Potassium superoxide

Potassium cations, K+

Superoxide anions, O−2

Names
IUPAC name

Potassium superoxide

Identifiers

CAS Number

* 12030-88-5 Y

3D model (JSmol)

* Interactive image

ChemSpider |

* 8329498 Y

ECHA InfoCard | 100.031.574
EC Number |

* 234-746-5

PubChem CID

* 61541

RTECS number |

* TT6053000

UN number | 2466

CompTox Dashboard (EPA)

* DTXSID30923314

InChI

* InChI=1S/2K.O2/c;;1-2/q2*+1;-2 N

Key: XXQBEVHPUKOQEO-UHFFFAOYSA-N N

* InChI=1/2K.O2/c;;1-2/q2*+1;-2

Key: XXQBEVHPUKOQEO-UHFFFAOYAV

SMILES

* [K+].[O-]=O

Properties

Chemical formula

| KO2
Molar mass | 71.096 g·mol−1
Appearance  | yellow solid
Density | 2.14 g/cm3, solid
Melting point | 560 °C (1,040 °F; 833 K) (decomposes)

Solubility in water

| Hydrolysis
Structure

Crystal structure

| Body-centered tetragonal[1][2]
Thermochemistry

Std molar
entropy (S⦵298)

| 117 J/(mol·K)[3]

Std enthalpy of
formation (ΔfH⦵298)

| −283 kJ/mol[3]
Hazards
Occupational safety and health (OHS/OSH):

Main hazards

| Corrosive, oxidizer, reacts violently with water
GHS labelling:[4]

Pictograms

Signal word

| Danger

Hazard statements

| H271, H314

Precautionary statements

| P210, P220, P221, P260, P264, P280, P283, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P306+P360, P310, P321, P363, P370+P378, P371+P380+P375, P405, P501
NFPA 704 (fire diamond)  |

Related compounds

Other cations

* Lithium superoxide
* Sodium superoxide
* Rubidium superoxide
* Caesium superoxide

Related potassium oxides

* Potassium oxide
* Potassium peroxide
* Potassium ozonide

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

N verify (what is YN ?)

Infobox references

Chemical compound

Potassium superoxide is an inorganic compound with the formula KO2.[5] It is a yellow paramagnetic solid that decomposes in moist air. It is a rare example of a stable salt of the superoxide anion. It is used as a CO2 scrubber, H2O dehumidifier, and O2 generator in rebreathers, spacecraft, submarines, and spacesuits.

## Production and reactions[edit]

Potassium superoxide is produced by burning molten potassium in an atmosphere of excess oxygen.[6]

K + O
2 → KO

The salt consists of K+
and O−
2 ions, linked by ionic bonding. The O–O distance is 1.28 Å.[1]

## Reactivity[edit]

Potassium superoxide is a source of superoxide, which is an oxidant and a nucleophile, depending on its reaction partner.[7]

Upon contact with water, it undergoes disproportionation to potassium hydroxide, oxygen, and hydrogen peroxide:

2 KO
2 \+ H
2O → 2 KOH + 3⁄2 O

2 \+ H
2O → KOH + 1⁄2 H

2 \+ 1⁄2 O
2[8]

It reacts with carbon dioxide, releasing oxygen:

2 KO
2 \+ CO2 → K2CO3 \+ 3⁄2 O

2 KO
2 \+ 2 CO2 \+ H2O → 2 KHCO3 \+ 3⁄2 O

Potassium superoxide finds only niche uses as a laboratory reagent. Because it reacts with water, KO
2 is often studied in organic solvents. Since the salt is poorly soluble in nonpolar solvents, crown ethers are typically used. The tetraethylammonium salt is also known. Representative reactions of these salts involve using superoxide as a nucleophile, e.g., in converting alkyl bromides to alcohols and acyl chlorides to diacyl peroxides.[9]

Ion exchange with tetramethylammonium hydroxide gives tetramethylammonium superoxide, a yellow solid.[10]

## Applications[edit]

The Russian Space Agency has had success using potassium superoxide in chemical oxygen generators for its spacesuits and Soyuz spacecraft. KO
2 has also been used in canisters for rebreathers for fire fighting and mine rescue work, but had limited use in scuba rebreathers because of its highly exothermic reaction with water.

