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Table 1 One-pot synthesis of benzamide from benzaldehyde, ammonia and hydrogen peroxide, meant the catalyst particles were exposed
a
hydrogen peroxide catalyzed by supported Rh(OH)
3
and related catalysts
to a severe hydrothermal environment. In order to prepare
hydrothermally stable and reusable catalysts for one-pot produc-
tion of amides, more robust and stable mesosilica shells are thus
required to serve as the scaffold for supporting and immobiliz-
3
ing the Rh(OH) species.
Ti
Selectivity (%)
In summary, we successfully synthesized a new core–shell
material consisting of center radially fibrous silica and
encapsulated TS-1 in a microemulsion system. With superior
hydrothermal and mechanical stability, TS-1@KCC-1 is a good
support for dispersing and stabilizing the Rh(OH)3 species,
leading to be a reusable catalyst that combines together the
catalytic properties of ammoximation and oxime rearrange-
content Aldehyde
No. Catalysts
(%)
conv. (%)
Amide
Oxime
b
1
2
3
4
5
TS-1
2.0
0.9
0
1.96
0.88
93.5
68.4
56.1
1.2
1.2
0.8
95.1
94.8
1.8
3.4 (17.2)
1.4 (1.9)
b
TS-1@KCC-1
c
Rh(OH)
Rh(OH)
Rh(OH)
3
/KCC-1
c
3
/TS-1
94.9 (79.5) 94.7 (76.4)
72.1 (71.2) 94.9 (94.9)
3
c/TS-1
@KCC-1
6
7
Rh(OH)
3
/TS-1
1.25
1.25
85.2 (77.9) 91.2 (64.8)
90.9 (76.3) 94.5 (45.4)
8.4 (25.4) ment. This bifunctional catalyst makes one-pot synthesis of
c
@
MS-P123
Rh(OH) /TS-1
MS-CTAB
benzamide possible.
3
0.3 (45.4)
c
@
The authors gratefully acknowledge the financial support
from the NSFC of China (20973064, 20925310, U1162102),
a
Conditions: cat, 0.2 g; H
2
O, 1.5 mL; benzaldehyde, 2 mmol; NH
3
ÁH
2
O,
b
c
2
.5 mmol; H O , 2.5 mmol. Reaction temp., 343 K; time, 1 h. Reac- MOST of China (2012BAE05B02), STCSM (12JC1403600), Shanghai
2 2
tion temp., 343 K for 1 h and then 433 K for 7 h. The values in
parentheses show the results after reuse.
Municipal Education Commission (13zz038) and Shanghai
Leading Academic Discipline Project (B409).
The reusability of Rh(OH) /TS-1@KCC-1 was compared with
3
Notes and references
Rh(OH)
3
/TS-1 in the one-pot synthesis of amide (ESI,† Fig. S7
/TS-1@KCC-1 could be reused four times
and S8). Rh(OH)
3
1
M. J. Climent, A. Corma and S. Iborra, Chem. Rev., 2010, 111, 1072.
without obvious decrease in aldehyde conversion and amide
selectivity, while it suffered a slight decrease in amide selectivity
after fifth reuse. This might be attributed to a partial leaching of
2 Y. Yang, X. Liu, X. Li, J. Zhao, S. Bai, J. Liu and Q. Yang, Angew.
Chem., Int. Ed., 2012, 51, 9164.
3
S. Okada, K. Mori, T. Kamegawa, M. Che and H. Yamashita,
Chem.–Eur. J., 2011, 17, 9047.
Rh(OH) species as the Rh content decreased from 1.6 wt% to
4 G. Yang, D. Wang, Y. Yoneyama, Y. Tan and N. Tsubaki, Chem.
Commun., 2012, 48, 1263.
3
1
.0 wt%. In contrast, the oxime selectivity of Rh(OH) /TS-1
3
5
P. Li, C. Cao, Z. Chen, H. Liu, Y. Yu and W. Song, Chem. Commun.,
012, 48, 10541.
decreased sharply during reuse although the aldehyde conver-
sion was maintained over 80%, indicating that it possessed a
stable ammoximation ability but lost easily the activity of oxime
rearrangement. ICP analysis indicated that its Rh content
decreased from 1.55 wt% to 0.2 wt%. Thus, considering the
advantages of confining and stabilizing effect of mesopores,
2
6 H. Peng, L. Xu, L. Zhang, K. Zhang, Y. Liu, H. Wu and P. Wu,
J. Mater. Chem., 2012, 22, 14219.
H. Fujiwara, Y. Ogasawara, K. Yamaguchi and N. Mizuno, Angew.
Chem., Int. Ed., 2007, 46, 5202.
