Efficient epoxidation of alkenes with sodium periodate catalyzed by reusable manganese(III) salophen supported on multi-wall carbon nanotubes

Article abstract of DOI:10.1016/j.apcata.2010.04.013

In this paper, efficient epoxidation of alkenes catalyzed by manganese(III) salophen chloride [Mn(salophen)Cl], supported on functionalized multi-wall carbon nanotubes MWCNTs, is reported. The MWCNT was modified with 1,4-diaminobenzene, 4-aminophenol and 4-aminothiophenol and [Mn(salophen)Cl] was attached to the supports via axial ligation. The prepared catalysts were used for efficient epoxidation of alkenes with NaIO₄ at room temperature. These new heterogenized catalysts were characterized by elemental analysis, FT-IR spectroscopy, diffuse reflectance UV-vis spectrophotometery and scanning electron microscopy. These heterogeneous catalysts were highly reusable in the oxidation reactions and reused several times without significant loss of their catalytic activity.

Full text of DOI:10.1016/j.apcata.2010.04.013

Applied Catalysis A: General 381 (2010) 233–241
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Applied Catalysis A: General
journal homepage: www.elsevier.com/locate/apcata
Efficient epoxidation of alkenes with sodium periodate catalyzed by reusable
manganese(III) salophen supported on multi-wall carbon nanotubes
a
a,b,∗
a
Shahram Tangestaninejad , Majid Moghadam
, Valiollah Mirkhani ,
a
a
Iraj Mohammadpoor-Baltork , Mohammad Saleh Saeedi
Department of Chemistry, Catalysis Division, University of Isfahan, Hezar jerib, Isfahan 81746-73441, Iran
a
b
Department of Nanotechnology Engineering, University of Isfahan, Isfahan 81746-73441, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
In this paper, efficient epoxidation of alkenes catalyzed by manganese(III) salophen chloride
Received 7 January 2010
Received in revised form 6 April 2010
Accepted 7 April 2010
[
Mn(salophen)Cl], supported on functionalized multi-wall carbon nanotubes MWCNTs, is reported.
The MWCNT was modified with 1,4-diaminobenzene, 4-aminophenol and 4-aminothiophenol and
Mn(salophen)Cl] was attached to the supports via axial ligation. The prepared catalysts were used for
[
Available online 14 April 2010
efficient epoxidation of alkenes with NaIO4 at room temperature. These new heterogenized catalysts
were characterized by elemental analysis, FT-IR spectroscopy, diffuse reflectance UV–vis spectropho-
tometery and scanning electron microscopy. These heterogeneous catalysts were highly reusable in the
oxidation reactions and reused several times without significant loss of their catalytic activity.
Keywords:
Manganese(III) salophen
Alkene epoxidation
Sodium periodate
©
2010 Elsevier B.V. All rights reserved.
Multi-wall carbon nanotubes
Heterogeneous catalysts
1
. Introduction
counterparts, heterogeneous systems present many advantages
such as easy separation and recovery of the catalyst from reac-
tion media, higher stability of catalytic species and catalyst
protection against destruction. Schiff base complexes (salen or
salophen) have been immobilized on different supports and their
catalytic activities have been investigated in organic synthesis
[26–40].
Carbon nanotubes (CNTs) have attracted much attention in
the synthesis, characterization and applications because of their
unique structural, mechanical, thermal, optical and electronical
properties. Since CNTs are insoluble in the most solvents, these
materials can be used as catalysts support [41–43].
In continuation of our previous works on the oxidation
of organic compounds catalyzed by supported manganese(III)
Schiff bases [44–50], here, we report highly efficient epoxida-
tion of alkenes with sodium periodate catalyzed by manganese(III)
salophen chloride, Mn(salophen)Cl, supported on functionalized
multi-wall carbon nanotubes, MWCNTs (Scheme 1).
The P-450 enzymes are known to oxidize a very extensive
range of endogenous and exogenous organic compounds, ranging
from medium chain alkanes such as n-heptane and n-octane, to
steroidal and polyaromatic compounds, and very large molecules
such as triterpenes and cyclosporine. A number of biomimetic
systems have been developed to mimic the function of P-450
enzymes [1,2]. In the last two decades, salen and salophen lig-
ands have received much attention, mainly because of their
extensive applications in the fields of synthesis and catalysis
[
3–10].
Several modified and supported reagents have been synthe-
sized and applied in catalysis and materials chemistry [11–15].
Transition metal Schiff base complexes are known as power-
ful homogeneous catalysts for oxidation of organic compounds
and various single oxygen atom donors such as NaClO, PhIO,
KHSO5, H O and NaIO4 have been used in these reactions
2
2
[
16–23]. But, the catalytic activity of these homogeneous cata-
lysts decreases due to formation of inactive dimeric ␮-oxo species
24,25]. One way to overcome this problem is to immobilize
2. Experimental
[
them on solid supports. In comparison with the homogeneous
Alkenes were obtained from Merck chemical company and
passed through a column containing active alumina to remove the
peroxidic impurities. Salophen ligand was prepared and metallated
according to the literature [51,52]. FT-IR spectra were obtained
with potassium bromide pellets in the range 400–4000 cm with a
Nicolet Impact 400D spectrometer. Scanning electron micrograph
∗ Corresponding author. Tel.: +98 311 7932705; fax: +98 311 6689732.
E-mail addresses: stanges@sci.ui.ac.ir (S. Tangestaninejad),
moghadamm@sci.ui.ac.ir, majidmoghadamz@yahoo.com (M. Moghadam).
−
1
0
926-860X/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.apcata.2010.04.013

