# Permanganate
Permanganate is the tetrahedral anion MnO₄⁻, in which manganese sits in its highest common oxidation state of +7, and it is one of the strongest oxidizing agents in routine use, most familiar as the deep purple crystalline salt potassium permanganate (KMnO₄, CAS 7722-64-7)[1](https://pubchem.ncbi.nlm.nih.gov/compound/KMnO4) • [2](https://chem.libretexts.org/Courses/East_Tennessee_State_University/CHEM_4110%3A_Advanced_Inorganic_Chemistry/08%3A_Coordination_Chemistry_-_Spectroscopy/8.05%3A_Charge_Transfer_Transitions). Its principal large-scale use is water and wastewater treatment, where it oxidizes dissolved iron, manganese, and taste- and odor-causing compounds[3](https://www.epa.gov/system/files/documents/2023-03/Potassium%20Permanganate%20Supply%20Chain%20Profile.pdf).
| Key fact | Detail |
|---|---|
| Formula and identity | MnO₄⁻; manganese in the +7 oxidation state, tetrahedral geometry; potassium salt KMnO₄, molar mass 158.034 g/mol[1](https://pubchem.ncbi.nlm.nih.gov/compound/KMnO4) • [2](https://chem.libretexts.org/Courses/East_Tennessee_State_University/CHEM_4110%3A_Advanced_Inorganic_Chemistry/08%3A_Coordination_Chemistry_-_Spectroscopy/8.05%3A_Charge_Transfer_Transitions) |
| Color | Deep purple, from a ligand-to-metal charge-transfer band near 528–530 nm[4](https://chem.libretexts.org/Courses/Providence_College/CHM_331_Advanced_Analytical_Chemistry_1/09%253A_Applications_of_Ultraviolet-Visable_Molecular_Absorption_Spectrometry/9.02%253A_Absorbing_Species/9.2.03%253A_Electronic_Spectra_-_Ultraviolet_and_Visible_Spectroscopy_-_Metal_to_Ligand_and_Ligand_to_Metal_Charge_Transfer_Bands) |
| Reduction products | Mn²⁺ in acid (5-electron change), MnO₂ in neutral or mildly basic solution, MnO₄²⁻ in strongly basic solution[5](https://chemguide.co.uk/inorganic/redox/equations.html) • [6](https://openstax.org/books/chemistry-atoms-first/pages/16-1-balancing-oxidation-reduction-reactions) |
| Solubility | 2.83 g/100 mL water at 0 °C and 6.38 g/100 mL at 20 °C[7](https://www.osti.gov/servlets/purl/4041453/) |
| Manufacture | Two-step process from manganese dioxide and potassium hydroxide: high-temperature oxidation to potassium manganate, then electrolysis[3](https://www.epa.gov/system/files/documents/2023-03/Potassium%20Permanganate%20Supply%20Chain%20Profile.pdf) |
| US market (2019) | Production about 11 million kg, consumption about 9 million kg; sole domestic manufacturer is Carus Corporation in Illinois[8](https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P1017BOA.txt) |
| Leading use | Water treatment (36.1% of US consumption) and wastewater treatment (22.8%)[3](https://www.epa.gov/system/files/documents/2023-03/Potassium%20Permanganate%20Supply%20Chain%20Profile.pdf) |
| Transport hazard | UN 1490, Division 5.1 oxidizer, Packing Group II[1](https://pubchem.ncbi.nlm.nih.gov/compound/KMnO4) |
## Structure and color
The permanganate ion consists of one manganese atom bonded to four oxygen atoms at the corners of a tetrahedron. Because manganese is in the +7 state it is formally a d⁰ ion, so the usual d–d transitions that color most transition-metal complexes are impossible; a d⁰ ion would be expected to be colorless[2](https://chem.libretexts.org/Courses/East_Tennessee_State_University/CHEM_4110%3A_Advanced_Inorganic_Chemistry/08%3A_Coordination_Chemistry_-_Spectroscopy/8.05%3A_Charge_Transfer_Transitions). The intense purple instead comes from a ligand-to-metal charge-transfer (LMCT) transition, in which an electron from a filled oxygen p orbital is promoted into an empty manganese orbital. The visible LMCT band of aqueous permanganate lies around 528–530 nm, and charge-transfer absorptions of this kind are selection-rule allowed and therefore very intense[4](https://chem.libretexts.org/Courses/Providence_College/CHM_331_Advanced_Analytical_Chemistry_1/09%253A_Applications_of_Ultraviolet-Visable_Molecular_Absorption_Spectrometry/9.02%253A_Absorbing_Species/9.2.03%253A_Electronic_Spectra_-_Ultraviolet_and_Visible_Spectroscopy_-_Metal_to_Ligand_and_Ligand_to_Metal_Charge_Transfer_Bands). Very high metal oxidation states combined with π-donor oxo ligands favor such transitions, which is why permanganate (Mn(VII)) and dichromate (Cr(VI)) are among the most strongly colored d⁰ species[2](https://chem.libretexts.org/Courses/East_Tennessee_State_University/CHEM_4110%3A_Advanced_Inorganic_Chemistry/08%3A_Coordination_Chemistry_-_Spectroscopy/8.05%3A_Charge_Transfer_Transitions).
