Molybdenum hexacarbonyl supported on functionalized multi-wall carbon nanotubes: Efficient and highly reusable catalysts for epoxidation of alkenes with tert-butyl hydroperoxide

Article abstract of DOI:10.1016/j.jorganchem.2010.05.008

In the present work, highly efficient epoxidation of alkenes catalyzed by Mo(CO)₆ supported on amines modified multi-wall carbon nanotubes, MWCNTs, is reported. The prepared catalysts were characterized by elemental analysis, scanning electron

Full text of DOI:10.1016/j.jorganchem.2010.05.008

Journal of Organometallic Chemistry 695 (2010) 2014e2021
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Molybdenum hexacarbonyl supported on functionalized multi-wall carbon
nanotubes: Efficient and highly reusable catalysts for epoxidation of alkenes
with tert-butyl hydroperoxide
Majid Moghadam a, , Shahram Tangestaninejad , Valiollah Mirkhani , Iraj Mohammadpoor-Baltork ,
b
,
a
,
a
a
*
*
a
Naghmeh Sadat Mirbagheri
Chemistry Department, Catalysis Division, University of Isfahan, 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:
Received 21 February 2010
Received in revised form
In the present work, highly efficient epoxidation of alkenes catalyzed by Mo(CO)6 supported on amines
modified multi-wall carbon nanotubes, MWCNTs, is reported. The prepared catalysts were characterized
by elemental analysis, scanning electron microscopy, FT-IR and diffuse reflectance UVeVis spectroscopic
methods. These new heterogenized catalysts, [Mo(CO) @amines-MWCNT], were used as highly efficient
6
catalysts for epoxidation of alkenes with tert-BuOOH. These robust catalysts could be reused several
times without loss of their catalytic activities.
24 April 2010
Accepted 6 May 2010
Available online 26 May 2010
Ó 2010 Elsevier B.V. All rights reserved.
Keywords:
Multi-wall carbon nanotubes
Molybdenum hexacarbonyl
Heterogeneous catalyst
Epoxidation
tert-Butylhydroperoxide
1. Introduction
The homogeneous catalysts of transition metals are often more
difficult to prepare and expensive to purchase. On the other hand,
Epoxidation of alkenes is of academic and industrial interest,
because epoxides are one of the most widely used intermediates in
organic synthesis. Epoxides undergo ring-opening reactions with
a variety of reagents to produce mono- or bi-functional organic
products [1e3].
some industrial problems such as deposition on reactor wall,
difficulty in recovery and separation of the catalyst from reaction
products are associated with homogeneous catalysts. One way to
overcome these disadvantages is immobilization of homogeneous
catalysts on solid supports.
Molybdenum complexes have been known as versatile and
useful catalysts for the epoxidation of alkenes by organic hydro-
peroxides. The most important example of industrial application of
molybdenum base catalysts is liquid-phase epoxidation of
propylene with alkyl hydroperoxides catalyzed by homogeneous
Mo(VI) compounds which is known as Halcon process. A number of
soluble molybdenum complexes with different ligands have been
synthesized and employed as homogeneous catalysts for epoxida-
tion of various alkenes [4e8].
Different approaches have been used for immobilization of
molybdenum complexes on various supports to obtain heteroge-
neous catalysts. Sherrington and coworkers have reported efficient
epoxidation of alkenes with tert-butyl hydroperoxide catalyzed by
reusableMo(VI) supportedonimidazole containingpolymers [9e12].
Other organic polymers including modified polystyrenes [13e17],
polyaniline [18], ion-exchange resins [19], ethyleneepropylene
rubber and modified poly(ethylene oxide) [20] have been used as
supportforimmobilization of molybdenum compounds. Ontheother
hands, several approaches have been reported for supporting of
molybdenum catalysts on silica [21e25], modified MCM-41 [26e34],
zeolites [35] and layered double hydroxides [36].
Recently, molybdenum complexes have been used for epoxi-
dation of alkenes and oxidation of alcohols with hydrogen peroxide
*
Corresponding authors. Tel.: þ98 311 7932712; fax: þ98 311 6689732.
E-mail addresses: moghadamm@sci.ui.ac.ir (M. Moghadam), stanges@sci.ui.ac.ir
[37,38].
(
S. Tangestaninejad).
0
022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.05.008

M. Moghadam et al. / Journal of Organometallic Chemistry 695 (2010) 2014e2021
2015
Table 1
[
Mo(CO) @amine-MWCNT]
6
O
The specification of MWCNT-COOH used in this study.
tert-BuOOH, CCl4
Scheme 1.
