Make your own free website on
Introduction To Organic Chemistry


Oxidation of Alkenes

(Potassium Permanganate)

Manganate(VII) ions are a strong oxidising agent, and in the first instance oxidise ethene to ethane-1,2-diol (old name: ethylene glycol). Looking at the equation purely from the point of view of the organic reaction:

The full equation depends on the conditions.

Under acidic conditions, the manganate(VII) ions are reduced to manganese(II) ions.

Under alkaline conditions, the manganate(VII) ions are first reduced to green manganate(VI) ions.

. . . and then further to dark brown solid manganese(IV) oxide (manganese dioxide).

This last reaction is also the one you would get if the reaction was done under neutral conditions. You will notice that there are neither hydrogen ions nor hydroxide ions on the left-hand side of the equation.

As you have seen above the product of the oxidation of alkenes result in a diol. That is an organic compound with two alcohol functional groups, that is the hydroxy group (OH).