Aromatic amine mediated ring opening of epoxides: A reaction catalyzed by biogenic iron oxide nanoparticles

Article abstract of DOI:10.1016/j.jics.2021.100056

An efficient green method was used for the synthesis of polyphenol capped iron oxide nanoparticles (ION) from an agro waste, peanut skin. The polyphenol capped ION was characterized by Fourier transformed infra-red (FTIR), Powder XRD and X-ray photoelectron spectroscopic (XPS) analysis. To evaluate the catalytic activities of ION, ring opening of epoxides by aromatic amines has been performed and the catalyst showed good activity with yields up to 90% of the major products using only 20 ?mg of the catalyst under solvent free neat condition at room temperature (28 ?°C) after 5 ?h. These nanoparticles can be reused for three times without significant loss in their activities.

Full text of DOI:10.1016/j.jics.2021.100056

Journal of the Indian Chemical Society 98 (2021) 100056
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Journal of the Indian Chemical Society
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Aromatic amine mediated ring opening of epoxides: A reaction catalyzed by
biogenic iron oxide nanoparticles
,
,
,*
Mita Halder a b, Anupam Singha Roy c d, Kamalika Sen a
a Department of Chemistry, University of Calcutta, 92 APC Road, Kolkata, 700 009, India
b Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
c European Bioenergy Research Institute, Aston University, Aston Triangle, Birmingham, B47ET, United Kingdom
d Regional Centre of Advanced Technologies and Materials, Faculty of Science and Department of Physical Chemistry, Faculty of Science, Palacky University in Olomouc,
78371, Olomouc, Czech Republic
A R T I C L E I N F O
A B S T R A C T
Keywords:
Biogenic
Agro waste
Iron oxide nanoparticles
Epoxide
An efficient green method was used for the synthesis of polyphenol capped iron oxide nanoparticles (ION) from an
agro waste, peanut skin. The polyphenol capped ION was characterized by Fourier transformed infra-red (FTIR),
Powder XRD and X-ray photoelectron spectroscopic (XPS) analysis. To evaluate the catalytic activities of ION, ring
opening of epoxides by aromatic amines has been performed and the catalyst showed good activity with yields up
to 90% of the major products using only 20 mg of the catalyst under solvent free neat condition at room tem-
perature (28 ꢀC) after 5 h. These nanoparticles can be reused for three times without significant loss in their
activities.
Beta-amino alcohol
1. Introduction
catalyst system is highly sought-after. Transition metal catalyzed ERO
by amines are widely reported in the literature [20–23]. However,
β-Amino alcohols are resourceful key intermediates for the gener-
ation of biologically potent molecules [1,2], amino acids [3,4], and
also several chiral auxiliaries [5]. They can act as intermediates or
precursors for manufacturing daily use products, cosmetics including
photo developers, perfumes, hair dyes, etc [6]. The most well-known
and straightforward strategy to synthesize β-amino alcohols is the
epoxide ring opening (ERO) by amines at a suitable temperature
(Scheme 1). Although, several drawbacks associated with this method,
like lower product yields, high reaction temperature, excess use of
amines, long reaction times, poor region selectivity and application of
hazardous solvents, limit their wide range applications [7–11]. Be-
sides, under basic or acidic conditions epoxides get polymerized giving
lower product yields. To eliminate these drawbacks several strategies
are currently available in literature, but most of them mainly gave
attention to the reactions catalyzed by activators, promoters and
several metal or non-metal-based catalysts, viz., metal halides [12],
ionic liquids [13], montmorillonite clay [14], zeolites [15], solid acids
[16,17] and Lewis acids [18,19]. However, most of these methodol-
ogies include the application of hazardous solvent systems, moisture
sensitive catalysts and expensive reagents. Therefore, development of
easy availability, cheap and eco-friendly nature of iron have made this
metal an ideal target for catalyzing the epoxide ring opening reaction.
Plant extracts are largely familiar for reducing the metal ions since the
early 1900s as these methods are readily scalable, less-expensive and
eco-friendly. During metal nanoparticles (NPs) formation, plant ex-
tracts are well proficient to act as a reducing agent together with
stabilizing agent. Biological components, for instance polyphenolic
compounds, alkaloids, terpenoids, proteins, sugars and several
phenolic acids, present in the plant extracts are known to act as both
reducing as well as stabilizing agents during the synthesis of metal
nanoparticles. Biological components, such as polyphenols, alkaloids,
terpenoids, phenolic acids, sugars and proteins present in the plant
extract are proved to be responsible for the bio-reduction of the metal
ions to their nano state.
In this context, the present work demonstrates the potential of the
peanut skin (agro-waste, collected from peanut) for the preparation of
polyphenol coated amorphous iron oxide nanoparticles. Thereafter, the
iron oxide nanoparticles (IONs) are employed to prepare the β-amino
alcohols through ring opening of epoxides using aromatic amines under
solvent-less conditions at ambient temperature.
a
stable, cheap, environment friendly recyclable heterogeneous
* Corresponding author.
E-mail addresses: kamalchem.roy@gmail.com, kschem@caluniv.ac.in (K. Sen).
https://doi.org/10.1016/j.jics.2021.100056
Received 16 December 2020; Received in revised form 2 May 2021; Accepted 20 May 2021
0019-4522/© 2021 Indian Chemical Society. Published by Elsevier B.V. All rights reserved.