MWCNT-COOH
Outside
diameter
Inside
diameter
Length
30
COOH
content
Specific surface
area
>110 m /g
2
20e30 nm
5e10 nm
m
m
1.5%
Carbon nanotubes (CNTs) have attracted much attention in the
synthesis, characterization, and other applications because of their
unique structural, mechanical, thermal, optical and electronical
properties [39e41].
Since CNTs are insoluble in the most solvents, these materials
can be used as catalysts support. For example, Pt nanoparticles
supported on CNTs have been used for methanol oxidation [42],
palladium nanoparticles supported on CNTs for semihydrogenation
of phenylacetylene [43], chiral vanadyl salen complex supported on
single-wall CNTs for enantioselective cyanosilylation of aldehydes
ꢀ
1
500e4000 cm with a BomeneHartmann instrument. Scanning
electron micrographs of the catalyst were taken on SEM Philips XL
30. H NMR spectra were recorded on a Bruker-Arance AQS
1
400 MHz. Gas chromatography experiments (GC) were performed
with a Shimadzu GC-16A instrument using a 2 m column peaked
with silicon DC-200 or Carbowax 20 m and n-decane was used as
internal standard. The ICP analyzes were performed on an ICP
Spectrociros CCD instrument. MWCNTs (multi-wall carbon nano-
tubes containing eCOOH groups, purity 96%) were purchased from
Shenzen NTP Factory (China).
[
44,45] and manganese(III) porphyrin supported on MWCNTs for
epoxidation of alkenes with NaIO [46].
In this paper, the preparation, characterization and investigation
of catalytic activity of Mo(CO) supported on amines modified
4
6
2
.1. Preparation of multi-wall carbon nanotubes supported
molybdenum hexacarbonyl
multi-wall carbon nanotubes in the epoxidation of alkenes with
tert-BuOOH is reported (Scheme 1).
2.1.1. Modification of MWCNT-COCl with amines
2
. Experimental
The carboxylic acid groups (MWCNT-COOH) in MWCNTs were
converted to acid chloride (MWCNT-COCl) according to the repor-
ted procedure [46].
All materials were commercial reagent grade and obtained from
Merck and Fluka. All alkenes were passed through a column con-
taining active alumina to remove peroxide impurities. A 400 W Hg
lamp was used for activation of metal carbonyl. FT-IR spectra were
obtained as potassium bromide pellets in the range
To a suspension of MWCNT-COCl (5 g) in DMF (50 mL), were
added 1,2-diaminobenzene (DAB), 2-aminophenol (AP) or 2-ami-
nothiophenol (ATP) (2.5 g) and triethylamine (5 mL). The mixtures
ꢁ
were vigorously stirred at 80 C for 72 h. After cooling the mixtures,
SOCl2
COOH
COCl
Reflux, 1 h
o
DMF, 80 C
H N
XH
Et N, 72 h
2
3
X= O, S, NH
O
C
N
H
hv (30 min)
HX
Mo(CO) THF
Mo(CO)6
+
THF
5
Reflux, 1 h
O
O
C
C
CO
Mo
+
NH
N
H
OC
CO
X
X
CO
CO
Mo
CO
CO
CO
CO
Scheme 2.

2016
M. Moghadam et al. / Journal of Organometallic Chemistry 695 (2010) 2014e2021
Table 2
Characteristics of the prepared catalysts.
Catalyst
N content Mo content C]O band UVeVis peak
ꢀ
1
(
mmol/g) (mmol/g)
(cm
)
(nm)
[
[
[
Mo(CO)
Mo(CO)
Mo(CO)
6
6
6
]
e
e
2004
1965
2000
1996
230, 286
231, 283
232, 284
228, 286
@DAB-MWCNT 2.98
@AP-MWCNT] 1.63
0.35
0.25
0.29
6
Mo(CO) @ATP-MWCNT] 1.43
the black solids were collected by filtration, washed thoroughly
with CH CN and dried in vacuum for several hours.
3
2.2. Preparation of the catalysts
Mo(CO) (2 g, 0.01 mmol) was dissolved in THF (60 mL) and
6
stirred under UV irradiation for 15 min. Then, amine modified
MWCNTs (2 g) was added to this solution and refluxed for 1 h. At
the end of the reaction, the solution was filtered, washed thor-
oughly with THF and dried in vacuum.