2
34
S. Tangestaninejad et al. / Applied Catalysis A: General 381 (2010) 233–241
of MWCNT was taken on a Philips XL 30 SEM instrument. Gas
chromatography experiments (GC) were performed with a Shi-
madzu GC-16A instrument using a 2 m column packed with silicon
DC-200 or Carbowax 20 m. In the GC experiments, n-decane was
used as internal standard. 1H NMR spectra were recorded on a
Bruker–Arance AQS 300 MHz spectrometer. MWCNTs (multi-wall
carbon nanotubes containing –COOH groups, purity 96%) were pur-
chase from Shenzen NTP Factory (China).f
Scheme 1. Epoxidation of alkenes with NaIO4 in the presence of
Mn(salophen)@MWCNT].
[
2.1.2. Modification of MWCNT-COCl with amines
1
,4-Diaminobenzene (DAB), 4-aminophenol (AP) or 4-
aminothiophenol (ATP)(2 g) and triethylamine (3 ml) were
added to a suspension of MWCNT-COCl (2 g) in DMF (50 ml).
The mixture was vigorously stirred at 120 C for 72 h. After
2
.1. Preparation of multi-wall carbon nanotubes supported
manganese(III) salophen, Mn(Salophen)Cl-MWCNT
◦
cooling the mixture, the black solids were collected by filtra-
tion, washed thoroughly with DMF and dried under vacuum for
2
.1.1. Chlorination of MWCNT-COOH
In a 100 ml round-bottom flask equipped with a condenser and
2
4 h.
a magnetic stirrer bar, MWCNT-COOH (5 g) and SOCl (30 ml) were
2
mixed and refluxed for 1 h under N2 atmosphere. After then, the
reaction mixture was cooled and the SOCl2 was evaporated. The
resulting precipitate was chlorinated multi-wall carbon nanotubes,
MWCNT-COCl.
2.1.3. Supporting of Mn(salophen)Cl on amine modified MWCNTs
To a solution of Mn(salophen)Cl (0.2 g) in CH CN (50 ml),
3
was added amine modified MWCNTs (1 g) and refluxed for
Table 1
The specification of MWCNT-COOH used in this study.
MWCNT-COOH
2
Outside diameter (nm)
0–30
Inside diameter (nm)
5–10
Length (␮m)
COOH content (%)
1.5
Specific surface area (m /g)
>110
2
30
Scheme 2. Preparation of [Mn(salophen)@MWCNT].
Table 2
Characteristic of the prepared catalysts.
N band (cm−1)
C
O band (cm
−1
)
UV–vis peak (nm)
Catalyst
N content (mmol/g)
Mn content (mmol/g)
C
[
[
[
[
Mn(salophen)Cl]
–
–
1605
1604
1603
1604
–
450
455
448
467
Mn(salophen)@DAB-MWCNT]
Mn(salophen)@AP-MWCNT]
Mn(salophen)@ATP-MWCNT]
0.86
0.47
0.45
0.12
0.10
0.09
1651
1656
1654

