Eco-friendly magnetic clinoptilolite containing Cu(0) nanoparticles (CuNPs/MZN): as a new efficient catalyst for the synthesis of propargylamines via A3 and KA2 coupling reactions

Article abstract of DOI:10.1002/aoc.4290

In this reaserch a new and eco-friendly magnetic catalyst for the synthesis of propargylamines is reported. Initial incorporation of Fe₃O₄ magnetic nanoparticles (MNPs) into the pores of the natural clinoptilolite zeolite followed by

Full text of DOI:10.1002/aoc.4290

Received: 27 September 2017
DOI: 10.1002/aoc.4290
Revised: 18 December 2017
Accepted: 19 December 2017
F U L L P A P E R
Eco‐friendly magnetic clinoptilolite containing Cu(0)
nanoparticles (CuNPs/MZN): as a new efficient catalyst for
3
2
the synthesis of propargylamines via A and KA coupling
reactions
Mohammad Mehdi Khakzad Siuki | Mehdi Bakavoli
| Hossein Eshghi
Department of Chemistry, Faculty of
In this reaserch a new and eco‐friendly magnetic catalyst for the synthesis of
Science, Ferdowsi University of Mashhad,
Mashhad 91775‐1436, Iran
propargylamines is reported. Initial incorporation of Fe O magnetic nanopar-
3
4
ticles (MNPs) into the pores of the natural clinoptilolite zeolite followed by
modification with epichlorohydrine and ethylenediamine and then immobiliza-
tion of CuNPs on the surface of functionalized zeolite gave the desired catalyst
Correspondence
Mehdi Bakavoli, Department of
Chemistry, Faculty of Science, Ferdowsi
University of Mashhad, Mashhad, 91775‐
(CuNPs/MZN). The CuNPs/MZN was fully characterized by various techniques
1436, Iran.
Email: mbakavoli@um.ac.ir
such as FT‐IR, CHN, TGA, ICP, XRD, SEM, TEM and BET. A host of
propargylamines were readily synthesized through using the catalyst in high
Funding information
3
2
yields and short reaction times via A and KA coupling reactions of alde-
hydes/ketones, amines, and phenylacetylene. The CuNPs/MZN was easily
separated from the reaction mixture by an external magnet and reused several
times successfully. The catalyst has the potential for catalysis of various organic
transformations.
Ferdowsi University of Mashhad Research
Council, Grant/Award Number: 3/39646
KEYWORDS
clinoptilolite, Cu nanoparticles, magnetic zeolite, nanocomposite, propargylamines
2
+
1
| INTRODUCTION
composites have been utilised for removal of Sr from
[
14]
aqueous solutions. Recently, green zeolite/Fe O nano-
3
4
[1,2]
[15,16]
Natural or synthetic zeolites
are microporous alumi-
composites have been synthesized, characterized
[
10–12,17]
nosilicate mineral compounds which are widely used as
waste water and gas treatment, catalysts, molecular sieve
and also in nuclear processing, agriculture, advanced
materials, and recently as nanocomposites in organic syn-
and used in organic transformations.
Propargylamines have been utilized in the synthesis of
various nitrogen‐heterocycles such as pyrrolidines, pyr-
roles, oxazoles as natural bioactive and pharmaceutical
[3,4]
[18]
thesis.
Among natural zeolites, clinoptilolite is the
compounds.
Among the various methods for the prep-
most important and extensively used for adsorption of
aration of propargylamines in the presence of homoge-
neous or heterogeneous catalysts, one pot, three
component reaction of aldehydes/ketones, secondary
[5,6]
heavy cations and gases,
removing of radioactive
materials from contaminated soils and ammonium from
[7,8]
3
2
urban waste water.
Magnetic zeolites have been pro-
amines and terminal alkynes (A /KA coupling) are more
[19–22]
duced by modifying their surface and inner pores with a
common without the need for any external oxidant.
[9]
magnetic component. Use of magnetic adsorbents pro-
vide easier separation and avoid tedious and time con-
The catalytic activation of the C–H bond of terminal
alkynes has been achieved with various transition
[10–13]
[23,24]
[25]
suming work‐ups.