2.3. General procedure for epoxidation of alkenes with TBHP
catalyzed by prepared catalysts
In a 25 mL round bottom flask equipped with a magnetic stirrer
bar, a mixture of alkene (1 mmol), tert-BuOOH (2 mmol), catalyst
(
100 mg) and CCl
The reaction progress was monitored by GLC. At the end of the
reaction, the reaction mixture was diluted with Et O (20 ml) and
filtered. The catalyst was thoroughly washed with Et O and the
4
(6 ml) was prepared and refluxed under stirring.
2
2
combined washing and filtrates were purified on a silica gel plate to
obtain the pure product.
2.4. Reusability of the catalyst
The reusability of the catalysts was studied in the repeated
epoxidation reaction of cyclooctene. The reactions were carried out
as described above. At the end of each reaction, the catalysts were
2
filtered, washed thoroughly with Et O, dried and reused.
3
. Results and discussions
3
.1. Preparation and characterization of the catalysts, [Mn
@DAB-MWCNT], [Mn(CO) @AP-MWCNT] and [Mn(CO)
MWCNT]
(
CO)
6
6
6
@ATP-
The specifications of multi-wall carbon nanotubes containing
carboxylic acid groups, MWCNT-COOH, which was used as
support, are listed in Table 1. Scheme 2 shows the preparation
route of the [Mn(CO)
and [Mn(CO) @ATP-MWCNT]. In this scheme, the most probable
modes for coordination of Mo(CO) to amines modified MWCNTs
are shown. First, in order to increase the reactivity of MWCNT-
COOH, the carboxylic acid groups were converted to acyl chloride.
Then, 1,2-diaminobenzene (DAB), 2-aminophenol (AP) or 2-ami-
nothiophenol (ATP) was reacted with MWCNT-COCl to obtain the
amine modified MWCNTs (DAB-MWCNT, AP-MWCNT and ATP-
6 6
@DAB-MWCNT], [Mn(CO) @AP-MWCNT]
6
Fig. 1. FT-IR spectrum of: (A) [Mo(CO)
6 6
@DAB-MWCNT]; (B) [Mo(CO) @AP-MWCNT]
6
and (C) [Mo(CO) @ATP-MWCNT].
6
The nitrogen content of the supports was determined by CHN
analysis which showed values of 4.16, 2.28 and 2.01% for DAB-
MWCNT, AP-MWCNT and ATP-MWCNT, respectively. Based on
these values, the nitrogen content of the supports were obtained
about 2.87, 1.63 and 1.44 mmol per gram of the DAB-MWCNT, AP-
MWCNT and ATP-MWCNT, respectively. The Mo content of the
catalysts was also measured by ICP, which showed values of about
MWCNT). The [Mn(CO)
and [Mn(CO) @ATP-MWCNT] catalysts were prepared by the
reaction of DAB-MWCNT, AP-MWCNT or ATP-MWCNT with
a solution of Mo(CO) THF (this compound was prepared by acti-
vation of Mo(CO) in THF under UV irradiation) [47]. These cata-
6 6
@DAB-MWCNT], [Mn(CO) @AP-MWCNT]
6
5
6
lysts were characterized by elemental analysis, scanning electron
microscopy, FT-IR and diffuse reflectance UVeVis spectroscopic
methods.
0.35, 0.25 and 0.29 mmol/g for [Mo(CO)
(CO) @AP-MWCNT] and [Mo(CO) @ATP-MWCNT], respectively
(Table 2).
6
@DAB-MWCNT], [Mo
6
6

M. Moghadam et al. / Journal of Organometallic Chemistry 695 (2010) 2014e2021
2017
6 6 6 6
Fig. 2. The UVeVis spectrum of: (A) [Mo(CO) ]; (B) [Mo(CO) @DAB-MWCNT]; (C) [Mo(CO) @AP-MWCNT]; (D) [Mo(CO) @ATP-MWCNT] and (E) MWCNTs.
The most informative spectroscopic data, which confirmed the
anchoring of the Mo(CO) on the functionalized MWCNTs, were
obtained by FT-IR spectra of [Mo(CO) @DAB-MWCNT], [Mo
CO) @AP-MWCNT] and [Mo(CO) @ATP-MWCNT] (Fig. 1 and Table
). The C]O stretching band of Mo(CO)
This band was appeared in the supported catalysts at 1964, 2000
3.2. Catalytic experiments
6
6
The prepared catalysts were used for epoxidation of olefins with
tert-BuOOH at room temperature. First, the reaction parameters
such as catalysts amount and kind of solvent were optimized in the
epoxidation of cyclooctene.
