Synthesis and Characterization of Magnetic Functionalized Ni and Cu Nano Catalysts and Their Application in Oxidation, Oxidative Coupling and Various Multi-Component Reactions

Article abstract of DOI:10.1007/s10562-020-03495-3

Abstract: Two magnetic nano catalysts of nickel and copper, Fe₃O₄@SiO₂@DOP-BenPyr-M(II), (M=Ni and Cu) have been synthesized. These catalysts were applied as recoverable, efficient and new heterogeneous catalysts for the high yielding and room temperature one-pot procedure of selective oxidation of sulfides to sulfoxides and oxidative coupling of thiols to disulfides. In addition, the catalytic activity of Fe₃O₄@SiO₂@DOP-BenPyr-Ni(II) was investigated as heterogeneous nanocatalyst for synthesis of 2,3-dihydroquinazolin-4(1H)-ones, 5-substituted 1H-tetrazoles and polyhydroquinolines. The synthesized catalysts were characterized by FT-IR, TGA, XRD, VSM, EDX, ICP and SEM techniques. These catalysts were recovered by an external magnet and reused several times without significant loss of catalytic efficiency. Graphic Abstract: [Figure not available: see fulltext.]

Full text of DOI:10.1007/s10562-020-03495-3

Catalysis Letters
https://doi.org/10.1007/s10562-020-03495-3
Synthesis and Characterization of Magnetic Functionalized Ni and Cu
Nano Catalysts and Their Application in Oxidation, Oxidative Coupling
and Various Multi‑Component Reactions
Maryam Hajjami1 · Shiva Sheikhaei2 · Fatemeh Gholamian2 · Zakieh Yousofvand2
Received: 17 October 2020 / Accepted: 11 December 2020
© The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature 2021
Abstract
Two magnetic nano catalysts of nickel and copper, Fe3O4@SiO2@DOP-BenPyr-M(II), (M=Ni and Cu) have been synthe-
sized. These catalysts were applied as recoverable, efcient and new heterogeneous catalysts for the high yielding and room
temperature one-pot procedure of selective oxidation of sulfdes to sulfoxides and oxidative coupling of thiols to disulfdes.
In addition, the catalytic activity of Fe3O4@SiO2@DOP-BenPyr-Ni(II) was investigated as heterogeneous nanocatalyst
for synthesis of 2,3-dihydroquinazolin-4(1H)-ones, 5-substituted 1H-tetrazoles and polyhydroquinolines. The synthesized
catalysts were characterized by FT-IR, TGA, XRD, VSM, EDX, ICP and SEM techniques. These catalysts were recovered
by an external magnet and reused several times without signifcant loss of catalytic efciency.
Graphic Abstract
O
Ar
O
O
O
O
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Ar-CHO
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NH4OAc
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O
N
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Solvent-Free, 100 oC
CN
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N
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N
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Si O
O
N
H2O2 , PEG, r.t
RS SR
R SH
O Si
O
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M=Ni or Cu
O
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NH2
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Ar
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+
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NH2
H2O2 , Solvent free, r.t
N
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Ar
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R'
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Extended author information available on the last page of the article
Vol.:(0123456789)
1 3

M. Hajjami et al.
Keywords Fe3O4@SiO2@DOP-BenPyr-M(II) · Sulfoxides · Disulfdes · 2,3-Dihydroquinazolin-4(1H)-ones · 5-Substituted
1H-tetrazoles · Polyhydroquinolines
activity, anti-allergic herbicides, complexing ability toward
various metals, information recording system and etc. Also
those were prepared by cycloadditions between nitriles and
azide anion [26–28]. Several pathways have been reported
for the synthesis of 5-substituted 1H-tetrazoles such as Cu-
MCM-41 nanoparticles [29], salen complex of Cu(II) sup-
ported on superparamagnetic Fe3O4@ SiO2 nanoparticles
[30] and etc.
1 Introduction
Magnetic nanoparticles have attracted much attention from
a wide range of applications as catalyst in many organic
reactions because of their high surface area, the active sites
and facile separation. Also magnetic nanoparticles have been
extensively reported in various felds [1–4], including bio-
sensor and therapeutic applications [5], organic transforma-
tion such as cross-coupling reactions and esterifcation [6],
medicine [7], hydrogenation of carbonyl compounds and
alkynes in the petrochemical and food industries [8] and etc.
Among the various magnetic nanoparticles, the direct use of
magnetic Fe3O4 nanoparticles are developed and disputably
the most extensively under investigation because of facilitate
their separation from the reaction mixture with an external
magnet and remain unchanged after reaction [9–11]. To pro-
tect and also prevent afect redox reactions of the magnetic
core with supplemental component, a silica shell was frst
coated on the magnetic core (SMNP), then the molecular
catalysts grafting on the silica surface by the binding sites
(Si–OH units) [1, 12]. Also control of properties of nano-
catalysts such as size, shape, morphology, and dispersity can
be achieved [13]. Therefore, developments of catalysts that
are stable and recoverable seem very attractive [14].
There upon the new occasion by application of magnetic
nanoparticles as catalyst can be obtained to the synthesis
of heterocyclic compounds such as 2,3-dihydroquinazolin-
4(1H)-ones, 5-substituted 1H-tetrazoles and polyhydro-
quinolines. Often heterocyclic structures owning potential
biological and pharmaceutical activities. Among them,
quinazolinone derivatives possess useful properties like anti-
tumor, anticancer [15], diuretic, herbicidal agents [16] and
etc. The common procedure for the synthesis of 2,3-dihy-
droquinazolin-4(1H)-ones is the condensation reaction of
anthranilamide with various aldehydes under a variety of
catalysts [17, 18], such as MNPs-TEDETA tribromide [19],
Cu-CNTs [20], silica-bonded n-propylsulfamic acid [21],
H3BO3-MCM-41 [22] and etc.
Synthesis of sulfoxides is in demand, because of this
compound are a common merit found in therapeutic agents
including antibacterial, anti-ulcer, antihypertensive, cardi-
otonic [31, 32] and antifungal [33]. Also, these compounds
have widespread utilization as polymer materials, and
ligands in asymmetric catalysis [34]. Also the selective oxi-
dation of thiols and synthesis of corresponding disulfdes
has gained signifcant importance due to many applications
of these products, such as: biological processes, chemical
industry [35], as useful reagents in organic synthesis, in
sulphenylation of enolates and other anions, essential moie-
ties of biological active compounds for peptides and pro-
tein stabilization [36], vulcanizing agents for rubber [37].
Overoxidation of disulfdes leading to other products such
as sulfnates, sulfoxides, sulfonates and sulfonic acids. Over-
come to this problem and selective oxidation of thiols has
attractive attention. Because of the selective oxidation have
many benefts such as low cost and energy, minimal waste,
short reaction time and less workup [38].
Therefore, design of a catalytic system that has not the
problem of overoxidation is necessary.
Magnetic nanoparticles (MNPs) due to mentioned ben-
efts have applied as a support for synthesis of new hetero-
geneous catalyst. In this light we are synthesized Fe3O4@
SiO2@DOP-BenPyr-M(II) (M=Ni and Cu) and applied
them as catalysts for the oxidation of sulfdes to sulfoxides
and oxidative coupling of thiols to disulfdes and also syn-
thesis of 2,3-dihydroquinazolin-4(1H)-ones, 5-substituted
1H-tetrazoles and polyhydroquinolines by the Ni catalyst.
As well as, polyhydroquinoline that include a six mem-
bered heterocyclic ring [19] possess vasodilator, hepato-
protective, antiatherosclerotic, bronchodilator, antitumor,
geroprotective, and antidiabetic activities [23]. This com-
pound synthesis from dimedone, arylaldehydes, ethyl ace-
toacetate and ammonium acetate and catalyzed by various
catalyst such as Fe3O4-SA-PPCA nanoparticles [24], MNPs-
TEDETA tribromide [19], sulfonic acid functionalized SBA-
15 [25] and etc.
2 Experimental
2.1 Materials and Physical Measurements
All reagents and solvents used in this work were purchased
from Aldrich or Merck chemical companies. All the melting
points were listed by open capillary method and are uncor-
rected. The synthesized catalysts were recognized by X-ray
difraction (XRD, GBC-Diftech MMA), thermogravimetric
analysis (TGA, PerkinElmer Pyris Diamond, UK), Fourier
Tetrazoles are valuable group of heterocycles that can use
in the multiple felds including antibiotic activity, biological
1 3