Magnetic clinoptilolite/CoFe O4
metals.
and among them, Cu is the most studied.
2
Appl Organometal Chem. 2018;e4290.
wileyonlinelibrary.com/journal/aoc
Copyright © 2018 John Wiley & Sons, Ltd.
1 of 12
https://doi.org/10.1002/aoc.4290

2
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KHAKZAD SIUKI ET AL.
Few methods have been reported for the synthesis of
propargylamines from ketones owing to low reactivity of
and selectivity and gives recycling properties to the
catalyst.
[
19,32]
[19,26]
ketones compared to aldehydes.
A literature survey disclosed that, Cu (OH)x–Fe O
To the best of our knowledge, there is no report
for the synthesis of poropargylamine with magnetic
zeolite/Fe O @Cu(0) nanocomposite, thus in this work,
3
4
was the first heterogeneous catalyst employed for the syn-
3
4
2
[21]
thesis of propargylamines via KA coupling.
Recently,
we wish to report the preparation of functionalized
magnetic nanocomposite of clinoptilolite zeolite with
epichlorohydrine and ethylenediamine linker and in situ
2
Ti (OEt) was employed as Lewis acid for neat KA cou-
4
pling reaction of acyclic and cyclic aliphatic ketones
under solvent free and green conditions to enhance the
activity of the substrates, yields, and lowering the reaction
[33]
generation of Cu NPs on the surface of composite
as
an excellent and efficient catalyst (CuNPs/MZN) for the
synthesis of various propargylamines (Scheme 1).
[27]
2
times.
In order to employ aromatic ketones in KA
coupling reactions, new reaction conditions based on
CuBr /sodium ascorbate and Ti (OEt) catalytic system
have been reported.
2
4
2
| EXPERIMENTAL
.1 | Chemicals
[28]
In comparison with heterogeneous copper catalyzed
2
3
A coupling reactions, a few heterogeneous copper‐based
2
systems have been reported for KA coupling reac-
All solvents were purchased from Merck. Natural
clinoptilolite zeolite was purchased from Afrazand com-
pany, semnan, Iran. Iron (III) chloride hexahydrate, iron
(II) chloridetetrahydrate, sodium hydroxide, copper (II)
acetate, sodium borohydride, ethylene glycol, ethanol,
hydrochloric acid and other compounds were obtained
from Sigma‐Aldrich in analytical grade and used without
further purification.
[
29–31]
3
tions.
To achieve the eco‐friendly protocol for A
2
and KA reactions, the primary goal is to develop an eco-
nomical, efficient, and more benign recyclable catalyst
with low catalyst loadings which makes the process more
viable compared to the homogeneous conditions.
Thus, there is a wide scope for improvement of hetero-
3
2
geneous copper catalysts (HCC) for A and KA coupling
transformations. Among heterogeneous copper contain-
ing catalysts, magnetic nanocatalysts are preferred to
conventional catalysts due to possessing a high surface‐
to‐volume ratio and dispersity of immobilized metal
nanoparticles, which enhances their stability, activity
2.2 | Apparatus
The melting point of the products was determined with an
Electrothermal Type 9100 melting point apparatus. The
SCHEME 1 The schematic pathway of
catalyst preparation

KHAKZAD SIUKI ET AL.
3 of 12
FT‐IR spectra were recorded on an Avatar 370 FT‐IR
Thermal Nicolet spectrometer. Mass spectra were
recorded on a 5973 Network Mass. Selective Detector.
H NMR and CNMR spectra were measured (CDCl3)
with a Bruker DRX‐300 AVANCE spectrometer at 300
ethanol (50.0 ml) several times, and dried under vacuum
at 50 °C.
