Hydrogen Peroxide elimination

Krishnamurty, K. V. et al., At. Abs. Newslett., 1976, 15, 68-70 When preparing soil and sediment samples for atomic absorption spectral analysis for trace metals, pre-oxidation with nitric acid before addition of hydrogen peroxide eliminates the danger of explosion. 

The intermediate formed in this oxidation is 2 1 complex of SchifPs base ligand 7.62 and vanadium. This intermediate then reacts with hydrogen peroxide, eliminating one of the ligands to give a vanadium hydroperoxide complex, which then oxidizes the sulfide to sulfoxide. 

Comparison to the Raschig Process. The economics of this peroxide process in comparison to the Raschig or hypochlorite—ketazine processes depend on the relative costs of chlorine, caustic, and hydrogen peroxide. An inexpensive source of peroxide would make this process attractive. Its energy consumption could be somewhat less, because the ketazine in the peroxide process is recovered by decantation rather than by distillation as in the hypcochlorite process. A big advantage of the peroxide process is the elimination of sodium chloride as a by-product this is important where salt discharge is an environmental concern. In addition to Elf Atochem, Mitsubishi Gas (Japan) uses a peroxide process. 

Chromium (ITT) can be analy2ed to a lower limit of 5 x 10 ° M by luminol—hydrogen peroxide without separating from other metals. Ethylenediaminetetraacetic acid (EDTA) is added to deactivate most interferences. Chromium (ITT) itself is deactivated slowly by complexation with EDTA measurement of the sample after Cr(III) deactivation is complete provides a blank which can be subtracted to eliminate interference from such ions as iron(II), inon(III), and cobalt(II), which are not sufficiently deactivated by EDTA (275). 

Many electroless coppers also have extended process Hves. Bailout, the process solution that is removed and periodically replaced by Hquid replenishment solution, must still be treated. Better waste treatment processes mean that removal of the copper from electroless copper complexes is easier. Methods have been developed to eliminate formaldehyde in wastewater, using hydrogen peroxide (qv) or other chemicals, or by electrochemical methods. Ion exchange (qv) and electro dialysis methods are available for bath life extension and waste minimi2ation of electroless nickel plating baths (see... 

Thiol spills are handled ia the same manner that all chemical spills are handled, with the added requirement that the odor be eliminated as rapidly as possible. In general, the leak should be stopped, the spill should be contained, and then the odor should be reduced. The odor can be reduced by sprayiag the spill area with sodium hypochlorite (3% solution), calcium hypochlorite solution (3%), or hydrogen peroxide (3—10% solution). The use of higher concentrations of oxidant gives strongly exothermic reactions, which iacrease the amount of thiol ia the vapor, as well as pose a safety ha2ard. The apphcation of an adsorbent prior to addition of the oxidant can be quite helpful and add to the ease of cleanup. 

The uv—hydrogen peroxide system has advantages over the iron—hydrogen peroxide (Fenton s reagent) procedures, eg, the reaction is not limited to an acid pH range and the iron catalyst and resulting sludges are eliminated. However, the system to date is not effective for dye wastewaters because of absorption of uv by colored effluent. 

Peroxvaad oxidation of bridged 5,6,7,8-tetrafluoro 1 4-dihydronaphthalene-1,4 imines gives aromatic fluorohydrocarbons by elimination of the imine bridge [91] (equation 84) Almost the same yields are achieved by oxidation with 30% hydrogen peroxide m refluxing methanol [91]... 

In addition to having typical A -oxide reactions, quinazoline 3-oxide also shows the same reactivity as quinazoline toward nucleophilic reagents, but the reaction goes a step further by eliminating water as shown in reaction 2d. Oxidation with hydrogen peroxide... 

Hydroxylation of the double bond of methyltestosterone by means of osmium tetroxide and hydrogen peroxide affords the 4,5 diol. This undergoes beta elimination on treatment with base to yield oxymestrone (83). ... 