Synthesis and Characterization of Magnetic Functionalized Ni and Cu Nano Catalysts and Their…
transform infrared spectroscopy (FT-IR, Bruker, Germany,
VRTEX 70), scanning electron microscopy (SEM, FESEM-
TESCAN MIRA3), energy dispersive X-ray (EDX, FESEM-
TESCAN MIRA3) and vibrating sample magnetometer
(VSM, MDKFD).
DOP-BenPyr-M(II) (M=Ni or Cu)] (0.01 g) at room temper-
ature under solvent-free conditions. After completion of the
reaction (monitored by TLC), the catalyst was separated by
an external magnet, then CH2Cl2 (4×5 mL) was added and
the mixture was washed with water (20 mL) and decanted.
The organic solvent was dried over anhydrous Na2SO4, then,
the mixture was fltered and solvent was evaporated to pro-
duce sulfoxides.
2.2 Synthesis of catalyst
For the synthesis of magnetic Fe3O4 nanoparticles, the mix-
ture of FeCl3·6H2O (5.858 g) and FeCl2·4H2O (2.221 g) in
100 mL deionized water was stirred until the salts dissolved
completely. Then, 10 mL of 30% aqueous ammonia was
added in to the reaction mixture under N2 atmosphere about
30 min at 80 °C under vigorous mechanical stirring. Finally,
the black precipitate of MNPs was collected and washed
with doubly distilled water [19]. Then for the coating of
a layer of silica on the surface of the Fe3O4 nanoparticles,
magnetic Fe3O4 nanoparticles (1 g) were dispersed in 10 mL
deionized water and 50 mL absolute ethanol, and sonicated
for 30 min. After sonication of MNPs, 5.39 g PEG, 10 mL
NH3 and 2 mL tetraethylorthosilicate (TEOS) was added
to the reaction mixture and stirred at room temperature for
38 h. Finally, the product (Fe3O4@SiO2) was isolated by
external magnet, washed with deionized water and ethanol
and dried at room temperature. The resultant product in the
previous step (Fe3O4@SiO2, 1 g) was dispersed in 25 mL
absolute ethanol using an ultrasonic bath for 30 min. Then
1.5 g of 4-(2-aminoethyl) benzene-1,2-diol (dopamine) was
added to the reaction mixture and stirred at room tempera-
ture for 24 h. The solid product was separated by an external
magnet and washed with ethanol to remove unreacted spe-
cies and dried at room temperature.
2.4 General Procedure for the Oxidative Coupling
of Thiols
In the typical procedure for oxidative coupling of thiols,
0.01 g Fe3O4@SiO2@DOP-BenPyr-M(II) (M=Ni or Cu) as
catalyst was added to a mixture of thiol (1 mmol), 0.4 mL
H2O2 and PEG and stirred at room temperature. The pro-
gress was monitored by TLC. After the completion of the
reaction, the catalyst was separated by an external magnet,
then product extracted with CH2Cl2 (4×5 mL). Anhydrous
Na2SO4 was used for drying of the organic layer, then, the
mixture was fltered and solvent was evaporated to obtain
the disulfde product.
2.5 General Procedure for the Preparation
of 2,3‑Dihydroquinazolin‑4(1H)‑ones
A mixture of 2-aminobenzamide (1.2 mmol), aldehydes
(1 mmol) and catalyst (Fe3O4@SiO2@DOP-BenPyr-Ni(II)
0.03 g) was stirred under solvent-free condition at 110 °C for
the appropriate time. After completion of the reaction (TLC
monitoring), the reaction mixture was cooled down to room
temperature and the crude product extracted by ethanol. At
the end, catalyst was separated using an external magnet,
washed with ethanol. The fltrate was evaporated to remove
solvent, and the crude solid product was recrystallized with
ethanol to aford pure 2,3-dihydroquinazolin-4(1H)-ones in
90–98% yields.
Then, 1 g of Fe3O4@SiO2@DOP was dispersed in 25 mL
absolute ethanol using an ultrasonic bath for 30 min. Then
2-benzoyl pyridine (2 mmol) and acetic acid (0.3 mL) were
added to mixture reaction and stirred in refux condition for
48 h. The solid product washed with ethanol and dried to
obtain the corresponding Fe3O4@SiO2@DOP-BenPyr.
In the fnal step, for the preparation of the catalysts,
Fe3O4@SiO2@DOP-BenPyr (1 g) was dispersed in 25 mL
absolute ethanol, and sonicated for 30 min. For the synthe-
sis of Fe3O4@SiO2@DOP-BenPyr-Ni(II), Ni(NO3)2·6H2O
(2 mmol) was added to the solution and stirred for 48 h in the
refux condition. Also for the preparation of Fe3O4@SiO2@
DOP-BenPyr-Cu(II), the Cu salt (Cu(NO3)2·3H2O, 3 mmol)
was applied. In the end of the procedure, the resultant solid
was separated with an external magnet, washed with ethanol
and dried at room temperature.
2.6 General Procedure for the Preparation
of Polyhydroquinoline Derivatives
A mixture of aldehyde (1 mmol), dimedone (1 mmol), ethyl
acetoacetate (1 mmol) and ammonium acetate (1.2 mmol)
was added to 0.03 g catalyst [Fe3O4@SiO2@DOP-BenPyr-
Ni(II)]. Then the reaction mixture was stirred at 100 °C
under solvent-free condition and the progress of the reac-
tion was monitored by TLC. The resulting solid product was
dissolved in the ethanol. Then, the catalyst was separated
by an external magnet and washed with ethanol. Also the
solvent was evaporated and the product was recrystallized
with ethanol for further purifcation, and the pure polyhyd-
roquinoline derivatives were obtained in good to excellent
yields (90–98%).
2.3 General Procedure for the Oxidation of Sulfdes
A mixture of sulfde (1 mmol) and H2O2 30% (0.4 mL)
was stirred in the presence of catalyst [Fe3O4@SiO2@
1 3

