Manganese porphyrin immobilized on montmorillonite: A highly efficient and reusable catalyst for the aerobic epoxidation of olefins under ambient conditions

Article abstract of DOI:10.1142/S1088424612500721

Highly efficient aerobic epoxidation of olefins catalyzed by cationic meso-tetrakis-(1-methyl-4-pyridyl) (TM4PyP) metalloporphyrins immobilized into montmorillonite (MT) interlayer was achieved. The heterogeneous catalysts were characterized by diffuse reflectance UV spectra, infrared, X-ray diffraction, nitrogen adsorption isotherm and scanning electron microscopy. Manganese porphyrin (MnTM4PyP-MT) showed excellent activity and selectivity for the aerobic epoxidation of olefins under ambient conditions, in which more 90% yields of epoxides were obtained. The clay basal spacing played significant role in the catalytic efficiency and selectivity for different olefins. The catalyst could be reused consecutively five times without significant loss of activity.

Full text of DOI:10.1142/S1088424612500721

Journal of Porphyrins and Phthalocyanines
J. Porphyrins Phthalocyanines 2012; 16: 1032–1039
DOI: 10.1142/S1088424612500721
Published at http://www.worldscinet.com/jpp/
Manganese porphyrin immobilized on montmorillonite:
a highly efficient and reusable catalyst for the aerobic
epoxidation of olefins under ambient conditions
Xiantai Zhou and Hongbing Ji*
School of Chemistry and Chemical Engineering, the Key Laboratory of Low-Carbon Chemistry & Energy
Conservation of Guangdong Province, Sun Yat-sen University, 510275, Guangzhou, PR China
Received 8 January 2012
Accepted 22 February 2012
ABSTRACT: Highly efficient aerobic epoxidation of olefins catalyzed by cationic meso-tetrakis-(1-
methyl-4-pyridyl) (TM4PyP) metalloporphyrins immobilized into montmorillonite (MT) interlayer was
achieved. The heterogeneous catalysts were characterized by diffuse reflectance UV spectra, infrared,
X-ray diffraction, nitrogen adsorption isotherm and scanning electron microscopy. Manganese porphyrin
(MnTM4PyP-MT) showed excellent activity and selectivity for the aerobic epoxidation of olefins under
ambient conditions, in which more 90% yields of epoxides were obtained. The clay basal spacing played
significant role in the catalytic efficiency and selectivity for different olefins. The catalyst could be
reused consecutively five times without significant loss of activity.
KEYWORDS: metalloporphyrins, montmorillonite, epoxidation, supported catalyst.
exchange capacity, montmorillonite is preferable to be
INTRODUCTION
used as the support for immobilizing metalloporphyrins
Catalytic epoxidation of olefins has attracted much
[10]. The montmorillonite-supported cationic metallopor-
attention both in industry and in organic synthesis,
phyrins have been applied in the oxidation of alkanes
for epoxides are among the most useful synthetic
and 2-mercaptoethanol, in which metalloporphyrins
intermediates [1]. Synthetic metalloporphyrins have
were immobilized in the clay by electrostatic bond
been used as cytochrome P-450 models and have been
[11]. Kameyama ever reported the aerobic epoxidation
found to be a highly efficient homogeneous catalyst for
of cyclohexene catalyzed by different cationic mont-
alkene epoxidation in combination with various oxidants
morillonite-supported cobalt porphyrins, in which 66%
e.g. iodosylbenzene [2], and hydrogen peroxide [3].
yield of epoxide was obtained in a reaction time of 9 h
However, decomposing easily during the epoxidation
[12]. The catalytic inefficiency of cobalt porphyrins could
and difficulty of recovery is the main weakness of
be attributed the uneasily accessible of high-valence
homogeneous catalysts. Great efforts have been made to
species which is considered as the active species in the
immobilize metalloporphyrins onto supports to promote
epoxidation, which is different from the cases of manganese
stability [4]. Metalloporphyrins could be immobilized on
and iron porphyrins. To our knowledge, the application of
a variety of supports, such as organic polymer materials
montmorillonte-supported cationic manganese porphyrins
[5], chemically modified silica surfaces [6], mesoporous
in the epoxidation of alkenes is still unknown.
molecular sieves [7], SBA-15 [8], chitosan [9].
