A permanganate () is a

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

with the manganate(VII)

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

, , the

conjugate base A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid gives a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as it loses a hydrogen ion in the reve ...

permanganic acid Permanganic acid (or manganic(VII) acid) is the inorganic compound with the formula H MnO4 and various hydrates. This strong oxoacid has been isolated as its dihydrate. It is the conjugate acid of permanganate salts. It is the subject of few p ...

. Because 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 has a +7

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical Electrical charge, charge of an atom if all of its Chemical bond, bonds to other atoms are fully Ionic bond, ionic. It describes the degree of oxidation (loss of electrons ...

, the permanganate(VII) ion is a strong

oxidising agent An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ''electron donor''). In ot ...

. The ion is a transition metal ion with a tetrahedral structure. Permanganate solutions are purple in colour and are stable in

neutral Neutral or neutrality may refer to: Mathematics and natural science Biology * Neutral organisms, in ecology, those that obey the unified neutral theory of biodiversity Chemistry and physics * Neutralization (chemistry), a chemical reaction in ...

or slightly

alkaline In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The ...

media.

Production

Permanganates can be produced by oxidation of manganese compounds such as

manganese chloride Manganese chloride may refer to: * Manganese(II) chloride Manganese(II) chloride is the dichloride salt of manganese, MnCl2. This inorganic chemical exists in the anhydrous form, as well as the dihydrate (MnCl2·2H2O) and tetrahydrate (MnCl2·4H ...

manganese sulfate Manganese(II) sulfate usually refers to the inorganic compound with the formula MnSO4·H2O. This pale pink deliquescent solid is a commercially significant manganese(II) salt. Approximately 260,000 tonnes of manganese(II) sulfate were produced wor ...

by strong oxidizing agents, for instance,

sodium hypochlorite Sodium hypochlorite is an alkaline inorganic chemical compound with the formula (also written as NaClO). It is commonly known in a dilute aqueous solution as bleach or chlorine bleach. It is the sodium salt of hypochlorous acid, consisting of ...

lead dioxide Lead(IV) oxide, commonly known as lead dioxide, is an inorganic compound with the chemical formula . It is an oxide where lead is in an oxidation state of +4. It is a dark-brown solid which is insoluble in water. It exists in two crystalline forms ...

: :2 MnCl₂ + 5 NaClO + 6 NaOH → 2 NaMnO₄ + 9 NaCl + 3 H₂O :2 MnSO₄ + 5 PbO₂ + 3 H₂SO₄ → 2 HMnO₄ + 5 PbSO₄ + 2 H₂O It may also be produced by the

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 ...

manganate In inorganic nomenclature, a manganate is any negatively charged molecular entity with manganese as the central atom.. However, the name is usually used to refer to the tetraoxidomanganate(2−) anion, MnO, also known as manganate(VI) because it c ...

s, with

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 ...

as a side-product: :3 Na₂MnO₄ + 2 H₂O → 2 NaMnO₄ + MnO₂ + 4 NaOH They are produced commercially by

electrolysis In chemistry and manufacturing, electrolysis is a technique that uses Direct current, direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of c ...

or air oxidation of alkaline solutions of manganate salts (). Potassium permanganate solutions 2

Uses

Permanganate compounds are common and strong disinfectants, used regularly to sanitize baths, toilets, and wash basins. It is a cheap and extremely effective compound for the task.

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 ...

is used as a disinfectant and water treatment additive in aquaculture. Permanganate compounds are useful

reagent In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...

s, but not very selective with

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

s when used in

organic synthesis Organic synthesis is a branch of chemical synthesis concerned with the construction of organic compounds. Organic compounds are molecules consisting of combinations of covalently-linked hydrogen, carbon, oxygen, and nitrogen atoms. Within the gen ...

Properties

Permanganates are

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

s of permanganic acid. They have a deep purple colour, due to a charge transfer transition from oxo ligand p orbitals to empty orbitals derived from manganese(VII) d orbitals. Permanganate(VII) is a strong

oxidizer An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ''electron donor''). In ot ...

, and similar to

perchlorate A perchlorate is a chemical compound containing the perchlorate ion, , the conjugate base of perchloric acid (ionic perchlorate). As counterions, there can be metal cations, quaternary ammonium cations or other ions, for example, nitronium cat ...

. It is therefore in common use in qualitative analysis that involves redox reactions (

permanganometry Permanganometry is one of the techniques used in chemical quantitative analysis. It is a redox titration that involves the use of permanganates to measure the amount of analyte present in unknown chemical samples. It involves two steps, namely the t ...

). According to theory, permanganate is strong enough to oxidize water, but this does not actually happen to any extent. Besides this, it is stable.

