Fe3O4/MIL-101(Fe) nanocomposite as an efficient and recyclable catalyst for Strecker reaction

Article abstract of DOI:10.1002/aoc.4217

A highly porous metal-organic framework, MIL-101(Fe), was prepared by a solvothermal method in the presence of amino-modified Fe₃O₄@SiO₂ nanoparticles, in order to achieve Fe₃O₄/MIL-101(Fe) nanocomposite, which was characterized by XRD, FT-IR, SEM, TEM, BET, and VSM. This hybrid magnetic nanocomposite was employed as heterogeneous catalyst for α-amino nitriles synthesis through three-component condensation reaction of aldehydes (ketones), amines, and trimethylsilyl cyanide in EtOH, at room temperature. The recoverability and reusability was admitted for the heterogeneous magnetic catalyst; no significant reduction of catalytic activity was observed even after five consecutive reaction cycles.

Full text of DOI:10.1002/aoc.4217

Received: 29 August 2017
DOI: 10.1002/aoc.4217
Revised: 9 November 2017
Accepted: 10 November 2017
F U L L P A P E R
Fe3O4/MIL‐101(Fe) nanocomposite as an efficient and
recyclable catalyst for Strecker reaction
Mohammad Mahdi Mostafavi | Farnaz Movahedi
Department of Chemistry and
A highly porous metal‐organic framework, MIL‐101(Fe), was prepared by a
Petrochemical Engineering, Standard
Research Institute, P.O. Box 31745‐139,
Karaj, Iran
solvothermal method in the presence of amino‐modified Fe3O4@SiO2 nanopar-
ticles, in order to achieve Fe3O4/MIL‐101(Fe) nanocomposite, which was char-
acterized by XRD, FT‐IR, SEM, TEM, BET, and VSM. This hybrid magnetic
Correspondence
Farnaz Movahedi, Department of
nanocomposite was employed as heterogeneous catalyst for α‐amino nitriles
Chemistry and Petrochemical
synthesis through three‐component condensation reaction of aldehydes
Engineering, Standard Research Institute,
P.O. Box 31745‐139, Karaj, Iran.
Email: fzmovahedi@yahoo.com
(ketones), amines, and trimethylsilyl cyanide in EtOH, at room temperature.
The recoverability and reusability was admitted for the heterogeneous magnetic
catalyst; no significant reduction of catalytic activity was observed even after
five consecutive reaction cycles.
KEYWORDS
heterogeneous catalysis, magnetic nanocomposite, MIL‐101(Fe), nanohybride catalyst, Strecker
reaction
1 | INTRODUCTION
compared to other porous materials, MOFs contain a high
density of catalytically active sites, in which the constitu-
New porous metal‐organic frameworks (MOFs) offer
innovative opportunities in scientific and technological
fields by combining the profits of both inorganic and
organic moieties, in which provide unique properties of
high surface areas and well defined cavities or channels
that can lead to potential applications in gas storage,[1]
separation,[2] optical devices,[3] sensors,[4] drug delivery,[5]
and heterogeneous catalysis.[6]
Today, scientists are interested with fabrication of new
nanocomposites based on combining functional micro and
nanoparticles (NPs) with MOFs, representing superior
properties. Metal nanoparticles/nanorods,[7–11] quantum
dots,[12] graphene,[13,14] silica nanospheres[15–17] and mag-
netic beads[14] are some of instances specified in design of
potential MOF skeletons. From the point of catalysis,
MOFs are potentially interesting candidates to be used
either as heterogeneous catalysts alone, or in combination
with the other catalytic centers as supporting matrixes.
This arises from their specific large surface areas, the abun-
dant metal ions and the tailorable porous structures. Also,
tional transition metals have free positions or can easily
exchange ligands.[18] Besides, integration of magnetic com-
pounds into MOFs is of great interest, because magnetic
separation and convenient acquisition of the composite
by external magnetic field contains more advantages in
comparison with the other separation methods.[19]
However, there are only several strategies to modulate
the physicochemical properties of MOFs with magnetic
materials. For example, Qiu and co‐workers have
reported the formation of core‐shell structure by a step‐
[20];
by‐step assembly strategy on the surface of Fe3O4
an
assembly method of physically mixing MIL‐101 and sil-
ica‐coated Fe3O4 microparticles under sonication has
been reported by Yan and co‐workers[21]; another
reported route is chemical bonding MOF‐5 with amino‐
functionalized Fe3O4 nanoparticles.[22] Indeed, easy
recovery function and efficient utility would be accom-
plished for all of these magnetic MOFs.