1
13
2.6 | Synthesis of CuNPs/MZN
and 75 MHz, respectively. Termogravimetric analysis
To a solution of copper (II) acetate in ethanol (0.50 g in 10
ml), MZEN, (0.50 g) was added and the mixture stirred for
24 h. Then the solvent was removed and the magnetic
composite was washed several times with water and etha-
nol and dried under vacuum. A small amount of dried
material (0.50 g) was poured in ethanol (10.0 ml), and
stirred under Ar, then a solution of sodium borohydrid,
(10 ml, 0.02 M) was added dropwise and stirred strongly
for 0.5 h. The black magnetic product was isolated by a
magnet and dried under vacuum at 50 °C, after washing
several times with water (50.0 ml) and ethanol (50.0 ml).
(
TGA) was performed on a Shimadzu Thermogravimetric
Analyzer (TG‐50). Transmission electron microscope
TEM) images were acquired on a TEM microscope Leo
12 AB120 KV Zeiss Germany. Inductively coupled
(
9
plasma (ICP) was obtained using a Varian, VISTA‐PRO,
CCD, Australia. X‐ray diffraction (XRD) patterns were
collected using a Braker D4 X‐Ray diffractometer with
Ni‐filtered Cu KR radiation (40KV, 30MA). Elemental
analysis was carried out using CHNS (O) Analyzer Model
FLASH EA 1112 series made by Thermo Finnigan. BET
analysis was performed by Autosorb1, Quantachrome,
Florida, USA.
2.7 | General procedure for synthesis of
propargylamines
2.3 | Preparation of magnetic zeolite
To
a
solution of benzaldehyde derivatives or
FeCl .6H O, (2.60 g) and FeCl .4H O, (1.0 g), molar ratio
cycloalkanones, (1.0 mmole), secondary amines (1.1
mmole), and phenylacetylene (1.0 mmole) in 1,2‐dichlo-
roethane, (2.0 ml), CuNPs/MZN catalyst (20.0 mg) was
added and the mixture was stirred at 80 °C for 1‐2 hrs.
The progress of reaction was monitored by TLC and after
completion the catalyst was removed with an external
magnet and washed with ethanol. The product
(propargylamine) was isolated from the reaction mixture
by column chromatography or plate chromatography by
using hexane‐ethyl acetate (5:1) as eluent to obtain the
pure compound. The product was identified by CHN,
3
2
2
2
2
:1, was dissolved in deionized water (12.50 ml) and cocn.
HCl (0.45 ml) was added at room temperature under
argon atmosphere. Natural zeolite, clinoptilolite, (2.0 g)
was added to the mixture. A solution of NaOH (125.0
ml, 1.50 M), was added dropwise to the suspension in 80
°C. Then the mixture was stirred strongly for 2 hrs at
1
00 °C. The prepared magnetic zeolite (MZ) was isolated
from the mixture by putting a magnet on the outer wall
of container and washed with distilled water (50.0 ml),
and ethanol (50.0 ml) several times and dried under
vacuumat 50 °C for 24 hrs.
1
13
Mass spectrometry, HNMR, and C NMR spectroscopy.
2
.4 | Synthesis of MZE
2.7.1 | 4‐(1,3‐Diphenylprop‐2‐yn‐1‐yl)
[19,34]
morpholine (Entry 1):
MZ, (1.0 g), was poured into a solution of NaOH (pH=10)
and was stirred at room temperature for 2 hrs. After sur-
face activation, the magnetic composite was isolated and
washed several times with deionized water (50.0 ml) and
ethanol (50.0 ml) and dried under vacuum at 50 °C. The
dried composite was added to a solution of epichlorohy-
drin (1.50 ml) in ethanol (10.0 ml), and the mixture was
stirred at 60 °C. After 24 hrs, the solvent was removed
and the resulting solid material was separated by an exter-
nal magnet, washed with ethanol and dried at 50 °C.
1
HNMR (300 MHz, CDCl ): δ= 2.69 (4H, t, J=4.35), 3.77‐
3
1
3
3.81 (4H, m), 4.85 (1H, s), 7.38‐7.70 (10H, m); C NMR
(CDCl , 75 Hz): δ= 50, 62.07, 67.20, 85.09, 88.54, 123.01,
3
127.83, 128.28, 128.31, 128.36, 128.64, 131.85, 137.84.
