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IUPAC name 2,2′-Azobis(2-methylpropionitrile)
Other names Azobisisobutyronitrile
CAS number 78-67-1
Molecular formula C8H12N4
Molar mass 164.21 g/mol
Appearance white crystalline
Density  ?
Melting point

103–105 °C

Boiling point


Solubility in water  ?
Dipole moment (gas)
Flash point  ?
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Azobisisobutyronitrile is a toxic compound often used as a foamer in plastics and rubber and as a radical initiator. It is commonly known as AIBN. Its most common chemical reaction is one of decomposition, eliminating a molecule of nitrogen gas to form two 2-cyanoprop-2-yl radicals:

These radicals can be used to to initiate free radical polymerizations and other radical reactions. For instance a mixture of styrene and maleic anhydride in toluene will react if heated, forming the polystyrene polymer, only very slowly unless an initiator such a AIBN is present. Another example of a radical reaction that can be initiated by AIBN is the anti-Markovnikov hydrohalogenation of alkenes.

AIBN is safer to use than benzoyl peroxide (another radical initiator) because the risk of explosion is far smaller. However, it is considered a flammable solid. It is soluble in methanol and ethanol, but is insoluble in water. It can explode if dissolved in acetone. AIBN is highly toxic. Wear a respirator/dust mask, protective gloves, & safety glasses when handling AIBN.

Several water-soluble azo initiators similar to AIBN are manufactured by DuPont[1] and Wako.[2]

See also

  • 1,1'-Azobis(cyclohexanecarbonitrile) or ABCN is another free radical initiator


  1. ^
  2. ^
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Azobisisobutyronitrile". A list of authors is available in Wikipedia.
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