On the other hand, among the wide range of multicom-
ponent reactions (MCRs), many attentions are focused on
Appl Organometal Chem. 2018;e4217.
wileyonlinelibrary.com/journal/aoc
Copyright © 2018 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.4217

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MOSTAFAVI AND MOVAHEDI
the strecker reaction. This three‐component coupling
between aldehydes (or ketones), ammonia and hydrogen
cyanide yields α‐amino nitriles, which are key intermedi-
ates for the synthesis of a wide variety of amino acids,
amides, diamines, and nitrogen‐containing heterocy-
cles.[23] Diverse strategies applied for the synthesis of α‐
amino nitriles contain a variety of Lewis or Bronsted acidic
catalysts, heterogeneous catalysts,[24,25] and recently sev-
eral MOFs.[26,27] Although, development of new synthesis
techniques to overcome the intrinsic drawbacks including
harsh reaction conditions and tedious workup procedures
and suggesting less expensive, environmentally benign
and expedient conditions is highly worthy.
Herein, a facile preparation of Fe3O4/MIL‐101(Fe)
nanocomposite is reported through in situ fabrication of
MIL‐101(Fe) in the presence of amino‐modified
Fe3O4@SiO2 NPs, using a solvothermal method. As a
result of electrostatic interactions between Lewis base reg-
ulators on the magnetic NPs surface and metal ions
belonging to MOF structure, chemical stabilization is
achieved. Thus, MOF crystals are uniformly enclosed by
Fe3O4 NPs to form a homogeneous magnetic product,
defined as Fe3O4/MIL‐101(Fe). Continuously, as part of
our previous studies to investigate catalytic performance
of new heterogeneous nanocomposites,[28–30] we have
examined the catalytic efficiency of a kind of MOF struc-
ture, combined with amino‐modified core‐shell magnetic
NPs, in order to extend merits of an environmentally‐
friendly metal catalyst to accomplish bond‐forming pro-
cesses. Indeed, we have shown that catalytic resources
could comprise in a single architecture to intensify the
catalytic function, in which is anticipated individually,
for synthetic methodologies. Therefore, we herein report
catalytic potential of the as‐prepared nanocomposite for
the synthesis of α‐amino nitriles through one‐pot three‐
component condensation reaction of aldehydes (or
ketones), amines and trimethylsilyl cyanide (TMSCN).
taken by a single point method at P/P0 = 0.98. FT‐IR mea-
surements were performed using KBr disc on a Thermo
IR‐100 infrared spectrometer (Nicolet). X‐ray diffraction
(XRD) was measured in a Philips PW 1730 instrument.
1
13
The H‐ and
C‐spectra were measured at 500.1 and
125.7 MHz, respectively, on a Bruker DRX 500‐Avance
FT‐NMR instrument with CDCl3 solvent.
2.2 | Catalyst preparation
2.2.1 | Preparation of amino‐modified
Fe3O4@ SiO2 nanoparticles
Initially, Fe3O4 NPs were synthesized by a simple chemical
co‐precipitation method as reported previously.[31] Briefly,
FeCl3·6H2O (5.838 g, 0.0216 mol) and FeCl2·4H2O (2.147 g,
0.0108 mol) were dissolved in 100 ml deionized (DI) water
and stirred mechanically at 85 °C under N2 atmosphere for
30 minutes. Then, 10 ml of 25% NH4OH was added into the
reaction mixture in one portion, in which resulted in the
formation of the black precipitates of magnetic NPs, imme-
diately. The reaction continued for another 30 minutes,
and then was cooled to room temperature. The as‐prepared
black precipitates was separated from the supernatant by
an external magnetic decantation, thoroughly washed
with DI water and saturated NaCl solution, and vacuum
dried at 80 °C overnight to achieve Fe3O4 NPs. Afterwards,
1.0 g of the as prepared magnetic NPs were homogenously
dispersed in 150 ml EtOH solution, under ultrasound con-
ditions. Next, 5 ml of 25% NH4OH was added to the solu-
tion and stirred for 30 minutes. Subsequently, 1 ml of
tetraethyl orthosilicate (TEOS) was added dropwise over
10 minutes and the reaction stirred vigorously at room
temperature for 24 hours. The resulting silica coated mag-
netic NPs (designated as Fe3O4@ SiO2) were collected by
an external magnet, then washed several times with DI
water and EtOH, and dried under vacuum at 80 °C for