Anal.calc. for C H NO: C, 82,31; H, 6.86; N,5.08; O,
19
19
5.72; Found: C, 82.28; H, 6.90; N, 5.05; M.S. (70 ev) m/z
+
(%): 277 (M , 100).
2
.7.2 | 4‐(1‐(4‐Methoxyphenyl)‐3‐
phenylprop‐2‐yn‐1‐l) morpholine
(Entry2)
[27,35,36]
2.5 | Synthesis of MZEN
1
To a solution of ethylenediamine (5.0 ml) in ethanol (10.0
ml), 1.0 g of MZE was added and stirred at 60 °C for 24
hrs. Then the magnetic composite was separated with a
magnet, and washed with distilled water (50.0 ml) and
HNMR (300 MHz, CDCL ): δ= 2.66‐2.70 (4H, m), 3.78‐
3
3.79 (4H, m), 4.79 (1H, s), 6.94‐6.97 (d, 2H, J=8.7, Ar),
7.36‐7.39 (2H, m, J=6.3, Ar), 7.59‐7.62 (d, 2H, J=8.2, Ar);
13
C NMR (CDCl , 75 Hz): δ= 49.87, 55.30, 61.49, 67.20,
3

4
of 12
KHAKZAD SIUKI ET AL.
8
1
6
5.48, 88.33, 113.62, 123.08, 128.29, 128.38, 129.78, 129.92,
31.85, 159.27. Anal.calc. for C H NO : C, 78.20; H,
X‐ray diffraction, (XRD), vibrating sample magnetometer,
(VSM), and Brunauer, Emmett and Teller (BET) surface
area analysis.
20
21
2
.87; N, 4.55; Found: C,78.15; H, 6.89; N, 4.56; O, 10.41;
+
M.S. (70 ev) m/z (%): 307 (M ,100).
FT‐IR spectroscopy was used for characterization of
the catalyst structure, (Figure 1). The FT‐IR spectrum of
clinoptilolite is dominated by some of the major zeolite
2
.7.3 | 1‐(1,3‐Diphenylprop‐2‐yn‐1‐yl)
‐1
framework bands in the range of 720‐790 cm υs (Si‐O),
[
19,34]
piperidine (Entry 6):
‐1
‐1
1
3
020 cm (Si‐OH), 1130 cm υas (Si‐O and Al‐O) and
‐
1
[37]
1
550 cm for isolated silanol (Si‐OH), (Figure 1a).
HNMR (300 MHz, CDCL ): δ= 1.58‐1.60 (2H, m), 1.63‐
3
‐1
The strong adsorption bands at 573 cm can be attrib-
uted to the stretching vibration of the Fe‐O band, which
confirms the presence of Fe O nanoparticles (Figure 1b
1
.79 (4H, m), 2.70 (4H, t, J =5.25), 4.94 (1H, s), 7.39‐7.45
(6H, m, 2×Ar), 7.62‐7.65 (2H, m, Ar), 7.76‐7.78 (2H, m,
13
Ar); CNMR (CDCl , 75 Hz): δ= 24.55, 26.26, 50.78,
3 4
3
[
38,39]
to Figure 1d).
The broad absorption band at 3444
6
1
2.46, 6.13, 88.03, 123.44,127.60, 128.18, 128.39, 128.66,
31.92, 138.61.
‐1
cm is related to stretching vibration of OH, demonstrat-
ing the presence of hydroxyl groups on the surface of
materials (Figure 1a to Figure 1e). The epoxy rings which
are anchored on the surface of zeolite and Fe O compos-
2
.7.4 | 1‐(3‐Phenyl‐1‐(p‐tolyl)prop‐2‐yn‐1‐
3
4
[19]
yl) piperidine (Entry7):
ite, (MZE), are characterized by the methylene C‐H
‐1
1
stretching at 2950 cm and C‐O‐C vibration stretching
HNMR (300 MHz, CDCL ): δ= 1.58‐1.63 (2H, m), 1.66‐
3
‐1
at 1240‐1260 cm .
