Azobisisobutyronitrile

Last updated
Azobisisobutyronitrile
AIBN Structural Formulae.svg
AIBN-3D-vdW.png
Names
IUPAC name
2,2′-Azobis(2-methylpropionitrile), 2-(azo(1-cyano-1-methylethyl))-2-methylpropane nitrile
Other names
Azobisisobutyronitrile
Azobisisobutylonitrile
AIBN
Identifiers
3D model (JSmol)
AbbreviationsAIBN
ChemSpider
ECHA InfoCard 100.001.030 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 201-132-3
PubChem CID
RTECS number
  • UG0800000
UNII
UN number 3234 1325
  • InChI=1S/C8H12N4/c1-7(2,5-9)11-12-8(3,4)6-10/h1-4H3/b12-11+ Yes check.svgY
    Key: OZAIFHULBGXAKX-VAWYXSNFSA-N Yes check.svgY
  • InChI=1/C8H12N4/c1-7(2,5-9)11-12-8(3,4)6-10/h1-4H3/b12-11+
    Key: OZAIFHULBGXAKX-VAWYXSNFBT
  • CC(C)(C#N)/N=N/C(C)(C)C#N
Properties
C8H12N4
Molar mass 164.21 g/mol
Appearancewhite crystals
Density 1.1 g cm−3
Melting point 103 to 105 °C (217 to 221 °F; 376 to 378 K)
poor
Hazards
GHS labelling:
GHS-pictogram-flamme.svg GHS-pictogram-exclam.svg
Warning
H242, H302, H332, H412
P210, P220, P234, P261, P264, P270, P271, P273, P280, P301+P312, P304+P312, P304+P340, P312, P330, P370+P378, P403+P235, P411, P420, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

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.

Contents

As an azo initiator, radicals resulting from AIBN have multiple benefits [1] over common organic peroxides. For example, they do not have oxygenated byproducts or much yellow discoloration. Additionally, they do not cause too much grafting and therefore are often used when making adhesives, acrylic fibers, detergents, etc.

Mechanism of decomposition

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

Because azobisisobutyronitrile readily gives off free radicals, it is often used as a radical initiator. This happens at temperatures above 40 °C, [2] but in experiments is more commonly done at temperatures between 66 °C and 72 °C. [3] This decomposition has a ΔG of 131 kJ/mol [3] and results in two 2-cyano-2-propyl (carbon) radicals and a molecule of nitrogen gas. The release of nitrogen gas pushes this decomposition forward due to the increase in entropy. And the 2-cyano-2-propyl radical is stabilized by the −CN group.

Chemical reactions

These radicals formed by the decomposition of AIBN 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.

Benzylic bromination

AIBN can be used as the radical initiator for Wohl–Ziegler bromination.

AIBN and tributyltin hydride (HSnBu3) reaction

Reaction

AIBN decomposes to create the 2-cyano-2-propyl radical, which then abstracts the hydrogen off of tributyltin hydride. This results in a tributyltin radical, which can be used in numerous reactions. For example, this radical could be used to remove a bromine from an alkene.

AIBN and Tributyltin Hydride (HSnBu3) Reaction.png

Mechanism

AIBN and Tributyltin Hydride (HSnBu3) Mechanism.png

Hydrohalogenation of alkenes

Reaction

This reaction starts out with AIBN decomposing into 2-cyano-2-propyl radicals that abstract a hydrogen from HBr to leave a bromine radical. This bromine radical adds to the alkene. In the hydrohalogenation of an alkene using AIBN, the halogen's regioselectivity is anti-Markovnikov.

Hydrohalogenation of Alkene Reaction.png

Mechanism

Hydrohalogenation of Alkene Mechanism.png

Poly(acrylic acid) production

It's in production of poly(acrylic acid).

Production and analogues

AIBN is produced from acetone cyanohydrin and hydrazine, then followed by oxidation: [4]

2 (CH3)2C(CN)OH + N2H4 → [(CH3)2C(CN)]2N2H2 + 2 H2O
[(CH3)2C(CN)]2N2H2 + Cl2 → [(CH3)2C(CN)]2N2 + 2 HCl

Related azo compounds behave similarly, such as 1,1′-azobis(cyclohexanecarbonitrile). Water-soluble azo initiators are also available. [5] [6]

Another possible way to produce AIBN

AIBN can also be produced by the reaction shown below. [7]

Production of AIBN.png

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. Pyrolysis of AIBN without a trap for the formed 2-cyanopropyl radicals results in the formation of tetramethylsuccinonitrile, which is highly toxic.

Related Research Articles

Alkene Hydrocarbon compound containing one or more carbon-carbon double bonds

In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond.

In organic chemistry, Markovnikov's rule or Markownikoff's rule describes the outcome of some addition reactions. The rule was formulated by Russian chemist Vladimir Markovnikov in 1870.

Free-radical addition is an addition reaction in organic chemistry which involves free radicals. The addition may occur between a radical and a non-radical, or between two radicals.

Azo compound Class of organic compounds

Azo compounds are compounds bearing the functional group diazenyl R−N=N−R′, in which R and R′ can be either aryl or alkyl.

In chemistry, radical initiators are substances that can produce radical species under mild conditions and promote radical reactions. These substances generally possess weak bonds—bonds that have small bond dissociation energies. Radical initiators are utilized in industrial processes such as polymer synthesis. Typical examples are molecules with a nitrogen-halogen bond, azo compounds, and organic and inorganic peroxides.

