Azobisisobutyronitrile


Azobisisobutyronitrile is an organic compound with the formula 2N2. This white powder is soluble in alcohols and common organic solvents but is insoluble in water. It is often used as a foamer in plastics and rubber and as a radical initiator.

Mechanism

In its most characteristic reaction, AIBN decomposes, eliminating a molecule of nitrogen gas to form two 2-cyanoprop-2-yl radicals:
These radicals can initiate free-radical polymerizations and other radical-induced reactions. For instance, a mixture of styrene and maleic anhydride in toluene will react if heated, forming the copolymer upon addition of AIBN. Another example of a radical reaction that can be initiated by AIBN is the anti-Markovnikov hydrohalogenation of alkenes.

Production and analogues

AIBN is produced from acetone cyanohydrin and hydrazine, then followed by oxidation:
Related azo compounds behave similarly, such as 1,1′-azobis. Water-soluble azo initiators are also available.

Safety

AIBN is safer to use than benzoyl peroxide because the risk of explosion is far less. However, it is still considered as an explosive compound, decomposing above 65 °C. A respirator dust mask, protective gloves and safety glasses are recommended. Pyrolysis of AIBN without a trap for the formed 2-cyanopropyl radicals results in the formation of tetramethylsuccinonitrile, which is highly toxic.