Hexamethylene diisocyanate

Hexamethylene diisocyanate
Hexamethylene diisocyanate
Hexamethylene diisocyanate
Names
Preferred IUPAC name
1,6-Diisocyanatohexane
Other names
HDI
1,6-hexane diisocyanate
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.011.350 Edit this at Wikidata
UNII
  • InChI=1S/C8H12N2O2/c11-7-9-5-3-1-2-4-6-10-8-12/h1-6H2 checkY
    Key: RRAMGCGOFNQTLD-UHFFFAOYSA-N checkY
  • InChI=1/C8H12N2O2/c11-7-9-5-3-1-2-4-6-10-8-12/h1-6H2
    Key: RRAMGCGOFNQTLD-UHFFFAOYAI
  • O=C=N\CCCCCC/N=C=O
Properties
C8H12N2O2
Molar mass 168.2 g/mol
Appearance Colourless liquid
Odor sharp, pungent[1]
Density 1.047 g/cm3, liquid
Melting point −67 °C (−89 °F; 206 K)
Boiling point 255 °C (491 °F; 528 K)
Vapor pressure 0.05 mmHg (25 °C)[1]
Viscosity 3 cP at 25 °C
Hazards
Flash point 130–140 °C (266–284 °F; 403–413 K) (Cleveland open cup)
NIOSH (US health exposure limits):
PEL (Permissible)
 none[1]
REL (Recommended)
 TWA 0.005 ppm (0.035 mg/m3) C 0.020 ppm (0.140 mg/m3) [10-minute][1]
IDLH (Immediate danger)
 N.D.[1]
Related compounds
Related isocyanates
 Isophorone diisocyanate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Hexamethylene diisocyanate (HDI) is the organic compound with the formula (CH2)6(NCO)2. It is classified as an diisocyanate. It is a colorless liquid.[2] It has sometimes been called HMDI[3] but this not usually done to avoid confusion with Hydrogenated MDI.

Synthesis[edit]

Compared to other commercial diisocyanates, HDI is produced in relatively small quantities, accounting for (with isophorone diisocyanate) only 3.4% of the global diisocyanate market in the year 2000.[4] It is produced by phosgenation of hexamethylene diamine.

Applications[edit]

Aliphatic diisocyanates are used in specialty applications, such as enamel coatings which are resistant to abrasion and degradation by ultraviolet light. These properties are particularly desirable in, for instance, the exterior paint applied to aircraft and vessels. HDI is also sold oligomerized as the trimer or biuret which are used in automotive refinish coatings.[5][6] Although more viscous in these forms, it reduces the volatility and toxicity. At least 3 companies sell material in this form commercially. It is also used as an activator in process of in situ polymerization of caprolactam i.e. cast nylon process. HDI is also used bisoxazolidine synthesis as the hydroxyl group on the molecule allows for further reaction with hexamethylene diisocyanate.[7][8]

Toxicity[edit]

HDI is considered toxic, and its pulmonary toxicity has been studied as well as its oligomers.[9][10][11][12]

See also[edit]

References[edit]

  1. ^ a b c d e NIOSH Pocket Guide to Chemical Hazards. "#0320". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ Christian Six; Frank Richter (2005). "Isocyanates, Organic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a14_611. ISBN 3-527-30673-0.
  3. ^ PubChem. "Hexamethylene diisocyanate". pubchem.ncbi.nlm.nih.gov. Retrieved 2022-08-04.
  4. ^ Randall, David; Lee, Steve (2002). The Polyurethanes Book. New York: Wiley. ISBN 978-0-470-85041-1.
  5. ^ Jeffries, Michael; Gambino, Charles; Pierce, Joe. "Acrylate Monomer Free/VOC Compliant Ultraviolet-A Radiation Curable Technology for Automotive Refinish Clear Coat" (PDF).
  6. ^ Gregorovich, Basil V.; Adamsons, Karlis; Lin, Li (2001-11-01). "Scratch and mar and other mechanical properties as a function of chemical structure for automotive refinish coatings". Progress in Organic Coatings. Athens 2000. 43 (1): 175–187. doi:10.1016/S0300-9440(01)00187-4. ISSN 0300-9440.
  7. ^ "2-[2-(propan-2-yl)-1,3-oxazolidin-3-yl]ethanol - Registration Dossier - ECHA". echa.europa.eu. Retrieved 2018-11-14.
  8. ^ Howarth, GA (July 2003). "Polyurethanes, polyurethane dispersions and polyureas: Past, present and future". Surface Coatings International Part B: Coatings Transactions. 86 (2): 111–118. doi:10.1007/bf02699621. ISSN 1476-4865. S2CID 93574741.
  9. ^ Lee, Chun-Ting; Friedman, Mitchell; Poovey, Halet G; Ie, Susanti R; Rando, Roy J; Hoyle, Gary W (2003-05-01). "Pulmonary toxicity of polymeric hexamethylene diisocyanate aerosols in mice". Toxicology and Applied Pharmacology. 188 (3): 154–164. doi:10.1016/S0041-008X(03)00096-6. ISSN 0041-008X. PMID 12729715.
  10. ^ Pauluhn, J. (2000-11-01). "Inhalation Toxicity of 1,6-Hexamethylene Diisocyanate Homopolymer (HDI-IC) Aerosol: Results of Single Inhalation Exposure Studies". Toxicological Sciences. 58 (1): 173–181. doi:10.1093/toxsci/58.1.173. ISSN 1096-0929. PMID 11053554.
  11. ^ Mohr, Jürgen Pauluhn, Ulrich (2001-01-01). "INHALATION TOXICITY OF 1,6-HEXAMETHYLENE DIISOCYANATE HOMOPOLYMERS (HDI-IC AND HDI-BT): Results of Subacute and Subchronic Repeated Inhalation Exposure Studies". Inhalation Toxicology. 13 (6): 513–532. doi:10.1080/08958370118600. ISSN 0895-8378. PMID 11445890. S2CID 13505170.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  12. ^ Wisnewski, Adam V.; Liu, Qing; Miller, Jing-Jing; Magoski, Nadine; Redlich, Carrie A. (2002-09-01). "Effects of hexamethylene diisocyanate exposure on human airway epithelial cells: in vitro cellular and molecular studies". Environmental Health Perspectives. 110 (9): 901–907. doi:10.1289/ehp.02110901. PMC 1240990. PMID 12204825.

External links[edit]

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