Mg–Al layered double hydroxide intercalated with manganese(III) 5,10,15,20-tetrakis(4-benzoate)porphyrinacetate as a highly reusable catalyst for epoxidation

Article abstract of DOI:10.1002/aoc.4657

The preparation and characterization are presented of a new catalytic material comprising Mg–Al layered double hydroxide and intercalated manganese(III) 5,10,15,20-tetrakis(4-benzoate)porphyrinacetate. Characterization was realized via various techniques. The prepared composite exhibited excellent catalytic activity in the selective epoxidation of various olefins with tetra-n-butylammonium hydrogen monopersulfate as an oxidant under mild reaction conditions. Furthermore, the catalytic system could be reused nine times without significant reduction in conversion percentage and any special care or additional treatment of the catalyst.

Full text of DOI:10.1002/aoc.4657

Received: 21 April 2018
DOI: 10.1002/aoc.4657
Revised: 19 June 2018
Accepted: 24 September 2018
F U L L P A P E R
Mg–Al layered double hydroxide intercalated with
manganese(III) 5,10,15,20‐tetrakis(4‐benzoate)
porphyrinacetate as a highly reusable catalyst for
epoxidation
Mojtaba Bagherzadeh
| Elnaz Mesbahi
Chemistry Department, Sharif University
of Technology, PO Box 11155‐3615,
Tehran, Iran
The preparation and characterization are presented of a new catalytic material
comprising Mg–Al layered double hydroxide and intercalated manganese(III)
5,10,15,20‐tetrakis(4‐benzoate)porphyrinacetate. Characterization was realized
via various techniques. The prepared composite exhibited excellent catalytic
activity in the selective epoxidation of various olefins with tetra‐n‐
butylammonium hydrogen monopersulfate as an oxidant under mild reaction
conditions. Furthermore, the catalytic system could be reused nine times with-
out significant reduction in conversion percentage and any special care or addi-
tional treatment of the catalyst.
Correspondence
Mojtaba Bagherzadeh, Chemistry
Department, Sharif University of
Technology, PO Box 11155‐3615, Tehran,
Iran.
Email: bagherzadeh@sharif.edu
KEYWORDS
epoxidation, intercalation, LDH, manganese, porphyrin
1 | INTRODUCTION
clays, due to high surface area and good anion‐
exchange properties, can act as hosts with a two‐
Epoxide moieties are a common feature in compounds
due to potential applications in the synthesis of pharma-
ceutical and drug intermediates.[1,2] Catalytic epoxida-
tion of olefins is an important transformation in
organic synthesis to generate the reactive three‐
membered epoxide ring.[3–7] Over the last three decades,
many efficient catalytic methodologies have been
developed for the synthesis of structurally diverse epox-
ides.[8–12] Manganese porphyrins have long been known
as valuable biomimetic catalysts for oxidation of both
unsaturated and saturated hydrocarbons because of
their high selectivity and efficiency;[13–17] in particular,
epoxidation of olefins with manganese porphyrins has
been extensively studied.[18–21] Homogeneous catalytic
media suffer from lack of recyclability, and to overcome
such a problem heterogenization of such systems would
be of help.[22–27]
dimensional expandable interlayer space for intercala-
tion of guest species or to bind such species to their
surface.[28–31] The intercalated solids not only prevent
aggregation and deactivation of the catalytically active
guest molecules but mostly promote a special envi-
ronment for the reaction between the active catalytic
species and the substrate and therefore increase
chemical and thermal stability of active molecules
during catalytic processes.[32,33] In addition, recovery
and reusability of the intercalated materials are more
feasible.
In the work presented here, manganese(III) 5,10,15,20‐
tetrakis(4‐benzoate)porphyrinacetate (MnTCPP) was
intercalated into Mg–Al LDH using the co‐precipitation
method (Scheme 1). The physicochemical properties of
the MnTCPP–LDH composite were then characterized.
The catalytic activity of the composite was studied in the
epoxidation of olefins for the design of new catalytic
materials.
Layered double hydroxides (LDHs), as a class of
synthetic two‐dimensional nanostructured anionic
Appl Organometal Chem. 2018;e4657.
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https://doi.org/10.1002/aoc.4657