**The color is analytically useful.** In redox titrations the purple permanganate ion serves as its own indicator: as it is reduced to the nearly colorless Mn²⁺, the endpoint is marked by the first persistent pink tinge of excess permanganate[9](https://demolab.chem.wisc.edu/titrations-the-reaction-between-oxalate-ion-with-permanganate/).
## Redox chemistry
The chemistry of permanganate depends strongly on pH, because the manganese(VII) center can be reduced to several different end states[5](https://chemguide.co.uk/inorganic/redox/equations.html):
- **Acidic solution.** Permanganate accepts five electrons per ion and is reduced to Mn²⁺. The half-reaction is \( \mathrm{MnO_4^- + 8H^+ + 5e^- \rightarrow Mn^{2+} + 4H_2O} \). Acidified potassium permanganate oxidizes iron(II) to iron(III) in a 1:5 molar ratio, and it oxidizes oxalate to carbon dioxide in the classic permanganate–oxalate titration[5](https://chemguide.co.uk/inorganic/redox/equations.html) • [9](https://demolab.chem.wisc.edu/titrations-the-reaction-between-oxalate-ion-with-permanganate/).
- **Neutral or mildly basic solution.** Reduction stops at manganese(IV), giving insoluble brown manganese dioxide (MnO₂), a 3-electron change[10](https://chem.libretexts.org/Courses/University_of_California_Davis/UCDemos/Oxidation_States_of_Manganese).
- **Strongly basic solution.** Permanganate is reduced only to the green manganate(VI) ion, MnO₄²⁻, a 1-electron change[6](https://openstax.org/books/chemistry-atoms-first/pages/16-1-balancing-oxidation-reduction-reactions) • [10](https://chem.libretexts.org/Courses/University_of_California_Davis/UCDemos/Oxidation_States_of_Manganese).
In organic chemistry, permanganate is a versatile oxidant. Under alkaline conditions it converts carbon–carbon double bonds (olefins) into vicinal diols in good yield, while in neutral or slightly basic solutions α-hydroxy ketones form; under acidic conditions cleavage of the double bond predominates[11](https://dspace.nitrkl.ac.in/dspace/bitstream/2080/871/1/oxidation.pdf). Strong oxidizing agents such as acidified permanganate convert primary alcohols to carboxylic acids and secondary alcohols to ketones, while tertiary alcohols, which lack a C–H bond on the hydroxyl-bearing carbon, are generally unreactive[12](https://www.monash.edu/student-academic-success/chemistry/reactions-of-organic-compounds/organic-reactions-and-synthesis-pathways/organic-reactions-oxidation). Historically, important quantities have been used to oxidize the methyl group of toluene and its derivatives to a carboxylic acid group in the production of saccharin and benzoic acid, with manganese dioxide obtained as a by-product[13](https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=91007S23.TXT).
