Permanganates with onium cations, soluble in non-polar and tittle polar org
anic solvents, make it possible to oxidize substrates which are insoluble i
n water. Permanganate is reduced in these media like in neutral aqueous sol
utions. In contrast to older views, the main intermediate in these reaction
s is Mn(IV) in the form of colloidal MNO2. The catalytic effect of this int
ermediate is associated with its large surface on which the reactants are a
dsorbed. Many oxidation reactions with solubilized permanganate exhibit an
autocatalytic mechanism.