(
2
6
6
ꢀ1
6
is appeared at 2004 cm .
ꢀ
1
and 1996 cm
MWCNT] and [Mo(CO)
Table 2). These observations clearly confirmed the attachment of
Mo(CO) to amine modified MWCNTs. On the other hand, UVeVis
spectroscopy, in the diffuse reflectance mode, was employed for
characterization of the supported catalysts. Mo(CO) showed
6 6
for [Mo(CO) @DAB-MWCNT], [Mo(CO) @AP-
6
@ATP-MWCNT], respectively (Fig. 1AeC and
3.2.1. The effect of catalysts amount in the epoxidation of
cyclooctene
In order to optimize the catalysts amount, different quantities of
each catalyst were used in the epoxidation of cyclooctene (1 mmol)
with tert-BuOOH (2 mmol). The best results were obtained with
100 mg of each catalyst (Table 3).
6
6
absorption peaks at 230 and 280 nm which were attributed to
Mo / CO charge transfer bands (Fig. 2A). These peaks were
appeared at 231 and 283 nm for [Mo(CO)
84 nm for [Mo(CO) @AP-MWCNT], 228 and 286 nm for [Mo
CO) @ATP-MWCNT] (Fig. 2BeD), while MWCNTs showed no
6
@DAB-MWCNT], 232 and
3.2.2. The effect of solvent on the epoxidation of cyclooctene
2
(
6
catalyzed by [Mo(CO)
6 6
@DAB-MWCNT], [Mo(CO) @AP-MWCNT] and
6
[Mo(CO) @ATP-MWCNT]
6
absorption peak in this region (Fig. 2E). These observations indi-
cated that molybdenum hexacarbonyl has been supported on
In order to choose the reaction media, different solvents were
checked in the epoxidation of cyclooctene with tert-BuOOH. Among
the different solvents such as acetonitrile, acetone, chloroform,
carbon tetrachloride and 1,2-dichlroethane, CCl was chosen as the
4
reaction medium, because the higher catalytic activity was
observed in this solvent (Table 4). It seems that non-coordinating
MWCNTs. The SEM images of the [Mo(CO)
CO) @AP-MWCNT] and [Mo(CO) @ATP-MWCNT] showed that the
nanotubes are aggregated and have retained their nanotube nature
Fig. 3).
6
@DAB-MWCNT], [Mo
(
6
6
(

2018
M. Moghadam et al. / Journal of Organometallic Chemistry 695 (2010) 2014e2021
Table 3
Optimization of the catalysts amount in the epoxidation of cyclooctene with TBHP.a
Catalyst
amount (mg)
Epoxide yield (%)b
[
Mo(CO) @DAB-
6
[Mo(CO)
MWCNT]
6
@AP-
[Mo(CO)
MWCNT]
6
@ATP-
MWCNT]
Time (20 min)
Time (35 min)
Time (30 min)
0
5
5
5
2
5
1
1
1
5
0
00
00
50
20
34
97
22
45
100
31 (35 min)
100
24
41
98
c
c
27 (40 min)c
98
35 (45 min)
97
a
b
c
Reaction conditions: cyclooctene (1 mmol), TBHP (2 mmol), catalyst, CCl
GC yield based on the starting alkene.
The reactions were carried out with cyclooctene (10 mmol), TBHP (2 mmol) and
4
(6 ml).
catalyst (neat reaction).
the catalysts are suspended in the solvent. This is due to the
bundled agglomerates of MWCNT that aggregate slowly and let the
catalysts to suspend without setting down for a long period of time.
6 6
The [Mo(CO) @DAB-MWCNT], [Mo(CO) @AP-MWCNT] and [Mo
(
CO) @ATP-MWCNT] were found as efficient catalysts for epoxi-
6
dation of alkenes with tert-BuOOH (Tables 5e7). In three catalytic
systems, the cyclohexene was oxidized in high yield and selectivity
to cyclohexene oxide and no by-product was observed. In the case
of linear alkenes such as 1-octene and 1-dodecene, the corre-
sponding epoxides were obtained in high yields with 100% selec-
tivity. In the case of stilbenes, trans-stilbene was epoxidized in
a stereospecific manner with complete retention of configuration
(88e99% yields), while oxidation of cis-stilbene was associated
with some loss of stereochemistry and a mixture of cis- and trans-
epoxides was obtained.
