Oxidation hydrogen peroxide disproportionation

The product is a solid yellow hydrated oxide. If prepared by a method in the absence of water, a black anhydrous product is obtained. Germanium(II) oxide is stable in air at room temperature but is readily oxidised when heated in air or when treated at room temperature with, for example, nitric acid, hydrogen peroxide, or potassium manganate(VII). When heated in the absence of air it disproportionates at 800 K ... 

Hydrogen peroxide tends to decompose in water, which explains why its solutions soon lose their oxidizing power. The reaction involved is disproportionation, combining the two halfreactions referred to above ... 

Hydrogen peroxide is normally sold for industrial use as a 30% by mass aqueous solution. When used as a hair bleach (as a 6% solution), it acts by oxidizing the pigments in the hair. A 3 % H2Q2 aqueous solution is used as a mild antiseptic in the home. Contact with blood catalyzes its disproportionation into water and oxygen gas, which cleanses the wound ... 

Olas and Wachowicz (2002) investigated the effects of tranx-resveratrol and vitamin C on oxidative stress in blood platelets. The level of 02 in control blood platelets and platelets incubated with resveratrol or vitamin C was recorded using a chemiluminescence method. On the other hand, Oh and others (2006) reported the x02 quenching activities of various freshly squeezed fruit and vegetable juices by measuring their inhibitory effects on the rubrene oxidation induced by x02 from disproportionation of hydrogen peroxide by sodium molybdate in a microemulsion system. 

Manganese is used by nature to catalyze a number of important biological reactions that include the dismutation of superoxide radicals, the decomposition of hydrogen peroxide, and the oxidation of water to dioxygen. The dinuclear manganese centers that occur in Lactobacillus plantar-aum catalase and Thermus thermophilus catalase have attracted considerable attention and many model compounds have now been synthesized that attempt to mimic aspects of these biological systems.The catalases have at least four accessible oxidation states (Mn Mn , Mn°Mn , Mn" Mn", and Mn Mn ) it is believed that the Mn"Mn"/Mn"Mn" redox couple is effective in catalyzing the disproportionation of water. 

It thus appears that hydrogen peroxide is a very powerful oxidizer, which should oxidize water. The comparison of (4,4 ) and (5,5 ) shows that H2O2 should oxidize itself (Fig. 3) in other words, hydrogen peroxide solutions should decompose by disproportionation ... 

The alkylation of quinoline by decanoyl peroxide in acetic acid has been studied kineti-cally, and a radical chain mechanism has been proposed (Scheme 207) (72T2415). Decomposition of decanoyl peroxide yields a nonyl radical (and carbon dioxide) that attacks the quinolinium ion. Quinolinium is activated (compared with quinoline) towards attack by the nonyl radical, which has nucleophilic character. Conversely, the protonated centre has an unfavorable effect upon the propagation step, but this might be reduced by the equilibrium shown in equation (167). A kinetic study revealed that the reaction is subject to crosstermination (equation 168). The increase in the rate of decomposition of benzoyl peroxide in the phenylation of the quinolinium ion compared with quinoline is much less than for alkylation. This observation is consistent with the phenyl having less nucleophilic character than the nonyl radical, and so it is less selective. Rearomatization of the cr-complex formed by radicals generated from sources other than peroxides may take place by oxidation by metals, disproportionation, induced decomposition or hydrogen abstraction by radical intermediates. When oxidation is difficult, dimerization can take place (equation 169). 

Paramagnetic NbIV octacyanide anions have been isolated as alkali metal or tetraalkylam-monium salts. K4[Nb(CN)8] has been obtained in low yield by air- or hydrogen-peroxide-oxidation of K5[Nb(CN)8] prepared by electrolytic reduction of NbCl5 in an MeOH-KCN medium.536 K4[Nb(CN)8j 2H20 disproportionated photolytically to restore the Nbm derivative. The [Nb(CN)8]4 anion is dodecahedral in the solid all Nb—C distances are equal... 

Hydrogen peroxide is a good oxidant in basic solution. It can transform Co2+ into Co3+, Fe2+ into Fe3+, and Mn2+ into Mn02. In acidic solution it can reduce Cr2Of to Cr3+ and M11O4 to Mn2+. Excess H202 spontaneously disproportionates in boiling water. 

Hydrogen peroxide is present to oxidize any tin(II) to tin(IV). The presence of stannate(II), [Sn(OH)3], causes a spongy non-adherent plate, possibly partly as a result of a disproportionation (equation 26). 

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