Peroxides oxidizing properties

Oxidation. Hydrogen peroxide is a strong oxidant. Most of its uses and those of its derivatives depend on this property. Hydrogen peroxide oxidizes a wide variety of organic and inorganic compounds, ranging from iodide ions to the various color bodies of unknown stmcture in ceUulosic fibers. The rate of these reactions may be quite slow or so fast that the reaction occurs on a reactive shock wave. The mechanisms of these reactions are varied and dependent on the reductive substrate, the reaction environment, and catalysis. Specific reactions are discussed in a number of general and other references (4,5,32—35). 

Hydrogen peroxide is used in many applications throughout a wide variety of industries. The principal use areas are shown in Table 9. Most ate based on the oxidizing properties of hydrogen peroxide. Some are derived from substitution, decomposition, or the formation of perhydrates. 

Molybdenum, tris(phenylenedithio)-structure, 1,63 Molybdenum alkoxides physical properties, 2,346 synthesis, 2,339 Molybdenum blue liquid-liquid extraction, 1,548 Molybdenum cofactor, 6,657 Molybdenum complexes acrylonitrile, 2,263 alkoxides, 3,1307 alkoxy carbonyl reactions, 2,355 alkyl, 3,1307 alkyl alkoxy reactions, 2,358 alkyl peroxides oxidation catalyses, 6,342 allyl, 3,1306... 

Volume 2 of Bretherick s Handbook of Reactive Chemical Hazards (Urben, 1999) lists many structures and individual chemical compounds having oxidizing properties. NFPA 432 can be consulted for typical organic peroxide formulations. Note, however, that some organic peroxide formulations bum with even less intensity than ordinary combustibles and present no chemical reactivity hazard. 

When the NFPA diamond is used for container or vessel labeling, and the white (bottom) quadrant contains OX, the material possesses oxidizing properties. It may be either an oxidizer or an organic peroxide. In either case, it should be considered to pose a chemical reactivity hazard. 

If you are certain that NO oxidizers are present, then proceed to Question 11. If you are uncertain as to whether a material is an oxidizer, a chemist or other expert should be consulted. Table 3.6, which was derived from NFPA 49 (2001) and Appendix B of NFPA 430 (2000), lists some typical oxidizers, but is by no means a complete list. Organic peroxides are not included individually in this list. NFPA 432 (1997) can be consulted for typical organic peroxide formulations. Volume 2 of Bretherick s Handbook (Urben 1999,287-291) lists many structures and individual chemical compounds having oxidizing properties. 

We have carried out a limited study of the effect of metal dialkyl dithiophosphates on a hydroperoxide-autocatalyzed oxidation system. Table III summarizes induction periods for the oxidation of squalane at 140 °C. These results do not unambiguously reflect the peroxide-decomposing property of each dithiophosphate radical capture also occurs. 

Hydrogen peroxide (HOOH) is sold in drugstores as a 3% aqueous solution for domestic use and is marketed as a 30% aqueous solution for industrial and laboratory use. Because of its oxidizing properties, hydrogen peroxide is used as a mild antiseptic and as a bleach for textiles, paper pulp, and hair. In the chemical industry, hydrogen peroxide is a starting material for the synthesis of other peroxide compounds, some of which are used in the manufacture of plastics. 

Vitamin C (ascorbate) (Fig. 9.5) has the ability to act as a reducing agent, i.e. it will tend to reduce more reactive species. This ability to reduce Fe3+ to Fe2+may be important in promoting iron uptake in the gut. Oxidation of ascorbate by reaction with reactive oxygen species or reactive nitrogen species seems to lead to its depletion. In vitro, vitamin C can also exert pro-oxidant properties. Fe3+ can react with ascorbate to form Fe2+ and the semi-dehydroascorbate or ascorbyl radical. The latter can react with hydrogen peroxide to form Fe3+, the hydroxyl radical and a hydroxide anion. A key question with regard to the pro- or anti- oxidant effects of ascorbate may therefore be the availability of transition metal ions. Neurons main-... 

It has been suggested that hydrogen peroxide and iron are the cause of this rapid depolymerization (30). It is possible that the initial attack by micro-organisms is not enzymatic but hydrolytic and oxidative in nature. If this is true, then a preservative system could be based on anti-oxidant properties of the chemical. If the initial attack can be stopped, then the total attack has been stopped. It is also possible that the initial and sustained attacks are caused by a combination of chemical... 

Furthermore, lacidipine was found to possess antioxidant activity at the same level of that of vitamin E in many tests, including hydrogen peroxide oxidation of rat neuronal cells [14]. The antioxidant property of lacidipine was further confirmed by experiments in vivo, in which low-density lipoprotein (LDL) oxidation was completely abolished [15]. Lacidipine also shows a direct protective effect on the vasculature at non-antihypertensive doses, indicating that its high lipophilicity combined with antioxidant potential can exert an additional therapeutic benefit [16-18]. 

In acidic solutions, the reaction was found to proceed through pathway (a). Isomeric dihydroxypentanones (I and II) were formed in small yields, and led to the formation of side-products. The mechanism of the reaction is still unclear, however the specific oxidizing properties of hydrogen peroxide probably plays an important role. 

The active species too is characterized by rather unusual properties and is different from soluble Ti-peroxides, known for their inertness in the epoxidation of simple olefins. As originally proposed by Clerici et al., the active sites contain Ti-OOH species, stabilized in a cyclic structure by the coadsorption of a protic molecule, generally the alcohol solvent. The oxygen transfer step to the double bond has electrophilic character thus resembling other peroxidic oxidants (Figure 15). 

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