## Production and supply
[Potassium permanganate](https://www.edgepedia.org/potassium-permanganate) is primarily produced through a two-step reaction of manganese dioxide and potassium hydroxide. Ground manganese dioxide is oxidized at high temperature with potassium hydroxide to produce potassium manganate (K₂MnO₄), and the resulting solution is then subjected to electrolysis, which crystallizes potassium permanganate out of the solution[3](https://www.epa.gov/system/files/documents/2023-03/Potassium%20Permanganate%20Supply%20Chain%20Profile.pdf):
\[ 2\,\mathrm{MnO_2} + 4\,\mathrm{KOH} + \mathrm{O_2} \rightarrow 2\,\mathrm{K_2MnO_4} + 2\,\mathrm{H_2O} \]
\[ 2\,\mathrm{K_2MnO_4} + 2\,\mathrm{H_2O} \rightarrow 2\,\mathrm{KMnO_4} + 2\,\mathrm{KOH} + \mathrm{H_2} \quad (\text{electrolysis}) \]
In the United States, total domestic manufacturing was approximately 11 million kilograms in 2019, with consumption estimated at 9 million kg after 1 million kg of imports and 3 million kg of exports. The sole reported domestic commercial manufacturer is the Carus Corporation facility in Illinois, which has been the only known operating domestic manufacturer since at least 1998; a portion of its output is used captively to make sodium permanganate[8](https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P1017BOA.txt). The product is supplied mainly as free-flowing grade crystals and transported by truck, rail, barge, and tanker; stored tightly closed in cool, dry conditions it has a shelf life in excess of 60 months[8](https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P1017BOA.txt).
## Uses
**Water treatment dominates consumption.** Past estimates place industrial and municipal water treatment at 36.1% of total US domestic consumption and industrial and municipal wastewater treatment at 22.8%; other uses include oil and gas well production water treatment (17.0%), air and gas purification (11.0%), chemical manufacturing (3.6%), remediation (1.7%), and metal processing (0.3%)[3](https://www.epa.gov/system/files/documents/2023-03/Potassium%20Permanganate%20Supply%20Chain%20Profile.pdf). In drinking water treatment, doses depend on the concentrations of metals and organics but are usually 0.3–5 mg/L, and the required dose is determined by jar testing[14](https://guidelines.nhmrc.gov.au/australian-drinking-water-guidelines/part-5/treatment-chemicals/potassium-permanganate). Its advantages include ease of use and effectiveness in oxidizing both iron and manganese and certain types of taste and odor[14](https://guidelines.nhmrc.gov.au/australian-drinking-water-guidelines/part-5/treatment-chemicals/potassium-permanganate).
**It is a pretreatment oxidant, not a primary disinfectant.** Although potassium permanganate can inactivate various bacteria and viruses, it is not used as a primary or secondary disinfectant at commonly used treatment levels; it serves mainly as an alternative to pre-chlorination, oxidizing organic precursors at the head of the plant and thereby minimizing downstream disinfection byproduct formation[15](https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=2000229L.TXT). Application results in the precipitation of manganese dioxide, a black precipitate removed by clarification or filtration; if not properly removed, the precipitate can create deposits in distribution systems, and manganese in finished water is regulated with a secondary maximum contaminant level of 0.05 mg/L[15](https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=2000229L.TXT). Overdosing must be avoided because unreacted permanganate colors the water pink[14](https://guidelines.nhmrc.gov.au/australian-drinking-water-guidelines/part-5/treatment-chemicals/potassium-permanganate).
Apart from water treatment, permanganate serves to bleach and decolorize oils, fats, waxes, and natural sponge; it also finds use in bleaching textiles, acts as a disinfectant and antiseptic, stains wood, and produces oxide coatings on aluminum that adhere tightly.[13](https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=91007S23.TXT) It has also found considerable use in treating wastes containing phenols, aldehydes, ketones, esters, olefins, mercaptans, amines, tannins, lignins, hydrogen sulfide, and lower oxides of nitrogen[13](https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=91007S23.TXT).
## Safety and handling
Potassium permanganate is a noncombustible but powerful oxidizing solid that accelerates the burning of combustible material; mixtures with finely divided combustibles may be explosive, and contact with liquid combustibles can cause spontaneous ignition[1](https://pubchem.ncbi.nlm.nih.gov/compound/KMnO4). It reacts violently with powdered metals, and explosions have occurred on contact with glycerol, concentrated hydrogen peroxide, or concentrated sulfuric acid in the presence of moisture[1](https://pubchem.ncbi.nlm.nih.gov/compound/KMnO4). The dark purple crystalline solid can cause serious eye injury, is a skin and inhalation irritant, and can be fatal if swallowed; the lethal dose is about 10 grams, and ingestion can cause gastrointestinal burns, methemoglobinemia, and liver and kidney injury[1](https://pubchem.ncbi.nlm.nih.gov/compound/KMnO4) • [15](https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=2000229L.TXT). Under OSHA requirements, oxidants such as permanganate are stored separately from organic chemicals such as polymers and activated carbon[15](https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=2000229L.TXT).
