The permanganate ion is MnO₄⁻. A permanganate is a compound that contains this group.

Because manganese is in the +7 oxidation state, the permanganate ion is a strong oxidizer.

In acidic solution, permanganate will reduce to the clear +2 oxidation state of the Mn²⁺ ion.

16H₃O ⁺ + 2MnO₄⁻ + 10Cl⁻ --> 2Mn²⁺ + 5Cl₂ + 24H₂O
6H⁺+2MnO₄⁻ + 5HCOOH = 8H₂O + 2Mn²⁺ + 5CO₂

In basic solution, permanganate will either reduce to the brown +4 oxidation state of MnO₂ or to the green +6 oxidation state of MnO₄²⁻

4OH⁻ + 2MnO₄⁻ + 3C₂O₄²⁻ --> 2MnO₂ + 6CO₃²⁻ + 2H₂O

3OH⁻ + 2MnO₄⁻ + HSO₃⁻ --> 2MnO₄²⁻ + SO₄²⁻ + 2H₂O

Examples

• potassium permanganate, KMnO₄
• sodium permanganate, NaMnO₄

See Permanganates for a list.

Production

Permanganates may be produced by oxidization of manganese compounds by strong oxidizing agents, for instance, sodium hypochlorite or lead dioxide:

2MnCl₂ + 5NaClO + 6NaOH = 2NaMnO ₄ + 9NaCl+ 3 H₂O
2MnSO₄ + 5PbO₂+ 3 H₂SO₄ = 2HMnO₄+ 5PbSO₄ + 2H₂O

Or by dismutation of manganates, like this:

3Na₂MnO₄ + 2H₂O=2NaMnO₄ + MnO₂ + 4NaOH

Discussion

Permanganates are salts of permanganic acid.

Permanganate is a strong oxidizer, and similar to perchlorate. Besides this, it is stable.

It is a useful reagent, though with organic compounds, it may just destroy them entirely.

Permanganates are not very thermically stable. For instance, potassium permanganate decomposes at 230°C:

2KMnO₄=K₂MnO₄+MnO₂+O₂

External links

• National Pollutant Inventory - Manganese and compounds Fact Sheet

Oxoanions | Permanganat | Permanganato | Permanganate | 過マンガン酸塩