7
8 J. W. Kim, K. Yamaguchi and N. Mizuno, Angew. Chem., Int. Ed.,
008, 47, 9249.
L. A. Long, Process Saf. Prog., 2004, 23, 114.
2
9
Rh(OH) /TS-1@KCC-1 was found to be superior to Rh(OH) /
3
3
10 R. Raja and J. M. Thomas, Z. Anorg. Allg. Chem., 2005, 631,
TS-1 in terms of suppressing Rh leaching.
2942.
1
1
1 P. Wu, T. Komatsu and T. Yashima, J. Catal., 1997, 168, 400.
2 P. Roffia, M. Padovan, G. Leofanti, M. A. Mantegazza, G. De Alberti
and G. R. Tauszik, US patent, US 4794198, 1988.
13 R. Ghosh Chaudhuri and S. Paria, Chem. Rev., 2011, 112, 2373.
4 J. Liu, S. Z. Qiao, J. S. Chen, X. W. David Lou, X. Xing and G. Q. Max
Lu, Chem. Commun., 2011, 47, 12578.
5 Y. Deng, D. Qi, C. Deng, X. Zhang and D. Zhao, J. Am. Chem. Soc.,
2008, 130, 28.
6 L. Xu, Y. Ren, H. Wu, Y. Liu, Z. Wang, Y. Zhang, J. Xu, H. Peng and
P. Wu, J. Mater. Chem., 2011, 21, 10852.
The advantage of using a fibrous silica shell for supporting
the Rh(OH) species was further verified by comparing the
hydrothermal stability of Rh(OH) /TS-1@KCC-1 with Rh(OH)
TS-1@MS-P123 and Rh(OH) /TS-1@MS-CTAB, the mesosilica
3
3
3
/
1
1
1
3
shells of the latter two catalysts were assembled by using
triblock copolymer P123 and CTAB as the template, respectively.
At a similar Rh loading (1.5–1.6 wt%), Rh(OH) /TS-1@MS-P123
3
and Rh(OH) /TS-1@MS-CTAB were both highly efficient for the
3
17 X. Qian, J. Du, B. Li, M. Si, Y. Yang, Y. Hu, G. Niu, Y. Zhang, H. Xu,
amide formation in the first run, but they decreased greatly the
amide selectivity in reuse (Table 1, no. 6 and 7). The SEM images
indicated that the morphology of Rh(OH) /TS-1@KCC-1 was
3
almost intact, while the mesosilica shells were totally degraded
for the other two materials after catalytic reaction (ESI,† Fig. S9).
TEM investigation also confirmed that the structure was well-
B. Tu, Y. Tang and D. Zhao, Chem. Sci., 2011, 2, 2006.
8 H. Peng, L. Xu, H. Wu, Z. Wang, Y. Liu, X. Li, M. He and P. Wu,
Microporous Mesoporous Mater., 2012, 153, 8.
9 V. Polshettiwar, D. Cha, X. Zhang and J. M. Basset, Angew. Chem.,
Int. Ed., 2010, 49, 9652.
0 V. Polshettiwar, J. Thivolle-Cazat, M. Taoufik, F. Stoffelbach,
S. Norsic and J. Basset, Angew. Chem., Int. Ed., 2011, 50, 2747.
1 A. Fihri, D. Cha, M. Bouhrara, N. Almana and V. Polshettiwar,
ChemSusChem, 2012, 5, 85.
2 A. Fihri, M. Bouhrara, U. Patil, D. Cha, Y. Saih and V. Polshettiwar,
ACS Catal., 2012, 2, 1425.
1
1
2
2
2
preserved in the used Rh(OH) /TS-1@KCC-1 catalyst (Fig. S10,
3
ESI†). The Rh species were almost undetectable for the used
Rh(OH) /TS-1@MS-P123 and Rh(OH) /TS-1@MS-CTAB catalysts.
3
3
23 H. Fujiwara, Y. Ogasawara, M. Kotani, K. Yamaguchi and N. Mizuno,
The presence of water, from either added solvent or aqueous
Chem.–Asian J., 2008, 3, 1715.
This journal is c The Royal Society of Chemistry 2013
Chem. Commun., 2013, 49, 2709--2711 2711