Search results for "OXIDATION"
showing 10 items of 1913 documents
Greatly enhanced intermolecular π-dimer formation of a porphyrin trimer radical trications through multiple π bonds.
2010
A trefoil-like porphyrin trimer linked by triphenylamine (TPA-TPZn(3)) was synthesized. A three-electron oxidation of TPA-TPZn(3) forms a radical trication (TPA-TPZn(3)(3+)), in which each porphyrin ring undergoes a one-electron oxidation. The radical trication TPA-TPZn(3)(3+) spontaneously dimerizes to afford (TPA-TPZn(3))(2)(6+) in CH(2)Cl(2) . The characteristic charge-resonance band due to the charge delocalization over the π system of (TPA-TPZn(3))(2)(6+) was observed in the NIR region. The initial oxidation potential of TPA-TPZn(3) is negatively shifted relative to that of the corresponding monomer porphyrin, which results from the stabilization of the oxidized state of TPA-TPZn(3) as…
Selective propane oxidation over MoVSbO catalysts. On the preparation, characterization and catalytic behavior of M1 phase
2009
Nb-free (SbO)(2)M(20)O(56) catalysts (M = Mo, V) presenting pure M1 phase have been prepared by a post-synthesis treatment with hydrogen peroxide of a heat-treated MoVSbO mixed metal oxide catalyst previously prepared by hydrothermal method. The characterization of catalysts and their results for propane oxidation suggest that the optimization in the preparation of the M1 phase depends strongly on the washing procedure. The optimal removing of Sb species formed during post-synthesis treatment can explain the improvement in the catalytic activity; while the better selectivity to acrylic acid of the catalysts obtained by post-synthesis treatment can be explained by the elimination of M2 phase…
Iron Fortification of Milk and Dairy Products
2013
Blood haemoglobin level is used to define anaemia. Thresholds are given by category of age, of sex, and also of physiological status such as pregnancy. For example, the threshold is 120 g L–1 of haemoglobin in blood for a nonpregnant adult woman, 110 for a pregnant woman, 130 for a man older than 15 years, 110 for a child under 5 years… Iron deficiency constitutes the most important worldwide problem of human nutrition. In 2005, 1.62 billions of people were concerned by iron deficiency. Iron deficiency is encountered mostly in poor countries and particularly in Western Pacific, except Australia and New Zealand, in India and Pakistan, in the great majority of countries in Africa, in South Am…
Electrochemical Abatement of Organic Pollutants in Water by Electro- Fenton with Natural Heterogeneous Catalysts Under Pressure
2020
In recent decades, electrochemical advanced oxidation processes (EAOPs) have proved as alternative technologies to conventional processes. Indeed, EAOPs can often allow to treat wastewater containing toxic and POPs. Among them, electro-Fenton (EF) is considered particularly promising for the treatment of recalcitrant organics, since it presents various advantages, including high abatements for many organic pollutants, simplicity of equipment and operations, relatively low cost and low consumption of chemicals. Recently, the utilization of some natural heterogeneous catalysts was proposed in order to avoid some disadvantages of the conventional EF process. In this frame, in this work EF proc…
Oppenauer Oxidation of Secondary Alcohols with 1,1,1-Trifluoroacetone as Hydride Acceptor
2007
1,1,1-Trifluoroacetone (2a) reacts as a hydride-acceptor in the Oppenauer oxidation of secondary alcohols (1) in the presence of diethylethoxyaluminum. The oxidant allows for selective oxidation of secondary alcohols in the presence of primary alcohols.
Solvent free oxidation of primary alcohols and diols using thymine iron(III) catalyst.
2010
In this study, we developed an efficient and selective iron-based catalyst system for the synthesis of ketones from secondary alcohols and carboxylic acids from primary alcohol. In situ generated iron catalyst of thymine-1-acetate (THA) and FeCl(3) under solvent-free condition exhibits high activity. As an example, 1-octanol and 2-octanol were oxidized to 1-octanoic acid and 2-octanone with 89% and 98% yields respectively.
Effect of flupirtine on Bcl-2 and glutathione level in neuronal cells treated in vitro with the prion protein fragment (PrP106-126).
1997
Flupirtine, trade name Katadolon, is a centrally acting nonopioid analgesic that has recently been found to display cytoprotective activity in vitro and in vivo on neurons induced to undergo apoptosis. This report shows that the PrP106-126 fragment of the prion protein, which is the likely etiological agent for a series of encephalopathies, is toxic to cortical neurons in vitro. Simultaneously, PrP106-126 influences the molecular GSH content and the bcl-2 expression in neurons. Significant toxicity (32% reduction in cell viability) was observed at a concentration of 50 microM of the peptide after 9 days of incubation, while at higher concentrations toxicity increased to 70%. Neurotoxicity w…
Activity of SiO2 supported gold-palladium catalysts in CO oxidation
2003
Abstract Bimetallic Au-Pd catalysts supported on silica with different Au/Pd atomic ratios were prepared by simultaneous reduction of palladium and gold precursors by ethanol in the presence of the polymer, polyvinylpyrrolidone (PVP). Formation of alloyed particles was detected by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and CO chemisorption measurements. The catalysts were tested in the catalytic oxidation of CO using a plug–flow reactor. The CO conversion was determined as a function of temperature. The monometallic palladium and the palladium-rich catalysts behaved quite similarly and were the most active catalysts. …
Synthesis and support composition effects on CH4 partial oxidation over Ni–CeLa oxides
2015
Abstract Two series of Ni (6 wt%) catalysts supported over CeO 2 , La 2 O 3 and mixed CeO 2 –La 2 O 3 were prepared by co-precipitation and by wet-impregnation. The effect of the two Ni loading procedures on the catalyst structural properties was investigated by XRD, TPR and XPS. The catalytic behavior of the catalysts was tested in the methane partial oxidation reaction performed at 1 atm in a temperature range of 400–800 °C using dilute feed gas mixture with CH 4 /O 2 = 2 and gas hourly space velocity of 60,000 ml g −1 h −1 . Total methane combustion was observed within the 450 °C ≤ T ≤ 650 °C temperature range. Above 650 °C partial oxidation of methane started to occur, reaching at 80…
A hybrid catalyst for decontamination of organic pollutants based on a bifunctional dicopper(II) complex anchored over niobium oxyhydroxide
2017
Abstract This article describes the preparation and characterization of a hybrid oxidation catalyst for decontamination of organic pollutants which involves a bifunctional dicopper(II) complex and the niobium(V) oxyhydroxide as the active species, the later one being also a solid support. The pH range for the existence of the active species was determined by potentiometric and UV–vis spectroscopy at 25 °C and 0.15 M NaCl in a H 2 O/EtOH (70:30 v/v) solvent mixture containing copper(II) and the ligand N , N -2,2′-ethylenediphenylenebis(oxamic acid) (H 4 L). As far as the hybrid material is concerned, FTIR, FT-Raman, TEM and SEM images, surface area and TG/DTA analyses showed the occurrence o…