M. Lakshmi Kantam et al.
COMMUNICATIONS
References
tion of complex III with O2 may afford the complex
Ru-hydroperoxide IV. The uptake of alcohol again
completes the cycle with the formation of O2 and
H2O.
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In conclusion, a newly designed ruthenium catalyst,
stabilized on nanocrystalline magnesium oxide by a
basicionicliquid, was found to be a potential candi-
date for aerobicalcohol oxidation.
Experimental Section
Preparation of the Catalyst
NAP-MgO (1.0 g) and choline hydroxide (0.5 mL) were
charged in a 50-mL, round-bottomed flask containing 25 mL
of dry THF and stirred under a nitrogen atmosphere for 4 h.
The CHNAP-MgO was then filtered and washed several
times with acetone and dried under vacuum. CHNAP-MgO
(1.0 g) was stirred with RuCl3 (0.415 g) in 75 mL of freshly
prepared deionized water at 258C for 24 h under a nitrogen
atmosphere. The catalyst was filtered, washed with deion-
ized water, acetone and dried overnight at 1108C. The pre-
pared Ru-CHNAP-MgO catalyst was grey in colour and
from the elemental analysis the Ru content in the catalyst
was 1.64 mmolgÀ1(Ru content: 16.6 wt%).
General Procedure for the Alcohol Oxidation with
Ru-CHNAP-MgO Catalyst
A dry 25-mL, two-necked, round-bottomed flask equipped
with a reflux condenser connected with a balloon filled with
oxygen was charged with Ru-CHNAP-MgO (1) catalyst
(0.2 g), alcohol (2 mmol) and toluene (5 mL). The resulting
mixture was stirred at 808C. After completion of the reac-
tion, (monitored by TLC and GC), the reaction mixture was
centrifuged to separate the catalyst, which was washed sev-
eral times with deionized water and dried before reuse. The
combined organic layers were dried over anhydrous Na2SO4
and the solvent was removed under reduced pressure. The
crude product was purified by column chromatography
(silica gel: 100–200 mesh using ethyl acetate and petroleum
ether) to give the corresponding aldehyde or ketone.
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Characterization of the catalysts and the mechanistic studies
are available in the Supporting Information.
Acknowledgements
We wish to thank the CSIR forfinancial suppotr underthe
Task Force Project CMM-0005. U. Pal thanks Council of Sci-
entific and Industrial Research, India, for a research fellow-
ship. Nanocrystalline MgO catalysts were obtained from
NanoScale Corporation, Manhattan, Kansas, USA.
1228
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2008, 350, 1225 – 1229