24 h. For surface modification with amino groups by intro-
ducing (3‐Aminopropyl)triethoxysilane (APTES), Fe3O4@
SiO2 (0.65 g) were dispersed in a 250 ml solution of 1:1 eth-
anol/water by sonication for 30 minutes, then 3 ml APTES
was added dropwise within 10 minutes under stirring vig-
orously. After completion of the reaction (6 hours), the pre-
cipitate was collected by centrifugation (RCF = 6000 × g,
10 min), washed with DI water and EtOH several times
and dried under vacuum at 80 °C overnight to yield
amino‐modified Fe3O4@ SiO2.[32]
2 | EXPERIMENTAL SECTION
2.1 | Materials and methods
The reagents and solvents used in this work were
obtained from Fluka or Merck and used without further
purification. The particle size and morphology were
investigated by a JEOL JEM‐2010 transmission electron
microscope (TEM) on an accelerating voltage of 200 kV,
and scanning electron microscope (SEM, LEO 1430VP
microscope with an accelerating voltage of 25 kV). The
Brunauer–Emmett–Teller (BET) surface area of the cata-
lyst was studied using a nitrogen adsorption instrument
(Micrometrics ASAP 2020). Pore size was calculated using
Density Functional Theory (DFT). Total pore volume was
2.2.2 | Preparation of Fe3O4/MIL‐101(Fe)
Preparation of Fe3O4/MIL‐101(Fe) nanocomposites was
achieved through a solvothermal procedure; 0.15 g of
amino‐modified Fe3O4@SiO2 NPs were added to a solution

MOSTAFAVI AND MOVAHEDI
3 of 10
of 3.38 g FeCl3.6H2O in 40 ml DMF, and sonicated for
30 minutes. Then, a solution of 1.03 g terephthalic acid
(H2BDC) in 10 mL DMF was added dropwise over
10 minutes. After stirring for more 30 minutes, the solution
was sealed in a 50 ml Teflon‐lined autoclave and heated in
stable conditions at 110°C for 24 hours. According cooling
to room temperature, the brown precipitate was isolated by
an external magnetic field, and washed with DMF several
times for two days. In order to further activation, the nano-
composite was redispersed in methanol to displace DMF.
The final product was achieved after magnetic decanting,
and then vacuum drying at 80°C for 24 hours (scheme 1).
Also MIL‐101(Fe) was synthesized as in the above proce-
dure without adding modified Fe3O4, according to the pre-
viously reported procedure.[33]
added in to a 10 ml round‐bottomed flask, sequentially,
then the mixture was stirred vigorously for appropriate
periods, at room temperature. The progress of the reaction
was checked by TLC. After completion, the catalyst was
separated by an external magnet, washed with MeOH
(3×5 ml), dried under vacuum conditions overnight, and
then reused as such for the next experiment. Also, the
organic phase of the reaction was sequestrated, the solvent
was removed under reduced pressure, and the desired α‐
amino nitrile obtained through a column of silica gel.
3 | RESULTS AND DISCUSSION
3.1 | Characterization of Fe3O4/MIL‐
101(Fe)
The crystal structure of MIL‐101(Fe) is investigated dur-
ing magnetization by X‐ray diffraction patterns as shown
in Figure 1. The XRD patterns of the Fe3O4 NPs at 30.0°
(220), 35.2° (311), 42.9° (400), 39.6° (422), 56.9° (511)
and 62.5° (440) are observed, indicative of a cubic spinel
2.3 | General procedure for synthesis of
the α‐amino nitriles
Aldehyde (or ketone) (1.0 mmol), amine (1.0 mmol),
TMSCN (1.1 mmol), EtOH (3 ml) and catalyst (10 mg) were
HOOC
COOH
1.NH4OH, 80 °C
2.TEOS
FeCl3.6H2O
3.APTES
FeCl3
DMF
FeCl2.4H2O
Fe3O4/MIL-101(Fe)
amino-modified Fe3O4@SiO2 NPs
SCHEME 1 Preparation of Fe3O4/MIL‐101(Fe) nanocomposite
FIGURE 1 XRD patterns of (a) amino‐
modified Fe3O4@SiO2, (b) MIL‐101, and
(c) Fe3O4/MIL‐101

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MOSTAFAVI AND MOVAHEDI
structure of the magnetite, matched well with the charac-
teristic peaks of Fe3O4 (JCPDS No. 19‐0629).[34] The aver-
age particle size of the magnetite calculated using the
Scherer equation[35] achieves 35 nm. The diffraction
peaks of the as‐synthesized nanocomposite show that
the Fe3O4 NPs and MOF structure are well preserved
because all diffraction peaks of the Fe3O4/MIL‐101 are
readily indexed to Fe3O4 NPs and MIL‐101, respectively,
indicating maintenance the crystalline form of the
nanocomposite.
