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Hexamethylenediamine

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Hexamethylenediamine[1][2]
Names
IUPAC name
Hexane-1,6-diamine
Other names
1,6-diaminohexane, 1,6-hexanediamine
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.004.255 Edit this at Wikidata
UN number 1783 (solution), 2280 (solid)
  • NCCCCCCN
Properties
C6H16N2
Molar mass 116.21 g/mol
Appearance White crystals or powder
Density 0.84 g/cm3
Melting point 42 °C (108 °F; 315 K)
Boiling point 205 °C (401 °F; 478 K)
960 g/100 mL
Acidity (pKa) 10.0, 11.1
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Toxic, Corrosive
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 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 fuelInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
2
0
Flash point 93 °C (102 °C for 90% aq. soln)
Explosive limits 0.7 - 6.3 %
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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, similar to piperidine. About 1 billion kilograms are produced annually.[3]

Synthesis

Hexamethylenediamine was first reported by Theodor Curtius.[4] It is presently produced by the hydrogenation of adiponitrile:

NC(CH2)4CN + 4 H2 → H2N(CH2)6NH2

The hydrogenation is conducted molten adiponitrile diluted with ammonia, 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).[3]

Applications

Hexamethylenediamine is used almost exclusively for the production of polymers, an application that takes advantage of its bifunctional structure. The great majority of the diamine is consumed by the production of nylon 6-6 via condensation with adipic acid. Otherwise hexamethylene diisocyanate (HDI) is generated from this diamine 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.[3] 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. 37 injured and 16 seriously injured.[5][6]

Stability

Hexamethylenediamine is stable in air but combustible. Like all organic compounds, it is incompatible with strong oxidants.

References

  1. ^ Merck Index, 11th Edition, 4614.
  2. ^ MSDS
  3. ^ a b c Robert A. Smiley "Hexamethylenediamine" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a12 629
  4. ^ T. Curtius et al. J. Prakt. Chem., 1900, volume 62, p. 189.
  5. ^ BBC News
  6. ^ BBC News
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