M. Halder et al.
Journal of the Indian Chemical Society 98 (2021) 100056
Scheme 1. Epoxide ring opening reactions over IONs.
2.3. General procedure for epoxide ring opening by amines
2. Experimental Section
2.1. Synthesis of polyphenol coated amorphous iron oxide nanoparticles
(IONs)
Polyphenol capped amorphous IONs were used as a heterogeneous
catalyst for the ring opening of epoxide with amines. The synthetic
procedure for this ERO reaction is detailed in electronic supplementary
information (ESI).
Polyphenol coated amorphous iron oxide nanoparticles were pre-
pared following our previously reported literature [24]. In a typical
synthetic procedure, 1 g peanut skin, collected from the sun-dried pea-
nuts obtained from local market, was immersed in 50 mL triple distilled
water and kept overnight at 4 ꢀC. Then after filtration the peanut skin
extract (PNS) was collected and its pH was adjusted to 3. Thereafter, iron
oxide nanoparticles (ION) were synthesized through the drop wise
addition of 2 mL Fe(NO3)3 solution (5 mM) to 5 mL of this PNS and an
instant color change following light brown to dark green to black indi-
cated the formation of polyphenol capped iron oxide nanoparticles. The
mixture was kept overnight at 4 ꢀC. Finally, the IONs were separated
through centrifugation at 10,000 rpm for 8 min followed by re-dispersion
in triple distilled water. The mass was then dried in an oven at 75 ꢀC for 4
h.
2.4. Procedure for recycling of the catalyst
After the completion of a reaction, the solution was centrifuged at
3000 rpm for 10 min to separate out the solid catalyst from the reaction
mixture so as to recycle the catalyst. The catalyst was separated, washed
thoroughly with distilled water and then by ethanol followed by drying
at 80 ꢀC in an oven for 2 h for reactivation. The catalyst could be recycled
proficiently and reused effectively for three successive runs without an
appreciable loss in the product yield.
3. Results and discussion
3.1. Characterization of biogenic IONs
2.2. Characterization of polyphenol coated amorphous iron oxide
nanoparticles (IONs)
Polyphenol capped amorphous iron oxide nanoparticles were pre-
pared from peanut skin extract through a simple and eco-friendly
method. The detailed estimation method and the data of total poly-
phenol content in the peanut skin extract before and after the synthesis of
the IONs were given in supporting information. Thereafter the nano-
particles were characterized and then utilized for the ERO reaction by
amines.
2.2.1. TEM analysis
Transmission microscopic (TEM) images were obtained to confirm
the nanodimension of the material. TEM images were obtained by a JEOL
JEM 2100 HR with EELS transmission electron microscopy. To obtain the
images a colloidal solution containing the IONs was drop cast on a
carbon-coated Cu grid. Then the grid was dried under an IR lamp before
introducing into the microscope.
3.1.1. TEM
TEM image (Fig. 1) shows that iron oxide nanoparticles of 15–60 nm
2.2.2. FTIR analysis
The Fourier Transform InfraRed (FTIR) spectra of the ION samples
were analysed and compared with the free ligand in the range 400–4000
cm-1 on a Perkin Elmer FT-IR 783 spectrophotometer with resolution 1
cm-1 using KBr pellets. FTIR analysis was done to understand the bonding
present in the nanomaterials and match the functionalities with the
previous experiment. For the experiment, a small fleck of the sample was
thoroughly mixed with dried KBr using a mortar-pestle. A pellet of the
mixture was prepared by applying 5 tons of pressure in a steel arrange-
ment through a hydraulic pressure. This pellet was placed on a sample
holder inside the FTIR instrument analyzer before obtaining the spectra.
2.2.3. Powder XRD
After synthesis the IONs were dried and then PXRD analysis was done
to analyze the nature of the material.
2.2.4. XPS
X-ray photo electron spectroscopy (XPS) was applied to analyze the
possible composition and the oxidation state of the elements present in
the IONs. XPS was executed on a Kratos Axis HSi X-ray photoelectron
spectrometer attached with a charge neutralizer and magnetic focusing
lens, utilizing Al K
fitting was achieved using Casa XPS version 2.3.14. Binding energies
α monochromatic radiation (1486.7 eV). Spectral
were corrected to the C 1s peak at 284.6 eV.
Fig. 1. TEM image of the IONs.
2