S. Tangestaninejad et al. / Applied Catalysis A: General 381 (2010) 233–241
235
Fig. 1. FT-IR spectra of: (A) [Mn(salophene)@DAB-MWCNT], (B) [Mn(salophene)@AP-MWCNT], (C) [Mn(salophen)@ATP-MWCNT] and (D) [Mn(salophen)@ATP-MWCNT].
4
8 h. At the end of the reaction, the mixture was cooled and
ture by simple filtration, washed with Et O and dried before using
2
each catalyst was filtered and washed thoroughly with CH CN,
it in the next run.
3
methanol and ether, successively, and dried in vacuum for several
hours.
3. Results and discussion
2.2. General procedure for alkene epoxidation with NaIO4
3.1. Preparation and characterization of the catalysts
catalyzed by [Mn(salophen)Cl-MWCNT]
[Mn(salophen)@DAB-MWCNT], [Mn(salophen)@AP-MWCNT] and
[
Mn(salophen)@ATP-MWCNT]
To a mixture of alkene (1 mmol) [Mn(salophen)@MWCNT]
(
500 mg) in CH CN (10 ml) was added a solution of NaIO (2 mmol)
The specifications of multi-wall carbon nanotubes, used as
3
4
in H O (5 ml). The reaction mixture was stirred magnetically at
room temperature. The progress of the reaction was monitored by
GC. At the end of the reaction, the reaction mixture was diluted
support, are listed in Table 1. These carbon nanotubes contain car-
boxylic acid groups, MWCNT-COOH.
2
Scheme 2 shows the preparation route for [Mn(salophen)@DAB-
MWCNT], [Mn(salophen)@AP-MWCNT] and [Mn(salophen)@ATP-
MWCNT]. First, in order to increase the reactivity of MWCNT-COOH,
the carboxylic acid groups were converted to acyl chloride. Then,
amines such as 1,4-diaminobenzene (DAB), 4-aminophenol (AP)
or 4-aminothiophenol (ATP) were reacted with MWCNT-COCl to
afford the amine modified MWCNTs (DAB-MWCNT, AP-MWCNT
and ATP-MWCNT). In the final step [Mn(salophen)Cl] was attached
to these supports via axial ligation.
with Et O (20 ml) and filtered. The catalyst was thoroughly washed
2
with Et O and combined washings and filtrates were purified on a
2
1
silica-gel plate or a silica-gel column. IR and H NMR spectral data
confirmed the identities of the products.
2.3. Catalyst reuse and stability
The reusability of each catalyst was investigated in the multiple
sequential epoxidation of cyclooctene as described above. At the
end of each reaction, the catalyst was separated from reaction mix-
The prepared catalysts were characterized by elemental
analysis, FT-IR spectroscopy, diffuse reflectance UV–vis spec-

2
36
S. Tangestaninejad et al. / Applied Catalysis A: General 381 (2010) 233–241
Fig. 2. The UV–vis spectrum of homogeneous [Mn(Salophen)Cl].
trophotometery (DR UV–vis) and scanning electron microscopy
SEM). The nitrogen content of the supports, measured by CHNS
(
analysis, showed values of 1.2%, 0.65% and 0.63% for DAB-MWCNT,
AP-MWCNT and ATP-MWCNT, respectively. Based on these val-
ues, the amount of nitrogen in DAB-MWCNT, AP-MWCNT and
ATP-MWCNT were calculated to be 0.86, 0.47 and 0.45 mmol/g
of each support, respectively. The Mn content of the cata-
lysts, measured by ICP, were 0.12, 0.10 and 0.09 mmol/g of
[
[
Mn(salophen)@DAB-MWCNT], [Mn(salophen)@AP-MWCNT] and
Mn(salophen)@ATP-MWCNT], respectively (Table 2).
The most informative evidence, which confirmed the anchor-
ing of the Mn(salophen)Cl to the functionalized MWCNTs, was
obtained by FT-IR spectra of [Mn(salophen)@DAB-MWCNT],
[
(
Mn(salophen)@AP-MWCNT] and [Mn(salophen)@ATP-MWCNT]
Fig. 1 and Table 2). The azomethene (C N) stretching band
−
1
of [Mn(salophen)Cl] is appeared at 1605 cm
(Fig. 1A),
while in the supported catalysts this band was observed at
−1
1
604, 1603 and 1604 cm
for [Mn(salophen)@DAB-MWCNT],
[
Mn(salophen)@AP-MWCNT] and [Mn(salophen)@ATP-MWCNT],
respectively (Fig. 1B–D and Table 2). In the supported catalysts,
the C O stretching bands of amide group were observed at
−1
1
651, 1656 and 1654 cm
for [Mn(salophen)@DAB-MWCNT],
[
Mn(salophen)@AP-MWCNT] and [Mn(salophen)@ATP-MWCNT],
respectively. These observations clearly confirmed the attachment
of Mn(salophen)Cl to amine modified MWCNTs. The diffuse
reflectance spectra provided further evidences for the presence
of Mn(salophen)Cl on the supports. The Mn(salophen)Cl showed
an absorption peak at 450 nm (Fig. 2). Their heterogeneous
counterparts [Mn(salophen)@DAB-MWCNT], [Mn(salophen)@AP-
MWCNT] and [Mn(salophen)@ATP-MWCNT] showed peaks at 455,
4
48 and 467 nm, respectively (Fig. 3). Since the MWCNT did not
show any peak in its diffuse reflectance spectrum, therefore, it is
confirmed that [Mn(salophen)Cl] has been supported on MWCNTs.
The scanning electron micrograph of MWCNT-COOH (Fig. 4)
shows the morphology of the MWCNTs used in this study.
3.2. Catalytic experiments
The prepared catalysts were used for the epoxidation of olefins
Fig.
[
[
3. Diffuse
Mn(salophene)@DAB-MWCNT], (C) [Mn(salophene)@AP-MWCNT] and (D)
Mn(salophen)@ATP-MWCNT].
reflectance
UV–vis
spectra
of:
(A)
MWCNT,
(B)
with sodium periodate at room temperature. First, the reaction
parameters such as catalysts amount, kind of solvent and oxidant
were optimized in the epoxidation of cyclooctene.
3
.2.1. The effect of catalysts amount in the epoxidation of
cyclooctene
In order to optimize the catalysts amount, different quan-
tities of each catalyst were used in the epoxidation of