The FT‐IR spectra for amino‐modified Fe3O4@SiO2,
MIL‐101(Fe), and Fe3O4/MIL‐101 are shown in Figure 2.
The intrinsic peak at 578 cm‐1 is ascribed for Fe–O
stretching mode in amino‐modified Fe3O4@SiO2 NPs.[36]
The adsorption band at 1090 cm‐1 is attributed to the
stretching vibration of O‐Si‐O, reflecting the silica coating
on the magnetite surface. The introducing of APTES is
confirmed by the bands at 2925 cm‐1 assigned to the C‐
MOF structures, in which are enclosed by F3O4 NPs
(Figure 3b, c). The electrostatic interactions between the
negatively charged Fe3O4 NPs and positively charged
MIL‐101, concludes in homogeneous dispersion of mag-
netic NPs on the surface of MIL‐101.[21] The TEM images
(3d, e) illustrate a regular octahedral crystalline structure
for MOF. Amino‐modified Fe3O4@SiO2 NPs can success-
fully adhere to the growing MOF crystals without break-
ing the crystal structures of MIL‐101. The Fe3O4 NPs
show an average size of 37 nm, in accordance with the
XRD analyses. In comparison, there is no obvious differ-
ence between the fresh nanocomposite with its reused
form after five catalytic cycles (Figure 3f).
The BET surface area and the total pore volume of the
Fe3O4/MIL‐101(Fe) determined by N2 adsorption and the
pore size distribution pattern using density functional the-
ory (DFT) are shown in Figure 4. In the pore size distribu-
tion pattern (Figure 4a), two pore diameter centers at
1.8 nm and 2.3 nm, suggest the nanocomposite possesses
both micropores and mesopores, respectively. The mea-
surements shows a type I isotherm, and the porous vol-
ume calculated from the adsorption branch of the
isotherm is 0.19 cm3·g−1. The surface area calculated by
a BET method is 404 m2 g‐1. Compared to the parent
MOF structures,[39] the obvious decrease in the textural
parameters dimensions, presumably arises from highly
dispersion of amino‐modified Fe3O4@SiO2 NPs on the
surface of MIL‐101.
H
stretching vibration of methylene groups, and
3413 cm‐1 associated to the N‐H stretching vibration.[37]
Meanwhile, the peak at 741 cm‐1 is assigned to the out‐
of‐plane bending vibration of C‐H groups in the benzene
ring of MIL‐101. In addition, the characteristic peaks of
carboxyl groups are evidenced by the symmetric
stretching band at 1385 cm‐1, along with the asymmetric
stretching bands at 1506 cm‐1 and 1681 cm‐1.[38] The
stretching and bending vibrational bands in the range of
600‐1600 cm‐1 correspond to benzene ring. For Fe3O4/
MIL‐101, co‐existence of characteristic peaks, confirms
attendance of modified magnetic NPs in the MOF
skeleton.
