Synthesis and evaluation of stable, efficient, and recyclable carbonylation catalysts: Polyether-substituted lmidazolium carbonyl cobalt lonic liquids

•Functionalized [H(OCH2CH2)nbim][Co(CO)4)] ILs are synthesized successfully.•Thermoregulated phase-separable catalysis (TPSC) system has been established.•The TPSC system exhibits good recycling efficiency in hydroesterification of 4-isobutylstyrene.

The synthesis and catalytic performance of stable, efficient, and recyclable multi-functionalized ionic liquid catalysts are reported for the first time. Through an optimized synthetic strategy, a series of polyether-substituted imidazolium cobalt tetracarbonyl salts, [H(OCH2CH2)nbim] [Co(CO)4)] (n = 8, 15, and 22, bim = butylimidazolium), and their intermediates, were successfully synthesized and characterized by IR, UV–vis, 1H NMR, 13C NMR, and TGA. The stability, solubility, and critical solution temperature of the ionic liquids were also determined. A thermoregulated phase-separation catalysis system for the hydroesterification of olefins has been established based on the above multi-functionalized ionic liquid catalyst. The results show that this catalysis system has a high recycling efficiency, and provides a potential method for an environmentally benign carbonylation process.

Graphical abstractPolyether-substituted imidazolium ionic liquids, representing an affirmative case of stabilizing the highly air sensitive cobalt tetracarbonyl anion, have been successfully synthesized and used in hydroesterification of 4-isobutylstyrene by thermoregulated phase-separable catalysis (TPSC) system. The TPSC system exhibits good recycling efficiency and provides a potential route for an environmentally benign carbonylation reaction.Figure optionsDownload full-size imageDownload high-quality image (103 K)Download as PowerPoint slide