Synthesis and Characterization of Pd(0)-SMT-MCM-41 and its Application in the Amination of Aryl Halides and Synthesis of 2,3-Dihydroquinazolin-4(1H)-Ones as Efficient and Recyclable Nanostructural Catalyst

Article abstract of DOI:10.1007/s10562-016-1905-4

Abstract: Palladium S-methylisothiourea [Pd(0)-SMT] has been grafted at the surface of functionalized mesoporous silica MCM-41 and used as an efficient and reusable heterogeneous nanocatalyst system for amination of various aryl halides and the one-pot synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives. The present methodology offers several advantages such as simplicity of procedure, easy isolation of the products and reused for several consecutive runs without significant loss of their catalytic efficiency. The characteristic structural features of this new catalyst was determined by various physico-chemical techniques such as FT-IR spectroscopy, XRD, SEM/EDS, ICP, TGA, BET surface area measurement and elemental analysis. Graphical Abstract: [Figure not available: see fulltext.]

Full text of DOI:10.1007/s10562-016-1905-4

Catal Lett
DOI 10.1007/s10562-016-1905-4
Synthesis and Characterization of Pd(0)-SMT-MCM-41 and its
Application in the Amination of Aryl Halides and Synthesis
of 2,3-Dihydroquinazolin-4(1H)-Ones as Eicient and Recyclable
Nanostructural Catalyst
Nourolah Noori1 · Mohsen Nikoorazm1 · Arash Ghorbani-Choghamarani1
Received: 31 July 2016 / Accepted: 30 October 2016
© Springer Science+Business Media New York 2016
Abstract Palladium
S-methylisothiourea
[Pd(0)-
Graphical Abstract
SMT] has been grafted at the surface of functionalized
mesoporous silica MCM-41 and used as an eicient and
reusable heterogeneous nanocatalyst system for amina-
tion of various aryl halides and the one-pot synthesis of
2,3-dihydroquinazolin-4(1H)-one derivatives. The present
methodology ofers several advantages such as simplicity
of procedure, easy isolation of the products and reused for
several consecutive runs without signiicant loss of their
catalytic eiciency. The characteristic structural features
of this new catalyst was determined by various physico-
chemical techniques such as FT-IR spectroscopy, XRD,
SEM/EDS, ICP, TGA, BET surface area measurement and
elemental analysis.
Synthesis and characterization of Pd(0)-SMT-MCM-41 and its application in the amination
of aryl halides and synthesis of 2,3-dihydroquinazolin-4(1H)-ones as efficient and recyclable
nanostructural catalyst
Mohsen Nikoorazm,* Arash Ghorbani-Choghamarani, Nourolah Noori
CHO
X
R
R
O
NH3
NH2
NH2
O
NH2
NH
R
N
H
R
Keywords Pd(0)-SMT-MCM-41 · Reusable
nanocatalyst · Amination of aryl halides ·
2,3-Dihydroquinazolin-4(1H)-one
1 Introduction
Considerable research eforts have been made in the recent
years towards development of silica mesoporous nanocom-
posite in particular MCM-41 as immobilized support [1, 2].
This silica mesoporous has hexagonal arrangement of one
dimensional mesoporous with large pore size in the range
20–100 Å. Due to its exclusive properties such as high sur-
face area, high pore volume (1.3 cm3 g−1), great diversity
* Mohsen Nikoorazm
e_nikoorazm@yahoo.com
1
Department of Chemistry, Faculty of Science, Ilam
University, P.O. Box 69315516, Ilam, Iran
1 3