1
.75 (4H, m), 2.46 (3H, s), 2.67 (4H, t, J= 4.9), 7.27 (2H,
‐
1
The bonds at 3436, and 3700 cm are due to stretching
d, J=8.1), 7.39‐7.43 (3H, m), 7.6‐7.62 (2H, m), 7.63 (2H,
d, J=8.1); C NMR (CDCl , 75 Hz): δ= 21.24, 24.58,
13
of the NH , and N‐H bonds or an overtone peaks of C‐O
2
3
stretching bonds at 1233 cm‐ at MZN (Figure 1d). In all
cases, vibration frequency was covered by the broad band
of stretching vibration O‐H and asymmetric vibration of
the Si–O–Si, and Al‐O‐Al bonds, respectively. The
decreased intensity of vibration band at 3400‐3700 cm‐
of CuNPs/MZN can be attributed to the coordination of
Cu nanoparticles to N,N and O species which are avail-
1
2
1
9.28, 50.70, 62.22, 86.46, 87.73, 123.50, 128.10, 128.36,
28.58, 128.86, 131.90, 135.64, 137.16.
1
2
.7.5 | 4‐(1‐(Phenylethynyl)cyclohexyl)
[21]
morpholine (Entry 12):
1
HNMR (300 MHz, CDCL ): δ= 1.28‐1.77 (8H, m), 2.05‐
3
[
38,39]
able on the surface of the composite.
2
.09 (3H, m), 2.76 (4H, t, J=4.8 Hz), 3.80 (4H, t, J=4.8
13
CHN analysis showed the presence of C, H, and N in
nanocomposite that confirms the good immobilization of
chlorohydrine‐ethylenediamine linker to the surface of
nanomagnetic composite.
Hz), 7.30‐7.48 (5H, m); C NMR (CDCl , 75 Hz):
δ= 22.78, 25.71, 29.34, 35.46, 46.67, 58.95, 67.50, 86.53,
3
8
9.78, 123.44, 128.23, 131.74; Anal.calc. for C H NO:
18 23
C, 80.29; H, 8.59; N, 5.18; Found: C, 80.26; H, 8.61; N,
+
The existence of CuNPs anchored on the surface of the
MZ was proved by ICP and EDS techniques. According to
the inductively coupled plasma, (ICP‐OES), results, the
5
.20; O, 5.94; M.S. (70 ev) m/z (%): 269 (M , 100).
‐1
3
| RESULTS AND DISCUSSION
amount of the Cu was determined, 1.8 mmol g . Also
the elemental analysis obtained from the EDS analyzes
As shown in Scheme 1, CuNPs/MZN catalyst was pre-
pared in 4 steps. First, the MZ was synthesized by green
[16]
quick precipitation method.
Then, epichlorohydrine–
ethylenediamine covalently bonded to negative oxygen
related to aluminosilicate groups on the surface of zeolite
or hydroxyl groups of Fe O NPs. Later, the ligands were
3
4
activated with NaOH solution in EtOH and treated with
copper (II) acetate which was complexed to N,N and O
available on linker and zeolite. Finally, Cu (II) nanoparti-
[
35]
cles were reduced to Cu(0) with NaBH as reductant.
4
The prepared catalyst, CuNPs/MZN, was character-
ized by FT‐IR, CHN, thermogravimetric analysis (TGA),
scanning electron Microscopy, (SEM), transmission elec-
tron microscopy, (TEM), energy dispersive X‐ray (EDX),
FIGURE 1 FTIR of (a) zeolite (b) magnetic zeolite (MZ) (c) MZE
(d)MZN (e) CuNPs/MZN

KHAKZAD SIUKI ET AL.
5 of 12
of catalyst (initial zeolite) before (Figure 2a) and after
immobilization of the Fe O and CuNPs (CuNPs/MZN),
3
4
(
Figure 2b), shows Fe O and CuNPs anchored well onto
3 4
the zeolite.
