Ni@Pd nanoparticles supported on ionic liquid-functionalized KCC-1 as robust and recyclable nanocatalysts for cycloaddition of propargylic amines and CO2

Article abstract of DOI:10.1002/aoc.3941

Novel heterogeneous catalyst systems comprised of a fibrous nanosilica-supported nano-Ni@Pd-based ionic liquid (KCC-1/IL/Ni@Pd) are described for the cyclization of propargylic amines with CO₂ to provide 2-oxazolidinones. KCC-1 with high surface area was functionalized with IL acting as a robust anchor so that the nano-Ni@Pd was well dispersed on the fibres of the KCC-1 microspheres, without aggregation. Because of the amplification effect of IL, high loading capacities of the nanocatalysts were achieved. The reported synthesis includes several advantages like solvent-free conditions, operational simplicity, short reaction times, environmentally benign reaction conditions, cost effectiveness, high atom economy and excellent yields, making it a genuinely green protocol.

Full text of DOI:10.1002/aoc.3941

Received: 31 March 2017
DOI: 10.1002/aoc.3941
Revised: 22 May 2017
Accepted: 26 May 2017
F U L L PA P E R
Ni@Pd nanoparticles supported on ionic liquid‐functionalized
KCC‐1 as robust and recyclable nanocatalysts for cycloaddition of
propargylic amines and CO2
Seyed Mohsen Sadeghzadeh
| Rahele Zhiani | Shokufe Emrani
Department of Chemistry, Faculty of
Sciences, Neyshabur Branch, Islamic Azad
University, Neyshabur, Iran
Novel heterogeneous catalyst systems comprised of a fibrous nanosilica‐sup-
ported nano‐Ni@Pd‐based ionic liquid (KCC‐1/IL/Ni@Pd) are described for
the cyclization of propargylic amines with CO2 to provide 2‐oxazolidinones.
KCC‐1 with high surface area was functionalized with IL acting as a robust
anchor so that the nano‐Ni@Pd was well dispersed on the fibres of the KCC‐1
microspheres, without aggregation. Because of the amplification effect of IL,
high loading capacities of the nanocatalysts were achieved. The reported synthe-
sis includes several advantages like solvent‐free conditions, operational simplic-
ity, short reaction times, environmentally benign reaction conditions, cost
effectiveness, high atom economy and excellent yields, making it a genuinely
green protocol.
Correspondence
Seyed Mohsen Sadeghzadeh, Department of
Chemistry, Faculty of Sciences, Neyshabur
Branch, Islamic Azad University, Neyshabur,
Iran.
Email: seyedmohsen.sadeghzadeh@gmail.
com
KEYWORDS
CO , cycloaddition, green chemistry, KCC‐1, nanoparticles, Ni@Pd
2
1
| INTRODUCTION
testing visible light‐driven chemical synthesis as an econom-
ically and energetically useful, green way for the construction
[
23–25]
Recently, green chemistry has attracted substantial consider-
of organic molecules.
Also, reactions under solvent‐
ation in terms of the difficult‐to‐overcome CO as greenhouse
gas encountered by the world population. To solve this prob-
free conditions usually involve easy and efficient work‐up
methods. For all these reasons, organo‐catalysed methods
under solvent‐free conditions have become a highly pursued
2
lem, CO could be used as a safe, cheap and renewable C1
2
[
26–29]
building block to synthesize useful organic compounds such
target in green chemistry.
[
1–4]
[5]
[6]
as dimethyl carbonate,
carbonates,
formic acid, urethanes, cyclic
Palladium nanoparticles (NPs) are of particular impor-
tance among the noble metals, owing to their superior cata-
[
7–9]
[10]
[11]
methanol,
polycarbonates
and others,
[
30,31]
which have been prepared using CO as a feedstock. One of
lytic performances.
Pd NP nanocatalysts are now
2
these methods is through the carboxylative cyclization of
propargylic amines with CO2 for the synthesis of 2‐
oxazolidinones that have important roles as chemical interme-
diates, chiral auxiliaries and antibacterial drugs. This
method is an atom‐economic reaction and importantly clean
receiving more and more attention for their catalytic activity
in the treatment of wastewaters containing 4‐nitrophenol or
[
32–34]
4‐chlorophenol pollutants.
In fact, many noble metal
[
12]
[13]
[14]
NP catalytic reactions happen only on the surface of the NPs
and large parts of the core are catalytically inactive. So, to cre-
ate a large percentage of noble metal atoms available for catal-
ysis and to reduce their use, the internal noble metal atoms
should be exchanged for other non‐noble metals such as Co,
Fe and Ni that have solvent compatibility, excellent stability,
catalytic activity and can be magnetically separated, in order
for CO fixation.
2
Light is considered an inexpensive, plentiful and eco‐
friendly benign form of energy and in the past few years
has received an excellent response from the research commu-
[15–22]
nity.
Consequently, a growing number of chemists are
Appl Organometal Chem. 2017;e3941.
wileyonlinelibrary.com/journal/aoc
Copyright © 2017 John Wiley & Sons, Ltd.
1 of 10
https://doi.org/10.1002/aoc.3941