The hysteresis loops were measured with a VSM to
investigate the magnetic property of the amino‐modified
Fe3O4@SiO2 and Fe3O4/MIL‐101(Fe) at room tempera-
ture (Figure 5). The plots indicate that both samples
exhibit superparamagnetic behavior with zero remanence
and coercivity. The superparamagnetic behavior is mainly
generated by the magnetite NPs in each sample. Easy sep-
aration of the catalyst with the aid of an external magnet,
The morphology and structure of the as‐prepared
Fe3O4/MIL‐101(Fe), characterized by SEM and TEM, are
shown in Figure 3. The Fe3O4 NPs are presented with
an approximate spherical shape (Figure 3a). The SEM
images exhibit concave octahedral morphologies for
FIGURE 2 FT‐IR spectra of (a) amino‐
modified Fe3O4@SiO2, (b) MIL 101, and
(c)Fe3O4/MIL 101

MOSTAFAVI AND MOVAHEDI
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FIGURE 3 The SEM images of (a) Fe3O4 NPs, (b, c) Fe3O4/MIL‐101(Fe), the TEM images of (d, e) Fe3O4/MIL‐101(Fe), and the SEM image
of (f) the recovered catalyst after five consecutive runs
3.2 | Catalytic activity of Fe3O4/MIL‐
101(Fe) nanocomposite
Because of regarding α‐amino nitriles as valuable inter-
mediates of preparing S‐ and N‐ containing heterocy-
cles,[40] pharmacologically relevant molecules[41] and
biologically active skeletons,[42–44] versatile precursors of
a‐amino acids used in synthesizing proteins,[45] besides
of chiral building blocks in the pharmaceutical indus-
try,[46] employing new catalytic approaches is currently a
highly desirable goal. Therefore the catalytic activity of
Fe3O4/MIL‐101(Fe) nanocomposite as a heterogeneous
catalyst was investigated for one‐pot synthesis of α‐amino
nitriles through Strecker reaction (scheme 2). In order to
establish the feasibility of the strategy and optimization
of the reaction conditions, the reaction of benzaldehyde,
aniline and TMSCN as a simple model reaction was
engaged. Various reaction conditions, were evaluated for
the model reaction, and the results are summarized in
Table 1. Fe3O4 NPs and MIL‐101(Fe) would catalyze the
reaction with 65% and 85% yields, respectively. Yet, their
combination in the form of the ultimate nanocomposite
boosts the yield to 98%.
To investigate the effects of media, the model conden-
sation reaction was carried out in various solvents by using
Fe3O4/MIL‐101(Fe) (10 mg per 1 mmol of reactants) as the
FIGURE 4 (a) Pore size distribution curve and (b) nitrogen
adsorption‐desorption isotherms of Fe3O4/MIL‐101(Fe)
is as a result of this specification. The saturation magneti-
zation, determined by using the law of approach to satura-
tion, is around 28.6 emu/g for the Fe3O4/MIL‐101(Fe).
catalyst (Table 1, entries 8‐11). Obviously, good catalytic
activity was accessed in a variety of solvents such as H2O,
CH2Cl2, and MeOH where 80% and more over conversions

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MOSTAFAVI AND MOVAHEDI
FIGURE 5 VSM curves for (a) amino‐
modified Fe3O4@SiO2 and (b) Fe3O4/MIL‐
101(Fe) at room temperature. The inset
indicates the magnetic recovery process of
Fe3O4/MIL‐101(Fe) nanocomposite by
applying an external magnetic field
R"
SCHEME 2 One‐pot synthesis of α‐
amino nitriles through Strecker reaction
under catalytic activity of Fe3O4/MIL‐
101(Fe) nanocomposite
O
HN
Fe3O4/MIL-101(Fe)
EtOH, rt
+
TMSCN
+
"R NH2
R
R
R'
CN
R'
TABLE 1 Optimization of the Fe3O4/MIL‐101(Fe) catalyzed model reaction for the α‐amino nitrile synthesisa
b
Entry
1
Catalyst
FeCl3.6H2O (10 mol%)
Solvent
EtOH
H2O
Time (min)
Yield
75
90
60
60
60
120
90
120
50
45
90
120
90
30
30
30
90
2
Fe3O4 MNPs (10 mol%)
Fe3O4 MNPs (10 mol%)
Fe3O4 MNPs (10 mol%)
MIL‐101(Fe) (10 mg)
68
3
EtOH
CH2Cl2
H2O
65
4
68
5
60
6
MIL‐101(Fe) (10 mg)
EtOH
CH2Cl2
H2O
85
7
MIL‐101(Fe) (10 mg)
67
8
Fe3O4/MIL‐101(Fe) (10 mg)
Fe3O4/MIL‐101(Fe) (10 mg)
Fe3O4/MIL‐101(Fe) (10 mg)
Fe3O4/MIL‐101(Fe) (10 mg)
Fe3O4/MIL‐101(Fe) (10 mg)
Fe3O4/MIL‐101(Fe) (5 mg)
Fe3O4/MIL‐101(Fe) (10 mg)
Fe3O4/MIL‐101(Fe) (20 mg)
No catalyst
80
9
CH2Cl2
MeOH
THF
88
10
11
12
13
14
15
16
88
62
Solvent‐free
EtOH
EtOH
EtOH
EtOH
78
90
98, 98, 97c
98
15
aReaction conditions: benzaldehyde (1 mmol), aniline (1 mmol), TMSCN (1.1 mmol), catalyst, solvent (3 ml), room temperature.
bIsolated yields.
cYields in rt, 40 °C, and 70 °C.
was obtained, respectively. Nevertheless, the reaction
contained more efficiency in EtOH and gave higher yields.