Previously, we have reported the supporting of [Mn(CO) ] on the
6
polystyrene via amine spacers [14e17]. The polystyrene, which was
used as support, had a size in the micron range. Comparison of the
catalytic activity of these MWCNTs supported [Mn(CO)
polystyrene supported [Mn(CO) ] catalysts showed that [Mo
@AP-MWCNT] and [Mo
@ATP-MWCNT] are more efficient than polystyrene bound
] (by comparison of their TOFs). This can be related to the
6
] and
6
(
(
[
CO)
CO)
Mn(CO)
6
@DAB-MWCNT],
[Mo(CO)
6
6
6
nanoparticle nature of the MWCNTs and isolation of active sites
which in turns increases the catalytic activities.
3.4. Catalyst reuse and stability
6
While, the homogeneous [Mo(CO) ] cannot recovered even one
time, the MWCNT supported catalysts can be filtered and reused
several times without significant loss of their activities. The
Table 4
The effect of solvent on the epoxidation of cyclooctene with tert-BuOOH catalyzed
a
by Mo(CO)
6
supported on modified MWCNTs.
Solvent
Epoxide yield (%)b
Mo(CO) @DAB-
6 6
Fig. 3. The SEM image of: (A) [Mo(CO) @DAB-MWCNT]; (B) [Mo(CO) @AP-MWCNT]
and [Mo(CO) @ATP-MWCNT].
6
Row
[
6
[Mo(CO)
MWCNT]
6
@AP-
[Mo(CO)
MWCNT]
6
@ATP-
solvents such as chlorinated ones are the best solvents for oxidation
reactions catalyzed by molybdenum-based catalysts.
MWCNT]
Time (20 min)
Time (35 min)
Time (30 min)
1
2
3
4
5
CCl
CHCl
ClCH
4
97
53
18
5
100
47
20
5
98
50
21
5
3
2
3
(
.3. Epoxidation of alkenes with tert-BuOOH catalyzed by [Mo
CO) @DAB-MWCNT], [Mo(CO) @AP-MWCNT] and [Mo(CO) @ATP-
MWCNT]
CH
2
Cl
6
6
6
CH
CH
3
CN
COCH
3
3
8
6
10
a
Reaction conditions: cyclooctene (1 mmol), tert-BuOOH (2 mmol), catalyst
The supported catalysts were used for epoxidation of olefins
with tert-BuOOH under optimized conditions. During the reaction,
(
100 mg), solvent (6 ml).
GC Yield based on the starting alkene.
b

M. Moghadam et al. / Journal of Organometallic Chemistry 695 (2010) 2014e2021
2019
Table 5
Epoxidation of alkenes with tert-BuOOH catalyzed by [Mo(CO)
@DAB-MWCNT].a
Epoxide yield (%)b
6
ꢀ1
Row
Alkene
Epoxide selectivity (%)
100
Time (min)
20
TOF (h
)
1
97
95
83.98
2
100
40
41.13
3
4
88
87
100
100
95
15.88
14.20
105
5c
88d
100
160
160
9.42
9.95
6c
93e
100
a
Reaction conditions: alkene (1 mmol), tert-BuOOH (2 mmol), catalyst (100 mg, 0.035 mmol), CCl
GLC yield based on the starting alkene.
4
(6 ml).
b
c
Both 1H NMR and GLC data approved the reported yields.
Only trans-epoxide was produced.
d
e
90% cis-Epoxide and 3% trans-epoxide were produced.
Table 6
Epoxidation of alkenes with tert-BuOOH catalyzed by [Mo(CO)
6
@AP-MWCNT].a
Epoxide yield (%)b
ꢀ1
Row
1
Alkene
Epoxide selectivity (%)
100
Time (min)
35
TOF (h
)
100
93
68.57
2
100
50
44.64
3
4
86
85
100
100
140
165
14.74
12.36
5c
95d
100
160
160
14.25
15.00
6c
100e
100
a
Reaction conditions: alkene (1 mmol), tert-BuOOH (2 mmol), catalyst (100 mg, 0.025 mmol), CCl
GLC yield based on the starting alkene.
4
(6 ml).
b
c
Both 1HNMR and GLC data approved the reported yields.