M. Hajjami et al.
2.7 General Procedure for Preparation
of 5‑Substituted 1H‑Tetrazoles
3 Result and Discussion
3.1 Preparation of Fe3O4@SiO2@DOP‑BenPyr‑M(II)
(M=Ni and Cu)
A mixture of sodium azide (1.1 mmol) and nitrile (1 mmol)
in the presence of 0.05 g of catalyst [Fe3O4@SiO2@DOP-
BenPyr-Ni(II)], was stirred at 120 °C in PEG-400. After
completion of the reaction (observed by TLC), the reaction
mixture was cooled down, and catalyst was isolated by an
external magnet, then 10 mL HCl (4N) and 20 mL H2O
was added to the residue solution. The products extracted
with ethyl acetate (20 mL). The organic solvent was dried
over anhydrous sodium sulfate, and concentrated to give
the crude solid product. The precipitate was crystallized in
a mixture of water and ethanol, and the pure 5-substituted
1H-tetrazoles were obtained in good to excellent yields
(70–94%).
In this paper we report novel and recoverable magnetite
nanocatalysts for oxidation of sulfdes to sulfoxides, oxida-
tive coupling of thiols to disulfdes, synthesis of 2,3-dihy-
droquinazolin-4(1H)-ones, 5-substituted 1H-tetrazoles and
polyhydroquinolines. These catalysts were synthesised by
the concise route outlined in Scheme 1. In order to prepare
Fe3O4@SiO2@DOP-BenPyr-M(II) (M=Ni and Cu), initially
magnetic nano particles of Fe3O4 has been synthesised by
a mixture of FeCl3·6H2O, FeCl2·4H2O in aqueous ammo-
nia under N2 atmosphere at 80 °C, then was coated with
TEOS. In the next step, the resultant product was reacted
with dopamine to aford MNPs@SiO2@DOP. The MNPs@
SiO2@DOP-BenPyr was prepared using reaction of MNPs@
SiO2@DOP with 2-benzoyl pyridine. In this step, the NH2
group of dopamine reacted with carbonyl group of 2-ben-
zoyl pyridine. Finally, for the synthesis of MNPs@SiO2@
DOP-BenPyr-Ni(II), the Ni(NO3)2·6H2O was applied. Also
Scheme 1 Synthesis of Fe3O4@
SiO2@DOP-BenPyr-M(II)
(M=Ni and Cu)
1 3

Synthesis and Characterization of Magnetic Functionalized Ni and Cu Nano Catalysts and Their…
for synthesis of MNPs@SiO2@DOP-BenPyr-Cu(II), the
Cu(NO3)2·3H2O was applied.
each of them contributed to stretching vibration of C–N
and bending of NH respectively. The spectrum of Fe3O4@
SiO2@DOP-BenPyr (Fig. 2c) indicates peak at 1623 cm−1
is assigned to the stretching of the C=N bond in the imine.
As shown in Fig. 2d, FT-IR spectra for Fe3O4@SiO2@
DOP-BenPyr-Ni(II) indicate several peaks such as: Fe–O
vibration, asymmetric and symmetric stretching vibration
of Si–O–Si, stretching of the C=N bond and C–H stretching
that each of the bonds show peaks at 588, 803–1094, 1626
and 2882–2986 cm−1. Coordination of the nitrogen with the
metal of nickel leads to shift the C=N bond. Eventually, we
investigate the FT-IR spectra of Fe3O4@SiO2@DOP-Ben-
Pyr-Cu(II). In this spectrum the adsorption band appears at
590 cm−1, assign to Fe–O vibrations. Also, asymmetric and
symmetric stretching vibration of Si–O–Si clear at 802 and
1097 cm−1. The peak appears at around 2873–2982 cm−1
corresponds to the aliphatic C–H stretching. In this spec-
trum, stretching of the C=N bond is shifted to 1627 cm−1
which is due to coordination of the nitrogen with the metal.
4 Catalyst Characterization
4.1 X‑ray Difraction (XRD)
After synthesis of the two nanocatalyst, we were character-
ized their by XRD, FT-IR, SEM, EDX, TGA, ICP and VSM
techniques. Figure 1 indicated the XRD pattern of Fe3O4,
Fe3O4@SiO2@DOP-BenPyr-Ni(II) and Fe3O4@SiO2@
DOP-BenPyr-Cu(II). This pattern indicated that the surface
modifcation of the Fe3O4 nanoparticles does not lead to
their phase change and the XRD patterns of two catalysts are
in accord with standard XRD pattern of Fe3O4.
4.2 FT‑IR Spectroscopy
Figure 2 shows FT-IR spectra for the Fe3O4@SiO2, Fe3O4@
SiO2@DOP, Fe3O4@SiO2@DOP-BenPyr, Fe3O4@SiO2@
DOP-BenPyr-Ni(II) and Fe3O4@SiO2@DOP-BenPyr-
Cu(II). The FT-IR spectra of Fe3O4@SiO2 show the peak
at 584 cm−1 contributed to the Fe–O vibration. The peaks
appeared at 1094 and 802 cm−1 corresponding to the asym-
metric and symmetric stretching vibration of Si–O–Si bond
respectively. Also the bands indicted at 3440 and 1624 cm−1
are, respectively, assigned to the O–H bonds which are
attached to the surface iron atoms and deforming vibrations
of adsorbed water. Figure 2b, is contributed to Fe3O4@
SiO2@DOP. The presence of the linked dopamine groups
are confrmed by C–H symmetric stretching vibrations that
appear at 2830–2905 cm−1 and also, the N–H stretching
vibration modes as a broad band that appear at 3403 cm−1.
This curve also shows the peaks at 1442 and 1620 cm−1
4.3 Scanning Electron Microscopy (SEM)
The surface morphology and particle sizes of the synthe-
sized catalysts were determined using SEM. The SEM
images of Fe3O4@SiO2@DOP-BenPyr-Ni(II) (Fig. 3a) and
Fe3O4@SiO2@DOP-BenPyr-Cu(II) (Fig. 3b) showed that
the catalysts were made up of uniform-sized particle with
a size less than 8 and 13 nm respectively. Also the shapes
of them are spherical with uniform size, and showed good
dispersity.
4.4 Energy Dispersive X‑ray (EDX)
For the confrmation of the kinds of elements present in
synthesized catalysts, the energy dispersive X-ray (EDX)
spectrum employed. As shown in Fig. 4a, the EDX spectrum
of Fe3O4@SiO2@DOP-BenPyr-Ni(II) indicates the several
elements such as: C, N, O, Si, Fe and Ni. Also the EDX
spectrum of Fe3O4@SiO2@DOP-BenPyr-Cu(II), shows the
elements of C, N, O, Si, Fe and Cu (Fig. 4b).
700
Fe3o4
600
Ni catalyst
Cu catalyst
500
400
300
200
100
0
4.5 Thermo Gravimetric Analysis (TGA)
The thermo gravimetric analysis (TGA) curve can be
showed the mass loss of the organic materials as they
decompose upon heating. As shown in Fig. 5, for the syn-
thesized catalysts, two weight loss steps were observed. The
frst mass loss at temperatures below 200 °C is contributed
to the removal of physically adsorbed surface hydroxyl
groups and solvent. The second mass loss contributed to
the thermal decomposition of organic groups grafted to
Fe3O4. The weight loss of 6% observed for Fe3O4@SiO2@
DOP-BenPyr-Ni(II) between 225 and 430 °C. Also the mass
0
20
40
2θ /degree
60
80
100
Fig. 1 XRD pattern of Fe3O4, Fe3O4@SiO2@DOP-BenPyr-Ni(II) and
Fe3O4@SiO2@DOP-BenPyr-Cu (II)
1 3

