Hexamethylenediamine

Hexamethylenediamine is the organic compound with the formula H2N(CH2)6NH2. The molecule is a diamine, consisting of a hexamethylene hydrocarbon chain terminated with amine functional groups. The colorless solid (yellowish for some commercial samples) has a strong amine odor. About 1 billion kilograms are produced annually.[4]

Hexamethylenediamine[1][2]
Names
Preferred IUPAC name
Hexane-1,6-diamine[3]
Other names
  • 1,6-Diaminohexane
  • 1,6-Hexanediamine
Identifiers
CAS Number
3D model (JSmol)
Beilstein Reference
 1098307
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.004.255
EC Number
  • 204-679-6
Gmelin Reference
 2578
MeSH 1,6-diaminohexane
PubChem CID
RTECS number
  • MO1180000
UNII
UN number 2280
InChI
  • InChI=1S/C6H16N2/c7-5-3-1-2-4-6-8/h1-8H2 N
    Key: NAQMVNRVTILPCV-UHFFFAOYSA-N N
SMILES
  • NCCCCCCN
Properties
Chemical formula
 C6H16N2
Molar mass 116.208 g·mol−1
Appearance Colourless crystals
Density 0.84 g/mL
Melting point 39 to 42 °C (102 to 108 °F; 312 to 315 K)
Boiling point 204.6 °C; 400.2 °F; 477.7 K
Solubility in water
 490 g L−1
log P 0.386
Thermochemistry
Std enthalpy of
formation (ΔfH⦵298)
 −205 kJ mol−1
Hazards
GHS labelling:
Pictograms
Signal word
 Danger
Hazard statements
 H302, H312, H314, H335
Precautionary statements
 P261, P280, P305+P351+P338, P310
NFPA 704 (fire diamond)
3
2
0
Flash point 80 °C (176 °F; 353 K)
Explosive limits 0.7–6.3%
Lethal dose or concentration (LD, LC):
  • 750 mg kg−1 (oral, rat)
  • 1.11 g kg−1 (dermal, rabbit)
Related compounds
Related alkanamines
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Synthesis

Hexamethylenediamine was first reported by Theodor Curtius.[5] It is produced by the hydrogenation of adiponitrile:

NC(CH2)4CN + 4 H2 → H2N(CH2)6NH2

The hydrogenation is conducted on molten adiponitrile diluted with ammonia,[6] typical catalysts being based on cobalt and iron. The yield is good, but commercially significant side products are generated by virtue of reactivity of partially hydrogenated intermediates. These other products include 1,2-diaminocyclohexane, hexamethyleneimine, and the triamine bis(hexamethylenetriamine).

An alternative process uses Raney nickel as the catalyst and adiponitrile that is diluted with hexamethylenediamine itself (as the solvent). This process operates without ammonia and at lower pressure and temperature.[4]

Applications

Hexamethylenediamine is used almost exclusively for the production of polymers, an application that takes advantage of its structure. It is difunctional in terms of the amine groups and tetra functional with respect to the amine hydrogens. The great majority of the diamine is consumed by the production of nylon 66 via condensation with adipic acid. Otherwise hexamethylene diisocyanate (HDI) is generated from this diamine by phosgenation as a monomer feedstock in the production of polyurethane. The diamine also serves as a cross-linking agent in epoxy resins.

Safety

Hexamethylenediamine is moderately toxic, with LD50 of 792–1127 mg/kg.[4][7] Nonetheless, like other basic amines, it can cause serious burns and severe irritation. Such injuries were observed in the accident at the BASF site in Seal Sands, near Billingham (UK) on 4 January 2007 in which 37 persons were injured, one of them seriously.[8][9]

Stability

Hexamethylenediamine is stable in air but combustible. It is incompatible with strong oxidants.

References
  1. Merck Index, 11th Edition, 4614.
  2. MSDS
  3. "1,6-diaminohexane - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification and Related Records. Retrieved 29 May 2012.
  4. Robert A. Smiley "Hexamethylenediamine" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a12_629
  5. Curtius, Theodor and Clemm, Hans (1900) "Synthese des 1,3-Diaminopropans und 1,6-Diaminohexans aus Glutarsäure resp. Korksäure" (Synthesis of 1,3-diaminopropane and 1,6-diaminohexane from glutaric acid and suberic acid, respectively), Journal für praktische Chemie, 2nd series, 62 : 189–211.
  6. "SRIC Report - Report 31C - Advances in Adiponitrile (ADN) and Hexamethylenediamine (HMDA) Processes | IHS Markit". ihsmarkit.com. Retrieved 2019-02-19.
  7. "MSDS - H11696". www.sigmaaldrich.com. Retrieved 2019-02-19.
  8. BBC News
  9. BBC News
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