Hexamethylene diisocyanate

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Hexamethylene diisocyanate
Hexamethylene diisocyanate
Hexamethylene diisocyanate
IUPAC name
Other names
1,6-hexane diisocyanate
3D model (JSmol)
ECHA InfoCard 100.011.350
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
Flash point 130–140 °C (Cleveland open cup)
US health exposure limits (NIOSH):
PEL (Permissible)
REL (Recommended)
TWA 0.005 ppm (0.035 mg/m3) C 0.020 ppm (0.140 mg/m3) [10-minute][1]
IDLH (Immediate danger)
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).
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Infobox references

Hexamethylene diisocyanate (HDI) is an organic compound in the class known as isocyanates. More specifically, it is an aliphatic diisocyanate. It is produced in relatively small quantities, accounting for (with isophorone diisocyanate) only 3.4% of the global diisocyanate market in the year 2000.[2] Aliphatic diisocyanates are used in special applications, such as enamel coatings which are resistant to abrasion and degradation from ultraviolet light. These properties are particularly desirable in, for instance, the exterior paint applied to aircraft and vessels. HDI is also sold oligomerized in the trimer or biuret. Although more viscous in these forms, it reduces the volatility and toxicity. At least 3 companies sell material in this form commercially.


There are two steps to the synthesis of pure HDI:[2]


HDI is a symmetrical molecule and thus has two isocyanate groups of equal reactivity.

See also[edit]


  1. ^ a b c d e "NIOSH Pocket Guide to Chemical Hazards #0320". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ a b Randall, David; Lee, Steve (2002). The Polyurethanes Book. New York: Wiley. ISBN 978-0-470-85041-1.

External links[edit]