M. Hajjami et al.
Fig. 2 FT-IR spectra for the
Fe3O4@SiO2 (a), Fe3O4@
SiO2@DOP (b), Fe3O4@SiO2@
DOP-BenPyr (c), Fe3O4@
SiO2@DOP-BenPyr-Ni(II) (d)
and Fe3O4@SiO2@DOP-Ben-
Pyr-Cu(II) (e)
loss of 5% observed for Fe3O4@SiO2@DOP-BenPyr-Cu(II)
between 240 and 440 °C. These results were confrmed that
the organic moieties have been supported on the surface of
Fe3O4 nanoparticles.
4-chlorobenzaldehyde with dimedone, ethylacetoacetate and
ammonium acetate was determined by ICP that was found
to be 0.0145 mol g−1 (0.4% leaching). These results from
ICP were showed that leaching of nickel during the reaction
is insignifcant, so the catalyst can be recovered and reused
several times.
4.6 Inductively Coupled Plasma Atomic Emission
Spectroscopy (ICP‑OES)
4.7 Vibrating Sample Magnetometry (VSM)
For the investigation of metal content in two synthesized
catalysts, we were applied inductively coupled plasma
atomic emission spectroscopy (ICP-OES). According to the
ICP-OES analysis, the exact amount of Cu in the catalyst
was obtained to be 0.0115 mol g−1. Also the Ni amount in
the Fe3O4@SiO2@DOP-BenPyr-Ni(II) was obtained to be
0.0153 mol g−1. In order to shown the analysis of leaching in
catalyst, the amount of Ni in recycled catalyst in reaction of
Figure 6 indicated the vibrating sample magnetometer
(VSM) analysis for Fe3O4, Fe3O4@SiO2@DOP-BenPyr-
Ni(II) and Fe3O4@SiO2@DOP-BenPyr-Cu(II). This analysis
is employed to measure the magnetic properties of catalysts.
This is clear that the bare MNPs showed the higher magnetic
value in comparison with functionalized Fe3O4, this result is
due to the coated silica and the layer that grafted to support.
1 3

Synthesis and Characterization of Magnetic Functionalized Ni and Cu Nano Catalysts and Their…
Fig. 3 SEM images of the Fe3O4@SiO2@DOP-BenPyr-Ni(II) (a) and
Fe3O4@SiO2@DOP-BenPyr-Cu(II) (b)
Fig. 4 EDX spectrum of Fe3O4@SiO2@DOP-BenPyr-Ni(II) (a) and
Fe3O4@SiO2@DOP-BenPyr-Cu(II) (b)
5 Catalytic Studies
After characterization of Fe3O4@SiO2@DOP-BenPyr-Ni(II)
and Fe3O4@SiO2@DOP-BenPyr-Cu(II), their catalytic
activity was investigated in some organic reactions.
First, oxidation of sulfdes was examined. In this light,
initially the reaction conditions were optimized by reaction
of methyl phenyl sulfde (1 mmol), 30% H2O2 and Fe3O4@
SiO2@DOP-BenPyr-M(II) (M=Ni or Cu) as a model reac-
tion in the presence of diferent organic solvents. As shown
in Table 1, solvent free condition is the best choice. Then
efect of catalysts on the synthesis of sulfoxides was studied
by varying amount of them. The results show that 0.01 g of
Fe3O4@SiO2@DOP-BenPyr-M(II) (M=Ni or Cu) was found
to be the most efective (Table 1, entry 4).
The optimal conditions for the oxidation of sulfides
obtained (Table 1, entry 4) and we explored the scope to
study the oxidation of other sulfdes. Finally, a wide range of
aromatic and aliphatic sulfdes were applied and successfully
Fig. 5 TGA profle of Fe3O4, Fe3O4@SiO2@DOP-BenPyr-Ni(II) and
Fe3O4@SiO2@DOP-BenPyr-Cu(II)
1 3