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BAGHERZADEH AND MESBAHI
stirring at room temperature for 10 h, the reaction prog-
ress was monitored by GC using the internal standard
method. For reusability studies, the catalyst was washed
thoroughly with ethanol and prepared for use in a subse-
quent run.
2.3 | Instrumentation
Diverse instruments were employed to characterize the
prepared catalyst. X‐ray diffraction (XRD) patterns were
obtained with an X’Pert Pro diffractometer system
(MPD PANalytical Company) using a Cu Kα radiation
source (the scan range (2θ) was from 5° to 80°). Fourier
transform infrared (FT‐IR) spectra were recorded with
an ABB Bomem MB‐100 FT‐IR spectrophotometer utiliz-
ing KBr discs at room temperature. The amount of man-
ganese was determined using inductively coupled plasma
(ICP) atomic emission spectroscopy (Varian 730‐ES).
Field‐emission scanning electron microscopy (SEM)
images were obtained using a TESCAN MIRA II
instrument. UV–visible spectra were recorded with a
Shimadzu UV‐2100 spectrometer. Transmission electron
microscopy (TEM) was performed using a Philips
CM200 microscope. GC analyses were carried out with
an Agilent Technologies 6890N, 19019 J‐413 HP‐5, capil-
lary 60 m × 250 μm × 1 μm.
SCHEME 1 Molecular structure of MnTCPP–LDH composite
2 | EXPERIMENTAL
Chemicals and solvents were purchased from the Fluka
and Merck. 5,10,15,20‐Tetrakis(4‐carboxyphenyl)porphy-
rin was prepared according to a previous report[34]
through the reflux of pyrrole and 4‐formylbenzoic acid
in propionic acid. To afford the corresponding
metalloporphyrin MnTCPP, the free base porphyrin was
metalated with Mn(OAc)2⋅4H2O according to the Adler
method reported in the literature.[35] Tetra‐n‐butylam-
monium hydrogen monopersulfate (n‐Bu4NHSO5),
which is the corresponding soluble salt of oxone (the
commercial triple potassium salt is insoluble in inorganic
solvents), was prepared and used.[36]
3 | RESULTS AND DISCUSSION
3.1 | Structural and morphological
characterizations
2.1 | Preparation of MnTCPP–LDH
composite
In order to investigate the formation of Mn(III) porphy-
rin in the LDH, XRD was used to identify the structure
of as‐prepared material (Figure 1). The XRD pattern of
the Mn(III) porphyrin–LDH composites exhibits com-
mon features with basal reflections of hydrotalcite‐like
structure of (003), (006) followed by (110), (113), the
typical pair of LDH materials.[26,37,38] These are in
agreement with LDH of Mg1−xAlx(OH)2(Cl)x⋅zH2O com-
position, and thus the layered structure for Mn(III)
porphyrin–LDH had been constructed. The significant
decrease in intensities of the four peaks mentioned
above could be considered as an indication of intercala-
tion of the metalloporphyrin compound in the LDH
structure. Other sharp peaks are ascribed to any crystal-
line component as contaminant in the composites.[39]
An amount of 21.34% of manganese in the Mn(III)
porphyrin–LDH composites was also determined using
ICP analysis.
A metal salt solution containing MgCl2⋅6H2O (3 mmol)
and AlCl3⋅6H2O (1 mmol) (molar ratio of 3:1) was pre-
pared in 18 ml of deionized water. This solution was
added dropwise to a vigorously stirred MnTCPP (2 mmol)
solution in 60 ml of deionized water. Freshly prepared
0.4 M NaOH solution was then added dropwise to the
solution to maintain constant pH (ca 11). The resultant
precipitate was aged by stirring at 65°C for 20 h. The pro-
cess of synthesis was continued with centrifugation of the
solution and completed through washing with deionized
water several times and drying in vacuum. The reactions
were wholly carried out in an inert atmosphere.
2.2 | General procedure for epoxidation of
olefins
To a solution of olefin (0.2 mmol), imidazole (0.1 mmol)
and catalyst (3.8 × 10−4 mmol) in CH3OH (1.0 ml) was
added n‐Bu4NHSO5 (0.4 mmol) as an oxidant. After
Morphological and textural properties of the Mn(III)
porphyrin–LDH composites are shown in the SEM images