S. Tangestaninejad et al. / Applied Catalysis A: General 381 (2010) 233–241
237
Fig. 4. SEM image of MWCNT.
Table 3
a
Optimization of the catalysts amount in the epoxidation of cyclooctene with NaIO4 .
Catalyst amount (mg)
Epoxide yield (%)b after 2.5 h
[Mn(salophen)@DAB-MWCNT]
[Mn(salophen)@AP-MWCNT]
[Mn(salophen)@ATP-MWCNT]
0
5
5
71
88
100
100
5
64
82
97
98
1
2
2
3
00
00
50
00
65
83
99
99
a
Reaction conditions: cyclooctene (1 mmol), oxidant, catalyst, CH3CN/H2O (10 ml/5 ml).
GC yield based on the starting alkene.
b
Table 4
a
The effect of oxidant on the epoxidation of cyclooctene catalyzed by [Mn(salophen)Cl] supported on modified MWCNT at room temperature .
Row
Oxidant
Solvent
Epoxide yield (%)b after 2.5 h
Mn(salophen)@DAB-MWCNT]
[
[Mn(salophen)@AP-MWCNT]
[Mn(salophen)@ATP-MWCNT]
1
2
3
4
5
6
NaIO4 (2 mmol)
NaIO4 (1 mmol)
H2O2
NaOCl
tert-BuOOH
(n-Bu)4NIO4
CH3CN/H2O
CH3CN/H2O
CH3CN/H2O
CH3CN
CH3CN
CH3CN
99
67
28
33
15
52
100
60
32
38
13
50
97
61
27
31
9
42
a
Reaction conditions: cyclooctene (1 mmol), oxidant (2 mmol), catalyst (500 mg), CH3CN/H2O (10 ml/5 ml).
GC yield based on the starting alkene.
b
Table 5
a
The effect of solvent on the epoxidation of cyclooctene with NaIO4 catalyzed by [Mn(salophen)Cl] supported on modified MWCNT at room temperature .
Row
Solvent
Epoxide yield (%)b after 2.5 h
Mn(salophen)@DAB-MWCNT]
[
[Mn(salophen)@AP-MWCNT]
[Mn(salophen)@ATP-MWCNT]
1
2
3
4
5
6
7
CH3CN/H2O (2:1)
CH3CN/H2O (1:1)
CH3OCH3/H2O
CH3OH/H2O
CH3CH2OH/H2O
CH2Cl2/H2O
99
54
79
61
50
26
17
100
49
72
65
54
22
19
97
50
65
52
56
24
12
CHCl3/H2O
a
Reaction conditions: cyclooctene (1 mmol), NaIO4 (2 mmol), catalyst (500 mg), solvent/H2O (10 ml/5 ml).
GC yield based on the starting alkene.
b