The crystal structure of magnetic zeolite, MZ and
CuNPs/MZN were characterized by XRD (Figure 3). Six
diffraction peaks located at 30.26°, 35.5°, 43.12°, 53.29°,
5
(
6.99°, and 62.6° from the (220), (311), (400), (422),
511), and (440) crystal planes confirm well with the stan-
dard Fe O cubic phase. Three peaks with 2θ=43.6, 50.8,
3
4
and 74.4 which attributed to the (111), (200), and (220)
planes is corresponding to the presence of Cu(0) nanopar-
ticles in the nanocomposite (JCPDS, File No. 04‐0836),
FIGURE 3 (a) XRD of MZ, (b) CuNPs/MZN
[38]
(Figure 3).
The particle size of CuNPs/MZN was studied by TEM
technique. The TEM image of sample (Figure 4b) shows
average size of Fe O4 and CuNPs are approximately
3
between 10‐15 nm in the diameter. Also, the morphologi-
cal features were studied by SEM technique. The SEM
image of CuNPs/MZN (Figure 4a) demonstrates that
these modified copper loaded MZ NPs are almost spheri-
cal, in aggregated form due to the magnetic nature of
catalyst.
The thermal stability of the MZN was characterized by
thermo gravimetric analysis (TGA). TGA curve in
Figure 5 demonstrates the weight loss up to 200 °C which
was related to the loss of absorbed water molecules on the
support or trapped water (nearly 10%) in the inner pores
of zeolite. The second weight loss is related to the decom-
position of organic compounds in the temperature range
FIGURE 4 (a) The SEM image of CuNPs/MZN (b) The TEM
image of CuNPs/MZN
[
39]
of 190‐600 °C;
Therefore, the result confirms that the
ligand was grafted successfully.
The magnetic behavior of CuNPs/MZN was proved by
VSM (vibrating sample magnetometer). As illustrated in
Figure 6, the value of saturation magnetic moment of
‐
1
catalyst is 22emμ g which indicates the catalyst is super
paramagnetic.
The N2 adsorption–desorption experiment was
recorded in order to evaluate the porosity of the initial
zeolite and final nanocomposite catalyst (CuNPs/MZN).
FIGURE 2 (a) EDS of clinoptilolite (b) EDS of CuNPs/MZN

6
of 12
KHAKZAD SIUKI ET AL.
Ph
Ph
O
O
N
CuNPs/MZN
+
+ Ph
Ph
H
N
H
O
1
SCHEME 2 A model reaction for evaluation of the catalyst
activity and optimization of reaction conditions during the
synthesis of compound 1
TABLE 2 Screening of the amount of the catalyst and tempera-
a
ture for the formation of compound 1
FIGURE 5 TGA analysis of MZEN
b
Entry
Catalyst (mg)
T (°C)
Isolated Yield (%)
1
‐‐‐‐‐
rt
Trace
2
3
4
5
6
7
8
9
10
20
10
20
5
rt
Trace
Trace
20
rt
50
50
80
80
80
80
30
10
10
15
20
50
78
95
a
Reaction conditions: aldehyde (1.0 mmol), amine (1.1 mmol), alkyne (1
mmol).
b
Isolated yield.
FIGURE 6 Magnetization curve of CuNPs/MZN
TABLE 3 Screening of various solvents for the formation of
compound 1
a
b
Entry
Solvent
Isolated Yield (%)
The experiment results show a decrease in BET surface
area, pore volume, and mean pore diameter of catalyst rel-
ative to initial zeolite (Table 1). This results confirm suc-
cessful supporting of Fe O and Cu NPs in the pores of
1
H
2
O
Trace
2
3
4
5
6
7
8
9
n‐hexane
Acetonitrile
Ethanol
Trace
Trace
Trace
Trace
10
3
4
initial zeolite.
The catalytic performance of the novel CuNPs/MZN
as an efficient magnetically nanocatalyst was investigated
Petroleumether
Toluene
DCM
3
for the synthesis of propargylamine compounds via A
70
2
and KA coupling reactions. After determining the molar
DCE
95
ratios of reactants based on mechanistic investigations
and previously reported literatures, the other reaction
conditions such as solvent, amount of catalyst and tem-
perature were optimized.
