S. Tangestaninejad et al. / Inorganic Chemistry Communications 13 (2010) 1501–1503
1503
Table 3
Comparison of catalytic activity of Mn(TPP)Cl/NaIO
4 8 4 4 4 4 4
/IL and Mn(Br TPP)Cl/NaIO /IL with Mn(TPP)Cl/NaIO /(n-Bu NBr) and Mn(TPP)Cl/n-Bu NIO .
Alkene
TOF (h−1)
Mn(Br
8
TPP)Cl/NaIO
4
/IL
Mn(TPP)Cl/NaIO
4
/IL
Mn(TPP)Cl/NaIO
4
4
/(n-Bu NBr)
4 4
Mn(TPP)Cl/n-Bu NIO
Cyclooctene
Cyclohexene
Styrene
α-Methylstyrene
trans-Stilbene
cis-Stilbene
Indene
200
98
74.43
98
33.33
40
100
100
86.2
100
151.5
33.3
29.3
97
37
14.6
14.5
16.3
14.2
12.5
13.7
14.6
26.5
24.4
26.3
13
23.6
26.3
stable trans-stilbene oxide requires a free rotation about the alkene C–
C bond at some intermediate steps. Despite of the high catalytic
activity of Mn(TPP)Cl in the epoxidation of alkenes at room
temperature, the catalyst was not reused even one time. Since,
introducing electron-withdrawing substituent on the porphyrin ring
increases its robustness toward degradation in the reaction media,
therefore, we decided to investigate the catalytic activity of Mn
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[
[
[
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50–180.
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404–1411.
1
[
1
(
Br
amount of catalyst was optimized in the epoxidation of cyclooctene
and the highest yield was obtained with 1 mol% of Mn(Br TPP)Cl. The
8
TPP)Cl epoxidation of alkenes in the presence of [bmim]BF
4
. The
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[
573–583.
8
[
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results showed that this catalyst has a similar catalytic activity in the
epoxidation of alkenes in comparison with Mn(TPP)Cl. The reusability
of Mn(Br TPP)Cl showed that this catalyst retained its catalytic
8
[12] I.G. Denisov, T.M. Makris, S.G. Sligar, I. Schlichting, Chem. Rev. 105 (2005)
253–2277.
2
[
13] P.D. Goryckit, T.L. Macdonald, Chem. Res. Toxicol. 7 (1994) 745–751.
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[
activity during the reaction and was reused three times without
significant loss of its catalytic activity.
In order to show the effectiveness of the presented method, the
turnover frequencies [28,29] of these two catalytic systems (Mn(TPP)
[15] B. Meunier, Chem. Rev. 92 (1992) 1411–1456.
[
[
[
16] J.T. Groves, T.E. Nemo, R.S. Myers, J. Am. Chem. Soc. 101 (1979) 1032–1033.
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Cl/NaIO
previously reported systems such as Mn(TPP)Cl/NaIO
and Mn(TPP)Cl/n-Bu NIO [30,31]. The results showed that in the
presence of [bmim]BF , the catalytic activity of manganese(III)
4
/IL and Mn(Br
8
4
TPP)Cl/NaIO /IL) were compared with our
[
21] M. Moghadam, S. Tangestaninejad, V. Mirkhani, I. Mohammadpoor-Baltork, A.A.
Abbasi-Larki, Appl. Catal. A Gen. 349 (2008) 177–181.
4
/(n-Bu NBr)
4
4
4
[
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Kargar, J. Mol. Catal. A Chem. 288 (2008) 116–124.
4
[23] Y. Lio, H.J. Zhang, Y. Lu, Y.Q. Cai, X.L. Liu, Green Chem. 9 (2007) 1114–1119.
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porphyrins increased (Table 3).
In summary, we have shown an efficient method for the
epoxidation of different alkenes with NaIO
4
catalyzed by Mn(TPP)Cl
]. The
[26] Z. Li, C.G. Xia, J. Mol. Catal. A Chem. 214 (2004) 95–101.
[
27] Experimental. All materials were of the commercial reagent grade. Alkenes were
obtained from Merck or Fluka. Gas chromatography (GC) experiments were
performed with a Shimadzu GC-16A instrument using a 2 m column packed with
and Mn(Br TPP)Cl in the presence of ionic liquid, [bmim][BF
8
4
mild reaction conditions, excellent yield and selectivity of epoxides
are the advantages of this method. On the other hand, introducing
electron-withdrawing substituents such as bromine increased the
catalyst robustness and the catalyst could be recoverable and
reusable.
silicon DC-200 or Carbowax 20 m. In the GC experiments, n-decane was used as
1
internal standard. H-NMR spectra were recorded on
a
Brucker 400 MHz
25 mL flask
(2 mmol in 5 ml
H O) was added to a mixture of alkene (1 mmol), Mn(TPP)Cl (0.02 mmol) or Mn
spectrometer.General procedure for epoxidation of alkenesIn
equipped with a magnetic stirring bar, a solution of NaIO
a
4
2
(Br
8 4
TPP)Cl (0.01 mmol), imidazole (0.1 mmol) and [bmim]BF (1 ml) in DCE
(
5 ml). The mixture was stirred at room temperature. Progress of the reaction was
Acknowledgement
monitored by GC. Since the ionic liquid is immiscible in n-hexane, at the end of the
reaction, the organic materials were easily extracted with n-hexane. Evaporation
of solvent and chromatography on a short column of silica gel gave the pure
product.
The support of this work by the Center of Excellence of Chemistry
of University of Isfahan (CECUI) is acknowledged.
[
28] J.P. Collman, A. Straumanis, Z. Wang, M. Quelquejeu, E. Rose, J. Am. Chem. Soc. 121
(
1999) 460–461.
[29] E. Rose, B. Andrioletti, Q.Z. Ren, Chem. Eur. J. 10 (2004) 224–230.
30] D. Mohajer, S. Tangestaninejad, Chem. Commun. (1993) 240–241.
[31] D. Mohajer, S. Tangestaninejad, Tetrahedron Lett. 35 (1994) 945–948.
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