Due to the large specific surface area, chemical and
mechanical stability, layered structure and high cation
We ever reported the aerobic epoxidation of
olefins catalyzed by homogeneous mono- and m-oxo
dimeric manganese or iron porphyrins [13], in
which the efficiency could be comparable to enzyme
catalysis. In continuation of our ongoing research
on the metalloporphyrins-based epoxidations, we
report herein the efficient aerobic epoxidation of
*Correspondence to: Hongbing Ji, email: jihb@sysu.edu.cn,
tel: +86 20-84113658
Copyright © 2012 World Scientific Publishing Company

MANGANESE PORPHYRIN IMMOBILIZED ON MONTMORILLONITE 1033
various alkenes catalyzed by montmorillonite-supported
manganese porphyrins catalyst under ambient conditions,
in which more 90% yields of epoxides were obtained.
The heterogeneous catalyst showed excellent activity
and could be reused consecutively five times without
significant loss of activity.
RESULTS AND DISCUSSION
Supported catalyst characterization
In this work, montmorillonite was used for the
immobilization of cationic metalloporphyrins because
it is easily commercially available clay with interlayer
surface. It is also easily exchanged with solute ions by
varying the cationic composition of the solution. In the
adsorption process, pyridyl ions of metalloporphyrins
are bound to the clay surface by sharing one or
several ligands with adsorbent cations as isolated
complexes. Consequently, meso-tetrakis-(1-methyl-4-
pyridyl)metalloporphyrins can be firmly anchored onto
its surface. In all immobilization procedures nearly all
metalloporphyrins were transferred to the solids and low
quantities were spectrometrically detected in solution by
atomic absorption analyses. Thus, the loaded amounts
of the MnTM4PyP, CoTM4PyP and FeTM4PyP was
4.7 × 10-5 mol/g, 3.8 × 10-5 mol/g and 3.5 × 10-5 mol/g,
respectively. The concentration of metalloporphyrins
immobilized in montmorillonite is 10 times more than
that of immobilized in silica and polystyrene based resin
[14, 15].
The immobilization process could also be chara-
cterized by the color change of the clays. Such as
MnTM4PyP, the change was from light green to brown,
with a final color of dark brown in the case of the dry
solid. The UV-visible spectra of metalloporphyrins
were recorded on a Shimadzu UV-2450 UV-vis
spectrophotometer in the 200 to 700 nm-range, using
water as solvent. The presence of metalloporphyrins in
the solid clay was determined by the diffuse reflectance
ultraviolet-visible spectra (DRS-UV-vis) as shown in
Fig. 1 (MnTM4PyP as an example). And all the results
were summarized in Table 1.
Fig. 1. The UV-vis spectra of MnTM4PyP and MnTM4PyP-MT
of metalloporphyrins in the clays. Fourier transform
infrared (FT-IR) spectra of the samples were recorded
in the range of 4000–400 cm-1 on a FT-IR spectrometer
(Bruker, VERTEX 70) using KBr pellet technique.
The results of FT-IR spectroscopic measurements
for cationic metalloporphyrins, montmorillonite and
metalloporphyrins immobilized in the clay (CoTM4PyP
as an example) were shown in Fig. 2.
For montmorillonite, a broad band at 3400 cm-1 is the
primary O–H stretching of hydroxyl functional group.
Another broad brand between 1032 and 1300 cm-1 can
be attributed to the stretching vibration of Si–O bond.
The strong absorption at 1609 cm-1 is ascribed to the
bending vibration of O–H bond. After CoTM4PyP was
immobilized on the clay, the basic characteristic peaks
for montmorillonite hardly changed. The characteristic
peak of CoTM4PyP at 1009 cm-1 disappeared. And
some new bands between 1300–1600 cm-1 were clearly
observed, which attributed to the pyrrole C=N stretching
of the skeleton of metalloporphyrins. In addition,
the broad peak at 1609 cm-1 is sharpened, coupling
with a blue shift of 34 cm-1. These changes indicated
the presence of metalloporphyrins immobilized onto
montmorillonite.
X-ray diffraction measurement was performed on a
D-MAX diffractometer with Cu Ka source and operated
Compared with those of MnTM4PyP in the region
of 400–700 nm, the Soret peak and Q peak for the
MnTM4PyP/MT appeared at 494 nm and at 588 nm,
having been red-shifted 31 nm and 27 nm, respectively.
The presence of the red-shifted Soret peak indicates that
there was a coordination bond between MnTM4PyP
and montmorillonite. The red shift could be interpreted
as the result of a p-interaction by the metalloporphyrins
aromatic ring and the surface of the clay. A similar red
shift was observed for FeTM4PyP and CoTM4PyP
immobilized in montmorillonite.
