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.

Oxidative Desulfurization Using Polyoxometalates

Abstract: Oxidative desulfurization of model compounds (benzothiophene, dibenzothiophene, 4,6-dimethyldibenzothiophene) with hydrogen peroxide/acetic acid using polyoxometalates as catalysts has been studied. The tetrabutylammonium salts of [W6O19]2-, [V(VW11)O40]4-, [PVW11O40]4-, and [PV2Mo10O40]4- were prepared, and their activities were compared with (VO)2P2O7. The experimental results show that the highest active catalyst is [V(VW11)O40]4-. The method was also used for the treatment of gas oil. The combination of solvent extraction and alumina adsorption can efficiently separate sulfone products. The resulting oil contained less than 0.055% sulfur, and this corresponds to 90 % removal.

Inactivation Mechanism of Ascorbate Peroxidase at Low Concentrations of Ascorbate; Hydrogen Peroxide Decomposes Compound I of Ascorbate Peroxidase

Abstract: One of the characteristic properties of ascorbate peroxidase (APX), which distinguishes it from guaiacol peroxidase, Cyt c peroxidase and glutathione peroxidase, is the rapid inactivation of the enzyme under conditions where an electron donor is absent. When thylakoid-bound APX (tAPX) in 100 f/M ascorbate was diluted 500-fold with an ascorbate-depleted medium, the enzymatic activity was lost with half time of about 15 s. The inactivation of tAPX was suppressed under anaerobic conditions and also by the addition of catalase, but it was unaffected by the addition of superoxide dismutase. These observations suggest that hydrogen peroxide at nanomolar levels, produced by autooxidation of ascorbate at lower than micromolar levels, might participate in the inactivation of tAPX. The participation of hydrogen peroxide was confirmed by the inactivation of tAPX upon incubation with hydrogen peroxide under anaerobic conditions. In the absence of ascorbate, the heme of the two-electron-oxidized intermediate of tAPX (designated Compound I) is decomposed by hydrogen peroxide. Thus, the instability of Compound I to hydrogen peroxide is responsible for the inactivation of APX when ascorbate is not available for Compound I and the enzyme cannot turnover.