M. Hajjami et al.
100
80
conditions, a mixture of 4-methylthiophenol (1 mmol),
H2O2 and Fe3O4@SiO2@DOP-BenPyr-M(II) (M=Ni or
Cu) as catalyst at room temperature applied as a model
reaction in the presence of several organic solvents. As
shown in Table 3, entry 4, PEG showed better results in
terms of the reaction yield and rate. Then the efect of vari-
ous amount of catalysts investigated and the best results
were obtained in 0.01 g of Fe3O4@SiO2@DOP-BenPyr-
M(II) (M=Ni or Cu) (Table 3, entry 4).
60
40
20
0
-10000
-5000
0
5000
Fe3O4
10000
-20
-40
-60
-80
-100
Ni catalyst
Cu catalyst
Then oxidative couplings of other thiols were tested
(Scheme 3). Results indicated that disulfdes produced in
high yields (Table 4).
H (Oe)
Proposed mechanism for oxidation of sulfdes and oxida-
tive coupling of thiols in the presence of Fe3O4@SiO2@
DOP-BenPyr-M(II) (M=Ni or Cu) indicated in Scheme 4.
At frst, the reaction of H2O2 with synthesized catalyst leads
to the synthesis of intermediate A that converted to active
oxidant B. Then, nucleophilic reaction of the sulfde or thiol
with intermediate B occurs to obtain the cations of C and D.
Finally, these cations converted to corresponding products
[43].
Fig. 6 VSM analysis of the Fe3O4, Fe3O4@SiO2@DOP-BenPyr-
Ni(II) and Fe3O4@SiO2@DOP-BenPyr-Cu(II)
Table 1 Optimization of the reaction conditions for the synthe-
sis of sulfoxide with methyl phenyl sulfde, H2O2 in the presence of
Fe3O4@SiO2@DOP-BenPyr-M(II) (M=Ni or Cu) as catalyst
Entry
Solvent
Catalyst (g)
M=Ni/Cu
Time (min)
M=Ni/Cu
Yield (%)a
M=Ni/Cu
M=Ni/Cu
In the next section of work, synthesis of 2,3-dihydro-
quinazolin-4(1H)-ones, polyhydroquinolines and 5-substi-
tuted 1H-tetrazoles in the presence of Fe3O4@SiO2@DOP-
BenPyr-Ni(II) was investigated.
1
2
3
4
5
6
7
8
9
Solvent free
Solvent free
Solvent free
Solvent free
Solvent free
Ethanol
0
30
Trace
56/48
74/69
98/96
97/97
40/38
63/58
0.0025
0.005
0.01
0.015
0.01
0.01
0.01
0.01
0.01
20/30
20/30
20/30
20/30
20/30
20/30
20/30
20/30
20/30
Initially, the prepared catalyst has been employed for the
synthesis of 2,3-dihydroquinazolin-4(1H)-ones (Scheme 5).
The optimized reaction conditions were applied to the
reaction between benzaldehyde and 2-aminobenzamide
for synthesis of 2-(phenyl)-2,3-dihydroquinazolin-4(1H)-
one (Table 5). In this light, various amounts of catalyst
[Fe3O4@SiO2@DOP-BenPyr-Ni(II)] and diferent solvent
were screened at diferent temperatures. It is obvious that the
best result is obtained when using the 0.03 g catalyst under
solvent-free condition at 110 °C for 1 h (Table 5, entry 3).
After the optimization of the reaction condition, 2,3-dihy-
droquinazolin-4(1H)-one derivatives (3a–3j) have been
synthesized using the optimum conditions and the products
were obtained in high yields. The turnover frequency (TOF)
is reported in h–1 and showed the efciency of the catalyst.
The results of these studies are summarized in Table 6.
The proposed mechanism for synthesis of 2,3-dihydro-
quinazolin-4(1H)-one showed in Scheme 6. Based on this
scheme, the 2-aminobezamide reacted with the activated
aldehyde and the intermediate E produced. Then dehydra-
tion of intermediate E occurred to formed imine intermedi-
ate F. Finally, the intramolecular cyclization of imine inter-
mediate F produced the fnal product [44].
H2O
EtOAc
CH2Cl2
n-Hex
Trace/trace
45/41
31/trace
10
Methyl phenyl sulfde (1 mmol), H2O2 (0.4 mL), solvent (3 mL), r.t
aPure yield
O
Fe3O4@SiO2@DOP-BenPyr-M(II)
H2O2 , Solvent free, r.t
S
S
R'
R''
R'
R''
R', R'' = aryl, alkyl
1a-1i
Scheme 2 Synthesis of sulfoxides
converted to the corresponding sulfoxides (Scheme 2). The
results are indicated in Table 2.
Then, in order to found the optimum conditions for syn-
thesis of polyhydroquinolines the reaction between 4-chlo-
robenzaldehyde, dimedone and ethyl acetoacetate was used
In second part of our search, we have focused on the
utility of these catalysts for oxidation of thiols to cor-
responding disulfdes. Initially, to optimize the reaction
1 3

Synthesis and Characterization of Magnetic Functionalized Ni and Cu Nano Catalysts and Their…
Table 2 Oxidation of sulfdes to the corresponding sulfoxides
Entry
Substrate
Product
Time (min)
M=Ni/Cu
Yield (%)a
M=Ni/Cu
M.p (ºC)
M=Ni/Cu
TOF (h−1
M=Ni/Cu
)
References
1
2
3
4
5
6
7
8
9
Dibenzyl sulfde
1a
1b
1c
1d
1e
1f
1g
1h
1i
25/35
20/30
5/7
10/15
85/90
5/5
10/15
5/10
45/60
97/94
98/96
90/89
93/93
96/96
95/95
96/93
90/92
95/92
130–131/130–131
32/33
Oil/oil
Oil/oil
Oil/oil
Oil/oil
Oil/oil
Oil/oil
60–65/62–64
15.21/14.01
19.21/16.69
70.58/66.33
36.47/32.34
4.42/5.56
74.50/99.13
37.64/32.34
70.58/48
[39]
[40]
[40]
[40]
[40]
[40]
[40]
[40]
[40]
Methyl phenyl sulfde
Tetrahydrothiophene
Dimethyl sulfde
2-(Phenylthio)ethanol
Diallyl sulfde
Dipropyl sulfde
2-(Methylthio)ethanol
Dodecyl methyl sulfde
8.27/8
Reaction conditions: sulfde (1 mmol), H2O2 (0.4 mL), Fe3O4@SiO2@DOP-BenPyr-M(II) (M=Ni or Cu) (0.01 g), solvent free, r.t
aPure yield
Table 3 Optimization of the reaction conditions for the synthesis
of disulfdes with 4-methylthiophenol and H2O2 in the presence of
Fe3O4@SiO2@DOP-BenPyr-M(II) (M=Ni or Cu) as catalyst
0.03 g catalyst and 1.2 mmol ammonium acetate, the best
results were obtained in solvent-free condition at 100 °C
after 120 min (Table 7, entry 3).
Entry Solvent
Catalyst
(g)
H2O2
(mL)
Time
(min)
Yield (%)a
After optimization the reaction, we assessed the reaction
of diferent electron-withdrawing and electron-donating
substituted aldehyde (Scheme 7). As shown in Table 8 the
wide range of polyhydroquinoline derivatives (4a–4j) were
obtained in excellent yields (90–98%).
M=Ni/Cu
M=Ni/Cu M=Ni/Cu
1
2
3
4
5
6
7
8
9
PEG
PEG
PEG
PEG
PEG
PEG
PEG
PEG
0
0.4
0.4
0.4
0.4
0.4
0.4
0.3
0.5
0.4
15
0
0.005
0.0075
0.01
0.015
0.02
0.01
0.01
0.01
10/15
10/15
10/15
10/15
10/15
10/15
10/15
10/15
69/64
83/78
98/96
97/97
96/96
75/69
98/98
48/43
As shown in Scheme 8, the proposed mechanism for syn-
thesis of polyhydroquinolines was indicated. Knoevenagel
condensation between aldehydes and active methylene com-
pounds produced the α,β-unsaturated compound. Then, the
Michael-type addition of the resultant intermediates occur
to form the fnal product [44].
In this part, for synthesis of 5-substituted 1H-tetrazoles,
we chose phenyl cyanide to react with sodium azide in the
presence of various amounts of Fe3O4@SiO2@DOP-Ben-
Pyr-Ni(II) as a model reaction (Table 9). We examined the
efects of various solvents such as DMSO, EtOH and PEG,
and diferent temperatures. Reaction in the PEG was cho-
sen as an efective medium for this reaction. As shown in
Table 9, 0.05 g catalyst at 120 °C in PEG were found to be
the ideal reaction conditions for the synthesis of 5-substi-
tuted 1H-tetrazoles (Table 9, entry 4).
Solvent
free
10
11
12
Ethanol
H2O
CH2Cl2
0.01
0.01
0.01
0.4
0.4
0.4
10/15
10/15
10/15
69/65
37/33
Trace/trace
4-Methylthiophenol (1 mmol), solvent (3 mL) and r. t
aPure yield
Fe3O4@SiO2@DOP-BenPyr-M(II)
R SH
After optimization the reaction, as shown in Table 10 the
wide range of nitriles were employed to aford the corre-
sponding 5-substituted 1H-tetrazole derivatives (Scheme 9).
The derivatives of 5-substituted 1H-tetrazole (5a–5h) were
synthesized in good to excellent yields (70–94%).
RS SR
2a-2i
H2O2 , PEG, r.t
R=aryl, alkyl
Scheme 3 Synthesis of disulfdes
A proposed mechanism for the preparation of 5-substi-
tuted1H-tetrazol is shown in Scheme 10. Initially, activated
nitrile reacted with sodium azide to aford the intermediate
G. Finally the intermediate G converted to compound H
as a model reaction in the presence of various amounts of
catalyst, ammonium acetate and diferent solvents and tem-
peratures (Table 7). It was observed that in the presence of
1 3

