Green non<italic>-</italic>phosgene process for manufacturing isocyanates

Abstract

Isocyanates are the core feed-stocks for the synthesis of polyurethane. At present, the industrial production of isocyanates mainly bases on the phosgene process, which is extremely toxic and yields large amounts of corrosive HCl. Non - phosgene process for isocyanates production is always one of the most important missions for green chemistry and related contents, and its implementation will bring about the revolutionary change for the polyurethane industry. This review focuses on the development of two-step route for aliphatic isocyanates in our lab as well as the existing problems, i.e., catalytic synthesis of N- substituted carbamates using various carbonyl sources, then thermal cracking target on isocyanate, especially for our strategy to the formation and depolymerization of the polymer derived from the thermal cracking process. Based on our research, a three-step non - phosgene process for isocyanate production is proposed, which provides a promissing technology for industrial application.