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Adiponitrile
Names
	Preferred IUPAC name Hexanedinitrile
	Other names Adipic acid dinitrile; Adipic acid nitrile; Adipyldinitrile; 1,4-Dicyanobutane; Hexanedioic acid dinitrile; Nitrile adipico; Tetramethylene cyanide; Tetramethylene dicyanide;
Identifiers
CAS Number	111-69-3 ;
3D model (JSmol)	Interactive image;
Beilstein Reference	1740005
ChemSpider	13876621 ;
ECHA InfoCard	100.003.543
EC Number	203-896-3;
MeSH	adiponitrile
PubChem CID	8128;
RTECS number	AV2625000;
UNII	SYT33B891I ;
UN number	2205
CompTox Dashboard (EPA)	DTXSID3021936 ;
	InChI InChI=1S/C6H8N2/c7-5-3-1-2-4-6-8/h1-4H2 Key: BTGRAWJCKBQKAO-UHFFFAOYSA-N ;
	SMILES N#CCCCCC#N;
Properties
Chemical formula	C6H8N2
Molar mass	108.144 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 (ΔfH⦵298)	84.5–85.3 kJ mol−1
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H315, H319, H330, H335
Precautionary statements	P260, P284, P301+P310, P305+P351+P338, P310
NFPA 704 (fire diamond)	4 2 0
Flash point	93 °C; 199 °F; 366 K (open cup)
Autoignition; temperature	550 °C (1,022 °F; 823 K)
Explosive limits	1.7–4.99%
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	155 mg kg−1 (oral, rat)
	NIOSH (US health exposure limits):
PEL (Permissible)	none
REL (Recommended)	TWA 4 ppm (18 mg/m3)
IDLH (Immediate danger)	N.D.
Related compounds
Related alkanenitriles	Glutaronitrile
Related compounds	hexanedioic acid; hexanedihydrazide; hexanedioyl dichloride; hexanediamide; 1,4-diisocyanobutane
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Adiponitrile is an organic compound with the chemical formula (CH₂)₄(CN)₂. This viscous, colourless dinitrile is an important precursor to the polymer nylon 66. In 2005, about one million tonnes of adiponitrile were produced.^[4]

Production

Early methods

Because of the industrial value of adiponitrile, many methods have been developed for its synthesis. Early industrial methods 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:^[4]

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 is rarely employed.

Modern methods

After patent application in 2004, the majority of adiponitrile is prepared by the nickel-catalysed hydrocyanation of butadiene, as discovered at DuPont, pioneered by William C. Drinkard. The net reaction is:

CH₂=CHCH=CH₂ + 2 HCN → NC(CH₂)₄CN

The process involves several stages, the first of which involves monohydrocyanation (the 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 to produce adiponitrile,^[4] the anti-Markovnikov product, as well as 2-methylglutaronitrile, a useful byproduct.

Another side reaction is the alkene metathesis of 3-pentenenitrile to yield dicyanobutenes, which are readily hydrogenated to adiponitrile as described above.

The other major industrial method involves hydrodimerization, starting from acrylonitrile:^[5]^[6]

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

The electrolytic coupling of acrylonitrile was discovered at Monsanto Company.

Applications

Almost all adiponitrile is hydrogenated to hexane-1,6-diamine for the production of nylon:^[7]

NC(CH₂)₄CN + 4 H₂ → H₂N(CH₂)₆NH₂

Like other nitriles, adiponitrile is susceptible to hydrolysis; however, the resulting adipic acid is less expensively prepared via other routes.

Production

In 2018, there existed approximately 1.5 million metric tons of capacity.^{[citation needed]} The main producers of adiponitrile were:^[8]^[9]

Ascend Performance Materials: Decatur, Alabama (US); 400 metric kilotons per year (kt/y), expanded to 580 kt/y by 2022
Invista: Victoria, Texas and Orange, Texas, (US)
Invista and BASF "Butachimie ADN plant": Chalampé (France); production to be increased from 100 kt/y in 2020 to 600 kt/y
Asahi Kasei (Japan)

BASF closed the 128 kt/y ADN plant at Seal Sands in 2009.^[10]

In 2015, the Shandong Runxing New Material 100 kt/y plant suffered an explosion and was not reopened.^[8] In 2022, Invista plans to open a 300–400 kt/y plant in Shanghai.^[11]

Safety

The LD₅₀ (median lethal dose) of adiponitrile is 300 mg/kg for oral ingestion by rats.^[4]

In 1990, ACGIH adopted a time-weighted average Threshold Limit Value of 2ppm for work-related skin exposure.^[12]

The NIOSH recommended skin exposure limit for a work-related time weighted average concentration is 4ppm (18 mg/m³).^[13]

Adiponitrile is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities.^[14]

References

^ "adiponitrile - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification. Retrieved 15 June 2012.
^ ^a ^b ^c ^d NIOSH Pocket Guide to Chemical Hazards. "#0015". National Institute for Occupational Safety and Health (NIOSH).
^ "Archived copy". Archived from the original on 2015-04-02. Retrieved 2015-03-26.{{cite web}}: CS1 maint: archived copy as title (link)
^ ^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
^ Cardoso, D. S.; Šljukić, B.; Santos, D. M.; Sequeira, C. A. (2017). "Organic Electrosynthesis: From Laboratorial Practice to Industrial Applications". Organic Process Research & Development. 21 (9) (published July 17, 2017): 1213–1226. doi:10.1021/acs.oprd.7b00004.
^ Baizer, Manuel M. (1964). "Electrolytic Reductive Coupling". Journal of the Electrochemical Society. 111 (2): 215. doi:10.1149/1.2426086.
^ Robert A. Smiley "Hexamethylenediamine" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a12_629
^ ^a ^b Alexander, Tullo (7 Oct 2018). "The chemical industry is bracing for a nylon 6,6 shortage". cen.acs.org. 96 (40). Retrieved 2 March 2021.
^ "Ascend Finalizes $175 Million ADN Project in Alabama | CHEManager". www.chemanager-online.com. Retrieved 2 March 2021.
^ Gale, Lindsay (1 April 2009). "End of the line for Seal Sands". KHL Group. Retrieved 28 April 2023.
^ "INVISTA China ADN project receives final construction permit". invista.com. Retrieved 2 March 2021.
^ 2009 TLVs and BEIs, American Conference of Governmental Industrial Hygienists, Signature Publications, page 11 of 254.
^ NIOSH Pocket Guide NIOSH Publication 2005-149; September 2005
^ "40 C.F.R.: Appendix A to Part 355—The List of Extremely Hazardous Substances and Their Threshold Planning Quantities" (PDF) (July 1, 2008 ed.). Government Printing Office. Archived from the original (PDF) on February 25, 2012. Retrieved October 29, 2011. {{cite journal}}: Cite journal requires |journal= (help)