HAP-Pd(0): A Highly Efficient Recyclable Heterogeneous Catalyst for the Selective Reduction of Carbon–Carbon Double Bond in α,β-Unsaturated Ketones

Abstract

A recyclable heterogeneous hydroxyapatite-supported palladium(0) catalyst was prepared by a simple procedure and successfully applied for the selective reduction of carbon–carbon double bond in α,β-unsaturated ketones using HCOONH₄ as hydrogen transfer agent. The workup procedure is simple, and the catalyst could be recovered by simple filtration and recycled for five consecutive runs without significant loss of activity.

GRAPHICAL ABSTRACT

Keywords:

• HAP-Pd(0)
• heterogeneous catalysis
• reductions
• selectivity
• α,β-unsaturated ketones

ACKNOWLEDGMENTS

We are grateful to Sophisticated Analytical Instrumentation Facility (SAIF), Punjab University, Chandigarh, for the SEM, TEM, and XRD and the Head, Institute Instrumentation Centre, Indian Institute of Technology, Roorkee, for AAS analysis.

Notes

^a Reaction conditions: 3-(4-methoxyphenyl)-1-phenylprop-2-en-1-one (1 mmol), HCOONH₄ (1.5 g), HAP-Pd⁰(0.3 g, 0.33 mol% Pd), solvent (5 mL) at 80 °C.

^b Yield refers to separation based on column chromatography.

^c The rest being the starting materials.

^a The reactions were carried out by stirring a mixture of α,β-unsaturated ketone (1 mmol), HCOONH₄ (1.5 g), HAP-Pd⁰ (0.3 g, 0.33 mol% Pd), and acetonitrile (5 mL) at 80 °C.

^b Yield refers to column chromatography yield.

^c The rest being the unreacted chalcones.

^a Reaction conditions: 3-(4-methoxyphenyl)-1-phenylprop-2-en-1-one (1 mmol), HCOONH₄ (1.5 g), HAP-Pd⁰ (0.3 g, 0.33 mol% Pd), acetonitrile (5 mL) at 80 °C.

^b Pd/C, Pd/SiO₂, and Pd/Al₂O₃ were prepared by a procedure similar to that described for HAP-Pd⁰. An amount of the catalyst equivalent to 0.33 mol% Pd was taken for the test reaction.

^c Yield refers to column chromatography yield, the rest being the starting materials.

^d Yield refers to maximum yield after 15 h. After this no further conversion was observed.