Persulphate-derived radicals

Fig. 3 Model of homogeneous nucleation related to entry for persulphate-derived radicals...

Such reactions can be initiated by free radicals, derived from compounds (initiators) such as benzoyl peroxide, ammonium persulphate or azobis-isobutyronitrile or by ionic mechanisms... 

Ozyacetic acids derived from o-phenylhenzol droxamic acids are oxidised by persulphate to phenanthridone through the intermediacy of an ami(fyl radical (A.R. Forrester et Tetrahedron Letters, 1977, 3601). 

A feature of both systems is the autocatalysis by SO4 and COa (derived from the reductant) radicals. A simple rate law is observed in the Ag -catalysed oxidation of aspartic acid (Rate = A a[S208 ][Ag ][Asp] ). Medium effects are important with inhibition by ions in the order Mg + > K+ > Na+ > H+ and NOs > S04 . The uncatalysed oxidations of glyoxal and glyoxylic acid have also been investigated. Potassium ruthenate (K2RUO4), which can be readily prepared from reaction of ruthenium trichloride with aqueous persulphate, can be used cata-lytically in the presence of 8208 for the oxidation of organic substrates under mild conditions. RuO " is considered to act as a two-electron oxidant. 

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