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{{chembox {{chembox
| Watchedfields = changed |Watchedfields = changed
| verifiedrevid = 396294932 |verifiedrevid = 446117924
|ImageFile_Ref = {{chemboximage|correct|??}}
| Name =
|ImageFile = AIBN Structural Formulae.svg
| ImageFile_Ref = {{chemboximage|correct|??}}
|ImageSize = 200px
| ImageFile = AIBN Structural Formulae.png
| ImageName = The chemical structure of AIBN |ImageName = The chemical structure of AIBN
| ImageFile1 = AIBN-3D-vdW.png |ImageFile1 = AIBN-3D-vdW.png
| ImageName1 = 3D model of the AIBN molecule |ImageName1 = 3D model of the AIBN molecule
| IUPACName = 2,2′-Azobis(2-methylpropionitrile) |IUPACName = 2,2′-Azobis(2-methylpropionitrile), 2-(azo(1-cyano-1-methylethyl))-2-methylpropane nitrile
| OtherNames = Azobisisobutyronitrile<br />Azobisisobutylonitrile<br />AIBN |OtherNames = Azobisisobutyronitrile<br />Azobisisobutylonitrile<br />AIBN
| Section1 = {{Chembox Identifiers |Section1={{Chembox Identifiers
| Abbreviations = AIBN |Abbreviations = AIBN
| InChI = 1/C8H12N4/c1-7(2,5-9)11-12-8(3,4)6-10/h1-4H3/b12-11+ |InChI = 1/C8H12N4/c1-7(2,5-9)11-12-8(3,4)6-10/h1-4H3/b12-11+
| PubChem = 6547 |PubChem = 6547
|RTECS = UG0800000
| InChIKey = OZAIFHULBGXAKX-VAWYXSNFBT
|UNNumber = 3234 1325
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
|UNII = FZ6PX8U5YB
| StdInChI = 1S/C8H12N4/c1-7(2,5-9)11-12-8(3,4)6-10/h1-4H3/b12-11+
|InChIKey = OZAIFHULBGXAKX-VAWYXSNFBT
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = OZAIFHULBGXAKX-VAWYXSNFSA-N
|StdInChI = 1S/C8H12N4/c1-7(2,5-9)11-12-8(3,4)6-10/h1-4H3/b12-11+
| CASNo = 78-67-1
| CASNo_Ref = {{cascite|correct|CAS}} |StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
|StdInChIKey = OZAIFHULBGXAKX-VAWYXSNFSA-N
| EC-number = 201-132-3
|CASNo = 78-67-1
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|CASNo_Ref = {{cascite|correct|CAS}}
| ChemSpiderID = 6299
|EC_number = 201-132-3
| SMILES = CC(C)(C#N)/N=N/C(C)(C)C#N
|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|ChemSpiderID = 6299
|SMILES = CC(C)(C#N)/N=N/C(C)(C)C#N
}}
|Section2={{Chembox Properties
|Formula = {{chem2|C8H12N4}}
|MolarMass = 164.21 g/mol
|Appearance = white crystals
|Density = 1.1 g cm<sup>−3</sup>
|Solubility = poor
|MeltingPtC = 103 to 105
}}
|Section7={{Chembox Hazards
|GHSPictograms = {{GHS02}}{{GHS07}}
|GHSSignalWord = Warning
|HPhrases = {{H-phrases|242|302|332|412}}
|PPhrases = {{P-phrases|210|220|234|261|264|270|271|273|280|301+312|304+312|304+340|312|330|370+378|403+235|411|420|501}}
}} }}
| Section2 = {{Chembox Properties
| Formula = C<sub>8</sub>H<sub>12</sub>N<sub>4</sub>
| MolarMass = 164.21 g/mol
| Appearance = white crystalline
| Density = 1.1 g cm<sup>−3</sup>
| Solubility =
| MeltingPtCL = 103
| MeltingPtCH = 105
| BoilingPt =
}}
| Section3 = {{Chembox Structure
| Dipole =
}}
| Section7 = {{Chembox Hazards
| RPhrases = {{R11}}, {{R25}}, {{R37/38}}, {{R41}}
| ExternalMSDS =
| EUClass =
| FlashPt =
}}
}} }}