Radical substitution Substitution reaction in organic chemistry involving free radicals

In organic chemistry, a radical-substitution reaction is a substitution reaction involving free radicals as a reactive intermediate.

In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term can be applied to any desymmetrizing reaction of the following type: 2 A → A' + A", regardless of whether it is a redox or some other type of process.

In chemistry hydrocyanation is a process for conversion of alkenes to nitriles. The reaction involves the addition of hydrogen cyanide and requires a catalyst. This conversion is conducted on an industrial scale for the production of precursors to nylon.

Hydrohalogenation

A hydrohalogenation reaction is the electrophilic addition of hydrohalic acids like hydrogen chloride or hydrogen bromide to alkenes to yield the corresponding haloalkanes.

<i>N</i>-Bromosuccinimide Molecule

N-Bromosuccinimide or NBS is a chemical reagent used in radical substitution, electrophilic addition, and electrophilic substitution reactions in organic chemistry. NBS can be a convenient source of Br, the bromine radical.

In chemistry, hydroboration refers to the addition of a hydrogen-boron bond to C-C, C-N, and C-O double bonds, as well as C-C triple bonds. This chemical reaction is useful in the organic synthesis of organic compounds. The development of this technology and the underlying concepts were recognized by the Nobel Prize in Chemistry to Herbert C. Brown. He shared the Nobel prize in chemistry with Georg Wittig in 1979 for his pioneering research on organoboranes as important synthetic intermediates.

The Dowd–Beckwith ring-expansion reaction is an organic reaction in which a cyclic β-keto ester is expanded by up to 4 carbons in a free radical ring expansion reaction through an α-alkylhalo substituent. The radical initiator system is based on AIBN and tributyltin hydride. The cyclic β-keto ester can be obtained through a Dieckmann condensation. The original reaction consisted of a nucleophilic aliphatic substitution of the enolate of ethyl cyclohexanone-2-carboxylate with 1,4-diiodobutane and sodium hydride followed by ring expansion to ethyl cyclodecanone-6-carboxylate. A side-reaction is organic reduction of the iodoalkane.

ABCN Chemical compound

1,1′-Azobis(cyclohexanecarbonitrile) or ACHN is a radical initiator. The molecular formula is NCC6H10N=NC6H10CN. It is a white solid that is soluble in aromatic solvents.

Hydrosilylation, also called catalytic hydrosilation, describes the addition of Si-H bonds across unsaturated bonds. Ordinarily the reaction is conducted catalytically and usually the substrates are unsaturated organic compounds. Alkenes and alkynes give alkyl and vinyl silanes; aldehydes and ketones give silyl ethers. Hydrosilylation has been called the "most important application of platinum in homogeneous catalysis."

Tributyltin hydride Chemical compound

Tributyltin hydride is an organotin compound with the formula (C4H9)3SnH. It is a colorless liquid that is soluble in organic solvents. The compound is used as a source of hydrogen atoms in organic synthesis.

Photoinitiator

A photoinitiator is a molecule that creates reactive species when exposed to radiation. Synthetic photoinitiators are key components in photopolymers.

<i>N</i>,<i>N</i>-Methylenebisacrylamide Chemical compound

N,N′-Methylenebisacrylamide (MBAm or MBAA) is the organic compound with the formula CH2[NHC(O)CH=CH2]2. A colorlesss solid, this compound is a crosslinking agent in polyacrylamides, e.g., as used for SDS-PAGE.

Radical (chemistry) Atom, molecule, or ion that has an unpaired valence electron; typically highly reactive

In chemistry, a free radical is an atom, molecule, or ion that has at least one unpaired valence electron. With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spontaneously dimerize. Most organic radicals have short lifetimes.

Electrophilic amination is a chemical process involving the formation of a carbon–nitrogen bond through the reaction of a nucleophilic carbanion with an electrophilic source of nitrogen.

<i>tert</i>-Butyl peroxybenzoate Chemical compound

tert-Butyl peroxybenzoate (TBPB) a chemical compound from the group of peresters (compounds containing the general structure R1-C(O)OO-R2) which contains a phenyl group as R1 and a tert-butyl group as R2. It is often used as a radical initiator in polymerization reactions, such as the production of LDPE from ethylene, and for crosslinking, such as for unsaturated polyester resins.

References

  1. AIBN initiator and other azo initiators. (n.d.). Retrieved from https://polymerchemistry.nouryon.com/products-applications/acrylic-polymer-initiators/aibn/
  2. 2,2′-Azobis(2-methylpropionitrile) 441090. (n.d.). Retrieved from https://www.sigmaaldrich.com/catalog/product/aldrich/441090?lang=en®ion=US
  3. 1 2 Clayden, J., Greeves, N., & Warren, S. (2017). Organic chemistry. MTM.
  4. Schirmann, Jean-Pierre; Bourdauducq, Paul. "Hydrazine". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a13_177.
  5. "Vazo Product Grades". www2.dupont.com.
  6. Water-soluble Azo initiators
  7. Overberger, C. G., O'Shaughnessy, M. T., & Shalit, H. (1949). The Preparation of Some Aliphatic Azo Nitriles and their Decomposition in Solution. Journal of the American Chemical Society, 71(8), 2661-2666. doi:10.1021/ja01176a018