Boyapati M. Choudary et al.
COMMUNICATIONS
Experiment 1: A mixture of AP-Mg-OsO4, a-methylstyrene
and NMO in H2O-CH3CN-acetone was stirred for 8 h. After
completion of the reaction, the catalyst was separated by
filtration. To one part of the filtrate were added fresh a-
methylstyrene, NMO and the mixture was stirred for 24 h.
There was no enhancement in the yield of the product. To the
second part of the solution were added a different olefin (trans-
stilbene), NMO and the mixture was stirred for 24 h. No
stilbene diol was formed.
Acknowledgements
K. Jyothi thanks the Indian Institute of Chemical Technology
(IICT), India, for the award of a research fellowship. We thank
Prof. Kenneth Klabunde for prereview and NanoScale Materi-
als Inc. (Dr. Ravi Mulukutla) for their generosity in supplying
the nanocrystalline MgO samples.
Experiment 2: A mixture of AP-Mg-OsO4, a-methylstyrene
and NMO in H2O-CH3CN-acetone was stirred at room
temperature. At different intervals (for every 2 h) the samples
were withdrawn and filtered. To these filtrates were added a
different olefin (trans-stilbene), NMO and the mixture was
stirred for 24 h. No stilbene diol was formed. Furthermore, no
osmium was detected in the filtrates by the SEM-EDX.
From the above experiments it was observed that no osmium
was leached during or at the end of the reaction when all the
constituents were present. It is, therefore, concluded that the
OsO4 is bound to the support during the reaction. It appears
that during oxidation with NMO the anionic form of OsO4 is
transformed into an Os(VIII) species, but is bound to the
support through some other electrostatic interaction that
includes hydrogen bonds with the Br˘nsted hydroxyl groups
of MgO.
Experiment 3: A mixture of AP-Mg-OsO4 and NMO in
H2O-CH3CN-acetone was stirred for 24 h at room temperature
and filtered. To the filtrate was added a-methylstyrene and the
mixture was stirred for 8 h. The diol was formed in good yield.
The result clearly shows that the catalyst suffers from
leaching of osmium upon treatment with the cooxidant in the
absence of the olefin.
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Supporting Information Available
Figure S1. XPS (survey scan) data of fresh catalyst. Figure S2.
TGA-DTA-Mass thermogram of MgOsO4R (MgOsO4 inter-
acted with olefin).
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48
¹ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
Adv. Synth. Catal. 2004, 346, 45 48