Isocyanate
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Isocyanate is the chemical group of atoms -N=C=O (1 nitrogen, 1 carbon, 1 oxygen), as opposed to cyanate, -O-C≡N, which is formed from cyanogen in the normal -ate manner. An isocyanate is a compound containing the isocyanate group.
Examples of isocyanate compounds used in the polymer industry are isomers of toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), and hexamethylene diisocyanate (HDI). They are used as monomer feedstock for polyurethane production. Some of their chemical structures are shown here:
Toluene_diisocyanates.PNG
Numbering of the ring atoms shown with blue numbers
Methylene_diphenyl_4,4'-diisocyanate.PNG
Numbering of the ring atoms shown with blue numbers
Isocyanates such as these can react with an alcohol to produce a urethane linkage. These compounds are reactive and therefore toxic and are known to cause asthma in humans, both through inhalation exposure and dermal contact. Exposure to these isocyanates and their vapors should be avoided.
See also cyanide, isothiocyanate, methyl isocyanate.
External Link
[|Hazards of TDI, MDI, and HDI (http://www.semcosh.org/polyurethanes.pdf)]