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Product name azobisisobutyronitrile
Synonyms 2,2-azo-bis-isobutyronitrile

GOST no data
CAS 78-67-1

2,2-Azo-bis-isobutyronitrile (AIBN) is a cololess crystalline solid. It is almost insoluble in water; poorly soluble in methanol, ethanol and diethyl ether. It has a good solubility in acrylonitrile (38g/100g at 25°C), chloroform (25g), methylene chloride (40g), methylmethacrylate (10g) respectively.

AIBN most characteristic chemical reaction is a thermal decomposition, eliminating a molecule of nitrogen gas N2 and resulting in two 2-cyanoprop-2-yl radicals formation:

N≡CC(CH3)2N=NC(CH3)2C≡N → N2 + 2(CH3)2Ċ(C≡N)

This thermal decomposition is defined as first-order reaction. The reaction constant is practically solvent-independent.

AIBN is quite stable in the temperature range 0-5°C, but can spontaneously ignite at higher temperatures. It also can explode upon detonation or friction. Some AIBN solutions (e.g. in acetone) are explosive also. At the same time AIBN is safer to use than benzoyl peroxide because the risk of explosion is smaller.

Like almost nitriles, azobisisobutyronitrile is a highly toxic compound. One should use protective gloves, respirator and safety glasses when handling it.


AIBN is prepared industrially by treatment of acetone cyanohydrin with ammonia or hydrazine followed by oxidation of intermediate product with sodium hypochlorite NaOCl or molecular chlorine Cl2:

AIBN manufacturing


There are two main ways for AIBN application:

  • as a one of the most frequently used radical initiatior. It polymerizes vinyl chloride, vilylidene chloride, styrene, methylmethacrylate, other acrylates, acrylonitrile, dienes. Polymer chains are initiated by 2-cyanoprop-2-yl radicals. In contrast to benzyl peroxide (other radical initiator) AIBN does not give oxidation by-products.
  • as a blowing agent (foamer) for plastics and elastomers. Nitrogen which eliminate at decomposion, form a porous structure in material;

Chemical structure of azobisisobutyronitrile

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