M. Hajjami et al.
Table 4 Oxidative coupling of thiols to the corresponding disulfdes
Entry
Substrate
Product
Time (min)
M=Ni/Cu
Yield (%)a
M=Ni/Cu
M.p (°C)
M=Ni/Cu
TOF (h−1
M=Ni/Cu
)
References
1
2
3
4
5
6
7
8
9
4-Methylthiophenol
Thioglycolic acid
2-Mercaptoethanol
2-Mercaptobenzothiazole
Thiophenol
2-Naphtalenethiol
2-Mercaptobenzoxazole
Thiosalicylic acid
2-Aminothiophenol
2a
2b
2c
2d
2e
2f
2g
2h
2i
10/15
7/10
5/10
15/25
3/5
60/75
15/20
10/15
20/25
98/96
90/93
95/92
98/96
96/92
98/97
97/95
96/96
93/90
36–38/35–38
Oil/oil
Oil/oil
176/177
53–55/53–55
135/133
85–88/87–88
277/276
80–84/80–82
38.43/33.39
50.42/48.52
74.50/48
25.62/20.03
125.49/96
[40]
[40]
[40]
[41]
[42]
[40]
[40]
[40]
[40]
6.40/6.74
25.35/24.78
37.64/33.39
18.23/18.78
Reaction conditions: thiol (1 mmol), H2O2 30% (0.4 mL) and Fe3O4@SiO2@DOP-BenPyr-M(II) (M=Ni or Cu) (0.01 g), r.t and PEG (3 mL)
aPure yield
that the 5-substituted 1H-tetrazoles was obtained with rear-
Fe3O4@SiO2@DOP-BenPyr-M(II)
O
rangement [45].
M= Ni or Cu
S
M
R'
R''
S
R
R
S
H2O2
6 Recyclability of the Catalysts
S
R'
R
H
M
O
S
O
M
Recyclability and reusability of the catalysts was studied
for oxidation of tetrahydrothiophene under the optimization
conditions. After completion of the reaction, the catalyst was
separated from the reaction mixture by an external magnet,
then the product was extracted with CH2Cl2 (4×5 mL) and
water (20 mL). Anhydrous Na2SO4 was used for dried of the
organic phase, fltered and solvent was evaporated. Finally,
the separated catalysts were dried and reused for the same
reaction again. As shown in Fig. 7, the two catalysts were
recovered and reused fve times without signifcant loss of
catalytic efciency.
R
H
H
R''
C
O
A
M
O
S
D
R'
S
R
H
M
O
S
R''
M
O
+ H2O
B
S
R'
R''
Scheme 4 Proposed mechanism for oxidation of sulfdes and oxida-
tive coupling of thiols in the presence of Fe3O4@SiO2@DOP-Ben-
Pyr-M(II) (M=Ni or Cu)
Also reusability of the Fe3O4@SiO2@DOP-BenPyr-
Ni(II) was tested for synthesis of polyhydroquinoline.
Scheme 5 Synthesis of 2,3
O
O
dihydroquinazolin-4(1H)-ones
O
NH2
Fe3O4@SiO2@DOP-BenPyr-Ni(II)
Solvent-Free, 110 oC
NH
Ar
H
+
NH2
N
H
Ar
3a- 3j
1 3

Synthesis and Characterization of Magnetic Functionalized Ni and Cu Nano Catalysts and Their…
Table 5 Optimization of the reaction conditions for the synthesis of
2,3-dihydroquinazolin-4(1H)-ones with benzaldehyde, 2-aminoben-
zamide in the presence of Fe3O4@SiO2@DOP-BenPyr-Ni(II) as cata-
lyst
Reusability of the Fe3O4@SiO2@DOP-BenPyr-Ni(II) was
confrmed by the reaction of 4-chlorobenzaldehyde with
dimedone, ethylacetoacetate and ammonium acetate as a
model reaction in solvent-free condition at 100 °C. After
completion of the reaction, catalyst was separated magneti-
cally and washed several times with ethanol to removal of
any organic residuals. The separated catalyst was reused for
many times in the next cycles without any signifcant loss of
its activity. The results shown in Fig. 7.
Entry
Catalyst (g)
Tempera-
ture (°C)
Solvent
Yield (%)a
1
2
3
4
5
6
7
8
0.01
0.02
0.03
0.04
0.05
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
110
110
110
110
110
78
100
110
77
60
80
100
120
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
EtOH
H2O
PEG
EtOAc
Solvent-free
Solvent-free
Solvent-free
Solvent-free
37
68
94
93
90
64
81
58
Trace
Trace
48
83
95
7 Comparison Results of Fe3O4@SiO2@
DOP‑BenPyr‑M(II) (M=Ni, Cu) with Other
Catalysts
9
To demonstrate the merit of the synthesized catalysts in
this work, the result of oxidation of methyl phenyl sulfde
(Table 11, entry 1–4), synthesis of 2,3-dihydroquinazolin-
4(1H)-one (Table 11, entry 5–7), synthesis of polyhydroqui-
noline (Table 11, entry 8–10) and synthesis of 5-substituted
1H-tetrazole (Table 11, entry 11–13) compared with the
previous reported in the literature. These results indicated
the efciency of the proposed methodology in terms of the
10
11
12
13
Reaction conditions: benzaldehyde (1 mmol), 2-aminobenzamide
(1.2 mmol), 1 h
aPure yield
Table 6 Synthesis of
2,3-dihydroquinazolin-4(1H)-
one derivatives
Entry Ar
Product Time (min) Yield (%)a TOF (h−1
)
M.p
References
1
2
3
4
5
6
7
8
9
10
C6H5
4-ClC6H4
4-BrC6H4
2-NO2C6H4
3-NO2C6H4
4-FC6H4
3a
3b
3c
3d
3e
3f
60
90
85
180
160
120
65
94
94
92
90
95
92
98
96
98
95
2.04
1.36
1.41
0.65
0.77
1
1.97
1.79
1.83
2.06
225–227 [44]
200–202 [19]
197–199 [44]
190–191 [19]
204–205 [19]
195–197 [44]
189–191 [21]
211–213 [19]
230–232 [44]
170–173 [19]
4-OCH3C6H4
3g
3,4-(OCH3)2C6H3 3h
4-CH3C6H4 3i
4-OCH2CH3C6H4 3j
70
70
60
Reaction conditions: aldehyde (1 mmol), 2-aminobezamide (1.2 mmol), solvent-free, Fe3O4@SiO2@DOP-
BenPyr-Ni(II) (0.03 g) and 110 °C
aPure yield
1 3

