Tuning double metal cyanide catalysts with complexing agents for the selective production of cyclic carbonates over polycarbonates

Abstract A double metal cyanide (DMC) complex based on (Zn 3 [Co(CN) 6 ] 2 ), an effective catalyst for the ring opening polymerization of epoxides and the copolymerization of carbon dioxide with epoxides, was successfully utilized for the solvent-free cycloaddition of CO 2 to styrene oxide (SO) by the introduction of cetyltrimethylammonium bromide (CTAB) as a complexing agent (CA). Several DMC catalysts were prepared by introducing co-complexing agents (co-CAs) along with the CA. From the XRD data, it was clear that all the catalysts were amorphous with no peak corresponding to the precursor ZnCl 2 . XPS analysis was performed to explain the successful introduction of the CA to the DMC catalyst, in which the binding energy of the zinc atom shifted from precursor ZnCl 2 to DMC. Elemental analysis and FT-IR also confirmed the incorporation of the CA with Zn 3 [Co(CN) 6 ] 2 . The DMC complex was proven to be an effective catalyst for the solvent-free synthesis of styrene carbonate by the cycloaddition of styrene oxide and CO 2 . This paper reports the tunability of the metal cyanide catalysts with CA for the selective preparation of cyclic carbonates over polycarbonates. 1 H NMR and FT-IR confirmed product formation. The effects of reaction parameters like catalyst amount, temperature, CO 2 pressure, and reaction time were also investigated.