2
38
S. Tangestaninejad et al. / Applied Catalysis A: General 381 (2010) 233–241
Table 6
a
Epoxidation of alkenes with NaIO4 catalyzed by [Mn(salophen)@DAB-MWCNT] .
Conversion (%)a
Epoxide yield (%)b
99
Time (h)
2.5
TOF (h
−1
)
Row
Alkene
1
99
6.60
2
3
97c
91d
94
85
2.5
3
6.47
5.06
4
93e
82
3
5.17
5
6
92
71
84
71
3
3
5.11
3.94
7
65
65 (trans-epoxide)f
6
1.80
f
f
8
9
69
42 (cis-epoxide) , 27 (trans-epoxide)
6
1.92
75
50
75
50
3
3
4.17
2.78
1
0
1
1
88
91
61 (1,2-epoxide), 27 (8,9-epoxide)
3.5
4.20
5.06
1
2
83
3
a
b
c
d
e
f
Reaction conditions: alkene (1 mmol), NaIO4 (2 mmol), catalyst (0.06 mmol), CH3CN/H2O (10 ml/5 ml).
GLC yield based on the starting alkene.
The by-product is allylic ketone.
The by-product is benzaldehyde.
The by-product is acetophenone.
Both 1H NMR and GLC data approved the reported yields.
cyclooctene (0.5 mmol) with NaIO4 (1 mmol). The best results
were obtained with 250 mg (0.05 mmol) of each catalyst
3.2.3. The effect of solvent on the epoxidation of cyclooctene
catalyzed by [Mn(salophen)@DAB-MWCNT],
(
Table 3).
[Mn(salophen)@AP-MWCNT] and [Mn(salophen)@ATP-MWCNT]
In order to choose the reaction media, different solvents were
checked in the epoxidation of cyclooctene with NaIO . Among the
different mixtures of acetonitrile, acetone, methanol, ethanol (sin-
gle phase systems), dichloromethane and chloroform (two phase
4
3
.2.2. The effect of oxidant on the epoxidation of cyclooctene
catalyzed by [Mn(salophen)@DAB-MWCNT],
[Mn(salophen)@AP-MWCNT] and [Mn(salophen)@ATP-MWCNT]
systems with Bu NBr as phase transfer catalyst), the 2:1 mixture
4
The ability of different single oxygen donors such as NaIO4,
of acetonitrile:water was chosen as the reaction medium, because
the higher catalytic activity was observed in this experimental con-
dition (Table 5). The higher catalytic activity in acetonitrile/water
mixture is attributed to polarity of solvent and solubility of NaIO4
in this medium.
H O , NaOCl, tert-BuOOH and n-Bu NIO was investigated in the
2
2
4
4
epoxidation of cyclooctene. The results, which are summarized in
Table 4, showed that NaIO4 is the best oxygen source because this
oxidant, which is inert in the absence of catalyst, can give good
oxidation conversion in CH CN/H O.
3
2

S. Tangestaninejad et al. / Applied Catalysis A: General 381 (2010) 233–241
239
Table 7
a
Epoxidation of alkenes with NaIO4 catalyzed by [Mn(salophen)@AP-MWCNT] .
Conversion (%)a
Epoxide yield (%)b
100
Time (h)
2.5
TOF (h
−1
)
Row
1
Alkene
100
8.00
2
3
100c
93d
98
86
2.5
3
8.00
6.20
4
96e
83
3
6.40
5
6
94
76
85
76
3
3
6.27
5.07
7
67
67 (trans-epoxide)f
6
2.23
f
f
8
9
67
43 (cis-epoxide) , 24 (trans-epoxide)
6
2.23
73
53
73
53
3
3
4.78
3.53
1
0
1
1
91
92
63 (1,2-epoxide), 28 (8,9-epoxide)
3.5
5.20
6.13
1
2
83
3
a
b
c
d
e
f
Reaction conditions: alkene (1 mmol), NaIO4 (2 mmol), catalyst (0.033 mmol), CH3CN/H2O (10 ml/5 ml).
GLC yield based on the starting alkene.
The by-product is allylic ketone.
The by-product is benzaldehyde.
The by-product is acetophenone.
Both 1H NMR and GLC data approved the reported yields.
3
.3. Epoxidation of alkenes with NaIO4 catalyzed by
(Tables 6–8). In three catalytic systems, the cyclohexene was
oxidized in high yield to cyclohexene oxide and 2-cyclohexen-1-
one was obtained in 2–4% yields. In the epoxidation of styrene and
p-methoxystyrene, the major products were styrene oxide and
p-methoxystyrene oxide and only small amounts of benzaldehyde
and p-methoxybenzaldehyde were produced, respectively. In
the oxidation of ␣-methylstyrene, the corresponding epoxide
was produced in high yield and acetophenone obtained as minor
product (11–13%). In the case of linear alkenes such as 1-octene
and 1-dodecene, the corresponding epoxides were obtained in
high yields with 100% selectivity. In the case of stilbenes, trans-
stilbene was epoxidized in a stereospecific manner with complete
retention of configuration (62–67% yields), while oxidation of
[
[
Mn(salophen)@DAB-MWCNT], [Mn(salophen)@AP-MWCNT] and
Mn(salophen)@ATP-MWCNT]
The supported catalysts were used for epoxidation of olefins
with NaIO4 under optimized conditions. During the reaction, the
catalysts are suspended in the solvent. This is due to the bun-
dled agglomerates of MWCNTs that aggregate slowly and let the
catalysts to suspend without setting down for a long period of
time.
The
[Mn(salophen)@DAB-MWCNT],
[Mn(salophen)@AP-
MWCNT] and [Mn(salophen)@ATP-MWCNT] were found as
efficient catalysts for epoxidation of alkenes with NaIO4

