What Is Azobisisobutyronitrile?
Azobisisobutyronitrile, commonly abbreviated as AIBN and also known as α,α’-azobisisobutyronitrile, is an organic compound widely used as a reagent. In IUPAC nomenclature, it is designated as “2,2′-(diazene-1,2-diyl) bis (2-methyl-propane nitrile),” with the CAS registration number 78-67-1. It is an azo compound with a cyano group, a colorless solid at room temperature, and has a molecular formula of C8H12N4 and a molecular weight of 164.21.
Azobisisobutyronitrile is soluble in organic solvents like ether and alcohols, but nearly insoluble in water.
Uses of Azobisisobutyronitrile
This compound decomposes easily, releasing 2-cyano-2-propyl radical along with nitrogen gas, a property widely utilized as a radical initiator in various radical reactions. It’s used in polymerization reactions for synthesizing vinyl compounds and polystyrene, hydrobromination of alkenes using hydrogen bromide (HBr), and as an intermediate in organic synthesis and a foaming agent in rubber and plastics.
Principle of Azobisisobutyronitrile
The principle of Azobisisobutyronitrile lies in its chemical properties and reactions. It decomposes under heat or light, forming nitrogen gas and 2-cyano-2-propyl radicals, which recombine to produce 2,2,3,3-tetramethylsuccinodinitrile in the absence of other reactants. This decomposition is facilitated by the electron-withdrawing effect of the adjacent cyano group and the energetic favorability of nitrogen gas formation.
The radicals generated are ideal as initiators for various radical reactions, with thermal decomposition typically occurring at 95-104°C. However, caution is needed as it can explode in acetone solutions and must be stored in a cool, dark, and light-shielded place.
Chemical Reaction of Azobisisobutyronitrile
As a radical initiator, AIBN is involved in reactions like the generation of tributyltin radical and the Wohl-Ziegler bromination reaction. In the former, AIBN-derived radicals draw hydrogen from tributyltin to form tin radicals for reduction reactions. In the latter, AIBN is used with N-bromosuccinimide (NBS) to brominate alkenes and aromatic compounds.
Types of Azobisisobutyronitrile
Azobisisobutyronitrile is available in two types: industrial grade for resin synthesis and laboratory reagents. Industrial products are typically used in large volumes in factories, whereas laboratory reagents are available in smaller quantities like 25g, 500g, and 12wt.% acetone solutions. Due to its degradability, it must be stored properly, and care should be taken to handle the internal pressure caused by generated nitrogen gas when opening the bottle.