Adiponitrile

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Adiponitrile
Skeletal formula of adiponitrile
Identifiers
CAS number 111-69-3 YesY
PubChem 8128
ChemSpider 13876621 YesY
UNII VK98I9YW5M YesY
EC number 203-896-3
UN number 2205
MeSH adiponitrile
RTECS number AV2625000
Beilstein Reference 1740005
Jmol-3D images Image 1
Properties
Molecular formula C6H8N2
Molar mass 108.14 g mol−1
Appearance Colourless liquid
Density 951 mg mL−1
Melting point 1 to 3 °C; 34 to 37 °F; 274 to 276 K
Boiling point 295.1 °C; 563.1 °F; 568.2 K
Solubility in water 50 g/L (20 °C)
Vapor pressure 300 mPa (at 20 °C)
Refractive index (nD) 1.438
Thermochemistry
Std enthalpy of
formation
ΔfHo298
84.5–85.3 kJ mol−1
Hazards
GHS pictograms The skull-and-crossbones pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
GHS hazard statements H301, H315, H319, H330, H335
GHS precautionary statements P260, P284, P301+310, P305+351+338, P310
EU classification Toxic T
R-phrases R25, R36/37/38
S-phrases S26, S36, S45
NFPA 704
Flammability code 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g., diesel fuel Health code 4: Very short exposure could cause death or major residual injury. E.g., VX gas Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 163 °C (325 °F; 436 K)
Explosive limits 1.7–4.99%
LD50 155 mg kg−1 (oral, rat)
Related compounds
Related alkanenitriles Glutaronitrile
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

Adiponitrile is the organic compound with the formula (CH2)4(CN)2. This dinitrile, a viscous, colourless liquid, is an important precursor to the polymer nylon-6,6. In 2005, about one billion kilograms were produced annually.[2]

Production[edit]

Early routes[edit]

Because of the industrial value of adiponitrile, many methods have been developed for its synthesis. Early industrial routes started from furfural and later by the chlorination of butadiene to give 1,4-dichloro-2-butene, which with sodium cyanide, converts to 3-hexenedinitrile, which in turn can be hydrogenated to adiponitrile:[2]

ClCH2CH=CHCH2Cl + 2 NaCN → NCCH2CH=CHCH2CN + 2 NaCl
NCCH2CH=CHCH2CN + H2 → NC(CH2)4CN

Adiponitrile has also been produced from adipic acid, by dehydration of the diamide, but this route is rarely employed.

Modern routes[edit]

The majority of adiponitrile is prepared by the nickel-catalysed hydrocyanation of butadiene, as discovered at duPont, pioneered by Drinkard. The net reaction is:

CH2=CHCH=CH2 + 2 HCN → NCCH2CH2CH2CH2CN

The process involves several stages, the first of which involves monohydrocyanation (addition of one molecule of HCN), affording isomers of pentenenitriles as well as 2- and 3-methylbutenenitriles. These unsaturated nitriles are subsequently isomerized to the 3-and 4-pentenenitriles. In the final stage, these pentenenitriles are subjected to a second hydrocyanation, in an anti-Markovnikov sense, to produce adiponitrile.[2]

Research has shown that the 3-pentenenitrile, formed in the first hydrocyanation, can undergo alkene metathesis to give dicyanobutenes, which are readily hydrogenated as described above.

The other major industrial route involves electrosynthesis, starting from acrylonitrile, which is dimerized:

2 CH2=CHCN + 2 e- + 2 H+ → NCCH2CH2CH2CH2CN

The electrolytic coupling of acrylonitrile was discovered at Monsanto Company.

Applications[edit]

Almost all adiponitrile is hydrogenated to 1,6-diaminohexane for the production of nylon:[3]

NC(CH2)4CN + 4 H2 → H2N(CH2)6NH2

Like other nitriles, adiponitrile is susceptible to hydrolysis. The resulting adipic acid however is more cheaply prepared by other routes.

Safety[edit]

The LD50 for adiponitrile is 300 mg/kg for oral ingestion by rats.[2]

In 1990, ACGIH adopted a time weighted average Threshold Limit Value of 2ppm for work related skin exposure. [4]

The NIOSH recommended skin exposure limit for a work related time weighted average concentration is 4ppm (18mg/m3). [5]

References[edit]

  1. ^ "adiponitrile - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification. Retrieved 15 June 2012. 
  2. ^ a b c d M. T. Musser, "Adipic Acid" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a01 269
  3. ^ Robert A. Smiley "Hexamethylenediamine" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a12 629
  4. ^ 2009 TLVs and BEIs, American Conference of Governmental Industrial Hygienists, Signature Publications, page 11 of 254.
  5. ^ NIOSH Pocket Guide NIOSH Publication 2005-149; September 2005

External links[edit]