Hexamethylenediamine

Hexamethylenediamine[1][2]

Skeletal formula of hexamethylenediamine
Ball and stick model of hexamethylenediamine
Spacefill model of hexamethylenediamine
Names
Preferred IUPAC name Hexane-1,6-diamine[3]
Other names 1,6-Diaminohexane 1,6-Hexanediamine
Identifiers
CAS Number	124-09-4^Y
3D model (JSmol)	Interactive image
Beilstein Reference	1098307
ChEBI	CHEBI:39618^N
ChEMBL	ChEMBL303004^N
ChemSpider	13835579^N
DrugBank	DB03260^N
ECHA InfoCard	100.004.255
EC Number	204-679-6
Gmelin Reference	2578
MeSH	1,6-diaminohexane
PubChem CID	16402
RTECS number	MO1180000
UNII	ZRA5J5B2QW^Y
UN number	2280
CompTox Dashboard (EPA)	DTXSID5024922
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):
LD50 (median dose)	750 mg kg^−1 (oral, rat) 1.11 g kg^−1 (dermal, rabbit)
Related compounds
Related alkanamines	Pentylamine Cadaverine Methylhexanamine Tuaminoheptane
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

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.[4]

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.[7][8] 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.[9][10] The diamine also serves as a cross-linking agent in epoxy resins.[11][12][13]

Safety

Hexamethylenediamine is moderately toxic, with LD₅₀ of 792–1127 mg/kg.[4][14][15] 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.[16][17]

See also

• 1,2-Diaminocyclohexane
• 2-Methylpentamethylenediamine

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. 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. 29 (12): 1113–1121. doi:10.1007/s13726-020-00865-x. ISSN 1735-5265. S2CID 221824894.
8. 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. 49 (7): 640–646. doi:10.1002/sia.6203. S2CID 99804759.
9. 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. 269 (9): 895–900. doi:10.1007/BF00657306. ISSN 1435-1536. S2CID 94481368.
10. 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. 43 (5): 2799–2816. doi:10.1007/s11164-016-2795-1. ISSN 1568-5675. S2CID 100565578.
11. 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. 53 (1): 45–55. doi:10.1002/polc.5070530108.
12. Dušek, K.; Pleštil, J.; Lednický, F.; Luňák, S. (1978-04-01). "Are cured epoxy resins inhomogeneous?". Polymer. 19 (4): 393–397. doi:10.1016/0032-3861(78)90243-4. ISSN 0032-3861.
13. 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. 157: 106336. doi:10.1016/j.porgcoat.2021.106336. ISSN 0300-9440. S2CID 236243177.
14. "MSDS - H11696". www.sigmaaldrich.com. Retrieved 2019-02-19.
15. Kennedy, Gerald L. (2005). "Toxicity of hexamethylenediamine". Drug and Chemical Toxicology. 28 (1): 15–33. doi:10.1081/dct-39681. ISSN 0148-0545. PMID 15720033. S2CID 84650430.
16. BBC News
17. BBC News