Table 1. The UV-vis data of metalloporphyrins and
metalloporphyrins/MT
Compound
Solvent
lmax, nm
Soret band
Q-band
MnTM4PyP
water
—
463
494
428
446
404
427
561
588
540
571
512
534
MnTM4PyP/MT
CoTM4PyP
water
—
CoTM4PyP/MT
FeTM4PyP
water
—
IR spectra of these metalloporphyrins-MT clays
further provide some information about the presence
FeTM4PyP/MT
Copyright © 2012 World Scientific Publishing Company
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1034 X. ZHOU AND H. JI
Table 2. The BET surface area and pore volume of MT and
metalloporphyrins-MT
Entry
Sample
BET surface
area, m2/g
Pore volume,
cm3/g
1
2
3
4
MT
34
83
67
66
0.043
0.085
0.059
0.056
MnTM4PyP-MT
CoTM4PyP-MT
FeTM4PyP-MT
parallel to lamella in this clay. Since the thickness of
a montmorillonite crystal layer is about 0.96 nm, the
thickness of the intercalated CoTM4PyP is estimated
at 0.413 nm. And the size of CoTM4PyP is estimated at
about 0.67 nm. The size of this cationic metalloporphyrins
in the axial direction changes depending on the angle of
pyridyl groups existing at the meso-position. Therefore,
the CoTM4PyP is inserted into the clearance space of
0.413 nm, indicating that the pyridine rings incline to an
angle of about 30o against the porphyrin plane.
Fig. 2. FT-IR spectra of CoTM4PyP, MT and CoTM4PyP/MT
For the montmorillonite before and after being
immobilized with metalloporphyrins, the BET surface
area and pore volume determined from nitrogen
adsorption-desorption isotherms (Micromeritics ASAP-
2010) are presented in Table 2. The BET surface area of
montmorillonite is 34 m2/g, which is much lower than
that of metalloporphyrins-immobilized montmorillonite.
Metalloporphyrins complex intercalated between the
montmorillonite layers could give rise to the formation
of new pores and the increase in surface area.
The morphology of the samples was examined by
scanning electron microscope (SEM). Figure 4(a)
shows the typical surface of montmorillonite, in
which some aggregates could be observed clearly. The
SEM micrograph of metalloporphyrins-immobilized
montmorillonite was shown in Fig. 4(b). It could be
known that particles of the supported catalyst were
dispersed well, with the average diameter of about
20 mm.
Fig. 3. XRD patterns of CoTM4PyP-MT (a) and MT (b)
at 40 kV and 30 mA, to determine the influence of
metalloporphyrins on the structure of the clay. The
diffraction patterns were recorded in the 2q value range
of 1–80° with a scanning rate of 8 o/min. The XRD curves
of MT and CoTM4PyP-MT were presented in Fig. 3. It
could be known that the struture of metalloporphyrins-
immobilized clay are similar to those observed for the
montmorillonite, indicating that they possess the same
morphology and crystalline strutures and the solid
support is structurally unchanged and the cationic
metalloporphyrins should be dispersed on the interlayer.
Moreover, a slight shift of the basal spacing d001
(the characteristic reflection) to the lower angle with the
corresponding increase in the d spacing was observed
after the incorporation of CoTM4PyP into the clay.
According to the Scherrer formula, the basal spacing of
CoTM4PyP-MTwas1.373nm,whichagreeswellwiththe
results reported by Kameyama [12]. Similarly, the basal
spacing of MnTM4PyP-MT, FeTM4PyP-MT was 1.396
nm and 1.389 nm, respectively. The metalloporphyrins
plane in montmorillonite was estimated to orient
Catalytic performance for the aerobic epoxidation of
olefins
With cyclohexene as model compound, the effects of
reaction conditions on the epoxidation in the presence
of montmorillonite-supported metalloporphyrins with
molecular oxygen as oxidant and isobutyraldehyde as
co-reductant have been investigated. Epoxide is the main
product for the oxidation, coupling with a little amount of
2-cyclohexen-1-one and 2-cyclohexen-ol.
