Z. Zhang et al. / Catalysis Communications 12 (2010) 318–322
321
Selectivity
Conversion
peroxo species reacted with the substrate and transferred active
oxygen to the double bond of the alkenes. Since 31P MAS NMR of the
used catalyst showed some structural changes, only a part of BTE-
1
00
PW11
the reaction and other peroxo species produce BTE-PW12
(PO ){WO(O {WO(O (H O)}] and species with low W/P ratio.
We believed that BTE-PW11 39 did not like some homogeneous or
phase-transferred controlled POMs catalysts which were dissolved in
hydrogen peroxide under the reaction condition. When BTE-PW11
O
39 was recovered from the peroxo species again after finishing
O40, BTE-
80
60
40
20
0
[
4
2
) }
2 2
2
)
2
2
O
O
39
reacted with hydrogen peroxide, it just formed a peroxo species (A)
which was insoluble in reaction solution. In order to prove this
hypothesis, BTE-PW11
without substrate in acetonitrile at 60 °C for 1.5 h. FT-IR of the material
Fig. 1 (c), (f)) which was treated with hydrogen peroxide showed the
O39 was treated with hydrogen peroxide simply
(
structure of the catalyst changed after reacted with hydrogen peroxide,
which indicated that the activated complex (A) existed.
1
2
3
4
5
6
7
8
9
10
4
. Conclusion
Cycle times
In summary, a heterogeneous catalytic material has been synthe-
Fig. 2. Epoxidation of cyclohexene by BTE-PW11
O39 for different cycles (a) conversion
(
b) selectivity. Reaction conditions: 2.5 mmol cyclohexene; 0.5 mmol hydrogen
sized by preparing insoluble inorganic–organic hybrid compound
peroxide; 3.6 μmol BTE-PW11
O39; 0.75 mL acetonitrile; reaction temperature: 60 °C,
based on a tripodal organic triammonium cation, BTE, and a
conversion (%)=epoxide (mol)/ hydrogen peroxide (mol). Selectivity (%)=epoxide
mol)/all products (mol). Conversions and selectivities were determined by gas
7−
catalytically active POM species, [PW11
O
39
]
. The catalytic system
(
consisting of BTE-PW11
O39/hydrogen peroxide/acetonitrile/olefin can
chromatography using an internal standard technique and were based on hydrogen
peroxide.
efficiently catalyze many kinds of alkenes epoxidation in normal to
good yields both at 60 °C and 30 °C. This active catalyst can be easily
recovered and reused without loss of activity. So BTE-PW11O39 is a
heterogeneous and reusable catalyst for the epoxidation of olefins.
and selectivity to cyclohexene oxide over ten reaction cycles. The
catalyst was recovered after each cycle by centrifugation. After the
tenth catalytic cycle, no significant changes were observed in IR spectra
(
Fig. 1 (c), (d), (e)). However, the 31P MAS NMR spectra (Fig. 3) reveal
Acknowledgements
that there are some structural changes for the catalyst after reaction.
This work was financially supported by the National Natural
Science Foundation of China (Grant Nos. 20702021 and 20803032).
We gratefully thank Prof. Wei.Wang for the measurment of solid state
NMR.
The peaks at −15.04 and −12.35 ppm could be attributed to BTE-
PW12
to BTE-[(PO
.84 ppm could be attributed to species with low W/P ratio [13].
A proposed reaction mechanism was given in Scheme 1. To begin
with, BTE-PW11 39 reacted with hydrogen peroxide to produce
O40 and BTE-PW11O39. The peak at 1.21 ppm could be attributed
4 2 2 2 2 2 2
){WO(O ) } {WO(O ) (H O)}] [13]. And the peak at
6
O
Appendix A. Supplementary data
2
−
peroxo species (A) [31] including [(PO
3
(OH){WO(O
){WO(O
2 2 2 4
) } )] , [(PO )
O)}]3 and [(PO
−
)
3−
[32]. The
{
WO(O
2
) }
2 2
{WO(O
)
2 2
(H
2
4
2
2 4
} ]
Supplementary data to this article can be found online at
doi:10.1016/j.catcom.2010.09.026.
References
[
[
1] B. Notari, Adv. Catal. 41 (1996) 253–334.
2] M. Klawonn, M.K. Tse, S. Bhor, C. Döbler, M. Beller, J. Mol. Catal. A: Chem. 218
(2004) 13–19.
[
[
[
[
3] T. Sakamoto, C. Pac, Tetrahedron Lett. 41 (2000) 10009–10012.
4] Y. Ding, B. Ma, D. Tong, H. Hua, W. Zhao, Aust. J. Chem. 62 (2009) 739–746.
5] C. Venturello, R. D'Aloisio, J. Org. Chem. 53 (1988) 1553–1557.
6] Y. Ishii, K. Yamawaki, T. Ura, H. Yamada, T. Yoshida, M. Ogawa, J. Org. Chem. 53
(1988) 3587–3593.
[7] Thematic issue on ‘polyoxometalates’, Chem. Rev. 98 (1998) 1–389.
[8] C. Venturello, E. Alneri, M. Ricci, J. Org. Chem. 48 (1983) 3831–3833.
[9] Y. Matoba, H. Inoue, J. Akagi, T. Okabayashi, Y. Ishii, M. Ogawa, Synth. Commun. 14
(1984) 865–873.
[
10] H. Yamamoto, M. Tsuda, S. Sakaguchi, Y. Ishii, J. Org. Chem. 62 (1997) 7174–7177.
[
11] K. Kamata, M. Kotani, K. Yamaguchi, S. Hikichi, N. Mizuno, Chem. Eur. J. 13 (2007)
639–648.
[12] R. Neumann, M. Gara, J. Am. Chem. Soc. 117 (1995) 5066–5074.
[13] W. Zhao, B. Ma, H. Hua, Y. Zhang, Y. Ding, Catal. Commun. 9 (2008) 2455–2459.
[14] Y. Ding, W. Zhao, H. Hua, B. Ma, Green Chem. 10 (2008) 910–913.
[15] Z. Xi, N. Zhou, Y. Sun, K. Li, Science 292 (2001) 1139–1141.
[16] J. Li, S. Gao, M. Li, R. Zhang, Z. Xi, J. Mol. Catal. A: Chem. 218 (2004) 247–252.
[17] S. Zhang, S. Gao, Z. Xi, J. Xu, Catal. Commun. 8 (2007) 531–534.
[18] O.A. Kholdeeva, in: M.B. Gunther (Ed.), Heterogeneous Catalysis Research
Progress, Nova Science Publ, 2008, pp. 267–297.
[
[
19] Y. Izumi, Res. Chem. Intermed. 24 (1998) 461–471.
20] N. Mizuno, K. Kamata, K. Yamaguchi, in: R. Richards (Ed.), Surface and
Nanomolecular Catalysis, CRC Press LLC, Boca Raton, Fla, 2006, pp. 463–492.
21] R. Neumann, in: J.-E. Baeckvall (Ed.), Modern Oxidation Methods, Wiley-VCH,
Weinheim, 2004, pp. 223–251.
[
Fig. 3. 31P MAS NMR spectra of (a) the fresh catalyst of BTE-PW11
BTE-PW11
O39; (b) the used
O
39
.
[22] M.T. Pope, Heteropoly and Isopoly Oxometalates, Springler-Verlag, Berlin, 1983.