BAGHERZADEH AND MESBAHI
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presence of magnesium, nitrogen and carbon in the
MnTCPP–LDH structure is indicated via the energy‐
dispersive X‐ray (EDX) spectrum, with the data displayed
in Figure 2b and summarized in Table 1.
TEM analysis revealed similar results. TEM images of
the MnTCPP–LDH composite showed circular to
hexagonal‐shaped particles with a diameter in the
nanometre range (Figure 3).
To study further the MnTCPP–LDH composite, the
UV–visible absorption spectrum of the compound was
also obtained. The characteristic Soret band of MnTPPC
observed at 470 nm is in accordance with the presence
of Mn(III) porphyrin in the LDH structure (Figure 4a).[40]
The FT‐IR spectrum of MnTCPP–LDH revealed the
appearance of intense signals at about 1400 and
1600 cm−1 attributed to the stretching of the aromatic
and conjugated C&bond;O and C&dbond;O bonds,
respectively (Figure 5). It is worth mentioning that the
signals are also in accordance with the characteristic
FIGURE 1 XRD patterns of (a) LDH and (b) MnTCPP–LDH
TABLE 1 Amount of various elements in MnTCPP–LDH
obtained via EDX analysis
in Figure 2a. The composite exhibited irregularly shaped
aggregates of plate‐like particles of nanometric sizes rang-
ing from 40 to 70 nm, which confirms that the plate‐
shaped morphology of LDH remained unchanged during
the intercalation of Mn(III) porphyrin molecules. The
Element
C
N
O
Mg Al Mn
Amount (wt%) 25.43 3.76 57.49 9.74 2.67 0.92 100.00
FIGURE 2 (a) SEM images and (b) EDX analysis of MnTCPP–LDH composite

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BAGHERZADEH AND MESBAHI
FIGURE 3 TEM images of MnTCPP–
LDH composite
doublet peak of the carbonate group appearing at the
same wavenumber. The result supports the intercalation
of porphyrin into the LDH layers.
3.2 | Catalytic effects
To examine the catalytic activity of our as‐synthesized
MnTCPP–LDH composite, the epoxidation of olefins
was selected. To obtain optimized conditions for this
reaction, cyclooctene was chosen as a model substrate
and the reaction was performed in the presence of
MnTCPP–LDH as the catalyst by taking n‐Bu4NHSO5
as the oxidant with the addition of imidazole as an
additive at room temperature. It should be noted that
olefin epoxidation does not occur in the absence of
imidazole in the reaction mixture. A set of reactions
was performed to investigate the effect of various sol-
vents, namely H2O, CH3CN, CH2Cl2, CH3OH and a
(1:1) mixture of CH3OH and CH2Cl2, on the model
reaction (Figure 6). A trace amount of product was
observed in the case of H2O, MeCN and CH2Cl2. On
the other hand, a relatively good yield was observed
when using CH3OH and a (1:1) mixture of CH3OH
and CH2Cl2 as solvent. Thus, CH3OH was used as a
solvent for the current reaction.
Moreover in order to choose the best reaction time,
the epoxidation of cyclooctene was carried out for various
reaction times. It can be seen that the complete
FIGURE 4 UV–visible absorption spectra of (a) MnTCPP–LDH
and (b) dispersed in methanol

