Isophorone diisocyanate

Isophorone diisocyanate
Names
IUPAC name
5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane
Other names
IPDI
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.021.692
Properties
C12H18N2O2
Molar mass 222.3 g/mol
Appearance Colourless to slightly yellow liquid[1]
Odor pungent[1]
Density 1.062 g/cm3 @ 20 °C, liquid
Melting point −60 °C (−76 °F; 213 K)
Boiling point 158 °C (316 °F; 431 K) at 1.33 kPa
Vapor pressure 0.0003 mmHg (20°C)[1]
Hazards
Flash point 155 °C (311 °F; 428 K) (PMCC)
US health exposure limits (NIOSH):
PEL (Permissible)
 none[1]
REL (Recommended)
 TWA 0.005 ppm (0.045 mg/m3) ST 0.02 ppm (0.180 mg/m3) [skin][1]
IDLH (Immediate danger)
 N.D.[1]
Related compounds
Related isocyanates
 Hexamethylene 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

Isophorone diisocyanate (IPDI) 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 hexamethylene diisocyanate) only 3.4% of the global diisocyanate market in the year 2000.[2] Aliphatic diisocyanates are used, not in the production of polyurethane foam, but 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.

Synthesis

IPDI is obtained by a five-step synthesis:[2]

  • Condensation: Conversion of acetone with a catalyst to produce isophorone
  • Hydrocyanation: Reaction of the isophorone with hydrogen cyanide to form isophorone nitrile
  • Reductive amination: Reaction of the isophorone nitrile with ammonia, hydrogen and a catalyst, to form a mixture of isophorone diamine conformers (25/75 cis/trans)
  • Phosgenation: Reaction of the isophorone diamine with phosgene to form a crude mixture containing IPDI conformers (25/75 cis/trans)
  • Purification: Distillation of the crude IPDI to extract pure IPDI

Chemistry

IPDI exists in two stereoisomers, cis and trans. Their reactivities are similar. Each stereoisomer is an unsymmetrical molecule, and thus has isocyanate groups with different reactivities. The primary isocyanate group is more reactive than the secondary isocyanate group.[2]

See also

References

  1. 1 2 3 4 5 6 "NIOSH Pocket Guide to Chemical Hazards #0356". National Institute for Occupational Safety and Health (NIOSH).
  2. 1 2 3 Randall, David; Lee, Steve (2002). The Polyurethanes Book. New York: Wiley. ISBN 0-470-85041-8.
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