Catalytic performance of the various supported
metalloporphyrins. Iron, manganese and cobalt were
the most frequently used metals in oxidation reactions
and those metals were chosen to synthesize the cationic
metalloporphyrins. The catalytic activity and selec-
tivity of different metalloporphyrins for cyclohexene
Copyright © 2012 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2012; 16: 1034–1039

MANGANESE PORPHYRIN IMMOBILIZED ON MONTMORILLONITE 1035
Fig. 4. SEM image of MT (a) and CoTM4PyP-MT (b)
Fig. 5. The aerobic epoxidation of cyclohexene catalyzed
by various montmorillonite-supported metalloporphyrins.
Cyclohexene (2 mmol), acetonitrile (4 mL), isobutylaldehyde
(6 mmol), catalyst (0.02 g), O2 bubbling, 3.0 h, room temperature
Fig. 6. Conversion rates profile of cyclohexene with different
amounts of MnTM4PyP-MT. (): without catalyst, (): 0.005 g,
(): 0.01 g, (): 0.015 g, (): 0.02 g, (D): 0.025 g. Cyclohexene
(2 mmol), acetonitrile (4 mL), isobutylaldehyde (6 mmol), O2
bubbling, 3.0 h, room temperature
epoxidation by molecular oxygen were investigated and
the results were presented in Fig. 5.
As shown in Fig. 5, the catalytic activity of the
metalloporphyrins appears to be dependent on the nature
of their central ions. The present results clearly show that
manganese porphyrins is considerably more selective
than cobalt and iron porphyrins catalysts for the aerobic
epoxidation of olefins. The catalytic activity of different
metalloporphyrins is probably influenced by their
electric potential and the stability of different valences of
metal atoms. In addition, comparing with cobalt and iron
porphyirns, MnTM4PyP-MT has the higher BET surface
area as shown in Table 2. The catalytic performance
for this heterogeneous catalyst is positive related with
surface area.
amount on the aerobic epoxidation of cyclohexene in the
presence of molecular oxygen and isobutyraldehyde.
AsshowninFig.6,only7%cyclohexenewasconverted
in blank experiment of catalyst when the reaction was
conducted for 3 h. The conversion of cyclohexene is
considerably enhanced when the manganese porphyrin
catalyst was used. As depicted clearly in Fig. 6, the
reaction rate increases with increasing catalyst contents.
Cyclohexene could be almost converted completely when
the amount of catalyst was 0.02 g (MnTM4PyP: 0.94 ×
10-3 mmol), in which the selectivity of epoxide was up to
95%. Therefore, the optimal amount of MnTM4PyP-MT
for the aerobic cyclohexene epoxidation was 0.02 g.
Effect of the solvent on the aerobic epoxidation. It
is well-known that the solvent plays an important and
Effect of catalyst amount on the aerobic epoxidation.
Figure 6 shows the influence of MnTM4PyP-MT catalyst
Copyright © 2012 World Scientific Publishing Company
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1036 X. ZHOU AND H. JI
Table 3. Effect of solvent on the epoxidation of cyclohexene catalyzed by
MnTM4PyP-MTa
Entry
Solvent
Dielectric
constant
Conv.,
%
Yield, %
Selectivity, %
1
2
3
4
5
6
Cyclohexane
Toluene
2.0
2.4
53
57
73
75
81
96
42
45
72
71
77
91
79
79
99
94
95
95
Dichloromethane
2-Propanol
Methanol
9.1
18.3
32.6
37.5
Acetonitrile
a Cyclohexene (2 mmol), isobutylaldehyde (6 mmol), catalyst (0.02 g), solvent (4 mL),
O2 bubbling, 3.0 h, rt.
sometimes decisive role in the catalytic behavior of a
catalyst. Therefore, the effect of solvents on reactivity
and selectivity was studied in the current catalytic system.
As shown in Table 3, the dielectric constant of solvent
is closely related with the efficiency for the aerobic
epoxidation catalyzed by montmorillonite-supported
manganese porphyrins. The conversion of cyclohexene
increased with the increasing dielectric constant of
solvent in direct proportion. Among the used solvents,
acetonitrile was more favorable for olefins epoxidation
in the catalytic system (entry 6). When the reaction was
conducted in the media with low dielectric constant such
as cyclohexane and toluene, the selectivity of epoxide
is much lower than that of reaction media with higher
dielectric constant. It seems that non-polar solvent could
promotetheoxidationofa-Hofthedoublebond, resulting
in generating more by-products such as 2-cyclohexen-1-
one. Although cyclohexane is a commonly used model
substrate for metalloporphyrin catalyzed oxidations
[16], no oxidized products such as cyclohexanone,
cyclohexanol or adipic acid from cyclohexane were
determined in this catalytic system. Moderate conversion
of cyclohexene (73%) but excellent selectivity of epoxide
was obtained in the dichloromethane media (entry 3). The
highly selective epoxidation with dichloromethane as
solvent consists well with the homogeneous epoxidation
catalyzed manganese porphyrins [13].
