Permanganate strike

Colour - A striking feature of transition-metal compounds is their colour. Whether it is the pale blue or pink hues of copper(ii) sulfate and cobalt(ii) chloride, or the intense purple of potassium permanganate, these colours tend to be associated most commonly with transition-metal compounds. It is rare for compounds of main group metals to be highly coloured. 

A striking example of the latter is the oxidation of Fe2+ with permanganate in acidic solution ... 

The first, and still one of the most striking, of the monolayer reactions investigated was the oxidation of a film of oleic acid (13,15) by permanganate. The double bond is oxidized thus ... 

In substituted ferrocenes, the substituent affects the reactivity of the substituted ring, the relative reactivity of the two rings and hence the reactivity of the molecule as a whole. Thus the ease of oxidation of ferrocene is reduced by electron withdrawing, —I, substituents and, in add media, the relative ease of oxidation is alltylferrocenes > ferrocene > acylferrocene. A striking example is ferrocenylcarboxaldehyde which resists oxidation by permanganate under conditions which will oxidize benzaldehyde to benzoic acid [285]. 

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