Carbon dioxide could be a virtually inexhaustible chemical reagent that is cheap and non-toxic. To achieve this, it has to be activated under low-energy conditions. Many catalysts for CO₂ activation and fixation are being developed, but most still require high temperatures and pressures. Antonello Decortes and Arjan Kleij, Institute of Chemical Research of Catalonia (ICIQ), Spain, have used a zinc-salphen complex [salphen=N,N’-phenylene-1,2-bis-salicylidene] to generate cyclic carbonates from CO₂.

The complex preparation did not require oxygen- and/or moisture-free conditions and, as it used Zn(II), it is not toxic. The cycloaddition of carbon dioxide to various epoxides could be performed under mild conditions (25 °C, pCO₂=0.2 MPa) and with a green reaction medium, 2-butanone. This represents one of the few catalytic processes that can exclusively produce cyclic carbonate structures under ambient conditions.

Images: (c) Wiley-VCH

• Ambient Fixation of Carbon Dioxide using a Zn^IIsalphen Catalyst
  A. Decortes, A. W. Kleij,
  ChemCatChem 2011.
  DOI: 10.1002/cctc.201100031