oxide to ruthenium and subsequent transfer of the oxygen to the metal to form a high-valent oxo-ruthenium species. It is proposed that the alkene approaches this metal oxo moiety from the top and that oxygen transfer to the alkene is concerted with concomitant stereoretention.

Decomposition of hydrogen peroxide on a two-component NiO-CdO catalyst and the effect of ionizing radiation on its catalytic properties

1979 ◽  
Vol 44 (4) ◽  
pp. 1015-1022 ◽  
Author(s):  
Viliam Múčka
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Nickel Oxide ◽  
Catalytic Properties ◽  
Cadmium Oxide ◽  
Chemisorb Oxygen ◽  
Composition Region ◽  
Chemisorbed Oxygen ◽  
Two Component

The catalytic properties of two-component catalyst nickel oxide-cadmium oxide with the proportions of the components covering the whole composition region 0-100% were examined by studying the decomposition of hydrogen peroxide in aqueous solution on it. In the range 0-25 mol.% CdO, cadmium oxide is found to affect infavourably the ability of nickel oxide to chemisorb oxygen. The amount of the chemisorbed oxygen increases several times on gamma irradiation of the samples. The effect of cadmium oxide on the catalytic activity of the system shows up in fresh samples only indirectly via the changed amount of the oxygen chemisorbed. In older samples the initial catalytic activity of the system is changed, which can be explained based on the concept of bivalent catalytic centres in terms of the co-action of the catalytic centres of the two oxides, which are in equilibrium. The irradiation of the system under study speeds up the processes leading to the establishing of this equilibrium which is thermally very stable, and results in a substantial increase of the catalytic activity of the samples investigated.

Hydrogen peroxide decomposition on a two-component CuO-Cr2O3 catalyst

1988 ◽  
Vol 53 (8) ◽  
pp. 1636-1646 ◽  
Author(s):  
Viliam Múčka ◽  
Kamil Lang
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Extreme Values ◽  
Catalytic Properties ◽  
Active Components ◽  
Catalytic Systems ◽  
Heterogeneous Catalytic ◽  
Peroxide Decomposition ◽  
Two Component ◽  
Catalytically Active

Some physical and catalytic properties of the two-component copper(II)oxide-chromium(III)oxide catalyst with different content of both components were studied using the decomposition of the aqueous solution of hydrogen peroxide as a testing reaction. It has been found that along to both basic components, the system under study contains also the spinel structure CuCr2O4, chromate washable by water and hexavalent ions of chromium unwashable by water. The soluble chromate is catalytically active. During the first period of the reaction the equilibrium is being established in both homogeneous and heterogeneous catalytic systems. The catalytic activity as well as the specific surface area of the washed solid is a non-monotonous function of its composition. It seems highly probable that the extreme values of both these quantities are not connected with the detected admixtures in the catalytic system. The system under study is very insensitive with regard to the applied doses of gamma radiation. Its catalytic properties are changed rather significantly after the thermal treatment and particularly after the partial reduction to low degree by hydrogen. The observed changes of the catalytic activity of the system under study are very probably in connection with the changes of the valence state of the catalytically active components of the catalyst.

Selective Oxidation of Sulfides to Sulfoxides/Sulfones by 30% Hydrogen Peroxide

2012 ◽  
Vol 187 (7) ◽  
pp. 822-830 ◽  
Author(s):  
Ying He ◽  
Xiaoyun Ma ◽  
Hai Feng Ji ◽  
Xin Bing Zha ◽  
Hongliang Jiang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Selective Oxidation ◽  
Oxidation Of Sulfides
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