Only trans-epoxide was produced.
d
e
95% cis-Epoxide and 5% trans-epoxide were produced.

2020
M. Moghadam et al. / Journal of Organometallic Chemistry 695 (2010) 2014e2021
Table 7
Epoxidation of alkenes with tert-BuOOH catalyzed by [Mo(CO)
@ATP-MWCNT].a
Epoxide yield (%)b
6
ꢀ1
)
Row
Alkene
Epoxide selectivity (%)
100
Time (min)
30
TOF (h
1
98
96
67.58
2
100
60
33.10
3
4
80
70
100
100
110
150
15.05
9.66
5c
99d
100
120
120
17.07
17.24
6c
100e
100
a
Reaction conditions: alkene (1 mmol), tert-BuOOH (2 mmol), catalyst (100 mg, 0.029 mmol), CCl
GLC yield based on the starting alkene.
4
(6 ml).
b
c
Both 1HNMR and GLC data approved the reported yields.
Only trans-epoxide was produced.
d
e
95% cis-Epoxide and 5% trans-epoxide were produced.
reusability of [Mo(CO)
6
@DAB-MWCNT], [Mo(CO)
6
@AP-MWCNT]
6
epoxide yields were 90, 93 and 91% for [Mo(CO) @DAB-MWCNT],
and [Mo(CO) @ATP-MWCNT] was investigated in the multiple
6
[Mo(CO) @AP-MWCNT] and [Mo(CO) @ATP-MWCNT], respectively
6
6
sequential epoxidation of cyclooctene with tert-BuOOH. At the end
of each reaction, the catalysts were separated by simple filtration,
washed with methanol and dried carefully before using it in the
next run. After using the catalysts for twenty consecutive times, the
(Table 8). In tenth first runs, the catalysts were as active as initial
catalysts, but in the next runs, the reaction times were completed in
longer times. The filtrates were collected for determination of Mo
leaching. The results showed that after two first runs, no
Table 8
a
The results of catalysts recovery and the amounts of Mo leached in the epoxidation of cyclooctene with tert-BuOOH.
Run
[Mo(CO)
6
@DAB-MWCNT]
[Mo(CO)
6
@AP-MWCNT]
6
[Mo(CO) @ATP-MWCNT]
Time (min)
Yield (%)b
Mo leached (%)c
Time (min)
Yield (%)b
Mo leached (%)c
Time (min)
Yield (%)b
Mo leached (%)c
1
2
3
4
5
6
7
8
9
20
20
15
15
15
15
20
20
20
20
25
25
25
30
30
35
35
45
45
85
97
97
97
97
97
97
97
96
96
96
96
96
95
95
95
95
92
92
90
90
1
35
35
35
35
35
35
35
35
35
35
40
40
40
50
50
50
50
90
95
135
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
96
2
30
25
25
25
25
25
25
25
25
25
25
30
30
30
35
35
40
45
45
95
98
98
98
98
98
98
98
98
98
98
97
97
94
94
93
93
93
93
92
91
4
0.6
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
1.6
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
2.5
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
10
11
12
13
14
15
16
17
18
19
20
96
96
93
a
b
c
Reaction conditions: Cyclooctene (1 mmol), tert-BuOOH (2 mmol), catalyst (100 mg), CCl
GLC yield based on the starting alkene.
Determined by ICP.
4
(6 ml).

M. Moghadam et al. / Journal of Organometallic Chemistry 695 (2010) 2014e2021
2021
molybdenum was detected in the filtrates by ICP. The Mo leaching
of these catalysts has the following order [Mo(CO) @ATP-
MWCNT] > [Mo(CO) @AP-MWCNT] > [Mo(CO) @DAB-MWCNT].
The higher Mo leaching in the case of [Mo(CO) @DAB-MWCNT] can
be attributed to the oxidation of arm and the appearance of a band
[13] S. Tangestaninejad, V. Mirkhani, M. Moghadam, G. Grivani, Catal. Commun. 8
2007) 839e844.
14] G. Grivani, S. Tangestaninejad, M.H. Habibi, V. Mirkhani, Catal. Commun. 6
2005) 375e378.
(
6
[
6
6
(
[15] G. Grivani, S. Tangestaninejad, M.H. Habibi, V. Mirkhani, M. Moghadam, Appl.
6
Catal. A: Gen. 299 (2006) 131e136.
[16] S. Tangestaninejad, M.H. Habibi, V. Mirkhani, M. Moghadam, G. Grivani, Inorg.
