Peroxodisulfate ions

The peroxodisulfate ion in aqueous solution is one of the strongest oxidising agents known. The standard oxidation—reduction potential for the following reaction is 2.08 V (77,78). 

Reactions involving the peroxodisulfate ion are usually slow at ca 20°C. The peroxodisulfate ion decomposes into free radicals, which are initiators for numerous chain reactions. These radicals act either thermally or by electron transfer with transition-metal ions or reducing agents (79). 

Chain mechanism. The reaction between formic acid and peroxodisulfate ions is... 

Peroxodisulfate ions oxidize aromatic amines md phenols to colored derivatives, paitic ularly under the catalytic influence of silver ions [1-4]. 

Because the standard cell potential is negative, we conclude that this cell reaction is nonspontaneous. This would not be a feasible method of producing peroxodisulfate ion. 

Peroxide titanate complexes, 25 98 Peroxide value, 20 827 in soap making, 22 736 Peroxidic compounds, 25 42 Peroxoborates, names, CAS numbers, and IUPAC names of, 18 398t Peroxocarbonates, 28 401 Peroxo compounds, 28 392-393, 397 Peroxodisulfate ion, 28 408 Peroxodisulfates, 28 392, 408-410 Peroxodisulfate salts, 28 418 uses for, 28 408-409 Peroxodisulfuric acid, 28 407 408 Peroxohydrate(s), 24 40 28 411—415 of melamine, 28 415 stabilization of, 28 413 Peroxo molybdate complexes, 2 7 22 Peroxomonophosphate ion, 28 403 Peroxomonophosphoric acid, 28 403 Peroxomonosulfates, 28 406 407... 

The oxidation of 2-carboxyphenylacetic acid by peroxodisulfate ion is catalysed by Ag(I). The kinetics of the oxidation of tetrahydrofurfuryl alcohol by ditelluratocup-rate(III) and by ditelluratoargentateCin) in alkaline media have been studied. 

CZE-ELD, with a Au microelectrode at —0.6 V vs. SSCE and a Pt wire as auxiliary electrode, using sodium borate buffer and dodecyltrimethylanunonium bromide for dynamic coating of the capillary internal surface, can be applied for separation and determination of ultra-trace amounts of many oxidizing substances. Thus, the concentration of peroxodisulfate (S208 ) and peroxomonosulfate (S05 ) ions in pickling baths can be monitored by this method. The faster emergence of the heavier peroxodisulfate ion is attributed to different adsorption of the two analyte ions by the capillary coating . ... 

The Mn(II)-catalysed oxidation of glucose by peroxodisulfate ions occurs via a radical-chain mechanism.26 Kinetics of oxidation of thiodiglycollic acid by (trans-cyclohexane-l,2-diaminc-/V, N, N, /V -tetraacetatolmanganateilJI) have been investigated.27 Oxidations of ketoses and aldoses by manganese(IV) in sulfuric acid media have a first-order dependence on sugar and fractional-order dependence on oxidant.28 A mechanism has been proposed for the oxidation of L-malic acid by Mn(III) pyrophosphate in aqueous acid, involving complex formation and radicals.29... 

The peroxodisulfate ion is one of the most powerful and useful of oxidizing agents ... 

Many oxidations (e.g., of oxalate) by the peroxodisulfate ion are catalyzed by Ag+ ion, and the kinetics are best interpreted by assuming initial oxidation to Ag2+, which is then reduced by the substrate. Decarboxylation of carboxylic acids are also promoted by Ag11 complexes, such as (18-I-IX) and others. 

On the other hand, Tiecco and co-workers reported the use of peroxodisulfate ions for the transformation of diselenides into the corresponding selenenyl... 

Hydrogen peroxide is obtained by electrolytic processes that involve the formation of peroxodisulfate ion and its subsequent hydrolysis. Sulfuric acid or ammonium sulfate-sulfuric acid solutions are electrolyzed at high current density ( 1 amp/dm2) at electrodes (usually Pt) that have high... 

S Nishida, M Kimura. Kinetic studies of the oxidation reaction of arsenic (III) to arsenic (V) by peroxodisulfate ion in aqueous alkaline media. J Chem Soc Dalton Trans 2 357-360, 1989. 

A typical substrate is the peroxodisulfate ion, with X being the sulfate ion and R the sulfate radical SO . 

Orban, M. Epstein, I. R. 1989a. Chemical Oscillators in Group VIA The Cu(II)-Catalyzed Reaction between Thiosulfate and Peroxodisulfate Ions, J. Am. Chem. Soc. Ill, 2891-2896. 

Even peroxo species like cetyltrimethylammonium (CTA) peroxodisulfate [264] or the hydrogen peroxide-urea complex (UHP) [265] were found to be suitable oxidants. The CTA counterion acts as a phase-transfer catalyst and is necessary to solubihze the peroxodisulfate ion in organic solvents, while the hydrogen peroxide-urea complex represents a concentrated and crystalline version of hydrogen peroxide. 

Figure 16.20 Energy level diagrams for the uncatalysed and catalysed oxidation of iodide ions and peroxodisulfate ions. 

Reactions of peroxodisulfate are often catalyzed by Ag(I), and the kinetics of the Ag(I)-catalyzed decomposition of peroxodisulfate ion to dioxygen have been investigated. The kinetics are not influenced by added cerium(III) but the formation of O2 is inhibited by Ce(III). The reaction is greatly accelerated by acrylamide and/or Cu(II) and this results in the absorption of oxygen. The Ag(I)-catalyzed reaction is thought to involve the formation of Ag(II) and SOi , and the following scheme has been proposed ... 

Before leaving the noncatenated oxoacids of the chalcogens, mention should be made of peroxodisulfuric acid, H2S20g, and the peroxodisulfate ion, [O3S-O-O-SOg] . The latter is a very strong oxidizing agent, as shown by the half-reaction of Equation (17.11) ... 

B Draw Lewis, VSEPR, and VBT (valence-bond theory) diagrams of the peroxodisulfate ion. 

Write an equation representing the oxidation of the manganous ion to permanganate by the peroxodisulfate ion. Assume an acid environment. Calculate E° and AG° for this reaction. 

From another standpoint, a positive oxidation number must not exceed the number of electrons in the external shell of the element. If it is negative, it must not exceed the number of electrons necessary to saturate the external shell. For example, for the redox couple peroxodisulfate—sulfate (S20g /S04 ) assigning the value —II to oxygen leads to the oxidation number h-VII for the two sulfur atoms of the ion peroxodisulfate. This result is wrong because the sulfur atom possesses six electrons only in its external shell. Actually, the peroxodisulfate ion contains a peroxo bridge in... 

During the course of an oxidation with the peroxodisulfate ion, each oxygen atom of the peroxo bridge captures one electron while the 0-0 bond is breaking and, finally, two sulfate ions are formed. The half-redox reaction can be written as... 

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