Procedure. The sample solution should preferably contain titanium as sulphate in sulphuric acid solution, and be free from the interfering constituents mentioned above. The final acidity may vary from 0.75 to 1.75M. If iron is present in appreciable amounts, add dilute phosphoric(V) acid from a burette until the yellow colour of the iron(III) is eliminated the same amount of phosphoric(V) acid must be added to the standards. If alkali sulphates are present in the test solution in appreciable quantity, add a like amount to the standards. Add 10 mL of 3 per cent hydrogen peroxide solution and dilute the solution to 100 mL in a graduated flask the final concentration of Ti may conveniently be 2-25 parts per million. Compare the colour produced by the unknown solution with that of standards of similar composition by any of the usual methods. 

The colour is unaffected by the presence of phosphate or fluoride. Titanium and molybdenum) VI) (which give colours with hydrogen peroxide) and tungsten interfere. Titanium may be removed by adding fluoride or hydrofluoric acid, which simultaneously remove the yellow colour due to iron(III). If titanium is absent, phosphate may be used to decolorise any iron(III) salt present. Oxalic acid eliminates the interference due to tungsten. In the presence of elements... 

Only sulfoxidation, and no elimination, occurs when the hydrochloride of 2 (R = Me) is treated with sodium periodate at room temperature.3 Ketone 4, which represents the tautomeric form of dibenzo[6,/]thiepin-10-ol, can be sulfoxidized with hydrogen peroxide at room temperature to provide sulfoxide 5 in 56% yield however, at reflux temperature oxidation occurs additionally at the carbon atom next to the oxo group and sulfone 6 is isolated in 79% yield.3... 

Similarly, the most common method of preparing the substituted, fully unsaturated thiolane system, e.g. thiophene dioxides, is by direct oxidation of the readily available substituted thiophenes with hydrogen peroxide, perbenzoic acid and m-chloroperbenzoic acid280 283. Alternatively, thiophene dioxides are conveniently prepared via the double elimination methodology280 305 illustrated in equation 117. 

The first synthesis of stable 3-hydroperoxy-sultams (24) which are a new class of sultam with oxidising properties, was reported. The synthesis involved oxidation of the isothiazolium salts (23) with hydrogen peroxide in acetic acid. Reduction of (24) with aqueous sodium bisulphite afforded the corresponding novel 3-hydroxysultams whereas thermolysis in ethanol resulted in the elimination of water to give 3-ketone derivatives, which are versatile as dieneophiles <96T783>. 

A 30% solution of hydrogen peroxide in water was purchased from Mallinckrodt Chemical Works. The reaction requires 2 molar equivalents of hydrogen peroxide, the first to oxidize the selenide to the selenoxide and the second to oxidize the elimination product, benzeneselenenic acid, to benzeneseleninic acid. The submitters recommend that the hydrogen peroxide solution be taken from a recently opened bottle, or titrated to verify its concentration. 

This concerted reduction by two ferrous species eliminates H02- (or O2 ) as an intermediate and explains the weak catalysis by Cu(II) (which is strong for V([II) and V(IV) autoxidations). Weiss has suggested that the species Fe. 02.Fe may be a stable intermediate, but Wells explains the presence of two Fe(Il) species in the rate law in terms of a pre-existing dimeric form of Fe(lf) containing an H2O bridge, for which there is evidence . The reduction is completed via the Fenton reaction vide infra). The hydrogen peroxide dianion is probably never free but is protonated whilst complexed to Fe(III). 

Preparing peracetic acid by the action of hydrogen peroxide on acetic acid is as hazardous. If the temperature is too low, compounds accumulate and cause the medium to detonate. Using peracetic acid solution as an oxidant causes detonations when its concentration is too high or if evaporation is attempted. An accident happened during such an operation (see reaction below). The best way to eliminate this peracid at the end of the reaction is to heat it in a water bath at a temperature that should not exceed 50°C and under reduced pressure. 

---