To investigate the effect of the catalyst concentration,
systematic studies were carried out in the presence of dif-
ferent amounts of the catalyst (5, 10, 20 mg) in EtOH,
affording α‐amino nitriles with 95%, 98% and 98% isolated
yields, respectively. Thus, the best yield is accessible in the
presence of just 10 mg Fe3O4/MIL‐101(Fe), and the use of
higher amounts of the catalyst (10 mg) did not improve
the result to an appreciable extent (Table 1, entry 15).
The temperature effect was examined at room tempera-
ture (rt), 40 °C, and 70 °C in EtOH in the presence of
Fe3O4/MIL‐101(Fe) (10 mg) (Table 1, entry 14). Higher
temperatures conditions didn’t increased the reaction

MOSTAFAVI AND MOVAHEDI
7 of 10
yields to more noticeable amounts. Therefore, room tem-
perature was chosen as the optimum temperature for the
reaction.
as well as aromatic amines and provided the inspiring
results in short reaction time with good to excellent yield
(Table 2, entries 17‐25).
Screening of substrates for different substituents in
benzaldehyde and aniline, revealed the reaction can toler-
ate a wide range of aldehydes bearing electron‐donating
groups as well as electron‐withdrawing groups, providing
the corresponding products in good to high yields
(Table 2, entries 2‐7), respectively, meanwhile, the aniline
bearing electron‐withdrawing group reacted milder than
aniline, concluded to moderate yields (Table 2, entries 12‐
16). Aliphatic amines demonstrated considerable activity
In order to expand the scope of substrates and
explore further catalytic activity of the as‐ mentioned
nanocomposite, a variety of aromatic and aliphatic
ketones were examined to give the corresponding prod-
ucts in good to high yields (Table 3, products 4a–4 h),
after short reaction times in the presence of 10 mg cata-
lyst in EtOH (3 mL), at room temperature. Even the ste-
rically hindered ketones, such as benzophenone, reacted
with para‐chloro aniline and TMSCN to give the
TABLE 2 The three‐component coupling reaction of aldehydes, amines, and TMSCN catalyzed by Fe3O4/MIL‐101(Fe) under ambient
conditionsa
Entry
1
R
R’
Product
3a
Time (min.)
Yield (%)b
Ph
Ph
35
98
2
4‐Me‐C6H4
4‐MeO‐C6H4
2‐Cl‐C6H4
3‐Br‐C6H4
4‐Cl‐C6H4
4‐NO2‐C6H4
Cinnamyl
n‐Pr
Ph
3b
3c
3d
3e
3f
60
45
45
40
30
90
60
45
60
50
90
90
90
90
180
30
40
60
90
120
90
60
90
90
90
89
94
92
97
94
85
89
82
97
92
95
90
83
72
95
92
85
90
93
97
92
82
89
3
Ph
4
Ph
5
Ph
6
Ph
7
Ph
3g
3h
3i
8
Ph
9
Ph
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
i‐Pr
Ph
3j
Ph
4‐Cl‐C6H4
4‐Cl‐C6H4
4‐Cl‐C6H4
4‐Cl‐C6H4
4‐Cl‐C6H4
4‐Cl‐C6H4
Benzyl
Benzyl
Benzyl
Benzyl
Benzyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
Cyclohexyl
3k
3l
4‐MeO‐C6H4
4‐Me‐C6H4
4‐Cl‐C6H4
4‐Br‐C6H4
4‐NO2‐C6H4
Ph
3m
3n
3o
3p
3q
3r
3s
4‐Cl‐C6H4
4‐Me‐C6H4
n‐Pr
3t
Cinnamyl
Ph
3u
3v
3w
3x
3y
4‐Cl‐C6H4
4‐NO2‐C6H4
4‐MeO‐C6H4
aThe reaction was carried out by addition of aldehyde (1 mmol), amine (1 mmol), and TMSCN (1.1 mmol) catalyzed by Fe3O4/MIL‐101(Fe) in EtOH (3 ml), at
room temperature.
bIsolated yields.

