Abstract
A water-soluble catalyst based on a silicotungstate polyoxometalate, K8[β-SiW11O39] · 14H2O, was developed for the oxidation of pyridines and alcohols with hydrogen peroxide. The reactions were carried out in water, and good yields of the corresponding heterocyclic N-oxides and ketones were obtained under relatively mild conditions. The catalyst could be easily recovered by extraction with ethyl acetate and reused several times.
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GRAPHICAL ABSTRACT
ACKNOWLEDGMENT
This work was financially supported by the National Natural Science Foundation of China (Grant No. 20803032).
Notes
b
a Reaction conditions: catalyst 9.3 µmol, water 1 mL, cyclohexanol 1 mmol, hydrogen peroxide 5 mmol, reaction temperature 90 °C, reaction time 7 h.
b Na2SiO3 · 9H2O 9.3 µmol, Na2WO4 · 2H2O 9.3 µmol.
a Reaction conditions: K8[β-SiW11O39] · 14H2O 9.3 µmol, water 1 mL, substrate 1 mmol, hydrogen peroxide 5 mmol, reaction temperature 90 °C, reaction time 7 h.
b 20 µmol of methyltrioctylammonium chloride was added.
c By-product was benzaldehyde.
a Reaction conditions: K8[β-SiW11O39] · 14H2O 9.3 µmol, water 1 mL, cyclohexanol 1 mmol, hydrogen peroxide 5 mmol, reaction temperature 90 °C, reaction time 7 h.
a Reaction conditions: K8[β-SiW11O39] · 14H2O 9.3 µmol, water 1 mL, substrate 1 mmol, hydrogen peroxide 5 mmol, reaction temperature: 90 °C, isolated yield.
b 20 µmol of methyltrioctylammonium chloride was added.