Allylation reactions organic radical ions

Studies on the kinetics and mechanism of the oxidation of ascorbic acid show the rate to be independent of the concentration of organic substrate. A chain mechanism is proposed with reaction between the radical anion of ascorbic acid and the peroxodisulphate ion. Although the influence of neutral salts is negligible and that of acid slight, the presence of allyl acetate strongly inhibits the rate, suggesting the formation of radical ions. In the reaction with lactic acid, a similar rate expression is observed although the description of the mechanism is different. 

Oxidation of C—bonds by copper ion catalyzed reaction with an organic peroxy ester (the Kha-rasch-Sosnovsky reaction) was at one time very popular for allylic oxidation and has been thoroughly reviewed. The reaction is usually carried out by dropwise addition of peroxy ester (conunonly r-butyl peracetate or r-butyl perbenzoate) to a stirred mixture of substrate and copper salt (0.1 mol % commonly copper(I) chloride or bromide) in an inert solvent at mildly elevated temperature (60-120 C). The mechanism involves three steps (i) generation of an alkoxy radical (ii) hyttogen atom abstractitm and (iii) radical oxidation and reaction with carboxylate anion (Scheme 11). 

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