Aerobic epoxidation of various olefins catalyzed by
MnTM4PyP-MT catalyst. To evaluate the scope of the
catalytic system, various alkenes were subjected to the
reaction system using only 0.02 g of montmorillonite-
supported manganese porphyrins (Table 4). As shown
in Table 4, most substrates could be smoothly converted
to the corresponding epoxides with high conversion rate
and excellent selectivity.
It seems that the efficiency of the epoxidation
in this catalytic system is not closely related with
the steric conformation of substrates. For instance,
1-methylcyclohexene could be converted completely
with less reaction time than cyclohexene (entries 1–2).
This phenomenon could further be demonstrated from
the oxidation of trans-stilbene (entry 4). In addition,
the steric hindrance of cyclohexene derivatives is more
favorable for the selectivity of epoxide (entries 2–3). It
maybe that the suitable space of the montmorillonite
interlayer make the a-position active site be free risk of
attacking from the metal high-valent species.
Similarly, in the epoxidation of other cycloolefin
e.g. cyclooctene, the reaction system exhibits high
catalytic performance and excellent selectivity of
epoxide (entry 6). However, slow oxidation occurred
and an unsatisfactory selectivity could be obtained for
the simple linear olefins such as 1-octene, 1-hexene and
trans-2-octene, even including styrene (entries 6–9). The
results were contrary to the homogeneous epoxidation
of olefins with Mn porphyrins as catalyst [13]. Another
salient feature of the present epoxidation is its high
regioselectivity. When (+)-limonene was subjected to the
epoxidation, the monoepoxide with the epoxide group on
the ring almost was the only product and its selectivity
was 98% (entry 10).
Catalyst reuse and stability. The stability of the
MnTM4PyP-MT catalyst was monitored using multiple
sequential aerobic epoxidation of cyclohexene in the
presence of isobutyraldehyde. The catalyst was recovered
by centrifugation, filtration, washed with acetonitrile and
dried before using it in the subsequent run. The results
are presented in Fig. 7.
From Fig. 7, the catalyst was consecutively reused
five times without a significant loss of its activity. The
leaching of the metalloporphyrins from the support to the
reaction medium was checked by taking UV-vis spectra
of the solution at the end of the reaction. No presence
of manganese porphyrins, characterized by the Soret
band was observed, indicating that the metalloporphyrins
remain tightly bound to the support during the oxidation
reaction. The results clearly showed that the supported
catalyst was active in the epoxidation and could be reused
without significant decrease in the catalytic activity and
with almost similar selectivity.
Plausible mechanism of the aerobic epoxidation.
As reported previously, the homogeneous epoxidation
catalyzed by metalloporphyrin complexes plus aldehyde
is considered to involve a radical and high-valent metal
Copyright © 2012 World Scientific Publishing Company
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MANGANESE PORPHYRIN IMMOBILIZED ON MONTMORILLONITE 1037
Table 4. Aerobic epoxidation of various olefins catalyzed by MnTM4PyP-MTa
Entry
Substrate
Product
Reaction Conv., %
time, h
Yield, %
O
1
2
3
96
91
98
2.5
>99
O
Ph
O
Ph
3
4
3
2
96
94
98
O
>99
O
5
4
4
87
93
86
82
O
6b
7
8
9
5
5
4
87
93
91
80
82
84
O
O
O
O
10
3
90
88
aCyclohexene (2 mmol), isobutylaldehyde (6 mmol), catalyst (0.02 g), acetonitrile (4 mL), O2
bubbling, rt. bThe by-product is benzaldehyde.
by sharp acceleration till completion. Moreover, the
oxidation could be subsequently quenched in the presence
of a free radical inhibitor.
High-valent porphyrin intermediate is generally
accepted as the active species for the oxidations
catalyzed by metalloporphyrins [17]. The epoxidation of
olefins is assumed to occur via reactive high-valent metal
oxo intermediates that are produced by the reaction of
peroxyacid with the metal catalysts from this mechanism
[18]. Therefore, in the aerobic epoxidation of olefins
catalyzed by montmorillonite-supported manganese
porphyrins system, the high-valent Mn porphyrins
intermediate is generated through at first. Then the
epoxide is produced by the reaction of carbon–carbon
double bond with the active high-valent Mn porphyrin
intermediate.
