Lead electrochemical oxidation

The purple permanganate ion [14333-13-2], MnOu can be obtained from lower valent manganese compounds by a wide variety of reactions, eg, from manganese metal by anodic oxidation from Mn(II) solution by oxidants such as o2one, periodate, bismuthate, and persulfate (using Ag" as catalyst), lead peroxide in acid, or chlorine in base or from MnO by disproportionation, or chemical or electrochemical oxidation. 

Pentafluorophenol is oxidized to different products depending on oxidation agents and reaction condibons The mtermediate is usually pentafluorophenoxy radical, which attacks the aromabc nng to give dimenc and tnmenc products Electrochemical oxidation of pentafluorophenol m hydrogen fluonde solvent and in the presence of a strong Lewis base or acid leads to a different rabo of products [61] (equation 55)... 

Electrochemical oxidation of alkyl aryl ethers results m oxidative dealkylation and coupling of the intermediate radicals ElectrooxidaUon m the presence of hydrogen fluonde salt leads to fluonnated dienones [66] (equation 58)... 

Minium (Pb,04) represents a more highly oxidized form of lead oxide that enhances the electrochemical oxidation of lead oxide to lead dioxide. 

Electrochemical oxidation of thiosulphinates leads cleanly to the corresponding thiosulphonate in reasonable yields with no observed side-products203. 

This is an electrochemical stoichiometry problem, in which an amount of a chemical substance is consumed as electrical current flows. We use the seven-step strategy in summary form. The question asks how long the battery can continue to supply current. Current flows as long as there is lead(IV) oxide present to accept electrons, and the batteiy dies when all the lead(IV) oxide is consumed. We need to have a balanced half-reaction to provide the stoichiometric relationship between moles of electrons and moles of Pb02. 

The various oxidation states of sulfur have been determined by polarography. The electrochemical oxidation of sulfide ions in aqueous solution may lead to the production of elementary sulfur, polysulfides, sulfate, dithionate, and thiosulfate, depending on the experimental conditions. Disulfides, sulfoxides, and sulfones are typical polarographically active organic compounds. It is also found that thiols (mer-captans), thioureas, and thiobarbiturates facilitate oxidation of Hg resulting thus in anodic waves. 

In this method the creation of defects is achieved by the application of ultrashort (10 ns) voltage pulses to the tip of an electrochemical STM arrangement. The electrochemical cell composed of the tip and the sample within a nanometer distance is small enough that the double layers may be polarized within nanoseconds. On applying positive pulses to the tip, the electrochemical oxidation reaction of the surface is driven far from equilibrium. This leads to local confinement of the reactions and to the formation of nanostructures. For every pufse applied, just one hole is created directly under the tip. This overcomes the restrictions of conventional electrochemistry (without the ultrashort pulses), where the formation of nanostructures is not possible. The holes generated in this way can then be filled with a metal such as Cu by... 

Fichter and Kern O first reported that uric acid could be electrochemically oxidized. The reaction was studied at a lead oxide electrode but without control of the anode potential. Under such uncontrolled conditions these workers found that in lithium carbonate solution at 40-60 °C a yield of approximately 70% of allantoin was obtained. In sulfuric acid solution a 63% yield of urea was obtained. A complete material balance was not obtained nor were any mechanistic details developed. In 1962 Smith and Elving 2) reported that uric acid gave a voltammetric oxidation peak at a wax-impregnated spectroscopic graphite electrode. Subsequently, Struck and Elving 3> examined the products of this oxidation and reported that in 1 M HOAc complete electrochemical oxidation required about 2.2 electrons per molecule of uric acid. The products formed were 0.25 mole C02,0.25 mole of allantoin or an allantoin precursor, 0.75 mole of urea, 0.3 mole of parabanic acid and 0.30 mole of alloxan per mole of uric acid oxidized. On the basis of these products a scheme was developed whereby uric acid (I, Fig. 1) is oxidized in a primary 2e process to a shortlived dicarbonium ion (Ha, lib, Fig. 1) which, being unstable, under-... 

At a terminal ac voltage of 4 V and a frequency of 30 Hz we observed a weak eel which was clearly identified as the IL emission of Pt(QO)2. It is+assumed that the ac electrolysis generates a redox pair Pt(QO)2 Pt(QO)2. The subsequent annihilation leads to the formation of electronically excited Pt(QO)2. The low eel intensity may be associated with the observation that the electrochemical oxidation and reduction of Pt(QO)2 is largely irreversible. CV measurements revealed an oxidation at E1. -... 

The electrochemical oxidation is often more sensitive to the reaction conditions than to the substituents. Platinum electrodes are recommended for methoxylation and the equivalent acetoxylation procedures.290 In acetonitrile buffered by hydrogen carbonate ion, 3,4-diethylfuran affords the 2,5-dihydroxy-2,5-dihydro derivative (84%) and Jones oxidation readily leads to diethylmaleic anhydride in what is claimed to be the best general method for such conversions.291 In unbuffered methanol and under current density control, the oxidation of 2-methylfuran appears to eliminate the methyl group since the product is the acetal-ester 111 also obtained from methyl 2-furoate.292 If sodium acetate buffer is used, however, the methyl group is retained but oxidized in part to the aldehyde diacetate 112 in a... 

Electrochemical oxidations at an electron-deficient platinum electrode have considerable resemblance to oxidations by lead(IV) salts or halogens in methanol but none whatever to oxidations by palladium(II) salts. At temperatures between 90 and 130°C in solution these smoothly convert... 

With a metal ion having four coordination centers, binding of four molecules (39) can occur. The reaction of four molecules of (39) with Hg(II) perchlorate in CH3CN produced complex (212) with a high yield [Eq. (150)]. Electrochemical oxidation of some phosphines on a mercury anode has been shown to lead to their complexes with Hg(II). Following this method, complex 212 was synthesized in high yield (92MI1). The M—P bonds were shown to be in an equatorial position. 

In the Cp2M(dithiolene) series, d° complexes were investigated essentially with Ti, and to a lesser extent with Zr and Hf, in their IV oxidation state. These complexes can be reversibly reduced to the d1, Tim anionic species but they were never isolated in the solid state. Attempts to oxidize these d° complexes were also unsuccessful, as electrochemical oxidation leads to their decomposition [23, 24]. The essential structural characteristic of these d° complexes is the strong folding of... 

The reaction is the electrochemical version of the well-known transmetallation with lead salts, and becomes significant when the lead anode oxidizes. The very high current yields (Ca 170-180%) imply that formation of R4Pb by nonelectrodic reactions takes place as well ... 

Electrochemical etching is one way of controlling the etch rate and determine a clear etch stop layer when bulk micromachining Silicon. In this case, the wafer is used as anode in an HF-Electrolyte. Sufficiently high currents lead to oxidation of the silicon. The resulting oxide which is dissolved by the HF-solution. Since lowly doped silicon material is not exhibiting a notable etch rate, it can be used as an etch stop. 

LEED studies of the UPD layers indicate unique superlattices which are highly dependent on the coverage as well as the particular single crystal surface. The UPD layers have also been examined with AES and XPS. These indicate that under some conditions lead in oxidized form is also present on the surface after the electrochemical measurements, thus complicating the interpretation of the LEED patterns. 

---