Barium manganate is an

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

with the

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwee ...

BaMnO₄. It is used as an oxidant in

organic chemistry Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; ...

. It belongs to a class of compounds known as manganates in which the manganese resides in a +6 oxidation state. Manganate should not to be confused with

permanganate A permanganate () is a chemical compound containing the manganate(VII) ion, , the conjugate base of permanganic acid. Because the manganese atom is in the +7 oxidation state, the permanganate(VII) ion is a strong oxidizing agent. The ion is a tra ...

which contains manganese(VII). Barium manganate is a powerful oxidant, popular in organic synthesis and can be used in a wide variety of oxidation reactions.

Properties

The manganate(VI) ion is a d¹ ion and is tetrahedral with bond angles of approximately 109.5°. The Mn−O bond lengths in BaMnO₄ and K₂MnO₄ are identical at 1.66 Å. In comparison, the Mn-O bond length in is longer than in MnO₄⁻ of 1.56 Å and shorter than the Mn−O bond found in MnO₂, 1.89 Å. Barium manganate is isomorphous with BaCrO₄ and BaSO₄. Barium manganate can appear as a dark blue or green to black crystals.Firouzabadi, H.; Mostafavipoor,Z. (1983), "Barium Manganate. A Versatile Oxidant in Organic Synthesis", ''Bull. Chem. Soc. Jpn.'' 56 (3): p914-917. . Barium manganate is indefinitely stable, active and can be stored for months in dry conditions.

Preparation

Barium manganate can be prepared from

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''manga ...

and

barium chloride Barium chloride is an inorganic compound with the formula Ba Cl2. It is one of the most common water-soluble salts of barium. Like most other water-soluble barium salts, it is white, highly toxic, and imparts a yellow-green coloration to a flame. ...

salt metathesis A salt metathesis reaction, sometimes called a double displacement reaction, is a chemical process involving the exchange of bonds between two reacting chemical species which results in the creation of products with similar or identical bonding a ...

to give insoluble barium manganate: :

Uses in organic synthesis

Barium manganate oxidizes a number of functional groups efficiently and selectively: alcohols to carbonyls, diols to lactones, thiols to disulfides, aromatic amines to azo-compounds, hydroquinone to p-benzoquinone, benzylamine to benzaldehyde,

hydrazones Hydrazones are a class of organic compounds with the structure . They are related to ketones and aldehydes by the replacement of the oxygen =O with the = functional group. They are formed usually by the action of hydrazine on ketones or aldehydes. ...

diazo compounds The diazo group is an organic moiety consisting of two linked nitrogen atoms ( azo) at the terminal position. Overall charge neutral organic compounds containing the diazo group bound to a carbon atom are called diazo compounds or diazoalkanes ...

, etc.Procter.G.; Ley, S. V.; Castle, G.H. (2004), "Barium Manganate", in Paquette,L., ''Encyclopedia of Reagents for Organic Synthesis'', New York:Wiley, {{doi:10.1002/047084289X. It does not oxidize saturated hydrocarbons, alkenes, unsaturated ketones, and tertiary amines. Barium manganate is a common substitute for MnO₂. It is easier to prepare, reacts more efficiently, and the substrate:oxidant ratios are closer to theory. Another use for barium manganate was as a pigment for making the artist’s color manganese blue. It is no longer used for that purpose; instead, paint manufacturers substitute a synthetic manganese blue hue.

References

Manganates Barium compounds Oxidizing agents