Azobisisobutyronitrile
Azobisisobutyronitrile (abbreviated AIBN) is an organic compound with the formula [(CH3)2C(CN)]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 diazo compounds behave similarly, e.g. 1,1'-azobis(cyclohexanecarbonitrile). Water-soluble azo initiators are also available.
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