Efficient Cu‐Based Mixed Oxides Catalyst for α‐Alkylation of Ketones with Alcohols

Abstract

A series of Cu‐based mixed oxides were prepared by calcinations of corresponding CuMgAl‐layered double hydroxides precursors at different temperatures with nominal Cu/Mg/Al ratios of 1 : 1 : 2(Cu‐LDH‐1), 1 : 2 : 1(Cu‐LDH‐2),1 : 1 : 1(Cu‐LDH‐3), and 2 : 1 : 1(Cu‐LDH‐4). The synthesized catalysts were characterized using X‐ray diffraction, high‐resolution transmission electron microscopy, scanning electron microscopy, X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, inductively coupled plasma atomic emission spectroscopy (ICP‐AES), and N₂ physisorption analysis techniques. All as‐obtained catalysts showed adequate catalytic performance for the α‐alkylation of ketones with alcohols through a hydrogen autotransfer mechanism. The catalyst CuMgAl‐I‐650 (obtained by calcining Cu‐LDH‐1 at 650 °C) displayed the highest activity and selectivity. Using this catalyst system, a wide range of branched ketones were synthesized in good to excellent isolated yields. Moreover, the catalyst CuMgAl‐I‐650 could be recycled and reutilized for four cycles without any significant loss of activity and selectivity. This study provides a very simple and inexpensive catalysis based on transition metals, which are in abundance on earth.