M. Hajjami et al.
Table 7 Optimization of the reaction conditions for the synthesis of
polyhydroquinoline with 4-chlorobenzaldehyde, dimedone, ethyl ace-
toacetate and ammonium acetate in the presence of Fe3O4@SiO2@
DOP-BenPyr-Ni(II) as catalyst
Ni
O
OH
N
H
O
NH2
+
N
OH
Ar
Yield (%)a
Ar
H
Entry Catalyst (g) Ammonium Tem-
Solvent
NH2
acetate
(mmol)
perature
H
(°C)
Ni
E
1
2
3
4
5
0.01
0.02
0.03
0.04
0.05
1.2
1.2
1.2
1.2
1.2
100
Solvent-
free
37
68
98
93
90
-H2O
100
100
100
100
Solvent-
free
O
OH
Solvent-
free
NH
NH
Solvent-
free
N
H
Ar
N
Ar
Solvent-
free
EtOH
H2O
PEG
EtOAc
Ni
6
7
8
9
0.03
0.03
0.03
0.03
0.03
1.2
1.2
1.2
1.2
1.2
78
100
100
77
81
Trace
78
38
Trace
F
Fe3O4@SiO2@DOP-BenPyr-Ni(II)
Ni
10
60
Solvent-
free
11
12
13
14
15
16
0.03
0.03
0.03
0.03
0.03
0.03
1.2
1.2
1.2
1.2
1
80
90
Solvent-
free
64
87
97
95
71
85
Scheme 6 Proposed mechanism for synthesis of 2,3-dihydroquinazo-
lin-4(1H)-one in the presence of Fe3O4@SiO2@DOP-BenPyr-Ni(II)
Solvent-
free
110
120
100
100
Solvent-
free
Solvent-
free
Solvent-
free
1.1
Solvent-
free
Reaction conditions: 4-chlorobenzaldehyde (1 mmol), dimedone
(1 mmol), ethyl acetoacetate (1 mmol) and 2 h
aPure yield
1 3

Synthesis and Characterization of Magnetic Functionalized Ni and Cu Nano Catalysts and Their…
Ar
O
O
O
O
O
OEt
Fe3O4@SiO2@DOP-BenPyr-Ni(II)
Solvent-Free, 100 oC
Ar-CHO
NH4OAc
+
+
+
OEt
N
H
O
4a-4j
Scheme 7 Synthesis of polyhydroquinolines
Table 8 Synthesis of
Entry Ar
Product Time (min) Yield (%)a TOF (h−1
)
M.p
References
polyhydroquinoline derivatives
1
2
3
4
5
6
7
8
9
10
C6H5
4a
4b
4c
4d
4e
4f
110
120
150
180
220
160
130
120
140
130
90
98
90
90
95
92
94
97
96
92
1.06
1.06
0.78
0.65
0.56
0.75
0.94
1.05
0.89
0.92
216–218 [19]
237–239 [19]
249–251 [19]
227–229 [19]
176–179 [19]
183–185 [44]
247–249 [19]
204–207 [44]
253–255 [19]
178–174 [44]
4-ClC6H4
4-BrC6H4
3-OHC6H4
3-NO2C6H4
4-FC6H4
4-OCH3C6H4
2g
3,4-(OCH3)2C6H3 4h
4-CH3C6H4 4i
4-OCH2CH3C6H4 4j
Reaction conditions: aldehyde (1 mmol), dimedone (1 mmol), ethyl acetoacetate (1 mmol), ammonium
acetate (1.2 mmol), solvent-free, Fe3O4@SiO2@DOP-BenPyr-Ni(II) (0.03 g) and 100 °C
aPure yield
Scheme 8 Proposed mechanism
for synthesis of polyhydro-
quinolines in the presence of
Fe3O4@SiO2@DOP-BenPyr-
Ni(II)
O
O
Ar
OEt
Ni
+
H2N
O
O
NH4OAc.Cat
O
Ar
H
OEt
O
Ar
O
O
O
OEt
Ni
N
H
O
O
Ar
H
O
Ar
O
NH4OAc. Cat
OEt
+
NH2
O
Fe3O4@SiO2@DOP-BenPyr-Ni(II)
Ni
1 3

M. Hajjami et al.
Table 9 Optimization of the reaction conditions for the synthesis of
5-substituted 1H-tetrazoles with phenyl cyanide and sodium azide in
the presence of Fe3O4@SiO2@DOP-BenPyr-Ni(II) as catalyst
N N
N
NH
CN
Fe3O4@SiO2@DOP-BenPyr-Ni(II)
PEG, HCl, 120 oC
Entry
Catalyst (g)
Temperature Solvent
(°C)
Yield (%)a
NaN3
+
R
R
5a- 5h
1
2
3
4
5
6
7
8
9
0
120
120
120
120
120
120
100
70
PEG
PEG
PEG
PEG
DMSO
EtOH
PEG
PEG
PEG
Trace
64
92
93
25
Trace
68
Trace
0
0.01
0.03
0.05
0.05
0.05
0.05
0.05
0.05
Scheme 9 Synthesis of 5-substituted 1H-tetrazoles
r.t
Ni
N
N
N
HN
N
Ar
C
N
NH
N
N
NaN3
Reaction conditions: phenyl cyanide (1 mmol), sodium azide
(1.1 mmol) and time 40 min
Ar
Ar
aPure yield
H
Na
N
HCl
N
Ni
N
N
Na+
N
N
Ar
Ni
N
N
Ar
G
Fe3O4@SiO2@DOP-BenPyr-Ni(II)
Ni
Scheme10 Proposed mechanism for synthesis of 5-substituted
1H-tetrazoles in the presence of Fe3O4@SiO2@DOP-BenPyr-Ni(II)
Table 10 Synthesis of
5-substituted 1H-tetrazole
derivatives
Entry Nitrile
Product Time (min) Yield (%)a TOF (h−1
)
M.p
References
1
2
3
4
5
6
7
8
C6H5–CN
4-ClC6H4–CN
4-BrC6H4–CN
4-NO2C6H4–CN 5d
3-NO2C6H4–CN 5e
2-OHC6H4–CN
3-ClC6H4–CN
2-ClC6H4–CN
5a
5b
5c
40
110
300
220
600
70
92
83
80
70
85
94
92
90
1.80
0.59
0.20
0.24
0.11
1.05
1.31
1.17
212–214 [44]
259–261 [44]
262–265 [44]
216–219 [44]
150–152 [44]
222–224 [44]
128–130 [44]
177–179 [44]
5f
5g
5h
55
60
Reaction conditions: sodium azide (1.1 mmol), nitrile (1 mmol), PEG, Fe3O4@SiO2@DOP-BenPyr-Ni(II)
(0.05 g) and 120 °C
aPure yield
1 3

