Copolymerization of propylene oxide and carbon dioxide (CO2) has been studied using different R-salophenCoOBzF5 (OBzF5 = pentaflorobenzoate, R = CH3, H, Cl, Cl2) based catalysts. The central moiety of the catalysts R-salophenCoOBzF5 has been kept the same and effect of the catalyst electron density on the copolymerization reaction has been studied. It has been observed that introduction of an electron withdrawing group (like Cl, Cl2) on the o-phenylenediamine backbone moiety of the catalyst makes it more selective for poly(propylene carbonate) synthesis. On the other hand, introduction of an electron donating group (like CH3) makes the catalyst selective for cyclic carbonate conversion. The effect of different type of co-catalysts has also been investigated using tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, [PPN]+Cl− ([PPN]+ = bis(triphenylphosphine)iminium), DMAP and tetrabutyl ammonium bromide.
This work was supported in part by the All India Council of Technical Education, New Delhi (India) under Project No. 8023/RID/RPS/068/11/12. The support of Sophisticated Analytical Instrumentation Laboratory, Thapar University, Patiala (Punjab), India is gratefully acknowleged. Award of Raja Ramanna Emeritus Fellowship to SN Upadhyay is gratefully acknowledged.