BAGHERZADEH AND MESBAHI
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FIGURE 5 FT‐IR spectra of (a) LDH
and (b) MnTCPP–LDH
conversion of cyclooctene to cyclooctene oxide was
achieved after 10 h (Figure 7).
Epoxidation of various olefins including cyclic and
linear olefins and aromatic olefins was carried out
using MnTCPP–LDH by employing aerobic oxidation
in the presence of imidazole as an additive. The results
showed that MnTCPP–LDH catalysed the epoxidation
of olefins to afford the corresponding epoxides in
conversions of 12–99% (TON = 63–526) and 100%
selectivity (Table 2). Due to probe electronic effects,
styrene derivatives having electron‐donating substitu-
ents (α‐methylstyrene and 4‐methoxystyrene) gave
higher epoxidation yield than styrene (entries 3–5).
However, the catalytic epoxidation of 1‐octene was
found less efficient (entry 8). Oxidation of cis‐stilbene
yielded cis‐stilbene epoxide exclusively (entry 7). The
lowest and the highest yields, depending on the nature
of the olefin, were obtained for cis‐stilbene and
cyclooctene, respectively (entries 1 and 7).
FIGURE 6 Effect of solvent on epoxidation of cyclooctene.
Reaction conditions: cyclooctene (0.2 mmol), n‐Bu4NHSO5
(0.4 mmol), catalyst (3.8 × 10−4 mmol), imidazole (0.1 mmol),
solvent (1 ml), room temperature, 3 h
A comparison of the catalytic activity of MnTCPP–
LDH, LDH and MnTCPP under the same reaction condi-
tions is provided in Table 3.
It is noteworthy that MnTCPP–LDH was stable as a
catalyst under the epoxidation conditions and could be
reused simply after separation and treatment. As
depicted in Figure 8, the catalyst retained its activity after
eight epoxidation runs and the yields did not change
significantly.
Regarding the product nature and previous reports
in the literature,[41–43] the catalytic cycle for MnTCPP–
LDH catalysing olefin epoxidations is proposed
(Scheme 2). The reaction starts from Mn(III) porphyrin
in the presence of n‐Bu4NHSO5 as oxidant and imidaz-
ole which results in the formation of a high‐valent
manganese–oxo intermediate (Mn(V)&dbond;O). The
FIGURE 7 Effect of reaction time on epoxidation of cyclooctene.
Reaction conditions: cyclooctene (0.2 mmol), n‐Bu4NHSO5
(0.4 mmol), MnTCPP–LDH (3.8 × 10−4 mmol), imidazole
(0.1 mmol), CH3OH (1 ml), room temperature

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BAGHERZADEH AND MESBAHI
TABLE 2 Epoxidation reactions catalysed by MnTCPP–LDH composite
Entry
Epoxidation reactiona
Conversion (%)b
TONc
1
99
526
3
36
190
4
5
86
60
452
316
7
8
12d
27
63
142
aReaction conditions: substrate (0.2 mmol), n‐Bu4NHSO5 (0.4 mmol), MnTCPP–LDH (3.8 × 10−4 mmol), imidazole (0.1 mmol), CH3OH (1 ml), room temper-
ature, 10 h.
bGC conversion measured relative to starting substrate.
cTON: moles of product/moles of catalyst.
dTrans product was not detected.
TABLE 3 Epoxidation of cyclooctene catalysed by various
compoundsa
Entry
Catalyst
Yield (%)
1
2
3
MnTCPP/Imh
LDH
Trace
30
MnTCPP–LDH/Imh
99
aGC conversion measured relative to starting substrate. Substrate (0.2 mmol),
n‐Bu4NHSO5 (0.4 mmol), CH3OH (1 ml), room temperature, 10 h.
FIGURE 8 Recycling results for MnTCPP–LDH in epoxidation of
cyclooctene
SCHEME 2 Proposed mechanism of catalytic epoxidation of cis‐
stilbene as a typical olefin in the presence of MnTCPP–LDH

