Chinese Journal of Catalysis ›› 2017, Vol. 38 ›› Issue (5): 805-812.DOI: 10.1016/S1872-2067(17)62824-9

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Cobalt carbonyl ionic liquids based on the 1,1,3,3-tetra-alkylguanidine cation: Novel, highly efficient, and reusable catalysts for the carbonylation of epoxides

Wei Zhanga,b, Feng Hana, Jin Tonga, Chungu Xiaa, Jianhua Liua   

  1. a. State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, Gansu, China;
    b. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2017-01-26 Revised:2017-03-23 Online:2017-05-18 Published:2017-05-10
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (21373248, 21673260, 21133011).

Abstract:

A series of novel cobalt carbonyl ionic liquids based on 1,1,3,3-tetra-alkyl-guanidine, such as [1,1-dimethyl-3,3-diethylguanidinium][Co(CO)4] (3a), [1,1-dimethyl-3,3- dibutylguanidinium] [Co(CO)4] (3b), [1,1-dimethyl-3,3-tetramethyleneguanidinium][Co(CO)4] (3c), and [1,1- dimethyl-3,3-pentamethyleneguanidinium] [Co(CO)4] (3d), were synthesized in good yields and were also characterized using infrared spectroscopy, ultraviolet-visible spectroscopy, 1H nuclear magnetic resonance (NMR) spectroscopy, 13C NMR spectroscopy, high‐resolution mass spectrometry, differential scanning calorimetry, and thermogravimetric analysis. The four compounds exhibited high thermal and chemical stability. In addition, the catalytic performance of these compounds was investigated in the carbonylation of epoxides, with 3a exhibiting the best catalytic activity without the aid of a base as the additive. The catalyst could be reused at least six times without significant decreases of the selectivity or conversion rate. Moreover, the catalyst system exhibited good tolerance with terminal epoxides bearing alkyl, alkenyl, aryl, alkoxy, and chloromethyl functional groups.

Key words: Cobalt carbonyl ionic liquid, Carbonylation, Epoxide, Tetra-alkylguanidine, Recyclability