Lanzhou Greenchem ILs (Center for Greenchemistry and catalysis), LICP, CAS. Ionic Liquids

  Through an optimized synthetic strategy, a series of novel alkylpyridinium cobalt tetracarbonyl salts, [C₁Py][Co(CO)₄] ( 2a), [C₄Py][Co(CO)₄] ( 2b) and [C₁₆Py][Co(CO)₄] ( 2c) (C_nPy = N-C_nH_2n+1-pyridinium), were successfully prepared in good yields, using a water–organic biphasic system. All the three compounds melt well below 100 °C and could be classified as ionic liquids. The compounds were fully characterized using IR, UV-Vis, ¹H NMR, ¹³C NMR, ESI-MS and elemental analysis, and 2c was structurally characterized by X-ray single crystal analysis. Compound 2b has been found to be an efficient and reusable catalyst for the alkoxycarbonylation of propylene oxide without the aid of a base additive.