Potassium hypomanganate is the

inorganic compound An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''. Inorgan ...

with the formula . Also known as potassium manganate(V), this bright blue solid is a rare example of a salt with the

hypomanganate In chemistry, hypomanganate, also called manganate(V) or tetraoxidomanganate(3−), is a trivalent anion ( negative ion) composed of manganese and oxygen, with formula . Hypomanganates are usually bright blue.D. Reinen, W. Rauw, U. Kesper, M. A ...

or manganate(V) anion, where the

manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...

atom is in the +5

oxidation Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...

state. It is an intermediate in the production of

potassium permanganate Potassium permanganate is an inorganic compound with the chemical formula KMnO4. It is a purplish-black crystalline salt, which dissolves in water as K+ and ions to give an intensely pink to purple solution. Potassium permanganate is widely us ...

and the industrially most important Mn(V) compound.

Properties

Potassium hypomanganate is oxidized in water to

potassium manganate Potassium manganate is the inorganic compound with the formula . This green-colored salt is an intermediate in the industrial synthesis of potassium permanganate (), a common chemical. Occasionally, potassium manganate and potassium ''per''mangana ...

: :2 K₃MnO₄ + H₂O + 0.5 O₂ → 2 KOH + 2 K₂MnO₄ However, it undergoes

disproportionation In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation state. The reverse of disproportionatio ...

in acidic solutions producing

manganese dioxide Manganese dioxide is the inorganic compound with the formula . This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for is for dry-cel ...

and potassium permanganate. In the absence of moisture, it is stable up to 900 °C. Above that temperature, it decomposes to

potassium oxide Potassium oxide ( K O) is an ionic compound of potassium and oxygen. It is a base. This pale yellow solid is the simplest oxide of potassium. It is a highly reactive compound that is rarely encountered. Some industrial materials, such as fertil ...

manganese(II,III) oxide Manganese(II,III) oxide is the manganese oxide with the chemical compound with formula Mn3O4. Manganese is present in two oxidation states, +2 and +3, and the formula is sometimes written as MnO· Mn2O3. Mn3O4 is found in nature as the mineral h ...

, and oxygen.

Preparative routes

The solid salt can be produced by the reaction of

potassium carbonate Potassium carbonate is the inorganic compound with the formula . It is a white salt, which is soluble in water and forms a strongly alkaline solution. It is deliquescent, often appearing as a damp or wet solid. Potassium carbonate is mainly used ...

and

manganese carbonate Manganese carbonate is a compound with the chemical formula Mn CO3. Manganese carbonate occurs naturally as the mineral rhodochrosite but it is typically produced industrially. It is a pale pink, water-insoluble solid. Approximately 20,000 metr ...

in the presence of

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

at 800 °C. However, in the industrial process of producing potassium permanganate, it is produced by fusing manganese dioxide and

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which utili ...

. The resulting hypomanganate further reacts with water to produce manganate. A solution of potassium hypomanganate is produced: *by two-electron reduction of

with excess

potassium sulfite Potassium sulfite is the inorganic compound with the formula K2SO3. It is the salt of potassium cation and sulfite anion. It is a white solid that is highly soluble in water. Potassium sulfite is used for preserving food and beverages. Histor ...

;.. : *by the single-electron reduction of

with

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscosity, viscous than Properties of water, water. It is used as an oxidizer, bleaching agent, and antiseptic, usua ...

in 10 M

solution;. : *by the single-electron reduction of potassium manganate with

mandelate Mandelic acid is an aromatic alpha hydroxy acid with the molecular formula C6H5CH(OH)CO2H. It is a white crystalline solid that is soluble in water and polar organic solvents. It is a useful precursor to various drugs. The molecule is chiral. The ...

in 3–10 M potassium hydroxide solution; : *by disproportionation when

is dissolved in a concentrated solution of potassium hydroxide; : The compound is unstable due to the tendency of the hypomanganate anion to disproportionate in all but the most alkaline solutions.

References

{{manganese compounds Potassium compounds Manganese(V) compounds