Hexamethylenediamine

Hexamethylenediamine[1][2]
Identifiers
CAS number 124-09-4 Y
PubChem 16402
ChemSpider 13835579 N
UN number 1783 (solution), 2280 (solid)
Jmol-3D images Image 1
Properties
Molecular formula C6H16N2
Molar mass 116.21 g/mol
Appearance White crystals or powder
Density 0.84 g/cm3
Melting point

42 °C, 315 K, 108 °F

Boiling point

205 °C, 478 K, 401 °F

Solubility in water 49 g/100 mL
Acidity (pKa) 10.0, 11.1
Hazards
R-phrases R20 R22 R34 R36 R37 R38
Main hazards Toxic, Corrosive
NFPA 704
2
3
0
Flash point 93 °C (102 °C for 90% aq. soln)
Explosive limits 0.7 - 6.3 %
 N (verify) (what is: Y/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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]

Contents

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