Peroxides from peroxydisulfate

In general, the importance of the acceptor properties of all types of compounds containing an 0—0 bond should be emphasized. A likely function of a peroxidic compound (hydrogen peroxide, alkyl peroxides, acyl peroxides, peroxydisulfate, to mention a few commonly used ones) under photochemical conditions (UV light) should be that of an electron acceptor from an excited state. Moreover, the electron acceptor efficiency is high in view of the dissociative nature of the ET step. 

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. 

Alkyl radicals for such reactions are available from many sources such as acyl peroxides and alkyl hydroperoxides, particularly by the oxidative decarboxylation of carboxylic acids using peroxydisulfate catalyzed by silver. Pyridine and various substituted pyridines have been alkylated at the 2-position in high yields by these methods. Quinoline similarly reacts at the 2-position, isoquinoline at the 1-position, and acridine at the 9-position. Pyrazine and quinoxaline also give high yields of 2-substituted alkyl derivatives <1974AHC(16)123>. 

The purification of the water has been previously described (10). With the exception of the arsenious oxide (from Carlo Erba, Italy), the chemicals used were Merck analytical products. The peroxymonosul-fate samples were obtained from hydrolysis of potassium peroxydisulfate solutions a 10"2M K2S208 solution in 1M sulfuric acid was heated at 60 °C. for 75 minutes and let cool overnight inside the thermostated bath (an ultrathermostat Colora was used). Under these conditions, the peroxydisulfate remaining in the solution, as well as the hydrogen peroxide formed in the simultaneous hydrolysis of the Caro s acid, are small when compared with the resulting peroxymonosulfate concentration. 

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