Neat
95
a
benzaldehyde (1 mmol), morpholine (1.1 mmol), phenylacetylene (1 mmol),
catalyst (3 mol %), 80 °C after 1 h.
b
Based on isolated yields.
TABLE 1 Specific surface area (SBET), Pore volume, and the mean pore diameter data of the Zeolite and CuNPs/MZN catalyst
2
3
Sample
S
BET (m /g)
Pore volume (cm /g)
Mean pore diameter (A ֯ )
Zeolite
143.30
52.17
0.09
0.06
24.60
CuNPs/MZN
23.06

KHAKZAD SIUKI ET AL.
7 of 12
3
2
TABLE 4 Three component aldehyde (ketone), terminal alkyne, and secondary amine ( A, and KA coupling) for the synthesis of
a
propargylamines in the presence of CuNPs/MZN catalyst
a
b
Entry
R
1
, R
2
Amine
Product
Time (h)
Yield (%)
1
Ph,H
1
95
2
3
4‐OMeC
6
H
4
,H
2
85
80
4‐(NMe
2
)C
6
H
4
,H
1.5
4
5
4‐Cl C
6
H
4
,H
2
2
95
85
4‐MeC
6
H
4
,H
6
7
Ph,H
1
2
95
90
4‐Me C
6
H
4
, H
8
9
4‐OMe C
6
H
4
,H
2
90
98
4‐Cl C
6
H
4
,H
1.5
(Continues)

8
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KHAKZAD SIUKI ET AL.
TABLE 4 (Continued)
a
b
Entry
R
1
, R
2
Amine
Product
Time (h)
Yield (%)
10
11
12
13
14
15
4‐Me C
6
H
4
,H
2
85
Trace
98
(CH
3
)
2
CH, H
5
Cyclohexanone
Cyclopentanone
Me,Propyl
1.5
1.5
2
95
Trace
Trace
Ph,CH
3
5
1
1
1
6
7
8
Cyclohexanone
Cyclopentanone
2‐Furyl,H
1.5
1.5
4
98
95
80
1
9
2‐Thiophenyl, H
10
75
(Continues)

KHAKZAD SIUKI ET AL.
9 of 12
TABLE 4 (Continued)
a
b
Entry
R
1
, R
2
Amine
Product
Time (h)
Yield (%)
2
0
Ph, H
12
80
2
1
Ph, H
48
‐
a
benzaldehyde (1 mmol), morpholine (1.1 mmol), phenylacetylene(1 mmol), catalyst (3 mol %), 80 °C.
b
based on isolated yields.
3
.1 | The optimization of reaction
dichloroethane (DCE), and dichloromethane (DCM) pro-
viding good yields, whereas H O, n‐Hexane, acetonitrile,
ethanol, petroleum ether, afforded no coupled reaction
after 1 hour. Therefore, the reaction could be carried out
in chlorosolvents such as DCM, and DCE with high yields
(Table 3).
conditions for the synthesis of
propargylamines
2
A model reaction with benzaldehyde, phenylacetylene,
andmorpholine was studied first to evaluate the catalytic
activity of CuNPs/MZN and optimize the reaction condi-
tion (Scheme 2).
In an effort to develop an optimal catalytic system,
various reaction parameters were screened for the prepa-
ration of propargylamines in the model reaction in differ-
ent amount of catalyst and temperatures and are
summarized in the Table 2. The optimum amount of
catalyst was 20 mg (3 mol %), and the best temperature
was 80 °C.
The above model reaction could be carried out in neat
condition well, but the reactions of solid derivatives of
benzaldehydes didn’t proceed well in these cases;
therefore, we selected DCM as solvent. Benzaldehyde
and its derivatives give a moderate to high yields of
propargylamines. The reactivity of ketones is lower than
aldehydes and among ketones, cycloalkanones behaves
as bezaldehyde and its derivatives (Table 4, entries 12,
13, 16, and 17). Aliphatic aldehydes and ketones didn’t
3
2
The solvent had a pronounced effect on these
reactions (Table 3, entries 1‐9). Neat condition, 1,2‐
take part in A and KA reactions with this catalyst
(entries 11, 14). Other than cyclic ketones, few acyclic
3
TABLE 5 The comparison of various catalysts in A coupling reaction for propargylamine synthesis
o
Entry
catalyst
Mol %
Solvent
Temp.( C)
Time (h)
Yield (%)
TOF
Ref.
