Hydrotalcite-Supported Ag/Pd Bimetallic Nanoclusters Catalyzed Oxidation and One-Pot Aldol Reaction in Water

Sangita Karanjit,Ayumu Tamura,Masaya Kashihara,Lok Kumar Shrestha,Katsuhiko Ariga,Kazuki Ushiyama,Kosuke Namba,Atsushi Nakayama

doi:10.3390/catal10101120

Sangita Karanjit, Ayumu Tamura + Show 6 more

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https://doi.org/10.3390/catal10101120

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Abstract

A highly active hydrotalcite-supported Ag/Pd bimetallic nanocluster catalyst has been developed by a simple, easy and safe chemical reduction method. The catalyst was characterized by high-resolution transmission electron microscopy (HR-TEM), which revealed very small (3.2 ± 0.7 nm) nanoclusters with a narrow size distribution. The bimetallic Ag/Pd catalyst showed strong cooperation between Ag and Pd for the alcohol oxidation reaction. The developed catalyst provided an efficient and environmentally friendly method for alcohol oxidation and one-pot cross-aldol condensation in water. A broad scope of α,β-unsaturated ketones with good to excellent yields were obtained under very mild conditions. This catalytic system offers an easy preparation method with a simple recovery process, good activity and reusability of up to five cycles without significant loss in the catalytic activity.

Highlights

Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Sho-machi, International Center for Materials Nanoarchitectonics, National Institute for Materials Science (NIMS), Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
One-pot oxidative coupling of alcohols that results in α,β-unsaturated ketones is limited hightotemperature
The temperature was reduced to 15 ◦ C, 2.5 mmol of 0.27 mM aqueous NaBH4 was added and stirring was continued for 1 h

Summary

Introduction

A highly active hydrotalcite-supported Ag/Pd bimetallic nanocluster catalyst has been developed by a simple, easy and safe chemical reduction method. A broad scope of α,β-unsaturated ketones with good to excellent yields were obtained under very mild conditions This catalytic system offers an easy preparation method with a simple recovery process, good activity and reusability of up to five cycles without significant loss in the catalytic activity. The synthesis of α,β-unsaturated ketones through direct oxidative coupling of primary and secondary alcohol is expected to be a more straightforward method, i.e., inexpensive and readily available alcohols and ketones can be used as starting materials and the reaction is an environmentally friendly process that combines the oxidation of alcohols to aldehydes and condensation of aldehyde with ketone producing. That results in α,β-unsaturated ketones is limited due to the requirement of toxic organic solvent and

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