ꢀ1
at 1060 cm (S]O stretching band) in the FT-IR of the recovered
catalyst confirmed this explanation.
Chem. Commun. 9 (2006) 575e578.
[17] G. Grivani, S. Tangestaninejad, A. Halili, Inorg. Chem. Commun. 10 (2007)
14e917.
9
Also, the catalytic behavior of the separated liquids was tested
by addition of fresh cyclooctene and tert-BuOOH to the filtrates
after each run. Execution of the oxidation reactions under the same
reaction conditions, as with catalyst, showed that the obtained
results were the same as blank experiments.
[
[
18] S. Velusamy, M. Ahamed, T. Punniyamurthy, Org. Lett. 6 (2004) 4821e4824.
19] S.V. Kotov, E. Balbolov, J. Mol. Catal. A: Chem. 176 (2001) 41e48.
[20] R.T. Stamenova, C.B. Tsvetanov, K.G. Vassilev, S.K. Tanielyan, S.K. Ivanov, J.
Appl. Polym. Sci. 42 (1991) 807e812.
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[22] J. Jarupatrakorn, M.P. Coles, T. Don Tilley, Chem. Mater. 17 (2005) 1818e1828.
[23] G. Wang, L.S. Feng, R.L. Luck, D.G. Evans, Z.Q. Wang, X. Duan, J. Mol. Catal. A:
Chem. 241 (2005) 8e14.
4
. Conclusion
[
[
24] Q.H. Yang, C. Copéret, C. Li, J.M. Basset, New J. Chem. 27 (2003) 319e323.
25] S. Tangestaninejad, M. Moghadam, V. Mirkhani, I. Mohammadpoor-Baltork,
K. Ghani, Inorg. Chem. Commun. 11 (2008) 270e274.
In conclusion, molybdenum hexacarbonyl supported on amines
[
[
[
[
[
26] S.M. Bruno, J.A. Fernandes, L.S. Martins, I.S. Gonçalves, M. Pillinger, P. Ribeiro-
Claro, J. Rocha, A.A. Valente, Catal. Today 114 (2006) 263e271.
27] M. Masteri-Farahani, F. Farzaneh, M. Ghandi, J. Mol. Catal. A: Chem. 248 (2006)
53e60.
modified MWCNTs are highly efficient catalysts for epoxidation of
alkenes with tert-BuOOH in CCl . Due to the particle size of
4
MWCNTs and dispersion of Mo species, the catalytic activity of
these heterogeneous catalyst are higher than our previously
reported catalysts. Finally, these catalysts are robust and recover-
able in the epoxidation of alkenes with tert-BuOOH.
28] A. Sakthivel, M. Abrantes, A.S.T. Chiang, F.E. Kühn, J. Organomet. Chem. 691
(2006) 1007e1011.
29] A. Sakthivel, J. Zhao, G. Raudaschl-Sieber, M. Hanzlik, A.S.T. Chiang, F.E. Kühn,
Appl. Catal. A: Gen. 281 (2005) 267e273.
30] A. Sakthivel, J. Zhao, M. Hanzlik, A.S.T. Chiang, W.A. Herrmann, F.E. Kühn, Adv.
Synth. Catal. 347 (2005) 473e483.
Acknowledgement
[31] M. Abrantes, S. Gago, A.A. Valente, M. Pillinger, I.S. Gonçalves, T.M. Santos,
J. Rocha, C.C. Romão, Eur. J. Inorg. Chem. (2004) 4914e4920.
[
[
32] M.J. Jia, A. Seifert, W.R. Thiel, Chem. Mater. 15 (2003) 2174e2180.
33] S. Tangestaninejad, M. Moghadam, V. Mirkhani, I. Mohammadpoor-Baltork,
K. Ghani, Catal. Commun. 10 (2009) 853e858.
We acknowledge the support of this work by Center of Excel-
lence of Chemistry of University of Isfahan (CECUI).
[
34] S. Tangestaninejad, M. Moghadam, V. Mirkhani, I. Mohammadpoor-Baltork,
K. Ghani, Chem. Soc. 5 (2008) S71eS79.
[35] A. Sakthivel, J. Zhao, F.E. Kühn, Catal. Lett. 102 (2005) 115e119.
36] S. Gago, M. Pillinger, A.A. Valente, T.M. Santos, J. Rocha, I.S. Gonçalves, Inorg.
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