[37]
I
1
Cu
2
(PiP)
2
0.4
Toluene
110
2
98
122.5
a
[40]
2
3
4
5
6
7
Ag Y zeolite
3.0
3.0
0.05
1.1
0.5
3.0
Neat
DCE
100
70
15
12
3
81
88
94
1.8
2.4
[39]
[Cu(N )]Cl ‐Y
2 2
S
0
[41]
[36]
Cu .Mont.
Toluene
Free
110
100
80
626
76.3
28
b
CuNPs/Magsilica
1
84
[21]
CuNPs/TiO
2
Neat
7
98
CuNPs/MZN
DCE
80
2
98
16.3
This Study
a
Y =Zeolite.
b
secondary amine is morpholine instead of piperidine.

10 of 12
KHAKZAD SIUKI ET AL.
3
aliphatic ketones could also be coupled, but aromatic
ketones do not undergo KA reactions (Table 4).
results heteroaromatic aldehydes attends in A reactions
2
slower than benzaldehyde derivatives, and among
Heteroaromatic aldehydes including 2‐furaldehyde
and 2‐thenaldehyde were also examined and produced
the corresponding products with yields of 80% and 75%,
respectively (Table 4, entries 18 and 19). Based on these
heteroaromatic ones 2‐furaldehyde is better than 2‐
thenaldehyde. In
a
strategy, the synthesis of
propargylamines was compared by keeping the same
benzaldehyde and phenylacetylene and using different
secondary amines such as piperidine, morpholine, and
diisopropylamine (Table 4, entries 1, 6, 20). The results
obtained from these studies revealed that an aliphatic
amine, i.e. diisopropylamine (Table 4, entry 20), shows a
lower isolated yields than the cyclic amines, i.e. piperi-
dine, and morpholine.
Also, the reaction of a bulky dipicrylamine having
electron withdrawing groups, was examined (Table 3,
entry 21) with benzaldehyde and phenyl acetylene, but
this reaction did not proceed to the corresponding propar-
gyl amine after 48 hrs.
3.2 | Comparison with other catalysts
As shown in Table 5, CuNPs/MZN seems to be a simple
and effective catalyst with respect to reaction times, sim-
plicity of procedure, facile work‐up and yields when com-
pared to those obtained using some of the other catalysts.
3.3 | Stability and reusability of catalyst
The catalyst could be used in air, and exclusion of air
wasn’t necessary in all experiments. Although the small
amount of catalyst (20 mg) was utilized, it could easily
be filtered and recovered by using a magnet on the outer
FIGURE 7 (a) Recycling experiment for catalyst (b) XRD pattern
of CuNPs/MZN after six consecutive cycles
SCHEME 3 Suggested mechanism

KHAKZAD SIUKI ET AL.
11 of 12
wall of container (after addition of dichloromethane) and
reused. Good catalyst performance in the coupling of
benzaldehyde, morpholine and phenylacetylene was
observed over six consecutive cycles (Figure 7a). The
crystal structure of CuNPs/MZN was characterized
by XRD after six consecutive recycles and showed no
apparently changes in its structure (Figure 7b). Also ICP
data revealed that the leaching of Cu was 0.21 wt. % after
six consecutive times.
ACKNOWLEDGMENTS
The authors gratefully acknowledge the partial support of
this study by the Ferdowsi University of Mashhad
Research Council (grant no.3/39646).
ORCID
Mehdi Bakavoli http://orcid.org/0000-0003-2801-1118
Hossein Eshghi http://orcid.org/0000-0002-8417-220X
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.4 | Suggested mechanism for
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