'''Azobisisobutyronitrile''' (abbreviated '''AIBN'''<ref>{{Cite book |last=Höfer |first=Rainer |title=Renewable Resources for Surface Coatings, Inks, and Adhesives |date=2022-11-11 |publisher=The Royal Society of Chemistry |isbn=978-1-78262-993-1 |language=en |doi=10.1039/9781788013024-fp015}}</ref>) is an ] with the ] {{chem2|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 ] and ] and as a ].
'''Azobisisobutyronitrile''' is a compound often used as a foamer in ] and ] and as a ]. It is commonly known as '''AIBN'''. Its most common chemical reaction is one of ], eliminating a molecule of ] gas to form two 2-cyanoprop-2-yl radicals:


As an azo initiator, radicals resulting from AIBN have multiple benefits<ref>AIBN initiator and other azo initiators. (n.d.). Retrieved from https://polymerchemistry.nouryon.com/products-applications/acrylic-polymer-initiators/aibn/</ref> over common ]s. 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==
These radicals can be used to initiate ]s and other radical reactions. For instance a mixture of ] and ] in ] will react if heated, forming the ] ], only very slowly unless an initiator such an AIBN is present. Another example of a radical reaction that can be initiated by AIBN is the ] hydrohalogenation of alkenes.
In its most characteristic reaction, AIBN ], eliminating a molecule of ] gas to form two 2-cyanoprop-2-yl radicals:]


Because azobisisobutyronitrile readily gives off free radicals, it is often used as a ]. This happens at temperatures above 40&nbsp;°C,<ref>2,2′-Azobis(2-methylpropionitrile) 441090. (n.d.). Retrieved from https://www.sigmaaldrich.com/catalog/product/aldrich/441090?lang=en®ion=US</ref> but in experiments is more commonly done at temperatures between 66&nbsp;°C and 72&nbsp;°C.<ref name="ClaydenMTM">Clayden, J., Greeves, N., & Warren, S. (2017). Organic chemistry. MTM.</ref> This decomposition has a Δ''G''<sup>‡</sup> of 131&nbsp;kJ/mol<ref name="ClaydenMTM"/> 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 ]. And the 2-cyano-2-propyl radical is stabilized by the −CN group.
==Safety==
AIBN is safer to use than ] (another ]) because the risk of explosion is far smaller. However, it is considered a flammable solid.
It is soluble in methanol and ethanol, but is insoluble in water. It can explode if dissolved in acetone.
AIBN is highly toxic. A respirator/dust mask, protective gloves, & safety glasses should be worn when handling AIBN.


== Chemical reactions ==
Several water-soluble azo initiators similar to AIBN are manufactured by ]<ref></ref> and Wako.<ref></ref>
These radicals formed by the decomposition of AIBN can initiate ]s and other radical-induced reactions. For instance, a mixture of ] and ] in ] will react if heated, forming the ] upon addition of AIBN. Another example of a radical reaction that can be initiated by AIBN is the ] hydrohalogenation of alkenes. AIBN has also been used as the radical initiator for ]. The AIBN-derived 2-cyano-2-propyl radical abstracts the hydrogen from ].<ref>{{cite journal |doi=10.15227/orgsyn.069.0066 |title=1,3,4,6-TETRA-O-ACETYL-2-DEOXY-a-D-GLUCOPYRANOSE |journal=Organic Syntheses |year=1990 |volume=69 |page=66|first1=Bernd|last1=Giese|first2=Kay S.|last2=Gröninger }}</ref> The resulting tributyltin radical can be used for removal of a bromine atom.


AIBN-derived radicals abstract a hydrogen from HBr to give a bromine radical, which can add to ]s. This type of ] of an alkene proceeds with anti-Markovnikov selectivity.
==See also==
:]
* 1,1'-Azobis(cyclohexanecarbonitrile) or ] is another free radical initiator

