Hydrogen peroxide

About: Hydrogen peroxide is a research topic. Over the lifetime, 42583 publications have been published within this topic receiving 1043732 citations. The topic is also known as: H2O2 & dioxidane.

The use of copper(II) oxide nanorod bundles for the non-enzymatic voltammetric sensing of carbohydrates and hydrogen peroxide

Abstract: CuO nanorod agglomerates were synthesised via a simple hydrothermal method in the presence of polyethylene glycol (PEG; Mw 20,000). The chemical composition, size and morphology of the prepared CuO material was investigated by X-ray powder diffraction, voltammetry and transmission electron microscopy. A basal plane pyrolytic graphite electrode (bppg) was modified with the CuO nanorods and used to study the direct oxidation of glucose, fructose and sucrose in an alkaline medium (0.1 M NaOH). The CuO nanorod modified electrode was shown to have far larger analytical signals in the presence of carbohydrates than an electrode modified with CuO microparticles and gave a limit of detection for glucose of 1.2 × 10−6 M which is comparable with the literature. As such it is a non-selective, non-enzymatic, total carbohydrate sensor. The CuO nanorod modified bppg electrode was also used for the detection of H2O2, it was shown that in this case it is preferential to look at the oxidation of the analyte due to interference of oxygen in the reductive window. A limit of detection of 2.2 × 10−7 M was obtained for the sensing of hydrogen peroxide in an alkaline solution.

Epoxidation of Alkenes with Bicarbonate-Activated Hydrogen Peroxide

Abstract: We describe here the discovery of the bicarbonate-catalyzed epoxidation of alkenes with aqueous hydrogen peroxide at nearneutral pH. For some substrates, the procedure is comparable in apparent synthetic utility to the best methods now available for H2O2-based alkene expoxidations that avoid extensive hydrolytic formation of diol (e.g., ligand-accelerated methyltrioxorhenium/ H2O2). The new process features a stable main group catalyst/ activator of unexpected simplicity (bicarbonate ion) and can be applied readily in water or mixed aqueous solutions under homogeneous conditions. Hydrogen peroxide is a high oxygen content, environmentally friendly oxidant for which water is the sole byproduct in heterolytic oxidations,2 but it is a slow oxidant in the absence of activation3 due to the poor leaving tendency of the hydroxide ion.4 Transition metal salts or complexes have been used as catalysts for alkene epoxidations with aqueous H2O2 .5,6 Other methods for activation of H2O2 include forming reactive peroxyacids from carboxylic acids,7 forming peroxycarboximidic acid from acetonitrile (Payne oxidation),8 generation of peroxyisourea,9 or using sodium perborate or sodium percarbonate (Na2CO3‚1.5H2O2) in strongly basic solution.10 Such systems can have one or more disadvantages, such as toxic or rapidly decomposed metal catalysts, oxidative decomposition of organic ligands, organic byproducts, or strongly acidic or basic reaction conditions that decompose the desired epoxide product. A method for activating hydrogen peroxide with bicarbonate ion was described by Drago and co-workers11 and Richardson et al.12 in their studies of sulfide oxidations in alcohol/water solvents. In the bicarbonate-activated peroxide (BAP) system,13 the active oxidant peroxymonocarbonate ion, HCO4, is formed with t1/2 ≈ 5 min (eq 1), presumably via the perhydration of CO2

Peroxiredoxin 2 and Peroxide Metabolism in the Erythrocyte

Abstract: Peroxiredoxin 2 (Prx2) is an antioxidant enzyme that uses cysteine residues to decompose peroxides. Prx2 is the third most abundant protein in erythrocytes, and competes effectively with catalase and glutathione peroxidase to scavenge low levels of hydrogen peroxide, including that derived from hemoglobin autoxidation. Low thioredoxin reductase activity in the erythrocyte is able to keep up with this basal oxidation and maintain the Prx2 in its reduced form, but exposure to exogenous hydrogen peroxide causes accumulation of the disulfide-linked dimer. The high cellular concentration means that although turnover is slow, erythrocyte Prx2 can act as a noncatalytic scavenger of hydrogen peroxide and a sink for hydrogen peroxide before turnover becomes limiting. The consequences of Prx2 oxidation for the erythrocyte are not well characterized, but mice deficient in this protein develop severe hemolytic anemia associated with Heinz body formation. Prx2, also known as calpromotin, regulates ion transport by associating with the membrane and activating the Gardos channel. How Prx2 redox transformations are linked to membrane association and channel activation is yet to be established. In this review, we discuss the functional properties of Prx2 and its role as a major component of the erythrocyte antioxidant system.

Photoinduced generation of hydrogen peroxide and hydroxyl radicals in melanins

Abstract: The hydrogen peroxide produced during photolysis of melanin pigments has been measured using an oxidase electrode. The photooxidation has been shown to occur via the superoxide intermediate. In the presence of superoxide dismutase the rate of photo-induced production of hydrogen peroxide is increased, reflecting the ability of melanin to scavenge superoxide radicals. Evidence for metal-ion dependent formation of hydroxyl radicals during photooxidation of melanin pigments was obtained using electron spin resonance-spin trapping procedures. Superoxide dismutase increased the rate of formation of hydroxyl radicals in the system. Mechanisms of metal ion-induced production of hydroxyl radicals during photolysis of melanin pigments are discussed.

The Rise of Hydrogen Peroxide as the Main Product by Metal-Free Catalysis in Oxygen Reductions.

Abstract: One of the recent trends in electrocatalytic reactions involves the oxygen reduction reaction (ORR), where a new paradigm has been shaped to exploit this reaction for the synthesis of hydrogen peroxide (H2 O2 ). H2 O2 is a very versatile chemical of high commercial value, prepared currently through poorly sustainable processes. The emergence of metal-free carbon catalysts for the selective synthesis of H2 O2 is expected to revolutionize ORR research, beckoning at the development of new industrial schemes. The complexities of the mechanism and the factors dominating the selectivity of the process have been unveiled through a combination of theoretical and experimental studies.