22azobisisobutyronitryl

2,2'-Azobis(isobutyronitrile), commonly abbreviated as AIBN, is an azo compound widely used as a radical initiator in free-radical polymerizations. The name “22azobisisobutyronitryl” appears to be a variant spelling of the same compound. AIBN belongs to the class of azo initiators that decompose upon heating to generate radicals which start polymerization chains.

Physically, AIBN is a white to off-white crystalline solid. It is insoluble in water but dissolves in many organic solvents such as acetone, acetonitrile, benzene, and tetrahydrofuran. It is typically stored as a solid and used in solution or as a solid dispersed in a monomer or solvent.

Decomposition and mechanism: When heated, the azo bond in AIBN cleaves to release nitrogen gas, yielding two radical species derived from isobutyronitrile units. These radicals initiate polymerization of vinyl monomers, producing polymer chains. The rate of decomposition is temperature dependent, allowing control over radical generation in many polymerization protocols.

Applications: AIBN is one of the most commonly used thermal radical initiators in polymer chemistry. It facilitates polymerization of styrene, acrylates, methacrylates, acrylonitrile, and related monomers in bulk, solution, or emulsion processes. It is valued for a relatively clean initiation at modest temperatures and for compatibility with many solvents and monomers.

Safety: AIBN can be hazardous; it may explode under mechanical shock or extreme heat and is an irritant and potential toxicant if inhaled or ingested. It should be handled in a fume hood, stored cool and dry, and kept away from oxidizers and sources of ignition using standard chemical safety practices.