Hydrogen peroxide, oxidant

ALCOHOLS,HIGHERALIPHATIC - SURVEY AND NATURALALCOHOLSMANUFACTURE] (Voll) -H202 as oxidant [HYDROGEN PEROXIDE] (Vol 13)... 

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). 

Etch Mechanisms. Most wet etches for the compound semiconductors employ oxidation of the semiconductor followed by dissolution of the oxide. For this reason, many wet etches contain the oxidant hydrogen peroxide, although nitric acid can also be used. One advantage of wet etching over dry is the absence of subsurface damage that is common with dry etching. Metal contacts placed on wet-etched surfaces exhibit more ideal characteristics than dry-etched surfaces. 

Similar hydroxylation-oxidations can be carried out using a catalytic amount of osmium tetroxide with A-methylmorpholine oxide-hydrogen peroxide or phenyliodosoacetate." A recent patent describes the use of triethylamine oxide peroxide and osmium tetroxide for the same sequence. Since these reactions are of great importance for the preparation of the di-hydroxyacetone side-chain of corticoids, they will be discussed in a later section. 

N-Methylmorpholine Oxide-Hydrogen Peroxide Oxidation. The preparation of A-methylmorpholine oxide-hydrogen peroxide is described in Reagents for Organic Synthesis by L. Fieser and M. Fieser. 

As an oxidant, hydrogen peroxide may be used either alone or in the presence of a catalyst. Such reactions are often carried out using acetic acid as a solvent. These latter reactions strictly involve oxidation by peracetic acid and will be dealt with in the next section. 

Tertiary amines can be converted to amine oxides by oxidation. Hydrogen peroxide is often used, but peroxyacids are also important reagents for this purpose. Pyridine and its derivatives are oxidized only by peroxyacids. In the attack by hydrogen peroxide there is first formed a trialkylammonium peroxide, a hydrogen-bonded complex represented as R3N-H202, which can be isolated. The decomposition of this complex probably involves an attack by the OH moiety of the H2O2. Oxidation with Caro s acid has been shown to proceed in this manner ... 

See Disulfur dichloride Mercury oxide Hydrogen peroxide... 

It has been pointed out earlier that peroxidases oxidize hydrogen peroxide by two-electron transfer mechanism to form Compound I. Thus for MPO, we have ... 

However, in addition to two-electron oxidation by native peroxidase, Compound I can oxidize hydrogen peroxide by one-electron mechanism ... 

Copper(II) sulfate Cumene hydroperoxide Cyanides Cyclohexanol Cyclohexanone Decaborane-14 Diazomethane 1,1-Dichloroethylene Dimethylformamide Hydroxylamine, magnesium Acids (inorganic or organic) Acids, water or steam, fluorine, magnesium, nitric acid and nitrates, nitrites Oxidants Hydrogen peroxide, nitric acid Dimethyl sulfoxide, ethers, halocarbons Alkali metals, calcium sulfate Air, chlorotrifluoroethylene, ozone, perchloryl fluoride Halocarbons, inorganic and organic nitrates, bromine, chromium(VI) oxide, aluminum trimethyl, phosphorus trioxide... 

Triphenylphosphine oxide hydrogen peroxidate, 3755 OXYGEN BALANCE... 

Potassium cyanide-potassiiun nitrite, 0527 Potassium pentacyanodiperoxochromate(5-), 1810 Potassiiun tricyanodiperoxochromate(3-), 1044 Tetrahydroxotritin(2+) nitrate, 4525 Tetrakis(hydroxymethyl)phosphonium nitrate, 1754 Tin(ll) nitrate, 4750 Tin(ll) perchlorate, 4109 Trihydrazinealuminium perchlorate, 0064 Trimethylhydroxylammonium perchlorate, 1323 Triphenylphosphine oxide hydrogen peroxidate, 3755 OXYGEN BALANCE DRUMS... 

The selective oxidation of saturated hydrocarbons is a reaction of high industrial importance. Besides a variety of other oxidants, hydrogen peroxide as a very clean oxidant has also been used for these purposes . As an example, in 1989 Moiseev and coworkers reported on the vanadium(V)-catalyzed oxidation of cyclohexane with hydrogen peroxide (Scheme 146) . When the reaction was carried out in acetic acid cyclohexanol and cyclohexanone were formed, bnt conversions were very poor and did not exceed 13%. Employing CF3COOH as solvent, complete conversions could be obtained within 5 min-ntes. Here, cyclohexyl trifluoroacetate was the main product (85% of the products formed) resulting from the reaction of cyclohexanol (the primary product of the oxidation) with CF3COOH. 

The Julia - Colonna asymmetric epoxidation of electron-deficient unsaturated ketones to the corresponding epoxides with high yields and high ee is well known. This technique produces chiral chemical entities from the clean oxidant, hydrogen peroxide, without the use of a toxic or water sensitive transition metal additive. 

The simultaneous addition of a fluorine atom and of a hydroxy group to a haloalkene may be achieved by using combinations of anhydrous hydrogen fluoride with chromium(VI) oxide, hydrogen peroxide, peracetic acid, or potassium permanganate.1... 

N-methylmorpholine oxide-hydrogen peroxide, 184, 221, 223 4-Methyl-19-nortestosterone, 89 16/3-Methyl-l 6a, 17a-oxidopregn-4-ene-... 

As important as calcium is probably iron [122]. Iron is the metal center of many essential proteins and enzymes, such as hemoglobin, an oxygen carrier, or peroxidase, that oxidizes hydrogen peroxide, or even the large family of cytochromes, which act as electron transfer proteins in many important biochemical processes [85]. New families of MRI contrast agents have been designed such that their relaxivity is iron concentration dependent [128-130]. The two latest are based on Gd(III) chelates (Fig. 20) but differ by the mechanism responsible for their iron sensitivity and will be described further. 

Triphenyl-1,4-pentaazadiene, 3748 Triphenylphosphine oxide hydrogen peroxidate, 3749 Triphenylphosphine oxide-oxodiperoxochromium(Vl), 3746 Triphenylphosphine, 3750... 

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