Hydrogen peroxide, reaction

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). 

Luminol chemiluminescence has also been recommended for measuring bacteria populations (304,305). The luminol—hydrogen peroxide reaction is catalyzed by the iron porphyrins contained in bacteria, and the light intensity is proportional to the bacterial concentration. The method is rapid, especially compared to the two-day period required by the microbiological plate-count method, and it correlates weU with the latter when used to determine bacteria... 

Peracid Processes. Peracids, derived from hydrogen peroxide reaction with the corresponding carboxyUc acids in the presence of sulfuric acid and water, react with propylene in the presence of a chlorinated organic solvent to yield propylene oxide and carboxyUc acid (194—196). 

In order to optimize the chemiluminescence response, we have investigated the mechanism of the complex reactions leading to chemical generation of chemiluminescence. A new peroxyoxalate-hydrogen peroxide reaction mechanism has emerged from our preliminary studies on the five contributing factors listed above. Two kinetic models are discussed, one for the... 

Table 4.2 Examples of phase transfer catalysed hydrogen peroxide reactions...

In principle there is a competition for the HO2 radical between peroxydisulphate and hydrogen peroxide [reactions (63) and (86)] however, when the stoichiometry is 1 1 reaction (86) can be neglected. Assuming that the chain length is large, with the usual steady-state approximation, we obtain the following rate equation ... 

As has already been mentioned, during the iron(II)-hydrogen peroxide reaction a number of organic compounds which do not react, or react only slowly with hydrogen peroxide, are readily oxidizable. In the induced oxidation of organic compounds, hydrogen peroxide plays the role of the actor and iron(II) is the inductor. 

Great promise exists in the use of graphitic carbons in the electrochemical synthesis of hydrogen peroxide [reaction (15.21)] and in the electrochemical reduction of carbon dioxide to various organic products. Considering the diversity in structures and surface forms of carbonaceous materials, it is difficult to formulate generalizations as to the influence of their chemical and electron structure on the kinetics and mechanism of electrochemical reactions occurring at carbon electrodes. 

Figure 19. Illustration of the crystal surface control on the hydrogen peroxide reaction pathway. (Reprinted with permission of B. Zhou, Headwaters, Inc.)...

A large volume (11.25 m3) of mixed fatty acids was to be bleached by treatment with successive portions of 50 wt% hydrogen peroxide. 2-Propanol (450 1) was added to the acids (to improve the mutual solubility of the reactants). The first 20 1 portion of peroxide (at 51°C) was added, followed after 1 min by a second portion. Shortly afterwards an explosion occurred, which was attributed to spontaneous ignition of a 2-propanol vapour-oxygen mixture formed above the surface of the liquid. Oxygen is almost invariably evolved from hydrogen peroxide reactions, and volatile flammable solvents are therefore incompatible components in peroxide systems. 

The chemical sensitization effect was 0.006 (calculated from the quantum yield of the photochemical transformation of 130 to 131, the yield of 131 obtained with the oxalate/hydrogen peroxide reaction, and the moles of oxalate employed). Higher chemical sensitization efficiencies (about 0.04) were observed when the oxalate/hydrogen-peroxide system was used in the addition of ethyl vinyl ether onto phenanthrene quinone... 

Other studies in this specific area are also based on the catalytic effect of a variety of metal ions such as copper (II), cobalt (II), nickel (II), iron (III), and manganese (II) on the luminol-hydrogen peroxide reaction providing a rapid and efficient detection mode for these five ions, when an online CL detector is used before separation by CE [88], This contribution combines capillary ion analysis (CIA) and CL detection by means of a postcapillary reactor similar to the one originally developed by Rose and Jorgenson [80] and finally modified by Wu... 

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+. 

In accord with this mechanism, a single two-electron oxidation of the enzyme into Compound I by hydrogen peroxide (Reaction (8)) is followed by two one-electron steps Reaction (9), in which substrate RH is oxidized to a radical R and Compound I is reduced to Compound II and Reaction (10), in which Compound II is reduced to native MPO, completing the catalytic... 

Figure 2. Schematic representation of electron transfer from an aromatic compound to O2 with a Cu-exchanged clay as the catalyst and the formation of polymers (Reaction A) and hydrogen peroxide (Reaction B).

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. 

Other gradient forces as in local heating generated by the exothermic hydrogen peroxide reaction were determined to be negligible because their contribution to velocity was less than a micron/second. Therefore, the interfacial force due to a concentration gradient appears to be the most reasonable dominant driving force for the Pt/Au nanorods. 

The result of this change in mechanism is that the major products at high temperatures are olefins and hydrogen peroxide and their secondary decomposition products, which of course include water. The relatively unstable alkyl hydroperoxide produced by the low temperature chain is replaced by the much more stable hydrogen peroxide. The result is that the secondary initiation, responsible for the cool flames, is replaced by a much slower initiation—the second-order decomposition of hydrogen peroxide (Reaction 6). 

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