Magnetically thiamine palladium complex nanocomposites as an effective recyclable catalyst for facile sonochemical cross coupling reaction

Article abstract of DOI:10.1002/aoc.4742

The carbon–carbon cross coupling reactions through transition-metal-catalyzed processes has been significantly developed for their important synthetic applications. In this research, we have shown that NiFe₂O₄@TASDA-Pd(0) is a highly active, novel and reusable catalyst with excellent performance for the Mizoroki–Heck coupling reaction of several types of iodo, bromo, and even aryl chlorides in DMF under ultrasound irradiation. The novel palladium catalyst prepared and characterized by using FT-IR spectrum, X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), thermo gravimetric analysis (TGA) and vibrating sample magnetometer (VSM). The catalyst can be recovered and recycled several times without marked loss of activity.

Full text of DOI:10.1002/aoc.4742

Received: 30 May 2018
DOI: 10.1002/aoc.4742
Revised: 31 October 2018
Accepted: 5 November 2018
F U L L P A P E R
Magnetically thiamine palladium complex nanocomposites
as an effective recyclable catalyst for facile sonochemical
cross coupling reaction
Hossein Naeimi
| Fatemeh Kiani
Department of Organic Chemistry,
Faculty of Chemistry, University of
Kashan, Kashan 87317, I.R., Iran
The carbon–carbon cross coupling reactions through transition‐metal‐
catalyzed processes has been significantly developed for their important syn-
thetic applications. In this research, we have shown that NiFe2O4@TASDA‐
Pd(0) is a highly active, novel and reusable catalyst with excellent performance
for the Mizoroki–Heck coupling reaction of several types of iodo, bromo, and
even aryl chlorides in DMF under ultrasound irradiation. The novel palladium
catalyst prepared and characterized by using FT‐IR spectrum, X‐ray diffraction
(XRD), scanning electron microscopy (SEM), Energy‐dispersive X‐ray spectros-
copy (EDX), thermo gravimetric analysis (TGA) and vibrating sample magne-
tometer (VSM). The catalyst can be recovered and recycled several times
without marked loss of activity.
Correspondence
Hossein Naeimi, Department of Organic
Chemistry, Faculty of Chemistry,
University of Kashan, Kashan 87317,
I.R., Iran.
Email: naeimi@kashanu.ac.ir
Funding information
University of Kashan, Grant/Award
Number: 159148/78
KEYWORDS
heterogonous catalyst, Mizoroki–heck reaction, NiFe2O4, Pd, ultrasound irradiation
1 | INTRODUCTION
homogeneous systems and heterogeneous systems.
Although the reported useful effects with homogeneous
Olefination of aryl halides, generally called the Heck
cross coupling reaction,[1–3] which first time was investi-
gated in 1971 has become a great and powerful tool for
the formation of useful trans‐stilbene derivatives.[4,5] The
Mizoroki–Heck coupling reaction is one of the most widely
used palladium‐catalyzed C–C cross coupling reactions
in modern organic synthesis, preparation of advanced
enantioselective natural products and biologically active
molecules, polymerization processes, production of
pharmaceuticals, hydrocarbons, agrochemical and fine
chemicals.[6–14] Many researchers investigated effective role
of solvents during their studies on C‐C cross coupling reac-
tions.[15–19] Dipolar aprotic solvents such as dimethyl sulf-
oxide, acetonitrile, dimethyl formamide and N‐methyl
pyrrolidone are common solvents applied in the coupling
reaction. Improvement of coupling reaction is highly
dependent on the reactivity of the palladium catalyst. Com-
monly, catalysts are separated into two categories:
system, problems associated with the separation and
recyclability of the expensive catalyst, limit their use in syn-
thetic and industrial applications. Therefore, it is necessary
to develop supported catalysts that can quickly be recycled
from the reaction system and reused. Thus, in order to over-
come these drawbacks, many researches on developing
effective procedures for Pd complexes on several different
solid supports, such as clays[20] activated carbon,[21] micro
porous polymers,[22] and magnetic nanoparticles have been
performed. Currently, magnetic feature provides a fantastic
approach for separating magnetic nanoparticles with an
external magnet. Magnetic nanoparticle supported catalysts
are the best case as they not only show considerable cata-
lytic activities but the magnetic nature of these particles
also allows for facile recycling of the catalyst without use
of the classical separation method.[23,24]
With the expanding environmental knowledge in
chemical reaction, the challenge of designing stable
Appl Organometal Chem. 2019;e4742.
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© 2019 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.4742

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NAEIMI AND KIANI
environmentally friendly methods has become the princi-
pal aim of green chemistry. From the first research on
using ultrasound in organic reactions,[25] the tendency
to use this tool in organic transformations developed
greatly. Acoustic cavitation is a physical effects that
assists organic synthesis under ultrasound irradiation.
This phenomenon consists the formation, growth, and
implosive collapse of bubbles in a solution during a short
range of time. Precipitate implosion of these bubbles in
the solution; create localized hot spots with short life
times. The hot spot has a tantamount temperature of
5000 °C and pressure of about 2000 atmospheres. These
transient, localized hot spots leading to a turbulent flow
in the solution and enhanced mass transfer.[26,27] There-
fore, in this, we focus on synthesis, full characterization
and application of NiFe2O4@TASDA‐Pd(0) complex
which appears to be highly active recyclable catalyst for
the Heck cross coupling reaction of styrene with various
aryl halides.
melting point apparatus and are uncorrected. The purity
determination of the substrates and reaction monitoring
were accomplished by TLC on silica‐gel polygram
SILG/UV 254 plates (from Merck Company).
2.2 | Catalyst preparation
New NiFe2O4@TASDA‐Pd(0) complex was prepared
based on the following procedure.
2.3 | General procedure for preparation of
NiFe2O4 nanoparticles
Nickel ferrite nanoparticles (NiFe2O4) were synthesized
by using co‐precipitation method, according to the proce-
dure reported in the literature.[28] 3 M solution of sodium
hydroxide was added drop wise to salt solutions of 0.4 M
ferric chloride (FeCl3. 6H2O) and 0.2 M nickel chloride
(NiCl2. 6H2O). The pH of the solution was constantly
monitored as the NaOH solution was added slowly. The
reactants were stirred using a magnetic stirrer till pH of
the solution was close to 13. Finally 3 drops of oleic acid
were added to the solution as a surfactant. The liquid pre-
cipitate was then brought to a reaction temperature of
80 °C and stirred for 40 min. The solutions were centri-
fuged and precipitation was washed several times with
double distilled water and ethanol to remove unwanted
impurities and the excess surfactant from the synthesized
sample. The sample was centrifuged for 15 min at
2000 rpm and then dried overnight at above 80 °C. The
acquired substance was then grinded into a fine powder
and then calcined for 10 hr at 600 °C. FT‐IR (KBr pellets,
cm−1): 597 (Fe‐O) and 421 (Ni‐O).
2 | EXPERIMENT
2.1 | Materials and apparatus
All commercially available reagents were used without
further purification and purchased from the Merck
Chemical Company in high purity. The used solvents
were purified by standard procedure.
The IR spectra were obtained as KBr pellets in
the range of 400–4000 cm−1 on a Perkin‐Elmer 781
spectrophotometer. For recorded the 1H NMR spectra
we used Brucker (400 MHZ) DRX‐400 spectrometer
in pure deuterated CDCl3 solvent at room temperature
with tetramethylsilane (TMS) as internal standards.
A multiwave ultrasonic generator (Sonicator 3200;
Bandelin, MS 73, Germany), equipped with
a
2.4 | General procedure for preparation of
nano‐NiFe2O4@SiO2 core‐shell
converter/transducer and titanium oscillator (horn),
12.5 mm in diameter, operating at 20 kHz with a maxi-
mum power output of 200 W, was used for the ultrasonic
irradiation. The crystallographic structure of prepared
catalyst was investigated on a Philips instrument with
1.54 Å wavelengths of X‐ray beam and Cu anode mate-
rial, at a scanning speed of 2° min−1 from 10° to 80°
(2θ). Scanning electron microscope (SEM) of nanoparti-
cles and catalysts were recorded on a FESEM Hitachi
S4160. Thermo gravimetric analysis (TGA) was per-
formed on a mettler TA4000 system TG‐50 at a heating
rate of 10 K min−1 under N2 atmosphere. Also, elemental
analyses of the catalyst with inductively coupled plasma
atomic emission spectroscopy were obtained from an
ICP‐AES simultaneous instrument (VISTA‐PRO). Melt-
ing points was obtained with a Yanagimoto micro
The core‐shell NiFe2O4@SiO2 nanoparticles were
obtained by a Stober method with minor modifica-
tions.[29] Generally, 100 ml of 75% ethanol/water solution
containing the above obtained NiFe2O4 MNPs were trans-
ferred into a three‐neck flask. After ultrasonic mixing
for 10 min, under the condition of N2 atmosphere, 4 ml
of tetraethoxysilane (TEOS) and 2 ml of ammonia
were added into NiFe2O4 MNPs suspension in turn under
vigorous stirring. The reaction system was kept at 35 °C
for 6 hr. Consequently, the black precipitates were
NiFe2O4@SiO2 MNPs, and were washed with deionized
water and ethanol for 3 times and dried at 80 °C for 10 h.
FT‐IR (KBr pellets, cm−1): 3426 (O‐H), 1091 (Si‐O‐Si),
601 (Fe‐O) and 469 (Ni‐O).[30]

NAEIMI AND KIANI
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by an external magnet and washed repeatedly with etha-
nol to remove the unreacted Pd (OAc)2, and then dried
under air to obtain 4 (Scheme 1).10 ml NaBH4 solution
(1 mmol) was added to the above solution with mechan-
ically stirring stirred at room temperature for 24 hours.
Then, the catalyst was separated from the mixture by an
external magnet, washed several times with methanol to
remove unreacted Pd (OAc)2 and dried under vacuum
to obtain a black solid powder (5).
2.5 | General procedure for
functionalization of NiFe2O4@SiO2 MNPs
surfaces
To our knowledge, the surface of silica nanoparticles can be
easily functionalized through aminopropyltriethoxysilane.
With vigorously stirring, 400 μL of APTES and 600 μL of
ammonia were added slowly to 50 mL of NiFe2O4@SiO2
MNPs solution suspended in 95% ethanol/water solution.
The solution was refluxed for 24 hr under an inert
atmosphere, separated by an external magnet and washed
subsequently with toluene, dichloromethane, and metha-
nol, and dried under reduced pressure at 80 °C for 10 hr
to obtain 1.[31]
2.7 | General procedure for the Mizoroki–
heck cross‐coupling reaction
A mixture of selected aryl halide (1 mmol), styrene
(1.2 mmol) and triethylamine (2 mmol) in the presence
2.6 | General procedure for the catalyst
NiFe2O4@TASDA‐Pd(0) (4)
of 0.002
g Pd complex 4 was added to N,N‐
dimethylformamide as solvent and the reaction mixture
was irradiated in ultrasonic apparatus with the power
45 Watt for 5–17 min according to Table 4. The progress
of the reaction was monitored by thin layer chromatogra-
phy (petroleum ether/ethyl acetate, 5:1). After completion
of the reaction, the catalyst was separated by an external
magnet, washed with absolute ethanol, dried, and used
for the next reactions without further purification. After
separation of the catalyst, CH2Cl2 (15 ml) was added
and the organic phase was washed with water
(3 × 10 ml), and dried over anhydrous MgSO4. The
resulting solution was evaporated under vacuum to give
the crude product. The column chromatography of the
crude product on silica gel using n‐hexane or different
mixtures of n‐hexane, ethyl acetate as the eluents
afforded the highly pure product (Table 4). The obtained
pure products were characterized by spectroscopic data
and melting points.
For synthesis of ligand 3, to a mixture of 1 (0.50 g) in dry
toluene (30 ml) at 0 °C, 1, 3, 5‐trichlorotriazine (TCT)
(2 mmol, 0.37 g) and diisopropylethyl amine (2 mmol,
0.34 ml) were added and the mixture was stirred at 0 °C
for 3 hr. In continue after consumption of TCT and pro-
ducing of 2, Cysteamonium Chloride (4 mmol, 0.45 g)
and diisopropylethyl amine (4 mmol, 0.68 ml) were added
slowly to this mixture and refluxed in dry toluene for
24 hr. The residue was separated from the mixture by
an external magnet, washed with CH2Cl2 for several
times and dried at 80 °C to obtain 3. The final catalyst
nanoparticles were prepared as brown solids by addition
of Pd (OAc)2 (10 mg, 0.45 mmol) to a dispersed mixture
of 3 in acetonitrile (5 ml) under nitrogen atmosphere at
room temperature. Then, the mixture was stirred for
6 hr at 60 °C and next allowed to proceed for an addi-
tional 45 min at 70 °C. The final complex was collected
SCHEME 1 Synthesis of the catalyst
NiFe2O4@TABMA‐Pd(0) (5)

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NAEIMI AND KIANI
4‐Formyl‐trans‐stibene; yellow solid; m.p = 118–
120 °C (Lit.[39] 115–116 °C). IR (KBr)/ν (cm−1): 2995,
2851, 1701, 1603, 1499, 910, 845. H NMR (400 MHz,
CDCl3) δ: 9.99 (s, 1H), 7.86 (d, J = 7.6 Hz, 2H), 7.64 (d,
J = 7.6 Hz, 2H), 7.55(d, J = 7.6 Hz, 2H), 7.40 (t,
J = 6.0 Hz, 2H), 7.29 (t, J = 6.4 Hz. 1H), 7.21 (d,
J = 16.4 Hz, 1H), 7.07(d, J = 16 Hz, 1H).
2.8 | Spectral data for trans‐stilbene
derivatives
1
Trans‐stilbene; Colorless solid; m.p = 120–122 °C (Lit.[32]
125 °C). IR (KBr)/ν (cm−1); 2992, 1602, 1495, 780. H
1
NMR (400 MHz, CDCl3) δ: 7.55 (d, J = 7.6 Hz, 2H), 7.39
(t, J = 7.6 Hz, 2H), 7.30 (d, J = 7.2 Hz, 1H), 7.15 (s, 1H).
4‐Methoxy‐trans‐stilbene; Colorless solid; m.p = 130–
132 °C (Lit.[33] 134–136 °C). IR (KBr)/ν (cm−1): 3009,
2835, 1606, 1513, 1445, 1368, 1291, 1182. 1H NMR
(400 MHz, CDCl3) δ: 7.49 (d, J = 8.8 Hz, 2H), 7.38 (d,
J = 8.0 Hz, 2H), 7.31–7.28 (2H, m), 7.15–7.12 (1H, m),
7.1 (d, J = 16.4 Hz, 1H), 7.0 (d, J = 16.4 Hz, 1H), 6.93
(d, J = 7.2 Hz, 2H),3.85 (3H, s).
4‐Methyl‐trans‐stilbene; Colorless solid; m.p = 118–
120 °C (Lit.[34] 119–122 °C). IR (KBr)/ν (cm−1): 2987,
1600, 1495, 1380, 885. 1H NMR (400 MHz, CDCl3) δ:
7.53 (d, J = 6.8 Hz, 2H), 7.48 (d, J = 7.6 Hz, 2H), 7.41
(t, J = 7.6 Hz, 2H), 7.26–7.23(1H, m), 7.18 (d,
J = 6.8 Hz, 2H), 7.12 (d, J = 16.6 Hz, 1H), 7.08 (d,
J = 16.6 Hz, 1H), 2.55 (3H, s).
1, 4‐Bis [(E)‐2‐phenylethenyl] benzene; light green solid;
m.p = 254–258 °C (Lit.[40] 254 °C) IR (KBr)/ν (cm−1): 3024,
1
1595, 1561, 1510, 1484, 1446, 968. H NMR (400 MHz,
CDCl3) δ: 7.52 (d, J = 8.4, 2H), 7.45 (d, J = 7.6, 1H), 7.36
(m, 2H), 7.28 (d, J = 15.6, 2H), 7.23 (d, J = 7.6, 1H), 7.14
(m, 1H).
3‐chloro‐trans‐stilbene; white solid; 62–64 °C (Lit[38]
64–69 °C). IR (KBr)/ν (cm−1): 3045, 2950, 1589. 1H
NMR (400 MHz, CDCl3) δ: 52 (m, 3H), 7.36 (m, 3H),
7.27 (m, 2H), 7.13 (m, 1H), 7.08 (d, J = 16 Hz, 1H), 7.01
(d, J = 16 Hz, 1H).
Methyl (E)‐4‐styryl benzoate; white solid, m.p = 154–
156 °C (Lit[41] 158 °C). IR (KBr)/ν (cm−1): 3024, 2945,
1708, 1602, 1434, 1277, 1179, 1105, 963, 835, 771, 698, 670,
1
4‐nitro‐trans‐stilbene; Yellow solid; m.p = 156–157 °C
(Lit.[35] 151–153 °C). IR (KBr)/ν (cm−1): 3022, 2935, 2837,
1686, 1594, 1574, 1494, 1448, 1338, 1158, 1103, 1078, 983,
579. H NMR (400 MHz, CDCl3) δ: 8.03 (d, J = 6.7 Hz,
2H), 7.50–7.58 (m, 4H), 7.46–7.32 (m, 3H), 7.28 (d,
J = 16 Hz, 1H), 7.13 (d, J = 16 Hz, 1H), 3.93 (s, 3H). The
FT‐IR and 1H NMR spectra of all compounds are included
in the Supplementary information.
1
972, 851, 773, 692. H NMR (400 MHz, CDCl3) δ: 8.25 (d,
J = 8.4 Hz, 2H), 7.65 (d, J = 8.4 Hz, 2H), 7.57 (d,
J = 7.5 Hz, 2H), 7.42–7.36 (m, 3H), 7.30 (d, J = 16 Hz,
1H) 7.14 (d, J = 16 Hz, 1H).
3 | RESULT AND DISCUSSION
3‐methyl‐trans‐stilbene; White solid; m.p = 41–43 °C
(Lit.[36] 40–45 °C). IR (KBr)/ν (cm−1): 3023, 1599, 1495,
Nickel ferrite nanoparticles were synthesized by using co‐
precipitation method, according to the procedure
reported in the literature.[33] The synthetic pathway for
preparation of the catalyst is shown in Scheme 1. In order
to characterize the catalyst structure, the synthesized
nano catalyst was analyzed using X‐ray diffraction
(XRD), Fourier transform infrared (FT‐IR) spectra, scan-
ning electron microscopy (SEM), energy‐dispersive X‐ray
spectroscopy (EDX), vibrating sample magnetometer
(VSM), and also, thermo‐gravimetric analysis (TGA)
techniques.
1
1448, 965, 782, 748, 692. H NMR (400 MHz, CDCl3) δ:
7.57 (d, J = 7.6 Hz, 2H), 7.43–7.38 (d of d, J = 14.4 Hz,
4H), 7.31 (t, J = 7.8 Hz, 2H), 7.17 (d, J = 6.4 Hz, 3H),
2.35 (s, 3H).
4‐Cyano‐trans‐stilbene; Yellow solid; m.p = 115–
117 °C (Lit.[34] 116–118 °C). IR (KBr)/ν (cm−1): 3021,
2836, 2361, 1605, 1505, 1363. 1H NMR (400 MHz, CDCl3)
δ: 7.72–7.53 (m, 5H), 7.46–7.30 (m, 4H), 7.22 (d, J = 16.4,
1H), 7.09 (d, J = 16.4, 1H).
4‐Acetyl‐trans‐stilbene; White solid, m.p = 134–
136 °C (Lit.[37] 135–137 °C). IR (KBr)/ν (cm−1): 2994,
1
1680, 1601, 1495, 1383, 880. H NMR (400 MHz, CDCl3)
δ: 7.96 (d, J = 8.0 Hz, 2H), 7.60 (d, J = 8.0 Hz, 2H), 7.55
(d, J = 7.6 Hz, 2H), 7.41 (t, J = 7.6 Hz, 2H), 7.31 (t,
J = 7.6 Hz, 1H), 7.25 (d, J = 16.4 Hz, 1H), 7.14 (d,
J = 16.4 Hz, 1H), 2.62 (s, 3H).
2‐Styryl‐naphthalene; colorless solid; m.p = 50–62 °C
(Lit.[38] 58–60 °C). IR (KBr)/ν (cm−1): 3045, 1593.1H
NMR (400 MHz, CDCl3): δ = 8.25 (d, J = 16 Hz, 1H),
8.18 (d, J = 6.4 Hz, 1H), 8.04 (d, J = 7.2 Hz, 1H), 7.99
(d, J = 8 Hz, 1H), 7.69 (t, J = 8.4 Hz, 2H), 7.83–7.75 (m,
3H), 7.72 (t, J = 7.2 Hz, m, 2H), 7.65 (t, J = 7.2 Hz, 1H),
7.44 (d, J = 15.2 Hz, 1H).
3.1 | Characterization results of
NiFe2O4@TASDA‐Pd(0)
Figure 1 shows the FT‐IR spectrum of NiFe2O4 NPs,
NiFe2O4@SiO2, NiFe2O4@SiO2–NH2 NPs, NiFe2O4@-
TASDA‐Pd(0) before reaction and NiFe2O4@TASDA‐
Pd(0) after reaction in the range 400–4000 cm−1. The
bands at 3415 and 1620 cm−1 can be assigned to the
stretching modes of absorbed water. The band at
597 cm−1 is attributed to the vibration of Fe―O bonds.
The characteristic band at 421 cm−1 can be assigned to

NAEIMI AND KIANI
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metal vibrations of Ni―O bonds (Figure 1a). In all three
spectra (Figure 1a, 1b, 1c), the revealed peaks of NiFe2O4
were observed at 421–601 cm−1, which could be attributed to
the characteristic absorption of Fe–O and Ni―O bond. In
NiFe2O4@SiO2 spectrum (Figure 1b), NiFe2O4@SiO2–NH2
spectrum (Figure 1c), final catalyst spectrum (Figure 1d),
and NiFe2O4@TASDA after five recycles (Figure 1e),
the intense peak at 1091, 1095, 1096, 1096 cm−1 was derived
from the Si–O–Si stretching vibrations. These peaks
proved that SiO2 has coated the surface of NiFe2O4. In
NiFe2O4@SiO2–NH2 spectrum, the characterized peaks at
1635, 1540 cm−1 could be attributed to the C–N stretching
vibrations and NH2 bending vibration. Moreover, the peak
at 2945 cm−1 is related to stretching vibration of CH2, the
peak at 1466 cm−1 is related to bending vibration of CH2
and the peak at 3439 cm−1 is assigned to the N–H
stretching vibration. These described peaks confirmed that
NiFe2O4@SiO2–NH2 NPs are prepared. The FT‐IR spec-
trum of NiFe2O4@TASDA absorption bands at 1625 cm−1
(C=N), 2983 cm−1 (C–H), 3421 cm−1 (N–H stretching vibra-
tion) and 778 cm−1 (C–S stretching vibration). The Figure 1
e shows the FT‐IR spectrum of NiFe2O4@TASDA‐Pd(0)
after five recycles. We did not observe significant change
in the FT‐IR spectrum of the catalysts after five repeated
reaction.
The powder XRD pattern of the nickel ferrite nano-
particles is shown in Figure 2a. All of the characteristics
peaks of NiFe2O4 are present in the diffraction pattern
and the diffraction peaks match with standard XRD pat-
tern (JCPDS file no. 03–0875). The sizes of the nanoparti-
cles are determined as around 30 nm from the Scherrer
equation using the peak broadening of the most intense
peak. Figure 2b shows the appearance of new peaks at
2θ = 39.7°, 46.3°, and 67.5 attributed to Pd species. The
results indicate that the Pd have been successfully
immobilized on NiFe2O4 particle surfaces.
FIGURE 1 FT‐IR spectrum of a) NiFe2O4 NPs, b) NiFe2O4@SiO2, c)
NiFe2O4@SiO2–NH2 NPs and d) NiFe2O4@TASDA before reaction,
e) NiFe2O4@TASDA after reaction
FIGURE 2 The X‐ray diffraction
patterns of a) calcinated NiFe2O4, b)
NiFe2O4@TABMA‐Pd(0)

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NAEIMI AND KIANI
Figure 3 shows the SEM image of NiFe2O4 and final
catalyst, in that the spherical morphology with an aver-
age diameter of about 50 nm for NiFe2O4 and 60 nm for
catalyst was observed. Elemental analysis was also per-
formed. Figure 4 shows the EDX spectra of NiFe2O4 and
final catalyst. The elemental analysis of NiFe2O4 NPs
indicated that the amounts of oxygen, iron and nickel
were about 54.55, 37.05, and 8.40%, respectively. The
FIGURE 4 (a) EDX spectrum of the NiFe2O4 nanoparticles. (b)
EDX spectrum of the NiFe2O4@TASDA‐Pd(0)
results showed the presence of C, N, O, Si, S, Fe, Ni and
Pd in the composites, which confirmed that the catalyst
has been successfully synthesized. Also, to support the
mentioned observation, the catalyst was subjected to
inductively coupled plasma (ICP) analyzer. ICP analysis
indicated the presence of Pd in the catalyst and the con-
tent of Pd was estimated to be 0.17 mmol g−1 (18.4%W).
Thermal stability of the synthesized catalyst was
investigated by TGA and the related curves are demon-
strated in Figure 5. Herein TGA analysis curves of
NiFe2O4@SiO2 and final catalyst are compared. Both
curves illustrate similar characteristics. As demonstrated
in Figure 5a, 6% decrease in weight before 150 °C is attrib-
uted to the removal of surface hydroxyl groups and phys-
ically adsorbed solvent and water molecules trapped in
SiO2 layer. The weight loss 7% between 400 and 600 °C
is attributed to the decomposition of less stable functional
groups for example hydroxyl grafted to the silica surface.
As illustrated in Figure 5b, a little weight loss (10%)
between 150 °C and 250 °C is attributed to the trapped
water. While the organic components (40%) was lost
between 250 and 400 °C. These results show that catalyst
is stable up to 250 °C and can be used in organic synthesis.
FIGURE
NiFe2O4@TASDA‐Pd(0) (b)
3
SEM images of NiFe2O4 nanoparticles (a)

NAEIMI AND KIANI
7 of 12
different parameters such as solvent, bases, various
amounts of catalyst and the effect of ultrasound
irradiation.
In our first set of experiments, we examined efficiency
of the different solvent in Mizoroki–Heck reaction.
Several organic solvents such as acetonitrile, ethanol,
dimethylformamide, dimethyl sulfoxide and toluene were
examined. According to data given in Table 1, entry 4,
DMF was the most efficient solvent for this transforma-
tion. Other solvents gave only moderate yields of the
product. In the following step, it was obtained the suit-
able base for the coupling reaction. We studied different
bases, among the various bases screened, NEt3 was found
to be the best base for this reaction (Table 1, entry 9). The
other bases such as Na2CO3 and K2CO3 gave moderate
yields of the product.
FIGURE 5 Thermo gravimetric analysis of a) NiFe2O4@SiO2 b)
NiFe2O4@TASDA‐Pd(0)
In continuation of this research, the activity of the
catalyst in different amounts on the reaction was inves-
tigated. No reaction was observed in the absence of
catalyst under ultrasonic irradiation (Table 2, entry1).
The results demonstrated that in the presence of ultra-
sonic irradiation and 0.02 g of the NiFe2O4@TASDA‐
Pd(0) catalyst, the reaction time is decreased to 8 min
and the yield increased sharply to 99% (Table 2, entry 5).
In next step, power of the ultrasonic irradiation was
optimized. The model reaction was performed in the
presence of 0.020 g of NiFe2O4@TASDA‐Pd(0) catalyst
in DMF under silent condition and various powers of
ultrasound irradiation to investigate the best operating
Magnetic properties of NiFe2O4 nanoparticles and
final catalyst were investigated with VSM at room tem-
perature (Figure 6). Magnetization of samples could be
completely saturated at high fields of up to 1.0 T and
the saturation magnetization of samples decreased from
35 to 3.5 emug−1, because of the functionalization by
extra organic layer. Furthermore, these results illustrate
that the magnetization property decreases by coating
and functionalization. It is of very importance that a cat-
alyst should possess enough magnetic properties for its
experimental application.