Theoretically, 1 kg of KO
2 absorbs 0.310 kg of CO2 while releasing 0.338 kg of O
2. One mole of KO
2 absorbs 0.5 moles of CO2 and releases 0.75 moles of oxygen.

## References[edit]

1. ^ a b Abrahams, S. C.; Kalnajs, J. (1955). "The Crystal Structure of α-Potassium Superoxide". Acta Crystallographica. 8 (8): 503–6. doi:10.1107/S0365110X55001540.
2. ^ "Information card for entry 2310803". Crystallography Open Database. Retrieved 28 July 2022.
3. ^ a b Zumdahl, Steven S. (2009). Chemical Principles (6th ed.). Houghton Mifflin. p. A22. ISBN 978-0-618-94690-7.
4. ^ "Potassium superoxide". pubchem.ncbi.nlm.nih.gov. Retrieved 14 December 2021.
5. ^ Hayyan M.; Hashim M. A.; AlNashef I. M. (2016). "Superoxide Ion: Generation and Chemical Implications". Chem. Rev. 116 (5): 3029–3085. doi:10.1021/acs.chemrev.5b00407. PMID 26875845.
6. ^ Jakob, Harald; Leininger, Stefan; Lehmann, Thomas; Jacobi, Sylvia; Gutewort, Sven (2007). "Peroxo Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH. doi:10.1002/14356007.a19_177.pub2. ISBN 978-3527306732.
7. ^ Johnson, Roy A.; Adrio, Javier; Ribagorda, María (2007). "Potassium Superoxide". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rp250.pub2. ISBN 978-0471936237.
8. ^ Kumar De, Anil (2007). A Text Book of Inorganic Chemistry. New Age International. p. 247\. ISBN 978-8122413847.
9. ^ Johnson, Roy A.; Adrio, Javier; Ribagorda, María (2001). "Potassium Superoxide". e-EROS Encyclopedia of Reagents for Organic Synthesis. Wiley. doi:10.1002/047084289X.rp250.pub2. ISBN 0471936235.
10. ^ Bohle, D. Scott; Sagan, Elisabeth S. (2004). Tetramethylammonium Salts of Superoxide and Peroxynitrite. Inorganic Syntheses. p. 36\. doi:10.1002/0471653683.ch1.

* v
* t
* e

Potassium compounds

H, (pseudo)halogens|

* KF
* KHF2
* KH
* KCl
* KClO
* KClO3
* KClO4
* KBr
* KBrO3
* KI
* KIO3
* KIO4
* KAt
* KCN
* KCNO
* KOCN
* KSCN

chalcogens|

* K2O
* KOH
* K2O2
* KO2
* KO3
* K2S
* KHS
* K2SO3
* KHSO3
* K2SO4
* KHSO4
* KHSO5
* K2S2O3
* K2S2O5
* K2S2O7
* K2S2O8
* K2Se
* K2SeO3
* K2SeO4
* K2Te
* K2TeO3
* K2TeO4
* K2Po

pnictogens|

* K3N
* KNH2
* KN3
* KNO2
* KNO3
* K3P
* KH2PO3
* K3PO4
* K2HPO4
* KH2PO4
* KPF6
* KAsO2
* K3AsO4
* K2HAsO4
* KH2AsO4

B, C group|

* B4K2O7
* K2CO3
* KHCO3
* K2SiO3
* K2SiF6
* K2Al2O4
* K2Al2B2O7

trans metals|

* K2PtCl4
* K2Pt(CN)4
* K2PtCl6
* K2ReCl6
* K4Fe(CN)6
* K3Fe(CN)6
* K3Fe(C2O4)3
* K2FeO4
* K2MnO4
* KMnO4
* K3CrO4
* K2CrO4
* K3CrO8
* KCrO3Cl
* K2Cr2O7
* K2Cr3O10
* K2Cr4O13
* K4Mo2Cl8

