toluendiisocyanian

Toluendiisocyanian, more commonly called toluene diisocyanate (TDI), is an aromatic diisocyanate used as a major chemical intermediate in polyurethane production. Its chemical formula is C9H6N2O2, reflecting two isocyanate (-NCO) groups attached to a toluene ring. TDI exists mainly as two isomers, 2,4-TDI and 2,6-TDI. In industry it is typically supplied as a mixture (often with a specified ratio, such as around 80:20 for the two isomers), though individual isomers are also obtainable.

Production of TDI follows a multi-step route starting from toluene. Toluene is first converted to dinitrotoluene, which is then hydrogenated to form toluene diamine. This diamine is subsequently reacted with phosgene to yield the diisocyanate. This sequence—nitration, reduction, and phosgenation—is the conventional industrial pathway for TDI and related diisocyanates.

Applications of TDI are dominated by polyurethane manufacture. It is a key monomer for producing flexible and rigid foams, coatings, elastomers, and adhesives. Polymers derived from TDI are valued for properties such as resilience, abrasion resistance, and versatility in consumer and industrial products.

Properties of TDI include its volatility and a sharp, irritating odor. It is a reactive compound that undergoes hydrolysis in the presence of moisture, releasing carbon dioxide and forming amine-containing products. TDI requires careful handling to avoid exposure, as isocyanates are irritants and potential sensitizers.

Safety and environmental considerations are central to its use. Occupational exposure limits and proper containment, ventilation, and personal protective equipment are standard, given the potential health hazards and regulatory controls associated with isocyanates.