## References
1. [Potassium Permanganate | KMnO4 | CID 516875, PubChem](https://pubchem.ncbi.nlm.nih.gov/compound/KMnO4)
2. [8.5: Charge Transfer Transitions, Chemistry LibreTexts](https://chem.libretexts.org/Courses/East_Tennessee_State_University/CHEM_4110%3A_Advanced_Inorganic_Chemistry/08%3A_Coordination_Chemistry_-_Spectroscopy/8.05%3A_Charge_Transfer_Transitions)
3. [Water Treatment Chemical Supply Chain Profile – Potassium Permanganate, US EPA (EPA 817-F-22-040, December 2022)](https://www.epa.gov/system/files/documents/2023-03/Potassium%20Permanganate%20Supply%20Chain%20Profile.pdf)
4. [9.2.3: Electronic Spectra – Metal to Ligand and Ligand to Metal Charge Transfer Bands, Chemistry LibreTexts](https://chem.libretexts.org/Courses/Providence_College/CHM_331_Advanced_Analytical_Chemistry_1/09%253A_Applications_of_Ultraviolet-Visable_Molecular_Absorption_Spectrometry/9.02%253A_Absorbing_Species/9.2.03%253A_Electronic_Spectra_-_Ultraviolet_and_Visible_Spectroscopy_-_Metal_to_Ligand_and_Ligand_to_Metal_Charge_Transfer_Bands)
5. [Writing ionic equations for redox reactions, Chemguide](https://chemguide.co.uk/inorganic/redox/equations.html)
6. [16.1 Balancing Oxidation-Reduction Reactions, OpenStax Chemistry: Atoms First](https://openstax.org/books/chemistry-atoms-first/pages/16-1-balancing-oxidation-reduction-reactions)
7. [Solubility study of potassium permanganate, OSTI](https://www.osti.gov/servlets/purl/4041453/)
8. [Potassium Permanganate Supply Chain – Full Profile, US EPA NEPIS](https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P1017BOA.txt)
9. [Titrations: The Reaction Between Oxalate Ion with Permanganate, UW–Madison Chemistry Demonstration Lab](https://demolab.chem.wisc.edu/titrations-the-reaction-between-oxalate-ion-with-permanganate/)
10. [Oxidation States of Manganese, Chemistry LibreTexts (UC Davis)](https://chem.libretexts.org/Courses/University_of_California_Davis/UCDemos/Oxidation_States_of_Manganese)
11. [Oxidation by permanganate: synthetic and mechanistic aspects, NIT Rourkela repository](https://dspace.nitrkl.ac.in/dspace/bitstream/2080/871/1/oxidation.pdf)
12. [Organic reactions: Oxidation, Monash University Student Academic Success](https://www.monash.edu/student-academic-success/chemistry/reactions-of-organic-compounds/organic-reactions-and-synthesis-pathways/organic-reactions-oxidation)
13. [Recommended Methods of Reduction, Neutralization, Recovery, or Disposal of Hazardous Waste, Volume XIII: Inorganic Compounds, US EPA NEPIS](https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=91007S23.TXT)
14. [Potassium permanganate, Australian Drinking Water Guidelines, NHMRC](https://guidelines.nhmrc.gov.au/australian-drinking-water-guidelines/part-5/treatment-chemicals/potassium-permanganate)
15. [Alternative Disinfectants and Oxidants Guidance Manual (EPA 815-R-99-014, April 1999), US EPA NEPIS](https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=2000229L.TXT)
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*Topic: Encyclopedia › Physical world and mathematics › Chemistry › Elements and inorganic substances › Oxides and oxygen compounds › Metal oxides and hydroxides › Transition-metal oxides*
*Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 15, 2026 · Edited: Sep 30, 2026; Oct 15, 2026 · Last review: Oct 15, 2026*
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