An ESR study of irradiated mixtures of hydrogen peroxide and Cu(II) complexes at 77 K

1988 ◽  
Vol 53 (12) ◽  
pp. 3080-3088 ◽  
Author(s):  
Pavel Stopka
Keyword(s):  
Hydrogen Peroxide ◽  
High Pressure ◽  
Catalytic Activity ◽  
Oxalic Acid ◽  
Hydroxyl Radicals ◽  
Room Temperature ◽  
Active Species ◽  
Mercury Lamp ◽  
Catalytically Active ◽  
High Concentrations

When aqueous solutions containing hydrogen peroxide and CuSO4 are irradiated by a high-pressure mercury lamp at room temperature and at 77 K, hydrogen peroxide decomposes and hydroxyl radicals generated in high concentrations coordinate to CuSO4. The catalytic activity of Cu(II), which depends on the choice of the ligand (triene, diene, ethylenediamine, ammonia, EDTA, oxalic acid and glycerine) and the proportion between the monomeric and dimeric forms of the Cu(II) complex, shows a maximum at a concentration of 10-4 mol dm-3. The catalytically active species is the monomeric Cu(II) complex, the dimer being inactive.

scholarly journals High Catalytic Activity of Heterometallic (Fe6Na7 and Fe6Na6) Cage Silsesquioxanes in Oxidations with Peroxides

2017 ◽  
Author(s):  
Alexey I. Yalymov ◽  
Alexey N. Bilyachenko ◽  
Mikhail M. Levitsky ◽  
Alexander A. Korlyukov ◽  
Victor N. Khrustalev ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Hydroxyl Radicals ◽  
Acetonitrile Solution ◽  
High Catalytic Activity ◽  
X Ray ◽  
Complex Ii ◽  
Alkyl Hydroperoxides ◽  
Catalytically Active ◽  
Very High

Two types of heterometallic (Fe(III),Na) silsesquioxanes [Ph5Si5O10]2[Ph10Si10O21]Fe6(O2‒)2Na7(H3O+)(MeOH)2(MeCN)4.5.1.25(MeCN), I, and [Ph5Si5O10]2[Ph4Si4O8]2Fe6Na6(O2‒)3(MeCN)8.5(H2O)8.44, II, were obtained and characterized. X-Ray studies established distinctive structures of both products, with pair of Fe(III)-O-based triangles surrounded by siloxanolate ligands, giving fascinating cage architectures. Complex II proved to be catalytically active in the formation of amides from alcohols and amines, thus becoming a rare example of metallasilsesquioxanes performing homogeneous catalysis. Benzene, cyclohexane and other alkanes, as well as alcohols, can be oxidized in acetonitrile solution to phenol, the corresponding alkyl hydroperoxides and ketones, respectively, by hydrogen peroxide in air in the presence of catalytic amounts of complex II and trifluoroacetic acid. Thus, the cyclohexane oxidation at 20 °C gave oxygenates in very high for alkanes yield (48% based on alkane). The kinetic behaviour of the system indicates that the mechanism includes the formation of hydroxyl radicals generated from hydrogen peroxide in its interaction with diiron species. The latter are formed via monomerization of starting hexairon complex with further dimerization of the monomers.

Sewage sludge as a precursor of adsorbents/catalysts for environmental applications

2007 ◽  
Vol 2 (1) ◽  
Author(s):  
A. Ros ◽  
C. Canals-Batlle ◽  
M.A. Lillo-Ródenas ◽  
E. Fuente ◽  
M. A. Montes-Morán ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Room Temperature ◽  
Waste Water Treatment ◽  
Textural Properties ◽  
Active Species ◽  
Elemental Sulphur ◽  
Gaseous Emissions ◽  
Removal Experiments ◽  
Catalytically Active

This paper focuses on the valorisation of solid residues obtained from the thermal treatment of sewage sludge. In particular, sewage sludge samples were collected from two waste water treatment plants (WWTPs) with different sludge line basic operations. After drying, sludges were heated up to 700 °C in appropriate ovens under diluted air (gasification) and inert (pyrolysis) atmospheres. The solids obtained, as well as the dried (raw) sludges, were characterised to determine their textural properties and chemical composition, including the speciation of their inorganic fraction. All the materials under study were employed as adsorbents/catalysts in H2S removal experiments at room temperature. It was found that, depending on the particular sludge characteristics, outstanding results can be achieved both in terms of retention capacities and selectivity. Some of the solids outperform commercially available sorbents specially designed for gaseous emissions control. In these adsorbents/catalysts, H2S is selectively oxidised to elemental sulphur most likely due to the presence of inorganic, catalytically active species. The role of the carbon-enriched part on these solids is also remarked.

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.

Hydrosilylation of alkenes and ketones catalyzed by nickel(II) indenyl complexes

2003 ◽  
Vol 81 (11) ◽  
pp. 1299-1306 ◽  
Author(s):  
Frédéric-Georges Fontaine ◽  
René-Viet Nguyen ◽  
Davit Zargarian
Keyword(s):  
Reaction Mechanism ◽  
Key Words ◽  
Room Temperature ◽  
Active Species ◽  
The Other ◽  
Silyl Ethers ◽  
Cationic Species ◽  
Catalytically Active ◽  
High Yields ◽  
Indenyl Complexes