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MOSTAFAVI AND MOVAHEDI
TABLE 3 One‐pot synthesis of α‐amino nitriles through the Strecker reaction of ketones, amines and TMSCN in the presence of Fe3O4/
MIL‐101(Fe) under ambient conditionsa
Entry
1
R
R’
R”
Product
4a
Time (min.)
Yield (%)b
92
Ph
Me
Ph
45
2
3
4
5
6
7
8
9
4‐Cl‐C6H4
4‐MeO‐C6H4
2‐NO2‐C6H4
Ph
Me
Me
Me
Ph
Ph
4b
4c
4d
4e
4f
40
45
90
90
45
60
60
180
89
80
87
80
85
80
86
74
Ph
Ph
Ph
4‐Br‐C6H4
R=R’= (CH2)5
Et
Me
4‐Cl‐C6H4
4‐Cl‐C6H4
4‐Cl‐C6H4
4‐Cl‐C6H4
4g
4h
4i
Et
Ph
Ph
aThe reaction was carried out by addition of ketone (1 mmol), amine (1 mmol) with TMSCN (1.1 mmol) catalyzed by Fe3O4/MIL‐101(Fe) in EtOH (3 ml) at room
temperature.
bIsolated yields.
corresponding product in good yields, although the reac-
tion proceeded relatively slowly (Table 3, entry 8). All
products are known compounds,[28,47] and found to be
identical with those reported in the literature, previously,
on the basis of their spectroscopic data (1H and 13C NMR
spectra).
The catalytic activity and the possibility of the catalyst
recyclability and reusability, was investigated in this sys-
tem (Table 4). After separation with an external magnet,
the catalyst washed with methanol (3×5 ml), dried under
vacuum at 100 °C, and then was used in the successive
runs. The results showed that the catalyst could be effec-
tively used for at least five consecutive more cycles with-
out much appreciable loss in its catalytic activity.
Finally, the catalytic performance of Fe3O4/MIL‐
101(Fe) nanocomposite was compared with other
TABLE 5 Comparison of catalytic activity of this work with sev-
eral known catalysts
Yield
Entry Catalyst
Conditions
(%)
Ref.
[48]
1
(Me2NH2) [Nd4(CO3) Water,
75%
2
L4(DMF)2(H2O)2]·2H2O
20 mol%
SDS, r.t.,
12 h
[26]
[47]
[49]
[50]
[51]
[52]
[53]
[54]
2
3
4
5
6
7
8
9
InGaPF‐1
MgI2.(Et2O)n
SiO2
Solvent‐free, r. 64%
t., 96 h
Solvent‐free, r. 95%
t.
Ball milling,
700 rpm, 3 h
96%
76%
91%
90%
94%
92%
Formic acid
Peg‐OSO3H
[Sipim]HSO4
I2
EtOH, r.t.,
40 min.
Water, r.t.,
10 min.
TABLE 4 Reusability of the Fe3O4/MIL‐101(Fe) catalysta
Recovery of the Fe3O4/
MIL‐101(Fe)
EtOH, r.t.,
75 min.
Entry
Fresh
Yield (%)b
98
100
CH3CN,
r.t., 1 h
1
2
3
4
5
98
98
97
96
96
99
99
98
97
97
NiCl2
CH3CN,
r.t., 12 h
[55]
[28]
10
11
Cu(OTf)2
CH3CN, rt, 6 h 89%
SA‐MNPs
Water, r.t.
10 min
97%
aReaction conditions: benzaldehyde (1 mmol), aniline (1 mmol), TMSCN
12
Fe3O4/
MIL‐101(Fe)
EtOH, r.t.
35 min.
98%
This
work
(1.1 mmol), the Fe3O4/MIL‐101(Fe) (10 mg), EtOH (3 ml), room temperature.
bIsolated yields.

MOSTAFAVI AND MOVAHEDI
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reaction. The advantages of catalyst high surface area,
appropriate pore size, and accessible active Lewis acid
sites, comprise a wide range of substituted benzaldehydes
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How to cite this article: Mostafavi MM,
Movahedi F. Fe3O4/MIL‐101(Fe) nanocomposite as
an efficient and recyclable catalyst for Strecker
reaction. Appl Organometal Chem. 2018;e4217.
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