Azobisisobutyronitrile

Azobisisobutyronitrile

Names
IUPAC name 2,2′-Azobis(2-methylpropionitrile), 2-(azo(1-cyano-1-methylethyl))-2-methylpropane nitrile
Other names Azobisisobutyronitrile Azobisisobutylonitrile AIBN
Identifiers
CAS Number	78-67-1
Abbreviations	AIBN
ChemSpider	6299
EC Number	201-132-3
Jmol interactive 3D	Image
PubChem	6547
InChI InChI=1S/C8H12N4/c1-7(2,5-9)11-12-8(3,4)6-10/h1-4H3/b12-11+ Key: OZAIFHULBGXAKX-VAWYXSNFSA-N InChI=1/C8H12N4/c1-7(2,5-9)11-12-8(3,4)6-10/h1-4H3/b12-11+ Key: OZAIFHULBGXAKX-VAWYXSNFBT
SMILES CC(C)(C#N)/N=N/C(C)(C)C#N
Properties
Chemical formula	C8H12N4
Molar mass	164.21 g/mol
Appearance	white crystals
Density	1.1 g cm^−3
Melting point	103 to 105 °C (217 to 221 °F; 376 to 378 K)
Hazards
R-phrases	R11, R25, R37/38, R41
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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:^[1]

2 (CH₃)₂C(CN)OH + N₂H₄ → [(CH₃)₂C(CN)]₂N₂H₂ + 2 H₂O

[(CH₃)₂C(CN)]₂N₂H₂ + Cl₂ → [(CH₃)₂C(CN)]₂N₂ + 2 HCl

Related diazo compounds behave similarly, e.g. 1,1'-azobis(cyclohexanecarbonitrile). Water-soluble azo initiators are also available.^[2][3]

Safety

AIBN is safer to use than benzoyl peroxide (another radical initiator) 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.

References

1. Jean-Pierre Schirmann, Paul Bourdauducq "Hydrazine" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. doi:10.1002/14356007.a13_177.
2. Product Grades
3. Water soluble Azo initiators

External links

• SIDS Initial Assessment Report for 2,2’-Azobis(2-methylpropionitrile) from the Organisation for Economic Co-operation and Development (OECD)