Abstraction of Cl– from the complexes (indenyl)Ni(PPh3)Cl generates cationic species that are effective precatalysts for the hydrosilylation of some olefins and ketones. For instance, the mixture of (1-Me-indenyl)Ni(PPh3)Cl and NaBPh4 (or methylaluminoxane) reacts at room temperature with ca. 100 equiv. each of PhSiH3 and styrene to produce [1-phenyl-1-ethyl](phenyl)silane, PhCH(CH3)(SiPhH2), in 50%–80% yield. The same system can also catalyze the hydrosilylation of 1-hexene and norbornene, but the products arising from these substrates consist of mixtures of regio- and stereoisomers. On the other hand, ketone hydrosilylation is regiospecific, giving the corresponding silyl ethers in high yields. A number of experimental observations have indicated that the initially generated Ni-based cation is not the catalytically active species. Indeed, the cationic initiators may be replaced by LiAlH4 or AlMe3, which generate the corresponding Ni-H or Ni-Me derivatives, respectively. Moreover, the observed regioselectivity for the addition of PhSiH3 to styrene (i.e., predominant addition of the silyl fragment to the α-C) is opposite of what would be expected if the reaction mechanism involved carbocationic intermediates. A new mechanism is proposed in which the active species is a Ni-H species originating from the transfer of H– from PhSiH3 to the initially generated Ni cation. Key words: hydrosilylation, nickel indenyl complexes, cationic complexes, hydride intermediates.

scholarly journals Insights into the mechanistic and synthetic aspects of the Mo/P-catalyzed oxidation of N-heterocycles

2014 ◽  
Vol 12 (19) ◽  
pp. 3026-3036 ◽  
Author(s):  
Oleg V. Larionov ◽  
David Stephens ◽  
Adelphe M. Mfuh ◽  
Hadi D. Arman ◽  
Anastasia S. Naumova ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Active Species ◽  
Catalytically Active ◽  
Synthetic Studies ◽  
Catalyzed Oxidation ◽  
Shed Light

Mechanistic and synthetic studies of the Mo/P-catalyzed N-oxidation of N-heterocycles with hydrogen peroxide shed light on the role and nature of the catalytically active species.

Chemoselective hydrogen peroxide oxidation of primary alcohols to aldehydes by a water-soluble and reusable iron(iii) catalyst in pure water at room temperature

2017 ◽  
Vol 41 (6) ◽  
pp. 2372-2377 ◽  
Author(s):  
Qi Yan ◽  
Ye Chen Fang ◽  
Yun Xue Jia ◽  
Xin Hong Duan
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Room Temperature ◽  
Pure Water ◽  
Water Soluble ◽  
High Catalytic Activity ◽  
Peroxide Oxidation ◽  
Primary Alcohols ◽  
Hydrogen Peroxide Oxidation

A novel, water-soluble and reusable FeCl3 catalyst showed high catalytic activity and chemoselectivity in the H2O2-oxidation of primary alcohols into aldehydes.

Studies of the reactions of hydroxyl radicals. II

1966 ◽  
Vol 291 (1424) ◽  
pp. 85-93 ◽  
Keyword(s):  
Hydrogen Peroxide ◽  
Carbon Monoxide ◽  
Hydroxyl Radicals ◽  
Room Temperature ◽  
Order Reaction ◽  
Methyl Radicals ◽  
Third Order ◽  
Experimental Conditions ◽  
Homogeneous Decomposition ◽  
Methane Carbon

The homogeneous decomposition of hydrogen peroxide has been used as a source of hydroxyl radicals. In part I values were reported for the relative rates of reaction of hydroxyl radicals with methane, carbon monoxide, formaldehyde and hydrogen peroxide. In this paper these values are confirmed for different experimental conditions and more consideration is given to details of subsequent reactions. The reaction of methyl radicals with oxygen has previously been shown to occur by a third order reaction both at 200 °C (Hoare & Walsh 1957) and at room temperature (Christie 1958). Present results show that the reaction is second order at 525 °C as suggested by Barnard & Honeyman (1964). In the absence of added oxygen, methyl radicals combine to give ethane which in turn reacts with hydroxyl radicals twelve times more rapidly than does methane.

scholarly journals THE CATALYTIC ACTIVITY OF THE DEVELOPING HEN'S EGG

1910 ◽  
Vol 12 (1) ◽  
pp. 12-18 ◽  
Author(s):  
M. C. Winternitz ◽  
W. B. Rogers
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Amniotic Fluid ◽  
Germinal Center ◽  
Room Temperature ◽  
Adult Rabbit ◽  
Blood Brain ◽  
Hen’S Egg ◽  
Fertilized Egg ◽  
Catalytic Power

A. The catalytic activity of the tissues of newly born and adult rabbits. 1. There is practically no difference between the catalytic power of the blood, brain or muscle of newly born and adult rabbits. 2. The kidneys and lungs are less active in the newly born, but increase rapidly during the first days of life. 3. The liver is more active in the newly born than in the adult rabbit. B. The catalytic activity of the developing hen's egg. 1. The entire fresh egg has a slight but definite catalytic power which remains practically constant even though the egg be kept for several months at room temperature. 2. The separate parts of the egg, germinal center, yolk and white have practically no activity when tested individually. 3. The entire unfertilized egg shows no catalytic activity even after incubation at 38° C. for twenty-one days. 4. The germinal portion of the incubated fertilized egg rapidly acquires the power of decomposing hydrogen peroxide, while the yolk and white together or separately show no such increase, nor is there any activity to be found in the amniotic fluid. 5. It seems, therefore, that the catalytic power of the developing egg is formed from the contents of the egg which themselves show little action, by the developing germinal portion, independent of all external influences except heat (38° C.) and air.

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