112
M. Araghi et al. / C. R. Chimie 16 (2013) 109–113
Table 3 (Continued )
Entry
16
Alcohol
Product
Yield (%)a
77
Time (min)
90
OH
O
17
71
75
140
140
CHO
CHO
CH OH
2
18
CH OH
2
a
GLC yield based on starting alcohol.
effect on the oxidation of benzylic alcohols. In the case of
linear alcohols such as n-octanol, the result showed that,
octanal was obtained in 71% yield. A good selectivity
observed in the case of cinnamyl alcohol and only alcoholic
group is oxidized and no epoxide was obtained.
[Mo(CO)5@APy-MWCNT] was also used for oxidation of
secondary alcohols and their corresponding ketones were
obtained in good yields.
by addition of fresh 4-chlorobenzyl alcohol and tert-
BuOOH to the filtrates after each run. Continuation of the
oxidation reaction under the same reaction conditions as
with catalyst showed that the obtained results were as
same as for the blank experiments.
4. Conclusion
In this article we have demonstrated the utility of
[Mo(CO)5@APy-MWCNT] catalyst in the oxidation of
primary and secondary alcohols to carbonyl compounds
with tert-butyl hydroperoxide. This supported catalyst is
highly reactive in the oxidation of a wide range of primary
and secondary alcohols. It showed the expected advan-
tages of heterogenous catalysts, namely, easy handling and
recyclability. The catalyst was highly reusable and recycled
10 times without appreciable decrease in its initial activity.
3.2. Catalyst reuse and stability
Heterogeneous catalysis is of great practical importance
in modern industry due to the numerous advantages it
involves. On the other hand, the reusability of a supported
catalyst is of great importance from economical and
environmental points of view, because transition metal
complexes are often expensive and very toxic. Therefore,
heterogenization of homogeneous catalysts makes them
useful for commercial applications. The reusability of
[Mo(CO)5@APy-MWCNT] was monitored by using multi-
ple sequential oxidation 4-chlorobenzyl alcohol with tert-
butyl hydroperoxide (Table 4). The catalyst was consecu-
tively reused several times (10 times were checked)
without loss of its initial activity. The amount of
molybdenum, which was detected in the filtrates in first
two runs, was low and after third run no molybdenum was
detected in the filtrates. These results demonstrated the
strong attachment of molybdenum to the MWCNT. The
catalytic behavior of the separated liquid was also tested
Acknowledgements
The financial support of this work by the Islamic Azad
University, Saveh Branch is acknowledged.
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a
Reaction conditions: 4-chlorobenzyl alcohol (1 mmol), tert-BuOOH
(2 mmol), catalyst (90 mg, 0.015 mmol), CCl4 (4 mL).
b
GC yield based on starting 4-chlorobenzyl alcohol.
c
Determined by ICP.