As discussed above, in investigating the catalytic
efficiency for various substrates, it is interesting to
find that the catalytic system is highly efficient for
the substrates with larger molecule bulk (entries 2–5,
Table 4), while poor selectivity of epoxides and the
necessary longer reaction time were observed for the
simple linear olefins (entries 6–9, Table 4). It indicates
Fig. 7. The stability and reuse of MnTM4PyP-MT catalyst in
the aerobic epoxidation of cyclohexene, ( ): conversion of
cyclohexene, ( ): selectivity of epoxide
intermediate mechanism. The feature of radical-involved
reaction could be informed from the profile of oxidation
of cyclohexene as shown in Fig. 6, in which the reaction
occurred first with induction period and then followed
Copyright © 2012 World Scientific Publishing Company
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1038 X. ZHOU AND H. JI
that the clay basal spacing plays significant role in
the catalytic efficiency and selectivity for different
olefins. The substrates with small molecule size
can pass through the interlayers easily. It decreases
the opportunities of molecules collision between
substrates and the anchored metal-oxo intermediate,
which results in the low reaction rates. Meanwhile, the
attack opportunities to the a-position site of olefins
by the metal-oxo intermediate could increase, which
leads to the low selectivity for the epoxide during the
oxidation.
Preparationproceduresofmontmorilloniteinterlayer-
fixed metalloporphyrins
A mixture of 100 mg meso-tetrakis-(1-methyl-4-
pyridyl)metalloporphyrin (Mn, Co, Fe) and mont-
morillonite (1 g) in 0.1 M nitric acid (100 mL) was
submitted to reflux and stirred for 5 h. Then, the mixture
was slowly cooled at room temperature. The solid was
filtered, washed with water and ethanol for several times.
And the solid was dried in vacuum at 80 °C. The amount
of metalloporphyrins adsorbed into clay was quantified
by measuring the amount of MTM4PyP (M=Mn, Co,
Fe) in the nitric acid and filtrate by Atomic Absorption
Spectrum (Shimadzu AA2580).
EXPERIMENTAL
Olefins were of analytical grade and purchased from
Alfa Aesar or Aldrich without further purification unless
indicated. Pyrrole and isobutyraldehyde were redistilled
before use. Other solvents were all of analytical grade.
The montmorillonite was purchased from Aladdin
Reagents.
General procedures of the aerobic epoxidation
A 20 mL Schlenck flask was charged with cyclo-
hexene (2 mmol), catalyst (0.02 g), acetonitrile (4 mL),
isobutyraldehyde (6 mmol), 0.2 mmol naphthalene (inert
internal standard) and then the mixture was stirred at
room temperature. Dioxygen was bubbled through the
solution. The consumption of the starting styrene and
formation of products was monitored by GC (Shimadzu
GC-2010 plus) or GC-MS (Shimadzu GCMS-QP2010).
For the recycling experiments, the catalyst was
recovered by centrifugation and first washed with
water (5 mL) for 5 times, and then with acetonitrile
(10 mL) to remove the occluded reactants and products.
After washing, the acetonitrile solution was checked
for the existence of reactants/products using gas
chromatography. The recycled catalysts were then dried
in vacuum at 80 °C for 6 h and re-used using the same
experimental conditions as described above.
Synthesis
of
meso-tetrakis-(1-methyl-4-pyridyl)
metalloporphyrin
Pyrrole (20 mL) and 4-pyridinecarbaldehyde (20 mL)
were refluxed in propionic acid (200 mL) for 60 min to
produce meso-tetrakis(4-pyridyl) porphyrin (T4PyP) with
the yield of 24%. Next, T4PyP (0.25 g) and manganese
acetate (1 g) were refluxed in dimethylformamide (35
mL) for 6 h under nitrogen atmosphere to form meso-
tetrakis-(4-pyridyl)manganese porphyrin (MnT4PyP)
with the yield of 88%.
