Synthesis of Polyurethane Raw Material Using CO2 as a Resource

Abstract

: Production of useful chemicals using CO 2 as a resource is attracting attention as a tech-nology to reduce CO 2 emissions and contribute to the prevention of global warming. Isocyanates, the raw material for polyurethanes that are mass-produced and used for long periods of time, are one of the ideal core chemicals as a target for this technology. Therefore, organic carbamates, which give isocyanates through pyrolysis, are focused attention as an intermediate compound for the synthesis of isocyanates from CO 2 . In this paper, we introduce the efficient and environmentally benign synthesis methods for organic carbamates from CO 2 using regenerable metal alkoxides, such as dialkyltin dialk-oxides R 2 Sn(OR’) 2 , titanium tetraalkoxides Ti(OR’) 4 , and tetraalkyl orthosilicates Si(OR’) 4 , which we have previously reported. By using these regenerable reagents, we have achieved the synthesis of a polyurethane raw material that consumes practically only amines and CO 2 , with H 2 O as the only by-product. In particular, the reaction using Si(OMe) 4 has succeeded in highly efficient synthesis of pre-cursors of the industrially important polyurethane raw materials (MDI, TDI, and HDI) using 1 atm of CO 2 .