Izocianai

Izocianai are a class of organic compounds characterized by the functional group R-N=C=O, where R is an organic substituent. This functional group, the isocyanate group, is highly reactive, particularly with nucleophiles. The presence of the cumulated double bonds in the N=C=O structure contributes to this reactivity. Isocyanates are typically synthesized through the reaction of amines with phosgene or phosgene equivalents. This reaction is a crucial step in the industrial production of many polymers.

The most prominent application of isocyanates is in the production of polyurethanes. Diisocyanates, such as toluene diisocyanate (TDI) and methylene diphenyl diisocyanate (MDI), react with polyols to form the characteristic urethane linkages that define polyurethanes. These polymers find widespread use in foams, coatings, adhesives, sealants, and elastomers. The properties of the resulting polyurethane can be tailored by selecting different isocyanates and polyols.

Beyond polyurethanes, isocyanates are used as intermediates in the synthesis of pesticides, herbicides, and pharmaceuticals. However, many isocyanates are toxic and highly irritating to the respiratory system and skin, necessitating careful handling and strict safety precautions during their production and use. Exposure to isocyanates can lead to respiratory sensitization and occupational asthma.