Oxidizing agents peroxodisulfates

Aqueous ceric solutions are widely used as oxidants in quantitative analysis they can be prepared by the oxidation of Ce ( cerous ) solutions with strong oxidizing agents such as peroxodisulfate, S20g ", or bismuthate, BiOg". Complexation and hydrolysis combine to render (Ce" +/Ce +) markedly dependent on anion and acid concentration. In relatively strong perchloric acid the aquo ion is present but in other acids coordination of the anion is likely. Also, if the pH is increased, hydrolysis to... 

As soon as the carbene complex is formed it shows extraordinary stabihty, even against strong acids and oxidizing agents fike peroxodisulfate [55-57, 59]. Therefore, these complexes can be used in catalytic processes which have not been possible before with the phosphine ligands, e.g. reactions under oxidizing conditions as the tendency to form phosphine oxides is too high. 

Other bidentate N-heterocyclic carbenes were used to form stable chelate complexes. A fine example is the use of palladium NHC complex 24 in the catalytic conversion of methane to methanol (Fig. 10) [111]. In this case the stability of the complexes is a requirement, since the reaction takes place in an acidic medium (trifluoroacetic acid) at elevated temperatures (80 °C) mediated by strong oxidizing agents (potassium peroxodisulfate). 

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

Cerium (IV) in solution is obtained by treatment of Ce111 solutions with very powerful oxidizing agents, for example, peroxodisulfate or bismuthate in nitric acid. The aqueous chemistry of CeIV is similar to that of Zr, Hf, and, particularly, tetravalent actinides. Thus Ce gives a phosphate insoluble in 4 M HN03 and an iodate insoluble in 6 M HN03, as well as an insoluble oxalate. The phosphate and iodate precipitations can be used to separate Ce from the trivalent lanthanides. Ce is also much more readily extracted into organic solvents by tributyl phosphate and similar extractants than are the Lnm lanthanide ions. 

Scheme 16 Polymerization of EDOT to PEDOTrPSS using polystyrene sulfonic acid as counter ion. The oxidizing agent can be, e.g., sodium peroxodisulfate [85]...

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) ... 

Polystyrenesulfonic acid (PSS) is the most prominent polymeric coimterion for PEDOT, and the complex of PEEXDTPSS is described in detail in Chapter 9. As shown in the early work of Jonas and Krafft on PEDOT dispersions, PEDOTPSS is, strictly speaking, a complex with two types of coimterions. The complex contains sulfate ions as obtained from the oxidation agents iron(III) sulfate and potassium peroxodisulfate as well as polystyrenesulfonic acid. However, the sulfate ion can easily be removed using, for example, ion exchange resins and a true PEDOTPSS complex is prepared. ... 

The most versatile oxidizing agents are peroxodisulfates, in particular those with monovalent cations such as sodium, potassium, or ammonium. i These peroxodisulfates are water-soluble and the oxidation potential of 2.12 V in acidic medium is sufficient for the oxidative polymerization of EDOT to the positively charged PEDOT polyelectrolyte. Peroxodisulfate has also been used in the form of the free acid, which is, however, less stable than the salts. ... 

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). 

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