Abstract
In this study, benzoin methyl ether and benzoin ethyl ether were highly selectively synthesized in one-pot reaction using the reusable NiAlCe-hydrotalcite catalysts, where the benzoin ether compounds are traditionally obtained in two steps through condensation and etherification. The high crystallinity NiAlCe-hydrotalcites with different Ni2+/Al3+/Ce3+ ratios were facilely synthesized by the coprecipitation method under a constant pH value. The reaction parameters (e.g., different Ni2+/Al3+/Ce3+ ratios, reaction time, temperature, amount and the stability of catalyst) were studied in details and it was found that the Ni2+/Al3+/Ce3+ ratios, reaction temperature and the reaction medium play crucial influence on the catalytic activity and products distribution. 99.2% selectivity of benzoin methyl ether was achieved at 85.4% conversion of benzaldehyde and 98.3% selectivity was obtained at 63.7% conversion using a NiAlCe-hydrotalcite catalyst with the Ni2+/Al3+/Ce3+ ratio of 22:10:1, respectively. Besides, NiAlCe-hydrotalcite catalysts were easily recycled through a simple separation process and show high stability over three consecutive runs.
Keywords: Benzoin methyl ether, benzoin ethyl ether, coprecipitation, NiAlCe-hydrotalcite, one-pot synthesis.
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