On the Mechanism of Polyurethane Formation Catalyzed by Metal Chelates and Organotin Compounds

The mechanism of the catalyzed linear polyurethane formation in the presence of dibutyltin dilaurate, copper acetylacetonate, and similar catalysts was investigated. It was found that the central ion coordinates with the isocyanate group. The second reacting component may be coordinated by the organic substituent or ligand groups near the central ion. It was concluded that the catalytic mechanism would vary depending on such reaction conditions as temperature, solvent, and the nature of the ligands near the central ion.