N. Noori et al.
in surface functionalization, homogeneity of the pores,
good thermal stability, accessible and tunable pores and has
attracted extensive attention [3–6]. MCM-41 has the potential
to be applied as catalyst support, adsorption [7] environmen-
tal puriication [8], drug delivery [9] and host for the inclu-
sion of bulkier guest molecules such as enzymes and orga-
nometallic compounds [10]. The appearance of the chemistry
of transition metals in the 1960s has deeply changed the sci-
ence of organic synthesis [11]. Palladium metal is classiied
as a transition metal which provides excellent opportunities
for catalytic reactions. Generally, the activity of homogene-
ous palladium catalysts is suiciently high; however, these
catalysts show as a major drawback a diicult recycling and
separation from the product which have limited their appli-
cations [12, 13]. In order to overcome the above drawbacks,
heterogenisation of palladium complexes via immobilization/
grafting onto solid supports especially MCM-41 has attracted
great attention because of its typical properties of easy sepa-
ration, catalyst recycling; it is also a great catalyst for trans-
formation reactions and in industrial ine chemical synthesis
[14–17]. Aniline is an important organic chemical for con-
structing natural products and is widely used as intermediates
for the production of medicine, dye, resin etc [18–20]. There-
fore, the development of highly eicient procedure for the
single step production of aniline via direct amination of aryl
halides under mild reaction conditions has acquire important
attention in green chemistry and synthetic chemistry [10,
21]. On the other hand, 2,3-dihydro-4(1H)-quinazolinones
derivatives are an important class of heterocyclic compounds
which have appeared as versatile biologically active com-
pounds possessing applications as vasodilating, tranquilizing,
diuretic, antibiotic, antitumor, anticancer, herbicidal activity,
antihypertensive agents and plant growth regulation abil-
ity [22–24]. Generally, 2,3-dihydroquinazolin-4(1H)-ones
were synthesized using the reductive cyclization of ketones
or aldehydes with 2-aminobenzamide in the presence of acid
catalysts [25]. Thus, there is a necessity to develop a simple
and eicient method for the synthesis of 2, 3-dihydroquinazo-
lin-4(1H)-ones derivatives in high yields under mild reaction
conditions. The present work describes synthesis and charac-
terization of Pd complex immobilized onto MCM-41 [Pd(0)-
SMT-MCM-41] which is used as a novel and eicient cata-
lyst for the synthesis of 2, 3-dihydroquinazolin-4(1H)-ones
derivatives through the reaction of aromatic aldehydes and
anthranilamide and anilines from amination of aryl halides.
3-chloropropyltrimethoxy silane (3-ClPTES), sodium
hydroxide, s-methyl isothiourea, palladium acetate and
solvents were purchased from Merck, Aldrich or Flucka
companies.
2.2 Measurements
IR analyses were carried out on FTIR as KBr pellets,
spectrophotometer (Bruker, Germany) Vertex 70 in the
range of 400–4000 cm−1, The physico-chemical charac-
teristics were carried out using X-ray powder difraction
(XRPD) on a Philips difractometer of X’pert company
with monochromatized Cu Kα radiation under the condi-
tions of 40 kV, λ = 1.5418 A and 30 mA. N2 adsorption–
desorption isotherm and BJH pore size were recorded by
(BELSORP-MINI), TGA of the samples was carried out
using a Shimadzu DTG-60 automatic thermal analyzer
in the temperature range 30–900 °C at a heating rate of
10 °C min−1 in air. The transmission electron microgra-
phys (TEM) were obtained with a Philips CM10 micro-
scope, working at 200 kV accelerating voltage. The par-
ticle morphology was recorded by measuring SEM using
FESEM-TESCAN MIRA3. The content of Pd was meas-
ured using inductively coupled plasma-optical emission
spectrometry (ICP-OES, perkin elmer, optima 800) and
elemental analysis was carried out on COSTECH, Eng-
land CHNS elemental analysis.
2.3 Synthesis of (3-Chloropropyl) Trimethoxysilane
Functionalized MCM-41
The synthesis of nanosized MCM-41 was carried out by
the sol–gel method using tetraethylorthosilicate (TEOS) as
the Si source, cetyltrimethylammonium bromide (CTAB)
as the template, and sodium hydroxide as the pH control
agent. In a typical procedure, to the solution of NaOH
(2 M, 3.5 mL) in deionized water (480 mL) at 80°C, sur-
factant CTAB (2.74 mmol, 1 g) was added. After the solu-
tion became homogeneous, TEOS (5 mL) was added drop-
wise to the solution under continuous stirring at 80°C, and
the mixture was stirred under relux for 2 h. The mixture
was cooled to the room temperature and the resulting
solid was gathered by iltration, washed with deionized
water and dried in an oven at 60°C and followed by cal-
cination at 550°C for 5 h with rate of 2°C min−1. Finally,
we obtained the mesoporous MCM-41. Then Mesoporous
silica (MCM-41) (1 g) was added to a solution of 3-chlo-
ropropyltrimethoxy silane (1 g) in n-Hexane (100 mL)
and reluxed for 24 h. The resulting white solid MCM-41-
(SiCH2CH2CH2Cl)x was iltered, and washed repeatedly
with n-hexane and inally dried under vacuum.
2 Experimental
2.1 Materials
The tetraethylorthosilicate (TEOS), cationic surfactant
cetyltrimethylammonium bromide (CTAB, 98%),
1 3

Synthesis and Characterization of Pd(0)-SMT-MCM-41 and its Application in the Amination of…
2.4 Synthesis of s-Methyl Isothiourea on Functionalized
MCM-41
2.6 General Procedure for Synthesis of Amination
of Aryl Halides
To the mixture of functionalized MCM-41 (1 g) and
s-methyl isothiourea (0.138 g) in toluene (30 mL), trieth-
ylamine (1.5 mmol) were added and stirred under relux
conditions for 24 h. After completion of the reaction, the
resulting solid was iltered, washed with ethanol and inally
dried to obtain SMT-MCM-41 (Scheme 1).
In a typical procedure, a mixture of aryl halide (1 mmol)
and ammonium hydroxide (28%) (1 mL, 0.003 mmol),
0.010 g of Pd(0)-SMT-MCM-41 as catalyst was added
and the reaction mixture was stirred at room tempera-
ture for an appropriate time (Table 3). The progress of
the reaction is followed by TLC. After completion of
the reaction, the product was extracted with ethyl ace-
tate (3 × 10 mL). The combined extracts were dried with
Na2SO4 followed by the evaporation of the solvent, yield-
ing the corresponding product with excellent yield.
2.5 Synthesis of the Pd(0)-SMT-MCM-41
Heterogeneous Catalyst
Pd(0)-SMT-MCM-41 was synthesized by stirring a mix-
ture of SMT-MCM-41 (1 g), palladium acetate (0.5 g) in
ethanol (50 mL) for 20 h under relux conditions. Then,
sodium borohydride (0.6 g) was added to this mixture and
kept under relux for 4 h. Finally, the resulting catalyst was
iltered, washed several times with ethanol, dried at 50°C
for 24 h (Scheme 1).
2.7 General Procedure for the Synthesis
of 2,3-Dihydroquinazolin-4(1H)-Ones Derivatives
A reaction tube was charged with anthranilamide
(1 mmol), aldehyde (1 mmol) and Pd(0)-SMT-MCM-41
(0.01 g) was stirred at 80 °C in ethanol (2 mL) for the
appropriate time (Table 5). The progress was monitored
by TLC. Upon completion, the reaction mixture was
cooled to room temperature, then, catalyst was separated
by simple iltration and the product was extracted with
CH2Cl2 (2 × 5 mL). Finally by the evaporation of the sol-
vent from the iltrate, the desired products were obtained.
OH
CTAB
80 o
TEOS
2 h
OH
OH
NaOH + deionized water
80 oC,
C
2.8 Selected Spectral Data
MCM-41
2.8.1 Aniline (Entry 1 and 2, Table 3)
O
1H NMR (400 MHz, CDCl3): δH = 7.26–7.24 (m, 2H),
6.87–6.83 (tt, J = 7.2 Hz, 1H), 6.77–6.73 (m, 2H), 3.66
(s, 2H) ppm.
Cl
Si
O
O
(MtO)3Si
Cl
2
MCM-41-Cl
2.8.2 4-Chloroaniline (Entry 3, Table 3)
NH
NH
CH3
SO4
CH3
1H NMR (400 MHz, CDCl3): δH = 7.14–7.11 (dt,
J = 8.8 Hz, 2H), 6.65–6.61 (dt, J = 8.8 Hz, 2H), 3.58
(broad, 2H) ppm.
O
O
H2N
S
S
N
H
Si
O
Toluene , (Et)3N , 24 h
SMT-MCM-41
2.8.3 4-Nitroaniline (Entry 7, Table 3)
1H NMR (400 MHz, CDCl3): δH = 8.11–8.08 (d,
J = 9.2 Hz, 2H), 6.66–6.64 (d, J = 8.8 Hz, 2H), 4.42
(broad, 2H) ppm.
N
Pd
O
S
N
H
Si
O
CH3
2.8.4 Pyridin-2-Amine (Entry 8, Table 3)
O
1H NMR (400 MHz, CDCl3): δH = 8.06–8.04 (d of t,
Pd (0)-SMT-MCM-41
J = 5.2 Hz, 1H), 7.42–7.37 (td, J = 7.6 Hz, 1H), 6.65–6.62
Scheme 1 Synthesis of Pd(0)-SMT-MCM-41 heterogeneous catalyst
1 3

N. Noori et al.
(t of d, J = 6 Hz, 1H), 6.51–6.49 (d, J = 8.8 Hz, 1H), 4.65
(s, 2H) ppm.
2.8.5 2-(4-Chlorophenyl)-2,3-Dihydoquinazo-
lin-4(1H)-One (Entry 6, Table 5)
1H NMR (400 MHz, DMSO-d6): δH=8.29 (s, 1H), 7.62–
7.42 (m, 5H), 7.25–7.21 (t, J=7.5, 1H), 7.11 (s, 1H), 6.74–
6.62 (m, 2H), 5.74 (s, 1H) ppm.
2.8.6 2-(4-Ethoxyphenyl)-2,3-Dihydoquinazo-
lin-4(1H)-One (Entry 4, Table 5)
1H NMR (400 MHz, DMSO-d6): δH =7.94–7.93 (b, 1H),
7.53–7.51 (m, 2H), 7.33 (s, 1H), 7.25 (s, 1H), 6.94–6.91
(m, 3H), 6.67–6.68 (m, 1H), 5.84 (s, 1H), 5.74 (s, 1H),
4.04–4.06 (q, J=4, 2H), 1.45–1.43 (s, 3H) ppm.
2.8.7 2-(4-Methylphenyl)-2,3-Dihydroquinazo-
lin-4(1H)-One (Entry 2, Table 5)
δH= 8.22 (s, 1H), 7.60–7.57 (d, J=7.5, 1H), 7.36–7.34 (d,
J=7.5, 2H), 7.25–7.13 (m, 3H), 7.01 (s, 1H), 6.74–6.63 (m,
2H), 5.72 (s, 1H), 2.47–2.43 (s, 3H) ppm.
2.8.8 2-(3,4-Dimethoxyphenyl)-2,3-Dihydoquinazo-
lin-4(1H)-One (Entry 5, Table 3)
Fig. 1 The XRD patterns of a top to down MCM-41, SMT-MCM-41
and Pd-SMT-MCM-41 at low angle (b) Pd(0)-MCM-41 at wide angle
1H NMR (400 MHz, DMSO-d6): δH =8.22 (s, 1H), 7.63–
7.61 (d, J=7.6, 1H), 7.27–7.23 (t, J=0.8, 1H), 7.14 (d,
J=1.6, 1H), 7.02–6.98 (m, 2H), 6.96 (s, 1H), 6.77–6.75 (d,
J=8, 1H), 6.71–6.66 (t, J=1.2, 1H), 5.72 (s, 1H), 3.78 (s,
3H), 3.75 (s, 3H) ppm.
The low angle XRD patterns for the MCM-41 and Pd(0)-
SMT-MCM-41 catalyst derived by post-synthetic grafting
are shown in Fig. 1. The X-ray pattern of the Si-MCM-41
(Fig. 1a) shows the a typical three-peak pattern with a very
strong relection at 2θ=2.41° due to the d100 plane and also
two other weaker relections at 2θ=3.87° and 2θ=4.33°
due to higher order d110 and d200 planes respectively indi-
cated the formation of a well-ordered mesoporous mate-
rial with hexagonal symmetry. the functionalized MCM-41
(SMT-MCM-41) presents well-deined (100) relection in
its XRD pattern, however there are no well resolved peaks
(110, 200) which are clearly visible corresponding MCM-
41 analogs, intensity of the peak at d100 was decreased with
an increase in loading amount of SMT-MCM-41, which
means that the hexagonal mesostructures are less ordered
due to successful introduction of SMT-MCM-41 into
mesoporous channels of MCM-41. An overall decrease
in the intensity of d100 was seen, this decrease in intensity
was signiicant for the Pd(0)-SMT-MCM-41 sample. The
intensity reduction may be mainly due to contrast match-
ing between the silicate framework and organic moieties
which are located inside the pores of mesoporous MCM-
41 and also to the irregular immobilization of palladium
on the nano channels of MCM-41. Figure 1b indicates the
2.8.9 2-(4-Bromophenyl)-2,3-Dihydoquinazo-
lin-4(1H)-One (Entry 9, Table 3)
1H NMR (400 MHz, DMSO-d6): δH =8.18–8.12 (m, 1H),
7.81–7.79 (m, 1H), 7.62–7.58 (m, 3H), 7.46–7.43 (m, 2H),
7.31–7.25 (m, 1H), 6.76–6.71 (d, J=19.2, 1H), 6.72–6.67
(m, 1H), 5.75 (s, 1H) ppm.
3 Result and Discussion
In continuation of our studies on application of new cata-
lysts in organic transformations [14, 15, 26, 27], we
decided to prepare a novel heterogeneous catalyst. In this
manner immobilized Pd(0)-SMT complex on MCM-41was
synthesized and applied as catalyst for the synthesis of 2,
3-dihydroquinazolin-4(1H)-ones derivatives through the
reaction of aromatic aldehydes and anthranilamide and ani-
lines from amination of aryl halides.
1 3

Synthesis and Characterization of Pd(0)-SMT-MCM-41 and its Application in the Amination of…
wide-angle XRD pattern of sample Pd(0)-SMT-MCM-41
in the region 2θ=30°–80°. Figure 1B shows the relections
at 39.9°, 46.4° and 68.3° where these peaks correspond to
(111), (200) and (220) respectively [21]. The typical dif-
fraction pattern of palladium fcc crystalline structure is
clearly observed, which is in agreement with reported ones
in the litteratur [28].
Pd(0)-SMT-MCM-41 nanocatalyst was also conirmed
by the EDS detector coupled to the SEM which showed
the presence of C, Si, N, O, S and Pd in functionalized
mesoporous MCM-41 (Fig. 3c). Furthermore, the amount
of Pd introduced into the MCM-41 found to be 16.8%,
which was obtained by inductively coupled plasma optical
emission spectrometry (ICP-OES).
Thermo gravimetric (TG) analysis of the samples is
given in Fig. 2. A one-step weight loss with approximate
amount of 6 wt% was observed for Si-MCM-41 which is
due to desorption of water. As seen in Fig. 2, three stages of
weight loss were observed for Pd(0)-SMT-MCM-41. About
5%, weight loss was observed in the irst stage (below
200°C) due to the loss of physically absorbed water and
organic solvents. In the second stage (350–550°C), weight
loss is around 10%, which was assigned to the decompo-
sition of covalently bonded organics. The weight loss in
the third stage (450–800°C) is very slight and is about
2%, which may be attributed to the thermal decomposition
of silanol groups. The TG curve of Pd(0)-SMT-MCM-41
shows weight loss about (10 wt %) at 200–450°C, which is
attributed to lose of graftedimmobilized organic groups on
the surface of MCM-41. In addition, to calculate the exact
percentage of organic groups immobilized on the MCM-
41surface, elemental analysis was carried out that the result
is as: C 6.90%, H 1.39%, N 0.39% and S 1.49%.
In order to observe the morphology of the studied sur-
faces, the synthesized materials have been characterized
by Scanning Electronic Microscopy (SEM), Fig. 3a, b are
shown micrograph of MCM-41 and Pd(0)-SMT-MCM-
41which conirms the presence of uniform particles size
with spherical shape for catalyst. SEM image Pd(0)-
SMT-MCM-41 (Fig. 3b) showed no changes occurred
during surface modiication and morphology of the solid
was saved. Moreover, the existence of metallic Pd in
TEM image of the supported Pd(0)-SMT-MCM-41
catalyst is depicted in Fig. 4. It is observed that the well-
ordered regular arrangement and also the hexagonal struc-
ture were still retained for the supported catalysts. Also,
TEM image shows the ine dispersion of palladium parti-
cles on the MCM-41. The places with darker contrast could
be assigned to the presence of Pd particles. The small dark
spots in the image could be attributed to Pd nanoparticles,
probably located into the support channels. Furthermore,
the larger dark spots over the channels most likely corre-
spond to Pd nanoparticles agglomerates on the external
surface.
Figure 5 shows the FT-IR spectra of MCM-41, function-
alized-MCM-41, MCM-41-Ligand, catalyst and recovered
catalyst. The absorption band around 1080–1200 cm−1 is
due to Si–O asymmetric stretching vibrations of Si–O–Si
bridges and 460 cm−1 corresponding to bending Si–O–Si
(Fig. 5a). The spectra of functionalized MCM-41 (Fig. 5b)
show C–H stretching vibration at 2932 cm−1. This spec-
trum also shows that the band attributed to the C–Cl
became overlapped by the intense band of the Si–O group
at 812 cm−1. In the FT-IR spectrum of MCM-41-ligand
(Fig. 5c), the stretching vibration bands at 1300 cm−1
(C–N), 1480 cm−1 (N–H) and 1655 cm−1 (C=N) conirm
the presence of s-methyl isothiourea onto the pores of
mesoporous MCM-41. The free ligand indicated a stretch-
ing vibration at 1655 cm−1 while in the catalyst this band is
shifts to lower frequency and appears at 1642 cm−1 indicat-
ing the formation of Pd-ligand bond (Fig. 5d). Interestingly,
the spectra of the recovered catalyst (Fig. 5e) conirms that
the catalyst is stable during the reactions.
Figure 6 shows the N2 adsorption–desorption iso-
therms of MCM-41, SMT-MCM-41 and Pd(0)-SMT-
MCM-41. Based on the IUPAC classiication these
samples display a typical type IV adsorption isotherm,
indicated the presence of the mesoporous materials. The
results for N2 adsorption–desorption containing the BET
surface area (SBET), the total pore volumes (Vtotal), the
pore diameters (DBJH) and wall thickness of the calcined
MCM-41, SMT-MCM-41 and Pd(0)-SMT-MCM-41sam-
ple are summarized in Table 1. As shown in Table 1, BET
analysis of MCM-41 shows a surface area of 986.16 m2/g
and with upon post synthetic grafting of SMT and then
Pd, the catalyst displays a considerably lower BET sur-
face area (350.25 m2 g−1) in comparison to the MCM-
41. In addition, the pore wall thickness values were
Fig. 2 TGA diagram of (green line) MCM-41and (blue line) Pd(0)-
SMT-MCM-41
1 3

N. Noori et al.
Fig. 3 SEM images of a MCM-
41, b Pd(0)-SMT-MCM-41 and
c EDS pattern of Pd(0)-SMT-
MCM-41
Fig. 4 Transmission electron
microscopy (TEM) of MCM-41
(left) and Pd(0)-SMT-MCM-41
catalyst (right)
calculated to be 0.902, 0.980 and 1.21 nm for MCM-41,
SMT-MCM-41 and Pd(0)-SMT-MCM-41 respectively,
the nitrogen adsorption–desorption isotherms studies
demonstrated that a signiicant decrease in BET surface
area and pore volume and increase of wall thickness of
SMT-MCM-41 and Pd(0)-SMT-MCM-41 in comparison
to the corresponding values for MCM-41 clearly indi-
cate that the Pd complex has been immobilized inside the
channels/onto the mesoporous wall of the MCM-41 sup-
port [29].
1 3

Synthesis and Characterization of Pd(0)-SMT-MCM-41 and its Application in the Amination of…
In order to optimize the reaction conditions, we chose
the iodobenzene as a sample of a non-activated aryl halide
with aqueous ammonia as a model reaction and inluence
of diferent parameters such as amount of catalyst, nature
of solvents and bases were screened and the results are
summarized in Table 2.
To study the efect amount of catalyst, systematic stud-
ies were carried out in the presence of diferent amounts
of the catalyst from 0.1 to 0.2 mol% at room temperature
under solvent-free conditions (Table 2, entries 1, 5 and 6).
The results show that there is a general trend of increase in
isolated yields of products by rising catalyst concentration.
Thus, the best yield is found in the presence of 0.2 mol% of
Pd (Table 2, entry 1). However, when the higher amount of
catalyst (0.2–0.24 mol%) was used, the catalyst still func-
tioned partly well, but the conversion was slight increases
in 98% of yield (Table 2, entry 4).
Fig. 5 FTIR spectra of a MCM-41, b functionalized-MCM-41, c
MCM-41-ligand, d catalyst and e recovered catalyst
To ind the best reaction conditions, the efects of vari-
ous solvents, such as PEG, DMF, EtOH, DMSO and
1,4-Dioxan were examined (Table 2, entries 7–9). It was
found that the reaction didn’t complete after 24 h under sol-
vent conditions. Finally, we decided to carry out the amina-
tion of aryl halides under solvent-free conditions (Table 2,
entry 1).
The results mentioned above conirm that the Pd(0)-
SMT-MCM-41 catalyst was synthesized, so the catalytic
activity of this synthesized catalyst was investigated in the
amination of various aryl halides using aqueous ammonia
to produce aniline derivatives (Scheme 2).
Table 1 Texture parameters
obtained from nitrogen sorption
studies
Sample
SBET (m2/g)
Pore diam by BJH Pore vol (cm3/g)
method (nm)
Wall diam (nm)
MCM-41
986.16
520.10
350.25
3.65
2.61
1.52
0.711
0.415
0.151
0.902
0.980
1.21
SMT-MCM-41
Pd(0)-SMT-MCM-41
Fig. 6 Nitrogen adsorption–
desorption isotherms of samples
a MCM-41 b SMT-MCM-41
and c Pd(0)-SMT-MCM-41
catalyst
1 3

N. Noori et al.
In order to ind appropriate base we explored the efects
of bases on the model reaction under solvent free condi-
tions. The diferent inorganic and organic bases including
(Et)3N, Na2CO3, K2CO3 and KOH were examined (Table 2,
entries 12–15). As shown in Table 2, it was found that the
reaction was performed in absence of base in terms of short
reaction time and high yield (Table 2, entry 1).
NH2
X
Pd (0)-SMT-MCM-41(Cat.)
NH4OH, r.t
R
R
X= Br, I
Scheme 2 Pd(0)-SMT-MCM-41 catalyzed the amination of aryl hal-
ides
Subsequently, using the optimized reaction conditions,
amination reactions of various electron-poor and electron-
rich aryl iodides or bromides derivatives with aqueous
ammonia were investigated. The representative results are
summarized in Table 3. It was observed that the catalyst
exhibits high catalytic activities for coupling of various aryl
halides with aqueous ammonia providing excellent yields
of desired products.
On the other hand, in order to extend of applications
of synthesized catalyst, we explored catalytic activity of
[Pd(0)-SMT-MCM-41] as a new heterogeneous and reusa-
ble catalyst in the one-pot synthesis of 2,3-dihydroquinazo-
lin-4(1H)-ones through the reaction of aromatic aldehydes
and anthranilamide (Scheme 3). In order to determine
the most appropriate reaction conditions, the reaction of
Table 2 Optimization of the reaction conditions
Entry Solvent
Base
Catalyst (mol%) Time (h) Yield %a
1
–
–
0.2
2.5
2.5
2.5
2.5
5
96
47
59
98
88
84
70
65
74
55
50
90
85
88
75
2
–
–
0.1
3
–
–
0.16
0.24
0.16
0.1
4
–
–
5
–
–
6
–
–
7
7
PEG
–
0.2
24
24
24
24
80
14
10
8
8
DMF
–
0.2
9
EtOH
–
0.2
10
11
12
13
14
15
DMSO
–
0.2
1,4-Dioxan
–
0. 2
0.2
–
–
–
(Et)3N
O
O
Na2CO3 0.2
K2CO3 0.2
R
NH
NH
CHO
NH2
NH2
Pd(0)-SMT-MCM-41
Ethanol,Reflux
R
+
KOH
0.2
20
Reaction conditions: iodobenzene (1 mmol), aqueous ammonia
(1 mL) at room temperature
aIsolated yield
Scheme 3 Pd(0)-SMT-MCM-41 catalyzed the synthesis of 2,3-dihy-
droquinazolin-4(1H)-one derivatives
Table 3 Amination of aryl
NH2
-
-
Pd 0 MT M M 41
( )
@
C
S
halides in the presence of Pd(0)-
SMT-MCM-41 using aqueous
ammonia
+
NH3
X
R
r.
t
a-
j
1
1
a
-
j
2 2
Entry Aryl halide
Product Time (h) Yield (%)a
M. p (ºC) (References) TOF(h−1
)
1
Iodobenzene
2a
2b
2.5
3
96
Oil [10]
192
2
Bromobenzene
93
Oil [10]
155
3
4-Bromochlorobenzene 2c
6
91
68–70 [30]
43–44 [10]
57–58 [30]
47–49 [10]
146–148 [30]
56–58
75.83
117.5
95
4
4-Iodotoluene
2d
2e
2f
2g
2h
2i
2j
–
4
94
5
4-Iodoanisole
5
95
6
2-bromonaphtalene
4-Bromonitrobenzene
2-bromopyridine
4-Bromophenol
4-Bromobenzonitrile
Iodobenzene
14
2
92
32.85
242.5
95
7
97
8
5
95
9
10
2.25
2.5
96
186–190
48
10
11
94
87–88 [10]
208.88
No reactionb
Reaction conditions: aryl halide (1 mmol), aqueous ammonia (1 mL) and catalyst (0.2 mol%) at room tem-
perature
aIsolated yield
bReaction conditions: the SMT-MCM-41 catalyst was used
1 3

Synthesis and Characterization of Pd(0)-SMT-MCM-41 and its Application in the Amination of…
Table 4 Optimization for the synthesis of 2,3-dihydroquinazolin-
4(1H)-one conditions for the cyclocondensation of 4-chlorobenzalde-
hyde and anthranilamide as a model subestrates under relux condi-
tions (except for these entries 8–10) for 20 min
To prove the true efectiveness of the catalyst, the reac-
tion was performed without catalyst. It was found that in
the absence of Pd(0)-SMT-MCM-41, the synthesis of
2,3-dihydroquinazolin-4(1H)-ones, did not proceed even
after 12 h (Table 4, entry 1). As indicated in Table 4 the
best result has been obtained with 0.16 mol % of catalyst
in terms of reaction time and isolated yield (Table 4, entry
3). In the next step, the efect of various solvents such as
acetonitrile, acetone, ethyl acetate, n-hexane and dichlo-
romethane was investigated by carrying out the model
reaction in the presence of Pd (0)-SMT-MCM-41 (Table 4,
entries 4–7). As shown in Table 4, among the screened sol-
vents, ethanol is found to be optimal solvent for the synthe-
sis of 2,3-dihydroquinazolin-4(1H)-ones (Table 4, entry 3).
Also, we found that model reaction yields were suscep-
tible to temperature changes. Therefore this reaction was
checked under diferent temperatures including room tem-
perature (25°C), 40, 60, and 80°C (Table 4, entries 3 and
8–10). It was observed that the yield increased as the reac-
tion temperature was raised. Thus, temperature 80°C was
the optimal one in this study (Table 4, entry 3).
Entry
Solvent
Catalyst
(mol %)
Temperature
(°C)
Yield (%)a
1
2
3
3
4
5
5
6
7
8
9
10
Ethanol
–
80
80
80
80
80
80
80
80
80
25
40
60
Traceb
35
Ethanol
0.1
Ethanol
0.16
0.2
97
Ethanol
98
Acetonitrile
Ethyl acetate
Dichloromethane
Acetone
0.16
0.16
0.16
0.16
0.16
0.16
0.16
0.16
60
77
45
63
n-Hexane
Ethanol
40
35
Ethanol
55
Ethanol
70
aIsolated yield
bAfter 12 h
Using the optimized reaction conditions, this process
was demonstrated by the wide range of substituted divers
aldehydes electron-donating (Table 5, entries 2–5) and elec-
tron-withdrawing (Table 5, entries 6–11) functional groups
to synthesize the corresponding products in excellent yields
anthranilamide and 4-chlorobenzaldehyde were selected as
model substrates and the inluence of the amount of cata-
lyst, nature of the solvents and the efect of temperature on
the reaction times and yields was studied.
Table 5 Synthesis of 2,3-dihydroquinazolin-4(1H)-ones catalyzed by Pd(0)-SMT-MCM-41 in ethanol and at 80°C
O
O
R
NH
NH
H
C
O
NH2
NH2
Pd (0)-SMT-MCM-41
Ethanol, Reflux
+
R
2a-2n
1a-1n
Entry
Aldehyde
Benzaldehyde
Product
Time (min)
Yield (%)a
M. p (ºC) (References)
TOF (h−1
)
1
2a
2b
2c
2d
2e
2f
2g
2h
2i
50
25
96
219–221 [31]
223–226 [23]
178–179 [31]
164–165 [31]
214–215 [23]
199–200 [25]
175–176 [23]
215–216 [31]
197–199 [23]
180–183 [22]
196–197 [31]
245–246 [31]
201–203 [23]
722.8
1493
928
2
4-Methylbenzaldehyde
4-Methoxybenzladehyde
4-Ethoxybenzladehyde
3,4-Dimethoxybenzladehyde
4-Chlorobenzaldehye
3-Bromobenzaldehyde
3-Nitrobenzladehyde
4-Bromobenzaldehyde
2-Nitrobenzladehyde
4-Fluorobenzaldehyde
Terephthalaldehyde
98
3
40
98
4
35
97
1039
654.5
1818.7
490
5
55
96
6
20
97
7
75
98
8
145
110
180
100
25
94
243.1
323.8
193.75
363.75
1470
575
9
95
10
11
12
13
14
2j
93
2k
2l
97
98
Cinnamaldehyde
2m
–
60
92
4-Chlorobenzaldehye
20
No reactionb
Reaction conditions: aldehyde (1 mmol), 2-aminobenzamide (1 mmol), catalyst (0.16 mol%) and solvent (10 mL) at relux temperature
aIsolated yield
bReaction conditions: the SMT-MCM-41 catalyst was used
1 3

N. Noori et al.
easy work up, high yields, eco-friendly, simplicity in: sepa-
ration of catalysts. The results indicate that the activity of
the catalyst was not much afected on recycling. Therefore,
the catalyst can be reused for ive times without any signii-
cant loss of activity.
Acknowledgement This work was supported by the research facili-
ties of Ilam University, Ilam, Iran.
Fig. 7 The recycling experiment of Pd(0)-SMT-MCM-41 in
the amination of iodobenzene (green column) and synthesis of
2-(4-chlorophenyl)-2,3-dihydroquinazolin-4(1H)-one (red column)
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In order to ind out whether the catalyst is truly heterogene-
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catalyst to the solution. The heterogeneity of the Pd(0)-
SMT-MCM-41 catalyst was examined by carrying out a hot
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1 3

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1 3