Polystyrene‐Supported N‐Heterocyclic Carbene–Silver Complexes as Robust and Efficient Catalysts for the Reaction of Carbon Dioxide and Propargylic Alcohols

Three polystyrene‐supported N‐heterocyclic carbene–silver complexes [PS‐NHC‐Ag(I)] and a polystyrene‐supported N‐heterocyclic carbene–copper complex [PS‐NHC‐Cu(I)] catalyst were synthesized and characterized by elemental analysis, Fourier transform infrared spectroscopy, inductively coupled plasma‐atom emission spectrometer, thermogravimetric analysis and scanning electron micrographs. The catalytic activity of the supported catalysts was investigated for the reaction of propargylic alcohols and carbon dioxide. PS‐NHC‐Cu(I) showed no catalytic activity to the reaction, while PS‐NHC‐Ag(I) showed a considerable high activity and selectivity for the reaction, yielding the corresponding α‐alkylidene cyclic carbonates in high to excellent yields under mild conditions. Most importantly, the supported catalysts could be separated easily from the products and reused up to 15 times without loss of their high catalytic activity, showing excellent stability. The effect of various reaction parameters such as carbon dioxide pressure, temperature, time, and catalyst loading on the reaction was also investigated.