2
40
S. Tangestaninejad et al. / Applied Catalysis A: General 381 (2010) 233–241
Table 8
a
Epoxidation of alkenes with NaIO4 catalyzed by [Mn(salophen)@ATP-MWCNT] .
Conversion (%)a
Epoxide yield (%)b
97
Time (h)
2.5
TOF (h
−1
)
Row
Alkene
1
97
6.90
2
3
96c
89d
92
80
3
3
5.71
5.30
4
91e
79
3
5.42
5
6
90
66
84
66
3
5.36
3.37
3.5
7
62
62 (trans-epoxide)f
7
1.58
f
f
8
9
65
41 (cis-epoxide) , 24 (trans-epoxide)
7
1.66
63
44
63
44
3
3
3.75
2.62
1
0
1
1
83
87
59 (1,2-epoxide), 24 (8,9-epoxide)
3.5
4.23
5.18
1
2
80
3
a
b
c
d
e
f
Reaction conditions: alkene (1 mmol), NaIO4 (2 mmol), catalyst (0.03 mmol), CH3CN/H2O (10 ml/5 ml).
GLC yield based on the starting alkene.
The by-product is allylic ketone.
The by-product is benzaldehyde.
The by-product is acetophenone.
Both 1H NMR and GLC data approved the reported yields.
Table 9
The results of catalysts recovery and the amounts of manganese leached in the epoxidation of cyclooctene with sodium periodate .
a
Run
[Mn(salophen)@DAB-MWCNT]
[Mn(salophen)@AP-MWCNT]
[Mn(salophen)@ATP-MWCNT]
Yield (%)b
Mn leached (%)c
Yield (%)b
Mn leached (%)c
Yield (%)b
Mn leached (%)c
1
2
3
4
5
99
93
90
88
88
1.5
1.0
0.6
0
100
92
89
87
87
2.1
1.5
1.0
0
97
88
84
81
81
2.7
1.9
1.1
0
0
0
0
a
Reaction conditions: alkene (1 mmol), NaIO4 (2 mmol), catalyst (500 mg), CH3CN/H2O (10 ml/5 ml).
GLC yield based on the starting alkene.
Determined by atomic absorption spectroscopy.
b
c

S. Tangestaninejad et al. / Applied Catalysis A: General 381 (2010) 233–241
241
cis-stilbene was associated with some loss of stereochemistry and
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[
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[
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we
have
reported
the
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of
[
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2
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[
[
bond [Mn(salophen)Cl]. This can be related to the nano-particle
nature of the MWCNTs with high specific surface area which in
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7
[
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[
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of
[Mn(salophen)@DAB-MWCNT],
1
[
2
[
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4
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spectrometry. The nature of the recovered catalysts was followed
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MWCNT are highly efficient catalysts for biomimetic epoxida-
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our previously reported catalysts. Finally, this catalyst is a robust
and recoverable catalyst toward hydrocarbon oxidation with
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We acknowledge the support of this work by Center of Excel-
lence of Chemistry of University of Isfahan (CECUI).