The preparation of α-alkylidene cyclic carbonates through a cyclization reaction of propargylic alcohols with CO2 is important in the industrial process. Herein, a novel mixed-valence heterometallic Cu/Eu-based cationic framework, 1-Eu, was successfully synthesized. The material features a unique 14 Å nanocage structure and was effectively employed in the catalytic conversion of propargylic alcohols with CO2. 1-Eu exhibits remarkable stability in various solvents as well as under acidic and basic conditions, and can maintain the framework stability even in the presence of the strong organic base DBU. Catalytic evaluations demonstrate that 1-Eu can efficiently promote the conversion of propargyl alcohol and CO2 to α-alkylidene cyclic carbonates under mild conditions. Furthermore, it demonstrates high catalytic activity in the conversion of the biomacromolecule norethindrone with CO2. Notably, even when low-concentration CO2 in simulated flue gas is used as the carbon source, 1-Eu remains highly effective in catalyzing the conversion of propargyl alcohol substrates to the corresponding α-alkylidene cyclic carbonate products. The results of the control experiment show that the synergistic catalytic effect between CuI/CuII and EuIII plays a crucial role in the activation of CO2 and propargyl alcohol, thereby facilitating the catalytic reaction.
Chen et al. (Sat,) studied this question.