Aerobic Oxidation Conditions Research Articles

ChemInform Abstract: N‐Formylation of Amines Catalyzed by Nanogold under Aerobic Oxidation Conditions with MeOH or Formalin.

AbstractFor the title reaction an active and selective catalyst is presented under basic conditions.

ChemInform Abstract: Ecofriendly and Efficient One‐Pot Procedure for the Synthesis of Quinazoline Derivatives Catalyzed by an Acidic Ionic Liquid under Aerobic Oxidation Conditions.

AbstractThe investigated catalytic system is separated from the reaction mixture by simple extraction and can be reused several times.

N-Formylation of Amines Catalyzed by Nanogold under Aerobic Oxidation Conditions with MeOH or Formalin

Abstract Gold nanoclusters stabilized by poly(N-vinyl-2-pyrrolidone) (Au:PVP) are active and selective catalysts for N-formylation of amines under aerobic oxidation using methanol or formalin as a formyl source.

Ecofriendly and Efficient One-Pot Procedure for the Synthesis of Quinazoline Derivatives Catalyzed by an Acidic Ionic Liquid Under Aerobic Oxidation Conditions

A three-component condensation reaction between 2-aminobenzophenone derivatives, formaldehyde or aromatic aldehydes, and ammonium acetate efficiently provides substituted quinazolines in a one-pot reaction in the presence of Brönsted acidic ionic liquid, 1-methylimidazolium triflouroacetate ([Hmim]TFA), in conjunction with aerobic oxidation. The ionic liquid was separated from the reaction mixture by simple extraction and was recycled three times without considerable loss in activity.

ChemInform Abstract: Passerini Three‐Component Reaction of Alcohols under Catalytic Aerobic Oxidative Conditions.

AbstractAlcohols instead of aldehydes or ketones are used in the process which includes a new ternary catalytic system.

Wet oxidation of precipitation yield inhibitors in sodium aluminate solutions: Effects and proposed degradation mechanisms

Organic compounds with adjacent hydroxyl groups inhibit gibbsite (“hydrate”) precipitation in the Bayer process for the production of alumina. These hydrate yield inhibitors can be degradation products from the breakdown of larger organic molecules extracted from bauxite ore in digestion. Wet oxidation can be used to remove organics from Bayer liquor, but the nature and amounts of products are difficult to predict, due to a lack of understanding of the complex mechanisms of degradation. This fundamental study was conducted to determine the susceptibility of a set of known yield inhibitors to destruction under aerobic wet oxidation conditions and compare the degradation of the compounds under anaerobic conditions typical of normal Bayer digestion. It is shown that of the yield inhibitors investigated, aliphatic compounds with more than 5 carbons in a chain, and aromatic compounds, are readily destroyed by wet oxidation at 165 °C in the presence of oxygen. Members of the C4 family of inhibitors are more stable and require higher temperatures for full destruction. Sodium oxalate was found to be the main organic degradation product from wet oxidation of the hydrate yield inhibitors studied. A general reaction mechanism involving base-catalysed oxidation by water is proposed. This mechanism explains the formation of the degradation products observed. It also explains how organics can be oxidised anaerobically, and how hydrogen is produced under Bayer process conditions. The implications of the findings are discussed in relation to the application of wet oxidation to Bayer process refineries.

Passerini Three-Component Reaction of Alcohols under Catalytic Aerobic Oxidative Conditions

Alcohols instead of aldehydes were used in the Passerini three-component reaction under catalytic aerobic conditions. Mixing alcohols, isocyanides, and carboxylic acids in toluene in the presence of a catalytic amount of cupric chloride, NaNO(2), and TEMPO afforded, under an oxygen atmosphere, the P-3CR adducts in good yields.

ChemInform Abstract: Tandem Oxidation Process Using Ceric Ammonium Nitrate: Three‐Component Synthesis of Trisubstituted Imidazoles under Aerobic Oxidation Conditions.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Tandem Oxidation Process Using Ceric Ammonium Nitrate: Three-Component Synthesis of Trisubstituted Imidazoles Under Aerobic Oxidation Conditions

By combining a ceric ammonium nitrate (CAN)–catalyzed aerobic oxidation of α-hydroxy ketones with a subsequent three-component condensation reaction using aldehydes and ammonium acetate, highly substituted imidazole derivatives can be assembled. This reaction is an important approach for the synthesis of highly substituted imidazole derivatives and was carried out in good to excellent yields in ethanol as an environmentally benign solvent.

Ruthenium-Catalyzed Oxidative Cyanation of Tertiary Amines with Molecular Oxygen or Hydrogen Peroxide and Sodium Cyanide: sp3 C−H Bond Activation and Carbon−Carbon Bond Formation

Ruthenium-catalyzed oxidative cyanation of tertiary amines with molecular oxygen in the presence of sodium cyanide and acetic acid gives the corresponding alpha-aminonitriles, which are highly useful intermediates for organic synthesis. The reaction is the first demonstration of direct sp(3) C-H bond activation alpha to nitrogen followed by carbon-carbon bond formation under aerobic oxidation conditions. The catalytic oxidation seems to proceed by (i) alpha-C-H activation of tertiary amines by the ruthenium catalyst to give an iminium ion/ruthenium hydride intermediate, (ii) reaction with molecular oxygen to give an iminium ion/ruthenium hydroperoxide, (iii) reaction with HCN to give the alpha-aminonitrile product, H2O2, and Ru species, (iv) generation of oxoruthenium species from the reaction of Ru species with H2O2, and (v) reaction of oxoruthenium species with tertiary amines to give alpha-aminonitriles. On the basis of the last two pathways, a new type of ruthenium-catalyzed oxidative cyanation of tertiary amines with H2O2 to give alpha-aminonitriles was established. The alpha-aminonitriles thus obtained can be readily converted to alpha-amino acids, diamines, and various nitrogen-containing heterocyclic compounds.

The Significance of Type II and PrxQ Peroxiredoxins for Antioxidative Stress Response in the Purple Bacterium Rhodobacter sphaeroides

Two peroxiredoxins, classified as Type II and PrxQ, were characterized in the purple non-sulfur photosynthetic bacterium Rhodobacter sphaeroides. Both recombinant proteins showed remarkable thioredoxin-dependent peroxidase activity with broad substrate specificity in vitro. Nevertheless, PrxQ of R. sphaeroides, unlike typical PrxQs studied to date, does not contain one of the two conserved catalytic Cys residues. We found that R. sphaeroides PrxQ and other PrxQ-like proteins from several organisms conserve a different second Cys residue, indicating that these proteins should be categorized into a novel PrxQ subfamily. Disruption of either the Type II or PrxQ gene in R. sphaeroides had a dramatic effect on cell viability when the cells were grown under aerobic light or oxidative stress conditions created by exogenous addition of reactive oxygen species to the medium. Growth rates of the mutants were significantly decreased compared with that of wild type under aerobic but not anaerobic conditions. These results indicate that the peroxiredoxins are crucial for antioxidative stress response in this bacterium. The gene disruptants also demonstrated reduced levels of photopigment synthesis, suggesting that the peroxiredoxins are directly or indirectly involved in regulated synthesis of the photosynthetic apparatus.