M. Halder et al.
Journal of the Indian Chemical Society 98 (2021) 100056
size are formed. It was clearly seen in the image that the iron oxide
nanoparticles are spherical in shape and they are distributed in the
polyphenol matrix. A porous structural pattern can also be seen with
amorphous morphology.
3.1.2. FTIR studies
The FTIR spectrum of the ION (Fig. 2) is well matched with our
previously reported catalyst. A broad peak at 3347 cm-1 and peak at
2922 cm-1 were observed for stretching of –OH and aliphatic –CH. The
peak at 1619 cm-1 corresponds to the carbonyl bond whereas the peaks at
1519, 1438, and 1372 cm-1 are due to aromatic –C C-, -C-H- bonds of
–
–
alkanes and phenolic –OH, respectively. The peaks in the range of 1281
to 773 cm-1 were observed due to the in plane and out of plane bending
vibrations of –CH bonds. The bands near 671 and 533 cm-1 correspond to
the Fe–O stretching vibrations of amorphous IONs.
3.1.3. Powder XRD
Powder XRD pattern of the as synthesized IONs is shown in Fig. 3. The
PXRD pattern shows the absence of any sharp peak that indicates the
amorphous nature of the IONs.
Fig. 3. PXRD data of IONs.
were used as solvent. On the contrary, superior result has been observed
under solvent-free neat condition (Table 1, Entries 2–6). It is found that
the reaction temperature has a great influence on the ERO reaction as
yield of the product significantly decreased with increase of reaction
temperature (Table 1, Entries 6–8). The amount of catalyst and the
duration of reaction were also varied (Table 1, Entries 9–12). Finally, it is
found that the best yield of the product (90%) was obtained using only
20 mg of the catalyst under solvent free neat condition at room tem-
perature (28 ꢀC) after 5 h.
3.1.4. XPS analysis
The XPS analysis was further studied to determine the chemical
compositions of IONs. XPS survey spectrum (Fig. 4a) shows the existence
of three elements (C, O and Fe) in the sample. The fine XPS spectra of Fe
2p is given in Fig. 4b. As shown in Fig. 4b, along with two satellite peaks
at ~719.5 and 734.8 eV, two major peaks at around 710.2 eV for Fe 2p3/2
and 724.1 eV for Fe 2p1/2 were observed which is in good agreement
with the reported value of Fe3þ in
α-Fe2O3 [25–27].
Next, following the above optimized reaction conditions, a number of
ERO reactions were performed using styrene oxide, epichlorohydrin and
glycidyl isopropyl ether as the epoxide partner and aniline, m-chloro
aniline as the associated amine. The results are summed up in Table 2.
The ERO of styrene oxide by aniline takes place through the preferential
attack at the more hindered benzylic carbon. This is because of the
presence of the phenyl group that renders the benzylic carbon become
more electrophilic in nature [28] (Table 2, Entry 1). In contrast,
epichlorohydrin and glycidyl isopropyl ether were efficiently converted
to their corresponding products with good yields (Table 2, Entries 2–3).
Here the attack of the nucleophilic amines takes place at the less hindered
carbon atom of the epoxide ring.
3.2. Biogenic ION catalyzed epoxide ring opening (ERO) by amines
The catalytic activity of IONs was investigated through ERO reactions
with aromatic amines. The reaction conditions were optimized using a
series of reactions between styrene oxide and aniline by varying reaction
parameters, like catalyst amount, solvent, reaction temperature, and
time. The results are presented in Table 1. The indispensable role of the
catalyst was investigated by performing an ERO reaction without any
catalyst which furnished a trace amount of the product after 8 h at room
temperature. (Table 1, Entry 1). A moderate yield of the product was
obtained when dichloromethane, water, tetrahydrofuran and toluene
Fig. 2. IR spectrum of the IONs.
3