BAGHERZADEH AND MESBAHI
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[11] T. Alemohammad, N. Safari, S. Rayati, M. Gheidi, A.
Mortazavimanesh, H. Khavasi, Inorg. Chim. Acta 2015, 434,
198.
reaction continues by attraction of a substrate towards
the
aforementioned
species
(Mn(V)&dbond;O)
giving rise to the formation of another intermediate
(likely via a concerted insertion) and finally the corre-
sponding epoxide.
[12] P. Guillo, M. I. Lipschutz, M. E. Fasulo, T. D. Tilley, ACS Catal.
2017, 7, 2303.
[13] B. Meunier, M. E. D. Carvalho, O. Bortolini, M. Momenteau,
Inorg. Chem. 1988, 27, 161.
4 | CONCLUSIONS
[14] M. Bagherzadeh, A. Mortazavi‐Manesh, RSC Adv. 2016, 6,
41551.
MnTCPP–LDH composite was prepared by intercala-
tion of MnTCPP into Mg–Al LDH through the co‐
precipitation method. The as‐obtained MnTCPP–LDH
was used as an efficient catalyst for the epoxidation
of olefins to synthesize epoxides. n‐Bu4NHSO5 was
used as oxidant under aerobic conditions at room
temperature. Notably, the performance of the
MnTCPP–LDH composite was preserved after being
recycled nine times showing a negligible loss of cata-
lytic activity.
[15] R. D. Paula, I. C. M. S. Santos, M. M. Q. Simões, M. G. P.
M. S. Neves, J. A. S. Cavaleiro, J. Mol. Catal. A 2015, 404‐
405, 156.
[16] W. Liu, J. T. Groves, J. Am. Chem. Soc. 2010, 132, 12847.
[17] H.‐H. Wang, H.‐Q. Yuan, M. H. R. Mahmood, Y.‐Y. Jiang, F.
Cheng, L. Shi, H.‐Y. Liu, RSC Adv. 2015, 5, 97391.
[18] C. Herica, Y. Sacco, J. R. L. Iamamoto, J. Smith, Chem. Soc.
Perkin Trans. 2001, 2, 181.
[19] J. P. Collman, V. J. Lee, X. Zhang, J. A. Ibers, J. I. Brauman,
J. Am. Chem. Soc. 1993, 115, 3834.
[20] A. Kalilur Rahiman, K. Rajesh, K. ShanmugaBharathi, S.
Sreedaran, V. Narayanan, Inorg. Chim. Acta 2009, 362,
1491.
ACKNOWLEDGEMENT
The support of this work by the Research Council
of Sharif University of Technology is gratefully
acknowledged.
[21] S.‐H. Peng, M. H. R. Mahmood, H.‐B. Zou, S.‐B. Yang, H.‐Y.
Liu, J. Mol. Catal. A 2014, 395, 180.
[22] X. Zhu, W. Chena, K. Wu, H. Lia, M. Fu, Q. Liu, X. Zhang, New
J. Chem. 2018, 42, 1501.
ORCID
[23] L. Zhang, M. Chen, Y. Jiang, M. Chen, Y. Ding, Q. Liu, Sens.
Actuators B 2017, 239, 28.
Mojtaba Bagherzadeh
3693
http://orcid.org/0000-0003-3009-
[24] L. Sun, Y. Ding, Y. Jiang, Q. Liu, Sens. Actuators B 2017,
239, 848.
[25] Q. Liu, P. Chen, Z. Xu, M. Chen, Y. Ding, K. Yue, J. Xu, Sens.
Actuators B 2017, 251, 339.
REFERENCES
[26] Q. Liu, Y. Yang, H. Li, R. Zhu, Q. Shao, S. Yang, J. Xu, Biosens.
Bioelectron. 2015, 64, 147.
[1] G. D. Faveri, G. Ilyashenko, M. Watkinson, Chem. Soc. Rev.
2011, 40, 1722.
[27] Q. Liu, Y. Yang, X. Lv, Y. Ding, Y. Zhang, J. Jing, C. Xu, Sens.
Actuators B 2018, 259, 775.
[2] Q. Zhao, C. Bai, W. Zhang, Y. Li, G. Zhang, F. Zhang, X. Fan,
Ind. Eng. Chem. Res. 2014, 53, 4232.
[28] G. Mishra, B. Dash, S. Pandey, Appl. Clay Sci. 2018, 153,
[3] M. Amini, M. M. Haghdoost, M. Bagherzadeh, Coord. Chem.
Rev. 2013, 257, 1093.
172.
[29] W. Kagunya, Z. Hassan, W. Jones, Inorg. Chem. 1996, 35,
[4] W. Nam, S.‐Y. Oh, Y. J. Sun, J. Kim, W.‐K. Kim, S. K. Woo, W.
Shin, J. Org. Chem. 2003, 68(20), 7903.
5970.
[30] Q. Wang, D. O'Hare, Chem. Rev. 2012, 112, 4124.
[5] F. Yang, B. B. Wang, Z. Shijian, S. Long, X. Liu, Y. Kong,
[31] Z. An, W. Zhang, H. Shi, J. He, J. Catal. 2006, 241, 319.
Micropor. Mesopor. Mater. 2017, 246, 215.
[32] M. Amini, M. Nikkhoo, S. M. F. Farnia, Appl Organometal.
Chem. 2017, 31, 3710.
[6] E. G. Vieira, N. L. D. Filho, Mater. Chem. Phys. 2017, 201,
262.
[33] T. Selvam, A. Inayat, W. Schwieger, Dalton Trans. 2014, 43, 10365.
[7] P. Neves, A. C. Gomes, F. A. A. Paz, A. A. Valente, I. S.
[34] A. D. Adler, F. R. Longo, W. Shergalis, J. Am. Chem. Soc. 1964,
86, 3145.
Gonçalves, M. Pillinger, Mol. Catal. 2017, 432, 104.
[8] D. T. Bregante, D. W. Flaherty, J. Am. Chem. Soc. 2017, 139, 6888.
[35] A. D. Adler, F. R. Longo, F. Kampas, J. Kim, J. Inorg. Nucl.
Chem. 1970, 32, 2443.
[9] Y. Huang, Z. Liu, G. Gao, G. Xiao, A. Du, S. Bottle, S. Sarina, H.
Zhu, ACS Catal. 2017, 7, 4975.
[36] B. R. Travis, B. P. Ciaramitaro, B. Borhan, Eur. J. Org. Chem.
2002, 20, 3429.
[10] M. Bagherzadeh, M. Amini, H. Parastar, M. Jalali‐Heravi, A.
Ellern, L. K. Woo, Inorg. Chem. Commun. 2012, 20, 86.
[37] Y. Zheng, Y. Chen, RSC Adv. 2017, 7, 1520.

