J IRAN CHEM SOC
Table 5 Comparison of the
result obtained for the synthesis
of benzaldehyde using RuO2@
ZrO2 (4 wt%) with other
Entry Catalyst
Solvent
Temp (°C) Time (min) Conversion (%) Ref.
1
2
3
4
5
MOF-supported Au NPs C6H5CH3
80
75
60
300
300
300
15
100
19
77
38
80
Nano-γ-Fe2O3
H2O2
catalysts reported in literature
Au-doped TiO2
Au-doped ZnO
RuO2@ZrO2 (4 wt%)
Solvent-free 100
Solvent-free 100
CH3CN
Ref
This work
Time (min)
Conversion (%)
and HR-TEM techniques. Also, we have developed a sim-
ple and highly efficient protocol for the oxidation of ben-
zylic alcohols to the corresponding aldehydes or ketones
using nano structured RuO2@ZrO2 as heterogeneous cata-
lyst under reflux condition and microwave irradiation in
acetonitrile. It is worthy to mention that the synthesis cata-
lyst along with the reaction media can be reused for further
reactions. Environmentally benign, easy work-up proce-
dure, saving energy and mild reaction conditions are some
advantages of this work.
85
80
100
75
80
50
25
5
10
10
0
1
2
3
Run
Acknowledgments The authors are grateful to the Research Coun-
cil of University of Guilan for partial support of this study.
Fig. 3 Reusability of RuO2@ZrO2 (4 wt%) in the model reaction
References
withdrawing groups in ortho- and meta-positions. Similar
reactivity was observed for the oxidation of alcohols to the
corresponding aldehydes under microwave irradiation.
Furthermore, in order to show the excellent catalytic
activity of this catalyst in comparison with the previously
reported heterogeneous systems, we compared the results
of the oxidation of benzylic alcohols in the presence of
RuO2@ZrO2 (4 wt%) and other reagents (Table 5). The
obtained results indicate the superiority of RuO2@ZrO2
(4 wt%) in terms of catalyst, temperature, conversion and
reaction times.
1. G. Sartori, R. Ballini, F. Bigi, G. Bosica, R. Maggi, P, Righi.
Chem. Rev. 104, 199 (2004)
2. R. Vadakkekara, M. Chakraborty, P.A. Parikh, Ind. Eng. Chem.
Res. 51, 5691 (2012)
3. X. Liu, C.M. Friend, Langmuir 26, 16552 (2010)
4. M.J. Beier, T.W. Hansen, J.D. Grunwaldt, J. Catal. 266, 320
(2009)
5. J. Hu, K. Sun, D. He, B. Xu, Chin. J. Catal. 28, 1025 (2007)
6. V.R. Choudhary, D.K. Dumbre, Catal. Commun. 10, 1738 (2009)
7. M. Salavati-Niasari, J. Mol. Catal. A Chem. 245, 192 (2006)
8. A. Tanaka, K. Hashimoto, H. Kominami, J. Am. Chem. Soc. 134,
14526 (2012)
The reusability of the synthesized catalysts is a signifi-
cant factor from environmental and economic points of
view. In heterogeneous catalysts, the leaching of metal is
a main problem which leads to loss of catalyst activity on
subsequent uses. In order to investigate the stability of the
catalytic systems, recycling experiments were performed.
After completion of the reaction, the catalyst was recovered
by centrifugation and washed with deionized water and
chloroform, then dried and reused in the subsequent runs.
The conversion result showed that RuO2@ZrO2 4 wt% can
be reused three times without significant loss of activity
9. S. Mandal, K.K. Bando, C. Santra, S. Maity, O.O. James, D.
Mehta, B. Chowdhury, Appl. Catal. A 452, 94 (2013)
10. S. Yurdakal, G. Palmisano, V. Loddo, V. Augugliaro, L. Palm-
isano, J. Am. Chem. Soc. 130, 1568 (2008)
11. D.I. Enache, D. Barker, J.K. Edwards, S.H. Taylor, D.W. Knight,
A.F. Carley, G.J. Hutchings, Catal. Today 122, 407 (2007)
12. Y.K. Kim, Z. Dohnálek, B.D. Kay, R. Rousseau, J. Phys. Chem.
C 113, 9721 (2009)
13. J. Zhu, K. Kailasam, A. Fischer, A. Thomas, ACS Catal. 1, 342
(2011)
14. T. Feng, J.M. Vohs, J. Phys. Chem. B 109, 2120 (2005)
15. M. Seman, J.N. Kondo, K. Domen, C. Reed, S.T. Oyama, J.
Phys. Chem. B 108, 3231 (2004)
16. S. Furukawa, T. Shishido, T.K. Teramura, ACS Catal. 2, 175
(2012)
17. T. Shishido, T. Miyatake, K. Teramura, Y. Hitomi, H. Yamashita,
T. Tanaka, J. Phys. Chem. C 113, 18713 (2009)
18. V. Jeena, R.S. Robinson, Chem. Commun. 48, 299 (2012)
19. J. He, T. Wu, T. Jiang, X. Zhou, B. Hu, B. Han, Catal. Commun.
9, 2239 (2008)
Conclusion
In conclusion, we attempted to synthesize RuO2@ZrO2
core–shell. The catalyst has been characterized by XRD
20. S. Higashimoto, N. Kitao, N. Yoshida, T. Sakura, M. Azuma, H.
Ohue, Y. Sakata, J. Catal. 266, 279 (2009)
1 3