M. Halder et al.
Journal of the Indian Chemical Society 98 (2021) 100056
Fig. 4. XPS spectrum of ION (a) full range XPS survey, (b) high resolution fine spectra of Fe 2p.
Table 3
Table 1
Comparative study table for the synthesis methods of β-amino alcohols using
various catalysts.
Optimization of different conditions for the ERO reaction using IONs.a
Entry
Catalyst amount (mg)
Solvent
Temp. (oC)
Time (h)
Yieldb (%)
Entry
1
Catalyst
Reaction
Condition
Time
5 h
Yield
92
Ref
29
1
2
3
4
5
6
7
8
–
–
rt
rt
rt
rt
12
5
5
5
5
5
5
5
5
5
3
6
trace
82
59
45
71
90
87
85
80
87
79
91
20
20
20
20
20
20
20
10
30
20
20
DCM
H2O
THF
Toluene
CeO2–ZrO2 (20 wt%)
TBHP, CCl4,
80 ꢀC,
2
3
4
5
6
7
MoO2(acac)2(5 mol%)
TiO2–ZrO2
Mesoporous-Zr-beta catalyst
CoFe@rGO (20%)
Nano Fe3O4 (10 mol%)
CoFe2O4
CCl4, 50 ꢀ
H2O, RT,
C
2.5 h
1.2 h
0.5 h
6 min
20 h
10
min
3 h
5 h
95
86
81
90
83
89
30
31
32
33
34
35
rt
-
rt
40
50
rt
rt
rt
35 ꢀ
C
–
–
–
–
–
–
Neat, 80 ꢀC
RT, Neat,
9
Neat, 80 ꢀ
C
10
11
12
8
9
MTF-1E (0.04 mmol Fe),
IONs(0.00249 mmol of Fe,
2.493 ꢁ 10-4 mol% of Fe)
Neat, RT,
RT, Neat
91
90
36
This
work
rt
a
Condition: Aniline (1.0 mmol), Styrene oxide (1.0 mmol), solvent (1.5 mL).
Isolated yield.
b
undergo agglomeration during synthesis. Therefore, the NPs can provide
larger surface area and hence their catalytic activity becomes higher. The
higher turnover frequency (TOF in min-1) of the synthesized products
using our freshly prepared IONs clearly justify this fact. Moreover, the
comparative study with several iron oxide-based catalysts also supports
this fact that our polyphenol coated IONs show comparatively better
catalytic activity.
Finally, we have compared the activity of our present nano-catalyst
with existing state-of-the-art catalysts used for ERO reactions (Table 3).
The comparative study table clearly reveals that our as synthesized nano-
catalyst shows excellent catalytic activity for the synthesis of β-amino
alcohols starting from styrene oxide and aniline. Plant extract mediated
synthesis of metal-based NP always produces finer nanoparticles. As
polyphenolic moeity helps to stabilize the metal NPs the latter do not
Table 2
ERO reaction of various epoxides with different anilines using IONs.a.
4

M. Halder et al.
Journal of the Indian Chemical Society 98 (2021) 100056
3.3. Recyclability of the catalyst
Recycling efficiency is the most significant characteristic property of
heterogeneous catalyst. In order to check the stability of IONs, HR-TEM
was studied of the reused catalyst after 3rd run (Fig. 5). The HR-TEM
analysis data clearly specifies that the nature of the catalyst remains
significantly unaltered after reuse as is reflected in the shadow around
the dark spots of metal ions. The FTIR spectrum of the reused IONs
(Fig. S1) depicts a slight degradation after three successive runs. The
broad peak at 3347 cm-1 for stretching of –OH is slightly shifted to 3343
cm-1. The peak at 1619 cm-1 due to the carbonyl bond now appears at
1622 cm-1 and the peaks at 1519, 1438, and 1372 cm-1 owing to aromatic
–
–C C-, -C-H- bonds of alkanes and phenolic –OH, respectively have
–
undergone slight shifts to 1516, 1442 and 1366 cm-1. The Fe–O
stretching vibration bands of amorphous IONs near 671 and 533 cm-1
also are shifted to 673 and 528 cm-1. These changes reflect that although
there are slight degradation of the catalyst after reuse and regeneration,
the main functionalities of the polyphenols remain to be attached in the
nanoparticles.
Fig. 6 showed the recycling activity of IONs for the ERO reaction of
styrene oxide and aniline. The figure clearly indicates that after the third
run the yield percentage decreases from 90 to 82%.
Fig. 6. Recyclability chart of IONs catalyst.
potential avenue towards large scale synthesis of a broad variety of value-
added fine chemicals.
4. Conclusion
Declaration of competing interest
The present work describes the biogenic production of Fe2O3 nano-
catalyst using peanut skin extract. A successful application of the cata-
lyst is reported towards ring opening of epoxides for the generation of
β-amino alcohol derivatives in presence of aromatic amines. The IONs
showed good chemical stability and appreciable catalytic activity. The
promising advantages presented by this protocol are the solventless neat
condition, simple operational method, universal applicability, mild and
green reaction conditions, recyclability of the catalyst with considerably
good product yields. The overall green and cost-effective methodology of
the catalytic process using iron oxide nano-catalyst reported herein is a
The authors declare that they have no known competing financial
interests or personal relationships that could have appeared to influence
the work reported in this paper.
Acknowledgment
MH is thankful to UGC for UGC-SRF and IIT Kanpur for providing the
necessary Institute Postdoctoral Fellowship. ASR acknowledges Royal
Society, UK for his Newton International Postdoctoral Fellowship, and
his Newton International Postdoctoral alumni fund.
Appendix A. Supplementary data
Supplementary data to this article can be found online at https://do
i.org/10.1016/j.jics.2021.100056.
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