Hexamethylenediamine Explained

Hexamethylenediamine or hexane-1,6-diamine, 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.[1]

Synthesis

Hexamethylenediamine was first reported by Theodor Curtius.[2] It is produced by the hydrogenation of adiponitrile:

NC(CH2)4CN + 4 H2 → H2N(CH2)6NH2The hydrogenation is conducted on molten adiponitrile diluted with ammonia,[3] 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.[1]

Applications

Hexamethylenediamine is used almost exclusively for the production of polymers, an application that takes advantage of its structure.[4] [5] 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.[6] [7] The diamine also serves as a cross-linking agent in epoxy resins.[8] [9] [10]

Safety

Hexamethylenediamine is moderately toxic, with of 792–1127 mg/kg.[1] [11] [12] 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.[13] [14]

See also

Notes and References

  1. Robert A. Smiley "Hexamethylenediamine" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.
  2. 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.
  3. Web site: SRIC Report - Report 31C - Advances in Adiponitrile (ADN) and Hexamethylenediamine (HMDA) Processes IHS Markit. ihsmarkit.com. 2019-02-19.
  4. Longseng . Rutchanon . Khaokong . Chuanpit . 2020-12-01 . Hexamethylene diamine-modified epoxidized natural rubber and its effect on cure characteristics and properties of natural rubber blends . Iranian Polymer Journal . en . 29 . 12 . 1113–1121 . 10.1007/s13726-020-00865-x . 221824894 . 1735-5265.
  5. Hu . Juncheng . Feng . Xia . Liu . Zhengyi . Zhao . Yiping . Chen . Li . July 2017 . Surface amine-functionalization of UHMWPE fiber by bio-inspired polydopamine and grafted hexamethylene diamine: Surface amine-functionalization of UHMWPE fiber by PDA and HMDA . Surface and Interface Analysis . en . 49 . 7 . 640–646 . 10.1002/sia.6203. 99804759 .
  6. Kim . C. K. . Kim . B. K. . Jeong . H. M. . 1991-09-01 . Aqueous dispersion of polyurethane ionomers from hexamethylene diisocyanate and trimellitic anhydride . Colloid and Polymer Science . en . 269 . 9 . 895–900 . 10.1007/BF00657306 . 94481368 . 1435-1536.
  7. Hu . Jin . Chen . Zhuo . He . Yong . Huang . Hong . Zhang . Xinya . 2017-05-01 . Synthesis and structure investigation of hexamethylene diisocyanate (HDI)-based polyisocyanates . Research on Chemical Intermediates . en . 43 . 5 . 2799–2816 . 10.1007/s11164-016-2795-1 . 100565578 . 1568-5675.
  8. Luňák . S. . Dušek . K. . 2007-03-08 . Curing of epoxy resins. II. Curing of bisphenol a diglycidyl ether with diamines . Journal of Polymer Science: Polymer Symposia . en . 53 . 1 . 45–55 . 10.1002/polc.5070530108.
  9. Dušek . K. . Pleštil . J. . Lednický . F. . Luňák . S. . 1978-04-01 . Are cured epoxy resins inhomogeneous? . Polymer . en . 19 . 4 . 393–397 . 10.1016/0032-3861(78)90243-4 . 0032-3861.
  10. Lainioti . Georgia Ch. . Savva . Panagiota . Druvari . Denisa . Avramidis . Pavlos . Panagiotaras . Dionisios . Karellou . Eva Iris Eleftheria . Kallitsis . Joannis K. . 2021-08-01 . Cross-linking of antimicrobial polymers with hexamethylene diamine to prevent biofouling in marine applications . Progress in Organic Coatings . en . 157 . 106336 . 10.1016/j.porgcoat.2021.106336 . 236243177 . 0300-9440.
  11. Web site: MSDS - H11696. www.sigmaaldrich.com. 2019-02-19.
  12. Kennedy . Gerald L. . 2005 . Toxicity of hexamethylenediamine . Drug and Chemical Toxicology . 28 . 1 . 15–33 . 10.1081/dct-39681 . 0148-0545 . 15720033. 84650430 .
  13. http://news.bbc.co.uk/1/hi/england/tees/6232239.stm BBC News
  14. http://news.bbc.co.uk/1/hi/england/tees/6234287.stm BBC News

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