Alternating copolymerization of carbon dioxide and propylene oxide catalyzed by (R, R)‐SalenCoIII‐ (2,4‐dinitrophenoxy) and Lewis‐basic cocatalyst

Abstract

AbstractA binary catalyst system of a chiral (R,R)‐SalenCoIII(2,4‐dinitrophenoxy) (salen = N,N‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐diphenylethylenediimine) in conjunction with (4‐dimethylamino)pyridine (DMAP) was developed to generate the copolymerization of carbon dioxide (CO2) and racemic propylene oxide (rac‐PO). The influence of the molar ratio of catalyst components, the operating temperature, and reaction pressure on the yield as well as the molecular weight of polycarbonate were systematically investigated. High yield of turnover frequency (TOF) 501.2 h−1 and high molecular weight of 70,400 were achieved at an appropriate combination of all variables. The structures of as‐prepared products were characterized by the IR, 1H NMR, 13C NMR measurements. The linear carbonate linkage, highly regionselectivity and almost 100% carbonate content of the resulting polycarbonate were obtained with the help of these effective catalyst systems under facile conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5050–5056, 2007