A new type of lewis acid-base bifunctional M(salphen) (M=Zn, Cu and Ni) catalysts for CO2 fixation

Article abstract of DOI:10.1002/cctc.201500113

A new type of Lewis acid-base bifunctional M(salphen) complexes (M=Zn^II, Cu^II, and Ni^II) pending two N-methylhomo- piperazine groups as nucleophiles were prepared by a one-pot method. The Zn(salphen) complexes proved to be efficient and recyclable homogeneous catalysts towards the solvent-free synthesis of cyclic carbonates from epoxides and CO₂ in the absence of a co-catalyst. The catalysts can be easily recovered and five times reused without significant loss of activity and selectivity. Bifunctional catalysts: A new type of Lewis acid-base bifunctional Zn(salphen) catalysts with an organic base, N-methylhomopiperazine, as a nucleophile were prepared by a one-pot method and successfully applied in the production of cyclic carbonates from CO₂ and epoxides. The catalysts used in this catalytic system are extremely stable and can be recycled at least five times and their activity is almost unchanged.