8 of 8
BAGHERZADEH AND MESBAHI
[38] Y. Wang, F. Zhang, S. Xu, X. Wang, D. G. Evans, X. Duan, Ind.
Eng. Chem. Res. 2008, 47(15), 5746.
[43] E. Mesbahi, N. Safari, M. Gheidi, J. Porphyrins Phthalocyanines
2014, 18, 354.
[39] K. de Freitas Castro, F. Wypych, A. Antonangelo, K. M.
Mantovani, A. Bail, G. M. Ucoski, K. J. Ciuffi, T. E. Cintra, S.
Nakagaki, J. Colloid Interface Sci. 2016, 478, 374.
How to cite this article: Bagherzadeh M,
Mesbahi E. Mg–Al layered double hydroxide
intercalated with manganese(III) 5,10,15,20‐
tetrakis(4‐benzoate)porphyrinacetate as a highly
reusable catalyst for epoxidation. Appl Organometal
Chem. 2018;e4657. https://doi.org/10.1002/aoc.4657
[40] S. Rayati, Z. Sheybanifard, C. R. Chim. 2016, 19, 370.
[41] M. Bagherzadeh, R. Latifi, L. Tahsini, M. Amini, Catal.
Commun. 2008, 10, 196.
[42] R. D. Arasasingham, G.‐X. He, T. C. Bruice, J. Am. Chem. Soc.
1993, 115, 7985.