Reactions

Thermal decomposition

Permanganates are not very stable thermally. For instance,

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 ...

decomposes at 230 °C 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 ...

and

, releasing

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 ...

gas: :2 KMnO₄ → K₂MnO₄ + MnO₂ + O₂

Acid-base reactions

In an

acid An acid is a molecule or ion capable of either donating a proton (i.e. Hydron, hydrogen cation, H+), known as a Brønsted–Lowry acid–base theory, Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis ...

ic solution, permanganate(VII) is reduced to the pale pink manganese(II) (Mn²⁺) with an oxidation state of +2. :8 + + 5 e⁻ → Mn²⁺ + 4 H₂O In a strongly

basic Basic or BASIC may refer to: Science and technology * BASIC, a computer programming language * Basic (chemistry), having the properties of a base * Basic access authentication, in HTTP Entertainment * Basic (film), ''Basic'' (film), a 2003 film ...

solution, permanganate(VII) is reduced to the green

ion, with an oxidation state of +6. : + e⁻ → In a neutral solution, however, it gets reduced to the brown

MnO₂ with an oxidation state of +4. :2 H₂O + + 3 e⁻ → MnO₂ + 4 OH⁻

Oxidation of organic compounds

When used to oxidize organic compounds, the exact chemical reaction depends on the organic reactant present. For example,

trichloroethane Trichloroethane (CHCl) may refer to either of two isomeric chemical compounds: * 1,1,1-Trichloroethane (methyl chloroform, CClCH) * 1,1,2-Trichloroethane 1,1,2-Trichloroethane, vinyl trichloride or 1,1,2-TCA, is an organochloride solvent with the ...

(C₂H₃Cl₃) is oxidised by permanganate ions to form

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

(CO₂),

(MnO₂), hydrogen ions (H⁺), and

chloride The term chloride refers to a compound or molecule that contains either a chlorine anion (), which is a negatively charged chlorine atom, or a non-charged chlorine atom covalently bonded to the rest of the molecule by a single bond (). The pr ...

ions (Cl⁻). :8 + 3 → 6 + 8 + + 4 + 9 A permanganate can oxidize an

amine In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of elec ...

to a

nitro compound In organic chemistry, nitro compounds are organic compounds that contain one or more nitro functional groups (). The nitro group is one of the most common explosophores (functional group that makes a compound explosive) used globally. The nit ...

, a

secondary alcohol In chemistry, an alcohol (), is a type of organic compound that carries at least one hydroxyl () functional group bound to a Saturated and unsaturated compounds, saturated carbon atom. Alcohols range from the simple, like methanol and ethanol ...

to a

ketone In organic chemistry, a ketone is an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone ( ...

, a

primary alcohol A primary alcohol is an alcohol in which the hydroxy group is bonded to a primary carbon atom. It can also be defined as a molecule containing a “–CH2OH” group. In contrast, a secondary alcohol has a formula “–CHROH” and a tertiary ...

aldehyde In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...

to a

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an Substituent, R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl ...

, a

terminal alkene In organic chemistry, terminal alkenes (alpha-olefins, α-olefins, or 1-alkenes) are a family of organic compounds which are alkenes (also known as olefins) with a chemical formula , distinguished by having a double bond at the primary, alpha ( ...

to a

oxalic acid Oxalic acid is an organic acid with the systematic name ethanedioic acid and chemical formula , also written as or or . It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name i ...

, and an

alkene In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or at the terminal position. Terminal alkenes are also known as Alpha-olefin, α-olefins. The Internationa ...

to a

diol A diol is a chemical compound containing two hydroxyl groups ( groups). An aliphatic diol may also be called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified. They are used as protecting gro ...

. This list is not exhaustive. In

oxidations one intermediate is a cyclic Mn(V) species:. : PermanganateMechanismOxidation

Compounds

* Ammonium permanganate, NH₄MnO₄ *

Barium permanganate Barium permanganate is a chemical compound, with the formula Ba(MnO4)2. It forms violet to brown crystals that are sparingly soluble in water. Preparation Barium permanganate may be produced by disproportionation of barium manganate in a mildly ...

, Ba(MnO₄)₂ *

Calcium permanganate Calcium permanganate is an oxidizing agent and chemical compound with the chemical formula Ca(MnO4)2. This salt consists of the metal calcium and two permanganate ions. Preparation The salt is prepared from the reaction of potassium permanganat ...

, Ca(MnO₄)₂ *

Lithium permanganate Lithium permanganate is an inorganic compound with the chemical formula LiMnO4. It can be produced by the reaction of lithium sulfate and barium permanganate, and the trihydrate LiMnO4·3H2O can be crystallized from the solution. It decomposes v ...

, LiMnO₄ *

, KMnO₄ *

Sodium permanganate Sodium permanganate is the inorganic compound with the formula sodium, NaPermanganate, MnO4. It is closely related to the more commonly encountered potassium permanganate, but it is generally less desirable, because it is more expensive to produce ...

, NaMnO₄ *

Silver permanganate Silver permanganate is an inorganic compound with the chemical formula AgMnO4. This salt is a purple crystal adopting a monoclinic crystal system. It decomposes when heated or mixed with water, and heating to high temperature may lead to explosion ...

, AgMnO₄

Safety

The fatal dose of permanganate is about 10 g, and several fatal intoxications have occurred. The strong oxidative effect leads to

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. The term "necrosis" came about in the mid-19th century and is commonly attributed to German pathologist Rudolf Virchow, who i ...

of the

mucous membrane A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It ...

. For example, the

esophagus The esophagus (American English), oesophagus (British English), or œsophagus (Œ, archaic spelling) (American and British English spelling differences#ae and oe, see spelling difference) all ; : ((o)e)(œ)sophagi or ((o)e)(œ)sophaguses), c ...

is affected if the permanganate is swallowed. Only a limited amount is absorbed by the intestines, but this small amount shows severe effects on the kidneys and on the liver.

References

{{Permanganates Transition metal oxyanions Oxometallates

Production

Uses

Properties

Reactions

Thermal decomposition

Acid-base reactions

Oxidation of organic compounds

Compounds

Safety

See also

References