Azobisisobutyronitrile

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Azobisisobutyronitrile
The chemical structure of AIBN
3D model of the AIBN molecule
Identifiers
Abbreviations AIBN
CAS number 78-67-1 YesY
PubChem 6547
ChemSpider 6299 YesY
EC-number 201-132-3
Jmol-3D images Image 1
Properties
Molecular 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 noted otherwise, 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[edit]

In its most characteristic reaction, AIBN decomposes, eliminating a molecule of nitrogen gas to form two 2-cyanoprop-2-yl radicals:

Formation of Radicals from AIBN.png

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[edit]

AIBN is produced by converting acetone cyanohydrin to the hydrazine 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[edit]

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[edit]

  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[edit]