==Production and analogues==
AIBN is produced in two steps from ]. Reaction with ] gives the substituted dialkylhydrazine. In the second step, the hydrazine is oxidized to the azo derivative:<ref name=Ullmann>{{Ullmann|first1=Jean-Pierre |last1=Schirmann |first2=Paul |last2=Bourdauducq |title=Hydrazine |doi=10.1002/14356007.a13_177}}</ref><ref>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</ref>
:{{chem2|2 (CH3)2C(CN)OH + N2H4 -> 2N2H2 + 2 H2O}}
:{{chem2|2N2H2 + Cl2 -> 2N2 + 2 HCl}}
Related ]s behave similarly, such as ]. Water-soluble azo initiators are also available.<ref>{{cite web|title=Vazo Product Grades|url=http://www2.dupont.com/Vazo/en_US/products/grades/grades.html|website=www2.dupont.com|access-date=2007-12-15|archive-date=2009-03-26|archive-url=https://web.archive.org/web/20090326071213/http://www2.dupont.com/Vazo/en_US/products/grades/grades.html|url-status=dead}}</ref><ref></ref>

==Safety==
AIBN is safer to use than ] (another ]) because the risk of explosion is far less. However, it is still considered as an explosive compound, decomposing above 65&nbsp;°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 ], which is highly toxic.


==References== ==References==
Line 67: Line 73:


==External links== ==External links==
*{{SIDS|name=2,2’-Azobis(2-methylpropionitrile)|id =78671}} *{{SIDS|name=2,2′-Azobis(2-methylpropionitrile)|id =78671}}


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Latest revision as of 16:37, 15 October 2024

Azobisisobutyronitrile
The chemical structure of AIBN
3D model of the AIBN molecule
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
3D model (JSmol)
Abbreviations AIBN
ChemSpider
ECHA InfoCard 100.001.030 Edit this at Wikidata
EC Number
  • 201-132-3
PubChem CID
RTECS number
  • UG0800000
UNII
UN number 3234 1325
CompTox Dashboard (EPA)
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
Melting point 103 to 105 °C (217 to 221 °F; 376 to 378 K)
Solubility in water poor
Hazards
GHS labelling:
Pictograms GHS02: FlammableGHS07: Exclamation mark
Signal word Warning
Hazard statements H242, H302, H332, H412
Precautionary statements 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 , 100 kPa). checkverify (what is  ?) Infobox references
Chemical compound

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.

As an azo initiator, radicals resulting from AIBN have multiple benefits 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:

Because azobisisobutyronitrile readily gives off free radicals, it is often used as a radical initiator. This happens at temperatures above 40 °C, but in experiments is more commonly done at temperatures between 66 °C and 72 °C. This decomposition has a ΔG of 131 kJ/mol 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. AIBN has also been used as the radical initiator for Wohl–Ziegler bromination. The AIBN-derived 2-cyano-2-propyl radical abstracts the hydrogen from tributyltin hydride. The resulting tributyltin radical can be used for removal of a bromine atom.

AIBN-derived radicals abstract a hydrogen from HBr to give a bromine radical, which can add to alkenes. This type of hydrohalogenation of an alkene proceeds with anti-Markovnikov selectivity.

Production and analogues

AIBN is produced in two steps from acetone cyanohydrin. Reaction with hydrazine gives the substituted dialkylhydrazine. In the second step, the hydrazine is oxidized to the azo derivative:

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.

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.

References

  1. Höfer, Rainer (2022-11-11). Renewable Resources for Surface Coatings, Inks, and Adhesives. The Royal Society of Chemistry. doi:10.1039/9781788013024-fp015. ISBN 978-1-78262-993-1.
  2. AIBN initiator and other azo initiators. (n.d.). Retrieved from https://polymerchemistry.nouryon.com/products-applications/acrylic-polymer-initiators/aibn/
  3. 2,2′-Azobis(2-methylpropionitrile) 441090. (n.d.). Retrieved from https://www.sigmaaldrich.com/catalog/product/aldrich/441090?lang=en®ion=US
  4. ^ Clayden, J., Greeves, N., & Warren, S. (2017). Organic chemistry. MTM.
  5. Giese, Bernd; Gröninger, Kay S. (1990). "1,3,4,6-TETRA-O-ACETYL-2-DEOXY-a-D-GLUCOPYRANOSE". Organic Syntheses. 69: 66. doi:10.15227/orgsyn.069.0066.
  6. Schirmann, Jean-Pierre; Bourdauducq, Paul. "Hydrazine". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a13_177. ISBN 978-3527306732.
  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
  8. "Vazo Product Grades". www2.dupont.com. Archived from the original on 2009-03-26. Retrieved 2007-12-15.
  9. Water-soluble Azo initiators

External links

Categories: