Names | |
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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) | |
Abbreviations | AIBN |
ChemSpider | |
ECHA InfoCard | 100.001.030 |
EC Number |
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PubChem CID | |
RTECS number |
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UNII | |
UN number | 3234 1325 |
CompTox Dashboard (EPA) | |
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Properties | |
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) |
poor | |
Hazards | |
GHS labelling: | |
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). |
Azobisisobutyronitrile (abbreviated AIBN [1] ) 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 [2] 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.
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, [3] but in experiments is more commonly done at temperatures between 66 °C and 72 °C. [4] This decomposition has a ΔG‡ of 131 kJ/mol [4] 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.
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. [5] 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.
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: [6] [7]
Related azo compounds behave similarly, such as 1,1′-azobis(cyclohexanecarbonitrile). Water-soluble azo initiators are also available. [8] [9]
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.
In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or in the terminal position. Terminal alkenes are also known as α-olefins.
Hydrazine is an inorganic compound with the chemical formula N2H4. It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly hazardous unless handled in solution as, for example, hydrazine hydrate.
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.
In chemistry, halogenation is a chemical reaction which introduces one or more halogens into a chemical compound. Halide-containing compounds are pervasive, making this type of transformation important, e.g. in the production of polymers, drugs. This kind of conversion is in fact so common that a comprehensive overview is challenging. This article mainly deals with halogenation using elemental halogens. Halides are also commonly introduced using salts of the halides and halogen acids. Many specialized reagents exist for and introducing halogens into diverse substrates, e.g. thionyl chloride.
In organic chemistry, free-radical addition is an addition reaction which involves free radicals. These reactions can happen due to the free radicals having an unpaired electron in their valence shell, making them highly reactive. Radical additions are known for a variety of unsaturated substrates, both olefinic or aromatic and with or without heteroatoms.
Azo compounds are organic compounds bearing the functional group diazenyl.
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.
A hydrohalogenation reaction is the electrophilic addition of hydrogen halides like hydrogen chloride or hydrogen bromide to alkenes to yield the corresponding haloalkanes.
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 organic chemistry, organic peroxides are organic compounds containing the peroxide functional group. If the R′ is hydrogen, the compounds are called hydroperoxides, which are discussed in that article. The O−O bond of peroxides easily breaks, producing free radicals of the form RO•. Thus, organic peroxides are useful as initiators for some types of polymerization, such as the acrylic, unsaturated polyester, and vinyl ester resins used in glass-reinforced plastics. MEKP and benzoyl peroxide are commonly used for this purpose. However, the same property also means that organic peroxides can explosively combust. Organic peroxides, like their inorganic counterparts, are often powerful bleaching agents.
In organic chemistry, hydroboration refers to the addition of a hydrogen-boron bond to certain double and triple bonds involving carbon. This chemical reaction is useful in the organic synthesis of organic compounds.
1-Bromobutane is the organobromine compound with the formula CH3(CH2)3Br. It is a colorless liquid, although impure samples appear yellowish. It is insoluble in water, but soluble in organic solvents. It is primarily used as a source of the butyl group in organic synthesis. It is one of several isomers of butyl bromide.
The Dowd–Beckwith ring-expansion reaction is an organic reaction in which a cyclic carbonyl 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 azobisisobutyronitrile 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.
Tetramethylsuccinonitrile or TMSN is an organic compound with the formula (C(CH3)2CN)2, classified as a dinitrile. It is a colorless and odorless solid. TMSN is the byproduct from the use of some radical initiators used in polymer manufacture.
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.
Diimide, also called diazene or diimine, is a compound having the formula HN=NH. It exists as two geometric isomers, E (trans) and Z (cis). The term diazene is more common for organic derivatives of diimide. Thus, azobenzene is an example of an organic diazene.
In chemistry, a photoinitiator is a molecule that creates reactive species when exposed to radiation. Synthetic photoinitiators are key components in photopolymers.
Carbon nitrides are organic compounds consisting only of carbon and nitrogen atoms.
In chemistry, 3,3,4,4-tetramethyltetrahydrofuran-2,5-dione is a heterocyclic compound with the formula C
8H
12O
3, or (CH3)2(COC2COO)(CH3)2. It is a white crystalline solid with a pungent camphoraceous odor.
tert-Butyl peroxybenzoate (TBPB) an organic compound with the formula C6H5CO3CMe3 (Me = CH3). It is the most widely produced perester; it is an ester of peroxybenzoic acid (C6H5CO3H). 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.