Oxidation by peroxydisulfate

Preparative methods based on oxidations by peroxydisulfate have long been known. Peroxydisulfate ions are capable of oxidizing virtually all functional groups, even hydrocarbons. The oxidation of phenol using potassium peroxydisulfate in alkaline solution, to yield a 1,2- or 1,4-dihydroxybenzene, is called the Elbs reaction and it had been already reported in 1893 (equation 12) . 

Primary and secondary alcohols are quantitatively oxidized by peroxydisulfate to the corresponding aldehydes and ketones. Thus benzyl alcohols give aldehydes, and in the presence of Ni(II) and ammonia they gives nitriles secondary alcohols give the corresponding ketones . Interestingly, isopropylbenzene reacts with acetates in the presence of peroxy disulfate/Fe(II) to give lactones (equation 18). ... 

That the above redox isomer is formed instead of the FenRuin one, can be demonstrated by careful analysis of the MLCT band of the product, as well as by the properties of the intervalence (IV) band. However, it is well known that the [Run(NH >)r,LV,+ ions are generally much more reactive that the [Fen(CN)5L]" analogues toward oxidation by peroxydisulfate (126,128), as required by the lower redox potential at the ruthenium center. A careful mechanistic analysis showed that, although the FeinRun isomer is the thermodynamically stable product, it is not the kinetically accessible one. Then, the reaction evolves as follows ... 

House, D. (1962). Kinetics and mechanism of oxidation by peroxydisulfate. Chem. Rev. 62,... 

Marcoux and Adams have carried out a study of the anodic oxidation of a range of azines in acetonitrile at a platinum electrode.347 With the exception of pyridine which could not be oxidized under these conditions, all the other azines were oxidized in a complicated process in which one electron per molecule was transferred to the electrode. The reaction was investigated in some detail for acridine, and the main product was found to be an acridyl-acridinium perchlorate (perchlorate being supplied by the supporting electrolyte). This result, which is directly comparable with that for pyridine oxidation by peroxydisulfate is persuasive evidence for the mediation of the... 

In-line digestion of waters, as initially demonstrated in the amperometric determination of phosphate involving oxidation by peroxydisulfate [140]. 

During oxidation of 4,5-dimethylimidazol by peroxydisulfate in water, the reaction is stopped just at the alcohol-formation step. The alcohol is stabilized due to intramolecular hydrogen bonding. This keeps the alcohol safe from further oxidation (Citterio and Minisci 1982 Scheme 7.51). 

The proposed mechanism agrees completely with that suggested by Allen for the copper-catalyzed oxidation of oxalate by peroxydisulfate (2). 

The copper-catalyzed oxidation of diethylamine by peroxydisulfate in alkaline solution (29) was also suggested as proceeding via Cu(III), and so was the catalytic decomposition of S20s 2 (18). Further, the formation of Cu(III) as intermediate may account for the Cu-catalyzed oxidation of Mn+2 to Mn04 by OBr " (38). 

A dark red-brown precipitate of Ag(pyrazine)2S208 was obtained by peroxydisulfate oxidation of Ag1 solutions containing pyrazine at 0-5 °C, In a related experiment, the 2-carboxylate derivative was obtained. Both reactions proceeded via the oxidation of white... 

Oxidation of cyclohexene by peroxydisulfate in the presence of copper(II) salts results in the formation of cyclopentanecarboxaldehyde as the main product in an aqueous acetonitrile solution (equation 261), and 2-cyclohexenyl acetate in an acetic acid solution (equation 262).588,589 Reaction (261) has been interpreted as the formation of a radical cation (186) by oxidation of cyclohexene with S2Og, followed by hydrolysis of (186) to the /3-hydroxy alkyl radical (187), which is oxidized by copper(II) salts to the rearranged aldehydic product (188 equation 263).589... 

Several other processes have been developed, however, to accomplish the oxidative decarboxylation of carboxylic acids oxidation by Pb(OAc)4, by iodosobenzene-diacetate, and by Ag(II) salt generated in situ in a catalytic cycle from a variety of peroxides (benzoyl peroxide, percarbonate, perborate) [2] other than the already mentioned peroxydisulfate. Representative examples are shown in Eqs (9)—(12) of Table 2. 

Gallopo, A. and J. Edwards (1971). Kinetics and mechanism of the spontaneous and metal modified oxidation of ethanol by peroxydisulfate ion. J. Org. Chem. 36,4089 1096. 

Toluene has been oxidized by the silver ion catalysed reaction with peroxy-disulfate. The reaction produces a mixture of bibenzyl, benzaldehyde and benzoic acids.299 Russian workers have described the conversion of 4-methoxy-toluene to the benzaldehyde by oxidation with peroxydisulfate in the presence of silver or copper ions and oxalic acid.300 The presence of copper salts in iron or copper catalysed peroxydisulfate oxidation is believed to suppress side-reactions.301 Phillips have patented a palladium(II)/tin(IV)/persulfate system for the oxidation of toluene derivatives.302 The reactions are carried out in carboxylic acid solvents (Figure 3.78). 

The nucleophilic radicals formed by the silver-catalyzed, oxidative decarboxylation of carboxylic acids by peroxydisulfate ions attack protonated imidazoles mainly at the 2-... 

Encapsulation chemistry similar to that described above (exchange of anilinium, followed by oxidation with peroxydisulfate) was foimd to produce polyaniline not only in zeolite Y, but also in montmorillonite clay. 5 Spectral features (UV-VIS, IR and EPR) of the products were indicative of emeraldine salt and base formation, respectively. The change in basal spacing of the montmorillonite upon intercalation provided additional evidence for the inclusion polymerization. 

Radical substitution reactions include alkylations and arylations in the main. Nucleophilic radicals produced by the silver-catalyzed oxidative decarboxylation of carboxylic acids (by peroxydisulfate ion) attack proton-ated azoles at the most electron-deficient sites.Thus, imidazole and 1-alkylimidazoles are methylated exclusively at C-2 in rather low yields. The use of isopropyl and t-butyl radicals gives improved yields, but benzyl and acyl radicals tend to dimerize rather than substitute the... 

Isatin, which can be considered a cyclic a-keto amide, is oxidized by hydrogen peroxide exclusively to isatoic anhydride, whereas with potassium peroxydisulfate, 2,3-dioxo-l,4-benzoxazine is obtained (equation 394) [260]. 

The oxidation of sulfacetamide sodium by peroxydisulfate ion to azobenzene derivatives follows second-order kinetics. The reaction is very sensitive to pH and the rate increases with increase in pH in the region 1.2-7.76. The rate decreases with decrease in dielectric constant of the medium, and a plot between log k2 and D 1 is linear. The reacion is inhibited by the presence of diphenylpicryl hydrazyl (102,103). 

A newly emerging class of reactions is oxidative substitution. An aromatic molecule reacts with a nucleophile to give a substitution product, a proton and two electrons or their equivalent. The aromatic molecule is first oxidized by a metal ion (or even an anode124)) to a radical cation intermediate which then is trapped and converted to product. Consider the reaction of alkylbenzenes with copper(II) chloride and peroxydisulfate ion. The peroxy compound converts toluene, for example, into its radical cation which is trapped in a reaction with the copper salt. Aromatiza-tion then gives products which are mostly o- and p-chlorotoluene, Scheme 15. In the... 

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