In the following step, MnT4PyP (0.2 g) and methyl
p-toluenesulfonate (12 g) were added to 100 mL dimeth-
ylformamide solution. The mixture was stirred for
12 h at 90 °C, and the solution was cooled to room
temperature. Ethyl ether (20 mL) was added in the
mixture and was kept overnight. After filtration, the filter
cake was washed thoroughly with ethyl ether and was
purified by recrystallization with water/acetone (1:2) to
CONCLUSION
In conclusion, highly efficient epoxidation of olefins
by molecular oxygen in the presence of montmorillonite-
supported metalloporphyrins has been reported. The
cationic meso-tetrakis-(1-methyl-4-pyridyl) (TM4PyP)
porphyrins (Co, Mn and Fe) immobilized into
montmorillonite were confirmed by diffuse reflectance
UV spectra, infrared, X-ray diffraction, nitrogen
adsorption isotherm and scanning electron microscopy.
MnTM4PyP-MT is considerably more selective than
cobalt and iron porphyrins catalysts for the aerobic
epoxidation of olefins. The catalytic system is highly
efficient for the substrates with larger molecule bulk due
to the clay basal spacing. The catalyst could be reused
consecutively five times without significant loss of
activity.
obtain
meso-tetrakis-(1-methyl-4-pyridyl)manganese
porphyrin (MnTM4PyP) with 80% yield. The other
metalloporphyrins could be synthesized with similar
procedures by replacing other metal ions. The spectral
and analysis data of metalloporphyrins catalysts were
listed as following. [MnTM4PyP]4+. EI-MS: m/z 731.
UV-vis (H2O): lmax, nm (log e) 464 (2.48), 559 (1.25). IR
(KBr): n, cm-1 1640, 1009. Anal. calcd. for C44H28N8Mn:
C, 72.22; H, 4.96; N, 15.31. Found: C, 71.79; H, 4.92; N,
15.16. [CoTM4PyP]4+. EI-MS: m/z 735. UV-vis (H2O):
l
max, nm (log e) 418 (2.47), 539 (0.93). IR (KBr): n,
cm-1 1640, 1005. Anal. calcd. for C44H28N8Co: C, 71.83;
H, 4.93; N, 15.23. Found: C, 71.43; H, 4.72; N, 14.96.
[FeTM4PyP]4+. EI-MS: m/z 732. UV-vis (H2O): lmax, nm
(log e) 415 (2.84), 543 (1.23). IR (KBr): n, cm-1 1638,
1002. Anal. calcd. for C44H28N8Fe: C, 72.13; H, 4.95; N,
15.29. Found: C, 72.32; H, 4.95; N, 15.31.
Acknowledgements
The authors thank the National Natural Science
Foundation of China (Nos. 20976203, 21036009 and
21176267), higher-level talent project for Guangdong
Copyright © 2012 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2012; 16: 1038–1039

MANGANESE PORPHYRIN IMMOBILIZED ON MONTMORILLONITE 1039
provincial universities and the Fundamental Research
Funds for the Central Universities for providing financial
support to this project.
ME and Dorostkar N. Catal. Commun. 2010; 11:
694.
7. a) Rahiman AK, Bharathi KS, Sreedaran S, Rajesh
K and Narayanan V. Inorg. Chim. Acta 2009; 362:
1810. b) Zimowska M, Michalik-Zym A, Poltow-
icz J, Bazarnik M, Bahranowski K and Serwicka
EM. Catal. Today 2007; 124: 55. c) Rahiman AK,
Rajesh K, Bharathi KS, Sreedaran S and Narayanan
V. Appl. Catal. A 2006; 314: 216.
8. Espinosa M, Pacheco S, Vargas S, Estevez M,
Llanos ME and Rodriguez R. Appl. Catal. A 2011;
401: 119.
9. Huang G, Luo J, Cai CC, Guo YA and Luo GW.
Catal. Commun. 2008; 9: 1882.
10. Bhattacharyya KG and Sen Gupta S. Adv. Colloid.
Interfac. 2008; 140: 114.
11. a) Haber J, Matachowski L, Pamin K and Poltowicz
J. Catal. Today 2004; 91–92: 195. b) Machado AM,
Wypych F, Drechsel SM and Nakagaki S. J. Colloid
Interf. Sci. 2002; 254: 158. c) Hassanein M, Gerges
S, Abdo M and El Khalafy S. J. Mol. Catal. A 2005;
240: 22.
12. Kameyama H, Narumi F, Hattori T and Kameyama
H. J. Mol. Catal. A 2006; 258: 172.
13. a) Zhou XT, Tang QH and Ji HB. Tetrahedron Lett.
2009; 50: 6601. b) Zhou XT, Ji HB, Xu HC, Pei LX,
Wang LF and Yao XD. Tetrahedron Lett. 2007; 48:
2691.