3.2 | Investigation of catalyst activity
TABLE 1 Optimization in the presence of different solvents and
basesa
To examine the catalytic performance of the nanocatalyst
and to characterize optimal conditions for Mizoroki–
Heck coupling reaction, iodobenzene and styrene was
selected as model reagents and were investigated under
Entry
Solvent
Base
Yieldb
1
2
3
4
5
6
7
8
9
EtOH
CH3CN
DMSO
DMF
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
KOH
75
81
68
91
35
55
46
78
99
Toluene
DMF
DMF
NaHCO3
K3PO4
NEt3
DMF
DMF
aReaction conditions: Iodobenzene (1 mm mmol), styrene (1.2 mmol),
amount of catalyst (30 mg), Power (50 w) time (30 min), base (2 mmol), sol-
vent (5 ml).
FIGURE
6
The vibrating sample magnetometer curve of
NiFe2O4 nanoparticles and NiFe2O4@TASDA‐Pd(0)
bIsolated yield.

8 of 12
NAEIMI AND KIANI
TABLE 2 Optimization of the various amount of catalysta
b
Entry Conditions Pd catalyst Time (min) Yield (%)
1
2
3
4
5
6
US
US
US
US
US
US
0
30
20
16
13
8
0
72
84
91
99
99
0.005
0.010
0.015
0.020
0.025
8
aReaction conditions: Iodobenzene (1 mmol), styrene (1.2 mmol), Power (50
w) and NEt3 (2 mmol) in DMF.
bIsolated yield.
suitable power of ultrasonic irradiation. The effective
power was found to be 45 watt (Table 3, entry 5).
SCHEME 2 Cross‐coupling of aryl halides and styrene
After optimization of the reaction conditions, a broad
range of structurally diverse aryl halides were reacted with
styrene in the presence of 20 mg of NiFe2O4@TASDA‐
Pd(0) catalyst and 2 mmol triethylamine with DMF as
solvent under ultrasonic irradiation at room temperature
(Scheme 2), and the results are displayed in Table 4.
To assess the effect of sonication on this reaction, we
initially investigated this reaction under thermal condi-
tions (Table 4). As displayed in Table 4, the reaction
performs efficiently in high yield between 2.5–12 hours
at 130 °C. As shown in Table 4, in the presence of
Pd nanocatalyst, excellent product yields were achieved
in shorter reaction time under ultrasound irradiation.
Ultrasonic irradiation differs from conventional
energy sources. We think that the main effect of ultra-
sound on this transformation perhaps related to a better
mass transfer and dispersion of the catalyst in the medium
in comparison with traditional methods, which makes the
catalyst very active in this reaction. Ultrasound advances
the chemical reactions in a solution through the produc-
tion of cavitations micro bubbles. The sudden implosion
of these micro bubbles in the solutions produces localized
hot spots with very short life cycle. The high local temper-
ature and pressures provide favorable conditions for
advancing a large number of organic reactions. Therefore,
the ultrasound can be increased the rate of reaction and
therefore decreased the energy consumption. The chemi-
cal and physical effects of ultrasound are based on acoustic
cavitations, which include formation, growth and collapse
of bubbles in a solution, which results in a high tempera-
ture and pressure pulse and due to increase in the reactant
impact surface area through cavitations event. The advan-
tages of sonication on organic reactions are the formation
of purer products in excellent yields, very short reaction
times, waste minimization and mild conditions which is
comparable to traditional methods.
In order to illustrate the merit of this proposed
research, we compared the obtained results with the
recently reported results. For this purpose, the reactions
of iodobenzene and styrene using 20 mg of catalyst in
DMF under ultrasonic irradiation in the presence of
2 mmol NEt3 were chosen as model reaction and the
comparison was performed on the basis of reaction condi-
tions, reaction time and obtained yields (Table 5, entry 1
vs. other entries). The advantages of this research which
make it exclusiveness than other previously reported pro-
cedures, are mild reaction condition, environmentally
benign, simple recycle of the nano catalyst by an external
magnet, reusability of the catalyst for five times without
considerable loss of catalytic activity, excellent yield of
trans‐stilbene and short reaction time. However, the
phosphine ligands have been applied to stabilize active
palladium intermediates, for Pd‐catalysed carbon–carbon
coupling reactions. While, the oxygen and water sensitiv-
ity, expensive, toxicity and unrecoverable of these classes
of ligands, prevents their usage in a diversity of synthetic
applications.
