Hydrogen peroxide reactions with metals

The thermodynamic functions (AH, AS, AG(298 K)) of hydrogen peroxide reactions with transition metal ions in aqueous solutions are presented in Table 10.1. We see that AG(298K) has negative values for reactions of hydroxyl radical generation with Cu1+, Cr2+, and Fe2+ ions and for reactions of hydroperoxyl radical generation with Ce4+, Co3+, and Mn3+. 

The first step in the chemical degradation mechanism is the production of hydrogen peroxide, which may be produced as a by-product of the oxygen reduction reaction on the cathode, or may be produced chemically by crossover of either hydrogen or oxygen to the opposite electrode. The hydrogen peroxide reacts with metal ion contaminants (M"+) acting as Fenton s catalysts to produce very reactive hydroperoxy and peroxy radicals, as described by equation (1.35) and equation (1.36). 

Divalent copper, cobalt, nickel, and vanadyl ions promote chemiluminescence from the luminol—hydrogen peroxide reaction, which can be used to determine these metals to concentrations of 1—10 ppb (272,273). The light intensity is generally linear with metal concentration of 10 to 10 M range (272). Manganese(II) can also be determined when an amine is added to increase its reduction potential by stabili2ing Mn (ITT) (272). Since all of these ions are active, ion exchange must be used for deterrnination of a particular metal in mixtures (274). 

Redox reactions with metal porphyrins (MPs) as photocatalysts. A spectacular example here is the reaction that couples upon illumination with the sunlight, methanol oxidation to formaldehyde with the formation of hydrogen peroxide in be nzene-methanol mixture (90 10)... 

Our approach utilized the metals gold, platinum, then later gold, platinum, and nickel electroplated in succession because the catalytic decomposition of hydrogen peroxide reaction we tested was most efficiently catalyzed with platinum.After fabrication of the nanowires they were freed by removing the conductive silver backing with nitric acid and the sacrificial template with a strong base, sodium hydroxide. Then nanorods were washed with deionized water and ultracentrifuged to achieve a neutral pH. 

Metal-catalyzed nitration by peroxynitrite also provides an alternative explanation to the Haber-Weiss reaction for the role of transition metals in oxidative tissue injury. The rate of peroxynitrite reaction with Fe " EDTA is 5700 M , which is in the same range as the rate of hydrogen peroxide reacting with... 

The author hopes that the chapter has shown how the reactivity, and selectivity towards oxygen transfer reactions of hydrogen peroxide can be utilized for synthetic purposes. Generally, for laboratory and industrial application, activation of hydrogen peroxide by transition metal ions is the method of choice, although in a number of cases, the transition metal route can lead to disposal and environmental problems. The reaction of hydrogen peroxide with organic compounds can, therefore, provide a viable alternative to metal ion activation. 

OSHA PEL TWA 2 mg(Sn)/m3 ACGIH TLV IW A 2 mg(SnVm3 SAFETY PROFILE Poison by ingestion, intraperitoneal, intravenous, and subcutaneous routes. Experimental reproductive effects. Human mutation data reported. Potentially explosive reaction with metal nitrates. Violent reactions with hydrogen peroxide, ethylene oxide, hydra2ine hydrate, nitrates, K, Na. Ignition on contact with bromine trifluoride. A vigorous reaction with calcium acetylide is initiated by flame. When heated to decomposition it emits toxic fumes of Cl. See also TIN COMPOUNDS. 

In the presence of metals, such as iron, hydrogen peroxide reacts with superoxide anion to produce hydroxyl radicals (OH ) and singlet oxygen ( O2) by the reaction shown below ... 

Tertiary alkylhydroperoxides are used most often as oxidizing agents with alkenes since primary or secondary alkylhydroperoxides are susceptible to rearrangement and decomposition. Alkylhydroperoxides are relatively soluble in organic solvents, are more stable, and are easier to handle than hydrogen peroxide.256 Both TBHP and cumyl hydroperoxide are commercially available and widely used. As with hydrogen peroxide, reaction of alkenes with hydroperoxides usually requires transition metal catalysts in order to form... 

Precaution Potentially explosive reaction with metal nitrates violent reactions with hydrogen peroxide, ethylene oxide, nitrates, K, Na Hazardous Decomp. Prods. Fleated to decomp., emits toxic fumes of CL Storage Moisture-sensitive... 

Toxicology ACGIH TLV/TWA 2 mg(Sn)/m LD50 (oral, rat) 700 mg/kg, (IP, mouse) 66 mg/kg, (IV, mouse) 17,800 pg/kg poison by ing., IP, IV, subcut. routes experimental reproductive effects human mutagenic data TSCA listed Precaution Potentially explosive reaction with metal nitrates violent reactions with hydrogen peroxide, ethylene oxide, nitrates, K, Na Hazardous Decomp. Prods. Heated to decomp.. 

Contact with many organic compounds can lead to immediate fires or violent explosions (consult Bretherick for references and examples). Hydrogen peroxide reacts with certain organic functional groups (ethers, acetals, etc.) to form peroxides, which may explode upon concentration. Reaction with acetone generates explosive cyclic dimeric and trimeric peroxides. Explosions may also occur on exposure of hydrogen peroxide to metals such as sodium, potassium, magnesium, copper, iron, and nickel. 

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