14. Cai JH, Huang JW, Zhao P,YeYJ,Yu HC and Ji LN.
J. Sol-Gel Sci. Techn. 2009; 50: 430.
15. Shi BL, Scobie M and Boyle RW. Tetrahedron Lett.
2003; 44: 5083.
16. a) Fu B,Yu HC, Huang JW, Zhao P, Liu J and Ji LN.
J. Mol. Catal. A 2009; 298: 74. b) Huang G, Luo
ZC, Xiang F, Cao X, GuoYA and JiangYX. J. Mol.
Catal. A 2011; 340: 60. c) Ye YJ, Huang JW, Cai
JW, Yu HC, Wu WH, Zhou XT, Ji HB and Ji LN.
Transit. Metal. Chem. 2010; 35: 627.
17. a) Meunier B, de Visser SP and Shaik S. Chem. Rev.
2004; 104: 3947. b) Meunier B. Biomimetic Oxida-
tions Mediated by Metal Complexes, Imperial Col-
lege Press: London, 2000. c) Ji HB and Zhou XT.
In Biomimetics, Learning from Nature; Biomimetic
Homogeneous Oxidation Catalyzed by Metallopor-
phyrins with Green Oxidants; In-Tech publishing:
Vienna, 2010.
REFERENCES
1. a) Rubajlo VL, Maslov SA and Zaikov GE. Liquid-
Phase Oxidation of Unsaturated Compounds, Nova
Science Publishers: Hauppauge, 1993. b) Xia QH,
Ge HQ, Ye CP, Liu ZM and Su KX. Chem. Rev.
2005; 105: 1603. c) McGarrigle EM and Gilheany
DG. Chem. Rev. 2005; 105: 1563. d) Wong OA and
Shi Y. Chem. Rev. 2008; 108: 3958.
2. a) Li Z, Xia CG and Ji M. Appl. Catal. A 2003; 252:
17. b) Castaman ST, Nakagaki S, Ribeiro RR, Ciuffi
KJ and Drechsel SM. J. Mol. Catal. A 2009; 300:
89. c) Murakami Y and Konishi K. J. Am. Chem.
Soc. 2007; 129: 14401.
3. a) De Paula R, Simoes MMQ, Neves MGPM and
Cavaleiro JAS. Catal. Commun. 2008; 10: 57. b)
Stephenson NA and Bell AT. J. Mol. Catal. A 2007;
275: 54. c) Stephenson NA and Bell AT. Inorg.
Chem. 2006; 45: 2758.
4. a) Faria AL, Mac Leod TCO and Assis MD. Catal.
Today 2008; 133: 863. b) Moghadam M, Tangestan-
inejad S, Mirkhani V, Mohammadpoor-Baltork I and
Moosavifar M. J. Mol. Catal. A 2009; 302: 68. c) Ye
YJ, Zhou XT, Huang JW, Cai JH, Wu WH, Yu HC,
Ji HB and Ji LN. J. Mol. Catal. A 2010; 331: 29.
5. a) Tangestaninejad S, Moghadam M, Mirkhani V
and Kargar H. Ultrason. Sonochem. 2006; 13: 32.
b) Gao BJ, Wang RX and Zhang Y. J. Appl. Polym.
Sci. 2009; 112: 2764. c) Ferrand Y, Daviaud R, Le
Maux P and Simonneaux G. Tetrahedron-Asymme-
try 2006; 17: 952. d) Burri E, Leeder SM, Severin
K and Gagne MR. Adv. Synth. Catal. 2006; 348:
1640. e) Mirkhani V, Moghadam M, Tangestanine-
jad S and Kargar H. Appl. Catal. A 2006; 303: 221.
f) Zhang JL, Huang JS and Che CM. Chem. Eur. J.
2006; 12: 3020.
6. a) Smith JRL, IamamotoY and Vinhado FS. J. Mol.
Catal. A 2006; 252: 23. b) Mirkhani V, Moghadam
M, Tangestaninejad S, Mohammdpoor-Baltork I,
Kargar H and Araghi M. Appl. Catal. A 2009; 353:
61. c) Eriksson KLE, Chow WWY, Puglia C, Back-
vall JE, Gothelid E and Oscarsson S. Langmuir
2010; 26: 16349. d) Ghiaci M, Molaie F, Sedaghat
18. Zhou XT and Ji HB. Chem. Eng. J. 2010; 156: 411.
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