S/CuMgAl-41 as an efficient Hybrid catalyst for asymmetric addition reaction in isopropyl alcohol solvent

Abstract

In this study, a series catalysts of CuMgAl-LDHs were successfully prepared by co-precipitation method. Subsequently, the catalyst S/CuMgAl-41 was prepared by modifying CuMgAl-41 with thiourea. The physical and chemical properties of the catalyst were characterized by XRD, N2 adsorption-desorption, SEM, ICP, FT-IR, TG-DSC and XPS. The catalytic performance of the catalyst was investigated. It showed that S/CuMgAl-41 exhibited synergistic catalytic activity with better ee value due to both acidic and alkaline active sites and confined spaces with proper interlayer spacing. When isopropyl alcohol was chosen as solvent, the S/CuMgAl-41 has the best catalytic effect for asymmetric aldol addition reaction between p-nitrobenzaldehyde (p-NBD) and acetone. Additionally, the process conditions for optimizing the asymmetric addition reaction have been thoroughly studied. It was found that S/CuMgAl-41 exhibited good reusability and stability. Moreover, the asymmetric aldol addition of acetone and p-NBD catalyzed by S/CuMgAL-41 can occur due to the result of synergistic effects of various factors, including acid-base active center, hydrogen bond, confined effect and anchoring effects between hydrotalcite laminate of S/CuMgAL-41. This novel catalytic design provides a new idea for asymmetric synthesis of p-NBD and acetone.