Hexamethylene diisocyanate
Appearance
Names | |
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IUPAC name
1,6-diisocyanatohexane
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Other names
HDI
1,6-hexane diisocyanate | |
Identifiers | |
3D model (JSmol)
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ChEBI | |
ChemSpider | |
ECHA InfoCard | 100.011.350 |
PubChem CID
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CompTox Dashboard (EPA)
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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 (Cleveland open cup) |
NIOSH (US health exposure limits): | |
PEL (Permissible)
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none[1] |
REL (Recommended)
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TWA 0.005 ppm (0.035 mg/m3) C 0.020 ppm (0.140 mg/m3) [10-minute][1] |
IDLH (Immediate danger)
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N.D.[1] |
Related compounds | |
Related isocyanates
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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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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.
Synthesis
There are two steps to the synthesis of pure HDI:[2]
- Phosgenation: Reaction of hexamethylene diamine with phosgene to form crude HDI
- Purification: Distillation of crude HDI to extract pure HDI
Chemistry
HDI is a symmetrical molecule and thus has two isocyanate groups of equal reactivity.
See also
References
External links
- NIOSH Safety and Health Topic: Isocyanates, from the website of the National Institute for Occupational Safety and Health (NIOSH)
- NIOSH Pocket Guide to Chemical Hazards - Hexamethylene diisocyanate