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DOI: 10.1039/C4RA15P92a1gGe 8 of 9
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with H2O2 is proposed in Scheme 3. In the initial period of
the reaction, the vanadium active species in the hybrid
catalyst reacts with H2O2 to generate the hydroperoxyl
radical HOO·, meanwhile, the high valent vanadium (V) is
reduced to vanadium (IV), in agreement with the previous
suggestion31. After that, the second hydrogen peroxide
molecule attacks the transition state of vanadium (IV) to
generate the hydroxyl radical HO·, whilst the vanadium (IV)
is oxidized reversely to the higher oxidation state vanadium
(V), which thus completes the catalytic cycle. Within the
cycle, the substrate cyclohexane molecule reacts with the
resulting radicals HOO· and HO· to give the products of
cyclohexanol and cyclohexanone via the known further
route.48,49
State Key Laboratory of Materials-Oriented Chemical Engineering,
College of Chemistry and Chemical Engineering, Nanjing Tech
University, Nanjing 210009, P. R. China. Tel: +86-25-83172264.
Fax: +86-25-83172261. E-mail: njutzhouyu@njtech.edu.cn (Y.
Zhou); junwang@njtech.edu.cn (J. Wang).
†
Electronic Supplementary Information (ESI) available: Details
of the synthesis and structure formulas of various control
catalysts, NMR of ionic liquid precursor
1H
[DPyAM]Br2·2HBr and the hybrid [DPyAM(H2)]1.25PMoV2
are provided. See DOI: 10.1039/b000000x/
1
2
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Scheme
3
Proposed catalytic mechanism for [DPyAM(H2)]1.25PMoV2-
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4787-4798.
,
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4. Conclusions
In this study, we develop a new catalyst by pairing the task-
specifically designed IL-cation of N,N’-bis-2-aminoethyl-
4,4’-bipyridinium with the Keggin-structured vanadium-
5-
13 K. Kamata, K. Yonehara, Y. Nakagawa, K. Uehara and N.
substituted
polyoxometalate
anion
PMo10V2O40
.
Mizuno, Nat. Chem., 2010,
14 W. Trakarnpruk and J. Jatupisarnpong, Appl. Petrochem. Res.,
2013, , 9-15.
2, 478-483.
Systematic characterizations for composition and structure
demonstrate that the catalyst is the POM-based multi-
cationic hybrid [DPyAM(H2)]1.25PMoV2. In the oxidation of
cyclohexane with H2O2, the catalyst offers an exceptional
activity with not only remarkable TON value but also
3
15 J. Jatupisarnpong and W. Trakarnpruk, Mendeleev Commun.,
2012, 22, 152-153.
relative high yield for KA oil (cyclohexanol
+
16 W. Trakarnpruk and W. Kanjina, J. Met. Mater. Miner., 2013, 23
,
cyclohexanone). The featured structure of the multi-cations
in the hybrid results in its solid-state nature and
heterogeneous property in this oxidation reaction. Overall,
the catalyst is stable and keeps constant yield during the
tested 5 cycles, thus providing an efficient heterogeneous
catalysis strategy for the oxidation of cyclohexane with
hydrogen peroxide.
31-35.
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Acknowledgements
20 G. Chen, Y. Zhou, P. Zhao, Z. Long and J. Wang,
ChemPlusChem, 2013, 78, 561-569.
The authors thank the National Natural Science Foundation
of China (Nos. 21136005, 21303038 and 21476109),
Jiangsu Province Science Foundation for Youths (No.
BK20130921), Specialized Research Fund for the Doctoral
Program of Higher Education (No. 20133221120002), and
the Project of Priority Academic Program Development of
Jiangsu Higher Education Institutions (PAPD).
21 G. Chen, Y. Zhou, Z. Long, X. Wang, J. Li and J. Wang, ACS
Appl. Mater. Inter., 2014, 6, 4438-4446.
22 Y. Zhou, G. Chen, Z. Long and J. Wang, RSC Adv., 2014,
4
,
,
42092-42113.
23 Y. Leng, H. Ge, C. Zhou and J. Wang, Chem. Eng. J., 2008, 145
335-339.
Notes and references
24 Y. Leng, P. Zhao, M. Zhang and J. Wang, J. Mol. Catal. A:
Chem., 2012, 358, 67-72.
8 | RSC Adv., 2014, 00, 00-00
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