Activated alkyl groups and polynuclear aromatics

The following outer-sphere oxidation mechanism is favoured over the radical-cation formation which is a feature of similar oxidations by Mn(III) acetate (p. 375). With toluene 

This is consistent with the observed products of oxidation, i.e. benzyl alcohol, benzaldehyde and benzoic acid and with the observed oxidation of cyclohexane. Radical-cations are, however, probably formed in oxidation of napthalene and anthracene. The increase of oxidation rate with acetonitrile concentration was intepreted in terms of a more reactive complex between Co(III) and CH3CN. The production of substituted benzophenones at high CH3CN concentration indicates the participation of a second route of oxidation. 

50% acetic acid) for the analogous oxidation by Ce(IV) perchlorate in aqueous acetic-perchloric acid mixture and one of 5.7 x 10 l.mole Tsec for oxidation by V(V) sulphate at 60 °C in 70 % aqueous acetic-sulphuric acid mixture ([H ] 4.5 M), both reactions giving benzaldehyde. 

The oxidations by Ce(IV) and V(V) are first-order in oxidant and substrate. The V(V) oxidation rate depends on Iiq and a p value of —3.75 is obtained the Ce(IV) oxidation rate depends on the square of /iq and the p value is -I-1.7. Both reactions probably involve a mechanism similar to that of the oxidation by Co(III). 

A few data on the Mn(III) sulphate oxidation of toluene have been reported . k2 = 1.58 X 10 l.mole sec at 35 °C and E = 32.40 kcal.mole The main products are benzyl alcohol and benzaldehyde. 

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