organic|

* KHCO2
* KCH3CO2
* K2C2O4
* KHC2O4
* KC12H23O2
* KC18H35O2
* C3H2K2O4
* C4H6KO4
* C5H7KO4

* v
* t
* e

Oxygen compounds

* Ag4O4
* Al2O3
* AmO2
* Am2O3
* As2O3
* As2O5
* Au2O3
* B2O3
* BaO
* BeO
* Bi2O3
* BiO2
* Bi2O5
* BrO2
* Br2O3
* Br2O5
* Br

* CO
* CO2
* C3O2
* CaO
* CaO2
* CdO
* CeO2
* Ce3O4
* Ce2O3
* ClO2
* Cl2O
* Cl2O2
* Cl2O3
* Cl2O4
* Cl2O6
* Cl2O7
* CoO
* Co2O3
* Co3O4
* CrO3
* Cr2O3
* Cr2O5
* Cr5O12
* CsO2
* Cs2O3
* CuO
* Dy2O3
* Er2O3
* Eu2O3
* FeO
* Fe2O3
* Fe3O4
* Ga2O
* Ga2O3
* GeO
* GeO2
* H2O
* 2H2O
* 3H2O
* H218O
* H2O2
* HfO2
* HgO
* Hg2O
* Ho2O3
* IO
* I2O4
* I2O5
* I2O6
* I4O9
* In2O3
* IrO2
* KO2
* K2O2
* La2O3
* Li2O
* Li2O2
* Lu2O3
* MgO
* Mg2O3
* MnO
* MnO2
* Mn2O3
* Mn2O7
* MoO2
* MoO3
* Mo2O3
* NO
* NO2
* N2O
* N2O3
* N2O4
* N2O5
* NaO2
* Na2O
* Na2O2
* NbO
* NbO2
* Nd2O3
* O2F
* OF
* OF2
* O2F2
* O3F2
* O4F2
* O5F2
* O6F2
* O2PtF6
* more...

Chemical formulas
*[CID]: Compound ID
*[EPA]: U.S. Environmental Protection Agency
*[H271]: H271: May cause fire or explosion: strong oxidizer
*[H314]: H314: Causes severe skin burns and eye damage
*[P210]: P210: Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
*[P220]: P220: Keep/Store away from clothing/.../combustible materials.
*[P221]: P221: Take any precaution to avoid mixing with combustibles.
*[P260]: P260: Do not breathe dust/fume/gas/mist/vapours/spray.
*[P264]: P264: Wash ... thoroughly after handling.
*[P280]: P280: Wear protective gloves/protective clothing/eye protection/face protection.
*[P283]: P283: Wear fire resistant or flame retardant clothing.
*[P301+P330+P331]: P301+P330+P331: IF SWALLOWED: Rinse mouth. Do NOT induce vomiting.
*[P303+P361+P353]: P303+P361+P353: IF ON SKIN (or hair): Remove/Take off immediately all contaminated clothing. Rinse skin with water [or shower].
*[P304+P340]: P304+P340: IF INHALED: Remove victim to fresh air and keep at rest in a position comfortable for breathing.
*[P305+P351+P338]: P305+P351+P338: IF IN EYES: Rinse continuously with water for several minutes. Remove contact lenses if present and easy to do. Continue rinsing.
*[P306+P360]: P306+P360: IF ON CLOTHING: Rinse immediately contaminated clothing and skin with plenty of water before removing clothes.
*[P310]: P310: Immediately call a POISON CENTER or doctor/physician.
*[P321]: P321: Specific treatment (see ... on this label).
*[P363]: P363: Wash contaminated clothing before reuse.
*[P370+P378]: P370+P378: In case of fire: Use ... to extinguish.
*[P371+P380+P375]: P371+P380+P375: In case of major fire and large quantities: Evacuate area. Fight fire remotely due to the risk of explosion.
*[P405]: P405: Store locked up.
*[P501]: P501: Dispose of contents/container to ...
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