Synthesis and Characterization of Magnetic Functionalized Ni and Cu Nano Catalysts and Their…
reaction yield and rate in comparison with other literature
reports.
100
90
80
70
60
50
40
30
20
10
0
96
95
98
94
94
97
93
96
96
94
8 Conclusions
In summary, we have designed two nano catalysts of Fe3O4@
SiO2@DOP-BenPyr-Ni(II) and Fe3O4@SiO2@DOP-Ben-
Pyr-Cu(II). These compounds were efcient, recyclable and
heterogeneous catalysts that employed for the high yielding
and room temperature one-pot procedure for the oxidation
of sulfdes and oxidative coupling of thiols. In addition to,
the catalyst activity of Fe3O4@SiO2@DOP-BenPyr-Ni(II)
was investigated for the synthesis of 2,3-dihydroquinazolin-
4(1H)-ones, polyhydroquinolines and 5-substituted 1H-tetra-
zoles. These most applicable prepared catalysts ofers sev-
eral advantages in various organic reactions, such as short
reaction times, simple workup, simple separation of hetero-
geneous catalysts by external magnet, easy recyclability of
catalysts, and high yields of products. Also the prepared
catalysts were characterized by FT-IR spectroscopy, TGA,
XRD, VSM, EDX, ICP and SEM techniques.
1
2
3
4
5
Run number
100
90
80
70
60
50
40
30
20
10
0
98
97
96
96
94
93
93
1
2
3
4
5
6
7
Run number
Fig. 7 Recyclability of Fe3O4@SiO2@DOP-BenPyr-Ni(II) (red col-
umn) and Fe3O4@SiO2@DOP-BenPyr-Cu(II) (green column) for
oxidation of sulfde and recyclability of Fe3O4@SiO2@DOP-BenPyr-
Ni(II) for synthesis of polyhydroquinoline (blue column)
Table 11 Comparison results of Fe3O4@SiO2@DOP-BenPyr-M(II) (M=Ni, Cu) with other catalysts
Entry
Condition
Time (min)
Yield (%)
References
1
2
3
4
5
6
7
8
TFE/SBA‐15 (0.02 g), r.ta
35
20
20
30
45
50
60
120
215
110
120
420
40
98
97
98
96
90
96
94
97
94
90
92
90
92
[46]
[47]
This work
This work
[22]
[23]
This work
[24]
[23]
This work
[29]
MNP-DABCO tribromide (10 mg), H2O2 30% (2.4 eq), solvent free, r.ta
Fe3O4@SiO2@DOP-BenPyr-Ni(II) (0.01 g), H2O2 30% (0.4 mL), solvent free, r.ta
Fe3O4@SiO2@DOP-BenPyr-Cu(II) (0.01 g), H2O2 30% (0.4 mL), solvent free, r.ta
H3BO3-functionalized MCM-41 (0.01 g), solvent-free, 80 °Cb
Boehmite-SSA (0.03 g), ethanol, 80 °Cb
Fe3O4@SiO2@DOP-BenPyr-Ni(II) (0.03 g), solvent-free, 110 °Cb
Fe3O4-SA-PPCA (0.01 g), EtOH, 50 °Cc
9
Boehmite-SSA (0.03 g), EtOH, 80 °Cc
10
11
12
13
Fe3O4@SiO2@DOP-BenPyr-Ni(II) (0.03 g), solvent-free, 100 °Cc
Cu-MCM-41, DMF, 120 °Cd
Fe3O4@SiO2/Salen Cu(II) (0.02 g), DMF, 120 °Cd
Fe3O4@SiO2@DOP-BenPyr-Ni(II) (0.05 g), PEG, 120 °Cd
[30]
This work
aOxidation of methyl phenyl sulfde
bSynthesis of 2,3-dihydroquinazolin-4(1H)-one by reaction of benzaldehyde with 2-aminobezamide
cSynthesis of polyhydroquinoline by reaction of benzaldehyde with dimedone, ammonium acetate and ethyl acetoacetate
dSynthesis of 5-substituted 1H-tetrazole by reaction of sodium azide with benzonitrile
1 3

M. Hajjami et al.
22. Sivaguru P, Parameswaran K, Kiruthiga M, Vadivel P, Lalitha A
(2015) J. Iran. Chem. Soc. 12:95
Acknowledgements Financial support to this work by the Ilam Univer-
sity and Bu-Ali Sina University is gratefully acknowledged.
23. Ghorbani-Choghamarani A, Tahmasbi B (2016) New J. Chem.
40:1205
Compliance with Ethical Standards
24. Ghorbani-Choghamarani A, Azadi G (2015) RSC Adv. 5:9752
25. Mohammadi Ziarani G (2010) Iran. J. Chem. Chem. Eng. 29:1
26. Pokhodylo NT, Matiichuk VS, Obushak ND (2010) Russian J.
Org. Chem. 46:556
Conflict of Interest Confict of interest authors declare that there is no
confict of interest involved.
27. Patil DR, Deshmukh MB, Dalal DS (2012) J. Iran. Chem. Soc.
9:799
28. Fazeli A, Oskooie HA, Beheshtiha YS, Heravi MM, Valizadeh H,
Bamoharram FF (2013) Monatsh. Chem. 144:1407
29. Abdollahi-Alibeik M, Moaddeli A (2016) J. Chem. Sci. 128:93
30. Dehghani F, Sardarian AR, Esmaeilpour M (2013) J. Organomet.
Chem. 743:87
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Publisher’s Note Springer Nature remains neutral with regard to
jurisdictional claims in published maps and institutional afliations.
Afliations
Maryam Hajjami1 · Shiva Sheikhaei2 · Fatemeh Gholamian2 · Zakieh Yousofvand2
2
* Maryam Hajjami
Department of Chemistry, Faculty of Science, Ilam
University, P.O. Box 69315516, Ilam, Iran
m.hajjami@basu.ac.ir; mhajjami@yahoo.com
1
Department of Organic Chemistry, Faculty of Chemistry,
Bu-Ali Sina University, 6517838683 Hamedan, Iran
1 3