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The international pictogram for oxidizing chemicals.

Dangerous goods label for oxidizing agents

In chemistry, an oxidizing agent (oxidant, oxidizer) is a substance that has the ability to oxidize other substances — in other words to cause them to lose electrons. Common oxidizing agents are oxygen, hydrogen peroxide and the halogens.

In one sense, an oxidizing agent is a chemical species that undergoes a chemical reaction that removes one or more electrons from another atom. In that sense, it is one component in an oxidation–reduction (redox) reaction. In the second sense, an oxidizing agent is a chemical species that transfers electronegative atoms, usually oxygen, to a substrate. Combustion, many explosives, and organic redox reactions involve atom-transfer reactions.

Electron acceptors

Electron acceptors participate in electron-transfer reactions. In this context, the oxidizing agent is called an electron acceptor and the reducing agent is called an electron donor. A classic oxidizing agent is the ferrocenium ion Fe(C
₅H
₅)⁺
₂, which accepts an electron to form Fe(C₅H₅)₂. One of the strongest acceptors commercially available is "Magic blue", the radical cation derived from N(C₆H₄-4-Br)₃.^[1]

Tetracyanoquinodimethane is an organic electron-acceptor.

Extensive tabulations of ranking the electron accepting properties of various reagents (redox potentials) are available, see Standard electrode potential (data page).

Atom-transfer reagents

In more common usage, an oxidising agent transfers oxygen atoms to a substrate. In this context, the oxidising agent can be called an oxygenation reagent or oxygen-atom transfer (OAT) agent.^[2] Examples include MnO⁻
₄ (permanganate), CrO²⁻
₄ (chromate), OsO₄ (osmium tetroxide), and especially ClO⁻
₄ (perchlorate). Notice that these species are all oxides.

In some cases, these oxides can also serve as electron acceptors, as illustrated by the conversion of MnO⁻
₄ to MnO²⁻
₄, manganate.

Common oxidizing agents

• 
  Oxygen (O₂)


• 
  Ozone (O₃)


• 
  Hydrogen peroxide (H₂O₂) and other inorganic peroxides, Fenton's reagent
  


• 
  Fluorine (F₂), chlorine (Cl₂), and other halogens
  


• 
  Nitric acid (HNO₃) and nitrate compounds


• 
  Sulfuric acid (H₂SO₄)


• 
  Peroxydisulfuric acid (H₂S₂O₈)


• 
  Peroxymonosulfuric acid (H₂SO₅)


• 
  Chlorite, chlorate, perchlorate, and other analogous halogen compounds


• 
  Hypochlorite and other hypohalite compounds, including household bleach (NaClO)


• Hexavalent chromium compounds such as chromic and dichromic acids and chromium trioxide, pyridinium chlorochromate (PCC), and chromate/dichromate compounds


• 
  Permanganate compounds such as potassium permanganate
  


• Sodium perborate


• 
  Nitrous oxide (N₂O), Nitrogen dioxide/Dinitrogen tetroxide (NO₂ / N₂O₄)


• 
  Potassium nitrate (KNO₃), the oxidizer in black powder
  


• Sodium bismuthate

Dangerous materials definition

The dangerous materials definition of an oxidizing agent is a substance that can cause or contribute to the combustion of other material.^[3] By this definition some materials that are classified as oxidising agents by analytical chemists are not classified as oxidising agents in a dangerous materials sense. An example is potassium dichromate, which does not pass the dangerous goods test of an oxidising agent.

The U.S. Department of Transportation defines oxidizing agents specifically. There are two definitions for oxidizing agents governed under DOT regulations. These two are Class 5; Division 5.1(a)1 and Class 5; Division 5.1(a)2. Division 5.1 "means a material that may, generally by yielding oxygen, cause or enhance the combustion of other materials." Division 5.(a)1 of the DOT code applies to solid oxidizers "if, when tested in accordance with the UN Manual of Tests and Criteria (IBR, see § 171.7 of this subchapter), its mean burning time is less than or equal to the burning time of a 3:7 potassium bromate/cellulose mixture." 5.1(a)2 of the DOT code applies to liquid oxidizers "if, when tested in accordance with the UN Manual of Tests and Criteria, it spontaneously ignites or its mean time for a pressure rise from 690 kPa to 2070 kPa gauge is less than the time of a 1:1 nitric acid (65 percent)/cellulose mixture."^[4]

Common oxidizing agents and their products

Agent	Product(s)
O2oxygen	Various, including the oxides H2O and CO2
O3ozone	Various, including ketones, aldehydes, and H2O; see ozonolysis
F2fluorine	F−
Cl2chlorine	Cl−
Br2bromine	Br−
I2iodine	I−, I− 3
ClO−hypochlorite	Cl−, H2O
ClO− 3 chlorate	Cl−, H2O
HNO3nitric acid	NO nitric oxide NO2nitrogen dioxide
SO2sulphur dioxide	S sulphur (Claus process, ultramarine production, more commonly reducing agent)
Hexavalent chromium CrO3chromium trioxide CrO2− 4 chromate Cr 2O2− 7 dichromate	Cr3+, H2O
MnO− 4 permanganate MnO2− 4 manganate	Mn2+ (acidic) or MnO2 (basic)
RuO4displaystyle ce RuO4 ruthenium tetroxide OsO4displaystyle ce OsO4 osmium tetroxide	in organic lab scale synthesis
H2O2, other peroxides	Various, including oxides and H2O
Tl(III) thallic compounds thallium	Tl(I) thallous compounds, in organic lab scale synthesis

See also

• Combustion


• Dye


• Electrosynthesis


• Organic oxidation


• Organic redox reaction


• Reducing agent

References

External links

• 
  Media related to Oxidizing agents at Wikimedia Commons