Hexamethylenediamine

Hexamethylenediamine was first reported by Theodor Curtius.Curtius, Theodor and Clemm, Hans (1900) [https://babel.hathitrust.org/cgi/pt?id=pst.000067440276;view=1up;seq=785 "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. 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,{{Cite web|url=https://ihsmarkit.com/products/SRICReport-Report31C-AdvancesinAdiponitrileADNandHexamethylenediamineHMDAProcesses.html|title=SRIC Report - Report 31C - Advances in Adiponitrile (ADN) and Hexamethylenediamine (HMDA) Processes {{!}} IHS Markit|website=ihsmarkit.com|access-date=2019-02-19}} 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.Robert A. Smiley "Hexamethylenediamine" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. {{doi|10.1002/14356007.a12_629}}

Hexamethylenediamine is used almost exclusively for the production of polymers, an application that takes advantage of its structure.{{Cite journal |last1=Longseng |first1=Rutchanon |last2=Khaokong |first2=Chuanpit |date=2020-12-01 |title=Hexamethylene diamine-modified epoxidized natural rubber and its effect on cure characteristics and properties of natural rubber blends |url=https://doi.org/10.1007/s13726-020-00865-x |journal=Iranian Polymer Journal |language=en |volume=29 |issue=12 |pages=1113–1121 |doi=10.1007/s13726-020-00865-x |s2cid=221824894 |issn=1735-5265}}{{Cite journal |last1=Hu |first1=Juncheng |last2=Feng |first2=Xia |last3=Liu |first3=Zhengyi |last4=Zhao |first4=Yiping |last5=Chen |first5=Li |date=July 2017 |title=Surface amine-functionalization of UHMWPE fiber by bio-inspired polydopamine and grafted hexamethylene diamine: Surface amine-functionalization of UHMWPE fiber by PDA and HMDA |url=https://onlinelibrary.wiley.com/doi/10.1002/sia.6203 |journal=Surface and Interface Analysis |language=en |volume=49 |issue=7 |pages=640–646 |doi=10.1002/sia.6203|s2cid=99804759 }} 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.{{Cite journal |last1=Kim |first1=C. K. |last2=Kim |first2=B. K. |last3=Jeong |first3=H. M. |date=1991-09-01 |title=Aqueous dispersion of polyurethane ionomers from hexamethylene diisocyanate and trimellitic anhydride |url=https://doi.org/10.1007/BF00657306 |journal=Colloid and Polymer Science |language=en |volume=269 |issue=9 |pages=895–900 |doi=10.1007/BF00657306 |s2cid=94481368 |issn=1435-1536}}{{Cite journal |last1=Hu |first1=Jin |last2=Chen |first2=Zhuo |last3=He |first3=Yong |last4=Huang |first4=Hong |last5=Zhang |first5=Xinya |date=2017-05-01 |title=Synthesis and structure investigation of hexamethylene diisocyanate (HDI)-based polyisocyanates |url=https://doi.org/10.1007/s11164-016-2795-1 |journal=Research on Chemical Intermediates |language=en |volume=43 |issue=5 |pages=2799–2816 |doi=10.1007/s11164-016-2795-1 |s2cid=100565578 |issn=1568-5675}} The diamine also serves as a cross-linking agent in epoxy resins.{{Cite journal |last1=Luňák |first1=S. |last2=Dušek |first2=K. |date=2007-03-08 |title=Curing of epoxy resins. II. Curing of bisphenol a diglycidyl ether with diamines |url=https://onlinelibrary.wiley.com/doi/10.1002/polc.5070530108 |journal=Journal of Polymer Science: Polymer Symposia |language=en |volume=53 |issue=1 |pages=45–55 |doi=10.1002/polc.5070530108}}{{Cite journal |last1=Dušek |first1=K. |last2=Pleštil |first2=J. |last3=Lednický |first3=F. |last4=Luňák |first4=S. |date=1978-04-01 |title=Are cured epoxy resins inhomogeneous? |url=https://dx.doi.org/10.1016/0032-3861%2878%2990243-4 |journal=Polymer |language=en |volume=19 |issue=4 |pages=393–397 |doi=10.1016/0032-3861(78)90243-4 |issn=0032-3861}}{{Cite journal |last1=Lainioti |first1=Georgia Ch. |last2=Savva |first2=Panagiota |last3=Druvari |first3=Denisa |last4=Avramidis |first4=Pavlos |last5=Panagiotaras |first5=Dionisios |last6=Karellou |first6=Eva Iris Eleftheria |last7=Kallitsis |first7=Joannis K. |date=2021-08-01 |title=Cross-linking of antimicrobial polymers with hexamethylene diamine to prevent biofouling in marine applications |url=https://www.sciencedirect.com/science/article/pii/S0300944021002071 |journal=Progress in Organic Coatings |language=en |volume=157 |pages=106336 |doi=10.1016/j.porgcoat.2021.106336 |s2cid=236243177 |issn=0300-9440}}

Hexamethylenediamine is moderately toxic, with {{LD50}} of 792–1127 mg/kg.{{Cite web|url=https://www.sigmaaldrich.com/MSDS/MSDS/DisplayMSDSPage.do?country=US&language=en&productNumber=H11696&brand=ALDRICH&PageToGoToURL=https://www.sigmaaldrich.com/catalog/product/aldrich/h11696?lang=en|title=MSDS - H11696|website=www.sigmaaldrich.com|access-date=2019-02-19}}{{Cite journal |last=Kennedy |first=Gerald L. |date=2005 |title=Toxicity of hexamethylenediamine |url=https://pubmed.ncbi.nlm.nih.gov/15720033/ |journal=Drug and Chemical Toxicology |volume=28 |issue=1 |pages=15–33 |doi=10.1081/dct-39681 |issn=0148-0545 |pmid=15720033|s2cid=84650430 }} 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.[http://news.bbc.co.uk/1/hi/england/tees/6232239.stm BBC News][http://news.bbc.co.uk/1/hi/england/tees/6234287.stm BBC News]

• 1,2-Diaminocyclohexane
• 2-Methylpentamethylenediamine

{{Reflist}}

Category:Monomers

Category:Diamines