TABLE 3 Study of the effect of ultrasonic irradiation on the
Mizoroki‐Heck cross‐couplinga
Entry
Power (w)
Time (min)
Yield (%)b
1
2
3
4
5
6
25
30
35
40
45
50
30
26
21
15
8
61
73
85
91
99
99
8
aReaction conditions: Iodobenzene (1 mmol), styrene (1.2 mmol) amount of
catalyst (20 mg), and NEt3 (2 mmol) in DMF.
bIsolated yield.

NAEIMI AND KIANI
9 of 12
TABLE 4 Mizoroki–Heck cross‐coupling of aryl halides and styrene in the presence of NiFe2O4@TASDA‐Pd(0)a
Thermal conditionsb
Time (h) Yieldd (%)
Ultrasonic conditionsc
Time (min) Yieldd (%)
Entry
Aryl halide
Product
1
4/96
8/99
2
3
5.5/87
10/95
6/90
5/81
12/96
9/94
4
5
7/87
14/95
6
7
3/78
8/72
6/92
14/92
8
7/91
13/94
9
6/94
2.5/95
7/80
12/98
5/98
10
11
15/93
12
13
7/90
7/85
14/93
12/93
(Continues)

10 of 12
NAEIMI AND KIANI
TABLE 4 (Continued)
Thermal conditionsb
Time (h) Yieldd (%)
Ultrasonic conditionsc
Time (min) Yieldd (%)
Entry
Aryl halide
Product
14
10/66
25/65
15
16
9/83
16/87
30/63
11/65
17
18
8/80
13/90
35/58
12/51
aReaction conditions: Aryl halide (1 mmol), styrene (1.2 mmol, for entry 12, 2.2 mmol), amount of catalyst (0.02 g) and NEt3 (2 mmol) in DMF.
bAt 130 °C.
cApplied power: 45 W.
dIsolated yield.
TABLE 5 Comparison of the results of trans‐stilbene synthesis in
present method with various reports in the literature
palladium (II) species. Then, the alkene coordinates to
palladium (II) species, which then undergoes an insertion
reaction to form the palladium (II) complex. The coupled
aryl and alkenyl compound of the palladium (II) complex
is then eliminated via a β‐hydride removal followed by
reductive elimination with base to retain the original pal-
ladium (0) (Scheme 3).
Time
(h)
Yield
(%)a
Entry Catalyst
Ref.
1
NiFe2O4@TASDA‐Pd(0)
0.13
99
This
work
[42]
[43]
[44]
[45]
[46]
2
3
4
5
6
Pd/NiFe2O4
2
4
3
7
2
50
97
98
90
90
Pd loaded NiFe2O4
Pd/NiFe2O4/GO
Si–PNHC–Pd
SPIONs‐bis (NHC)‐pd
(II)
[47]
[4]
7
8
9
Pd/MFC
2
66
75
71
palladium acetate
PdCl2(SEt2)2
2
[48]
23
aIsolated yield.
3.3 | The proposed reaction mechanism
The pathway of the olefination of halobenzenes with
NiFe2O4@TASDA‐Pd(0) catalyst in DMF with NEt3 is
proposed, which is shown in Scheme 2. Initially, oxida-
tive addition of aryl halides to palladium (0) leads to a
SCHEME 3 The proposed reaction mechanism

NAEIMI AND KIANI
11 of 12
activity and leaded to the corresponding product in high
yields (Figure 7). Also the SEM image for the characteri-
zation of catalyst after five recycles was shown in Figure 8
. After five repeated reaction cycles, it was observed any
significant change in the morphology of the catalyst, but
some Pd particles might be aggregated onto the surfaces
of the matrices.
4 | CONCLUSION
In conclusion, we have reported a novel, efficient, mild,
fast, clean, and safe sonochemical method for the synthe-
sis of trans‐stilbene derivatives by NiFe2O4@TASDA‐
Pd(0) catalyst at room temperature. We have applied
palladium catalyst as a highly active, reusable and recov-
erable heterogeneous catalyst in the Mizoroki–Heck
cross‐coupling reactions. This reactions produced the
corresponding trans‐coupled products stereo selectively
in excellent yields and acceptable reaction times. The cat-
alyst can be separated by external magnet and reuse sev-
eral times without any significant loss of activity which is
an additional sustainable characteristic of this method.
The products have been confirmed by spectroscopic and
physical data such as; IR, 1H NMR, and melting point.
FIGURE 7 Reusability of catalyst for the synthesis of trans‐
stilbene derivatives
ACKNOWLEDGEMENTS
The authors are grateful to University of Kashan
for supporting this work by Grant No. 159148/78.
ORCID
Hossein Naeimi https://orcid.org/0000-0002-9627-596X
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How to cite this article: Naeimi H, Kiani F.
Magnetically thiamine palladium complex
nanocomposites as an effective recyclable catalyst
for facile sonochemical cross coupling reaction.
Appl Organometal Chem. 2019;e4742. https://doi.
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