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SADEGHZADEH ET AL.
to reduce the use of noble metals without compromising the
general operation of the catalyst. All of these features greatly
increase the potential use of these catalysts.
recorded with a VERTEX 70 spectrometer (Bruker) in trans-
mission mode using spectroscopic‐grade KBr pellets for all
powders. The size and structure of NPs were observed using
a Philips CM10 transmission electron microscopy (TEM)
instrument operating at 100 kV. Powder X‐ray diffraction
(XRD) data were obtained using a Bruker D8 Advance model
with Cu Kα radiation. Thermogravimetric analysis (TGA)
was carried out with a Netzsch STA449F3 at a heating rate
of 10°C min under nitrogen. H NMR and C NMR spec-
tra were recorded with a Bruker DRX‐300 AVANCE spec-
trometer at 300.13 and 75.46 MHz and a Bruker DRX‐400
AVANCE spectrometer at 400.22 and 100.63 MHz, respec-
tively. Elemental analyses for C, H and N were performed
using a Heraeus CHN‐O‐Rapid analyser. Purity determina-
tion of the products and reaction monitoring were accom-
plished using TLC on silica gel polygram SILG/UV 254
plates. Mass spectra were recorded with a Shimadzu
GCMS‐QP5050 mass spectrometer.
[35–38]
Recently, Polshettiwar et al. reported the synthesis of
new fibrous silica nanosphere material (KCC‐1) with high
surface area, large open pore structure and high thermal
[39]
and hydrothermal stabilities.
Therefore, most of its sur-
face area is accessible, yielding unusually high activity in
[
40–54]
−1
1
13
catalysis.
KCC‐1 is extremely advantageous in the
design of inorganic–organic hybrid sensing materials owing
to its unique physical properties such as easily accessible
active sites, large open pore structure, excellent solvent
dispersibility, favourable biocompatibility, high surface area
and superparamagnetism. KCC‐1 is a good candidate for
use as a support in the design of efficient nanocatalysts.
One unique feature of KCC‐1 is its high surface area, which
originates from its fibrous morphology and not from its
[
55–60]
mesoporous channels (like in SBA‐15 or MCM‐41).
We have demonstrated the usefulness of the fibrous mor-
phology of KCC‐1 compared to conventional ordered meso-
porous silica for various applications.
2
.2 | General procedure for preparation of
[61–66]
KCC‐1 NPs
Engaged in the development of novel catalysts and noble
metal NPs with well‐dispersed and highly available active
sites, herein, we report a simple and efficient synthesis of a
metal–organic framework, containing magnetically recycla-
ble and inexpensive Ni@Pd NPs, and its application for the
preparation of 2‐oxazolidinone by reaction of propargylic
Tetraethyl orthosilicate (2.5 g) was dissolved in a solution of
cyclohexane (30 ml) and 1‐pentanol (1.5 ml). A stirred solu-
tion of cetylpyridinium bromide (1 g) and urea (0.6 g) in
water (30 ml) was then added. The resulting mixture was con-
tinually stirred for 45 min at room temperature and then
placed in a Teflon‐sealed hydrothermal reactor and heated
120°C for 5 h. The silica formed was isolated by centrifuga-
tion, washed with deionized water and acetone, and dried in a
drying oven. This material was then calcined at 550°C for 5 h
in air.
amine and CO under the greenest conditions (Scheme 1).
2
KCC‐1‐supported ionic liquid (IL) was used as a new sub-
strate to stabilize Ni@Pd NPs to afford KCC‐1/IL/Ni@Pd
nanocatalyst with increased availability of active sites and
high surface area. KCC‐1/IL showed perfect catalytic reac-
tion rate and excellent reusability in the catalytic reaction.
The powerful activity of this catalyst is ascribed to its high
availability of active sites and low possibility of aggregation
and leaching of the NPs on the KCC‐1/IL/Ni@Pd support
system.
2
.3 | General procedure for preparation of
KCC‐1/IL NPs
KCC‐1 NPs (2 mmol) and tetrahydrofuran (THF; 20 ml)
were mixed together in a beaker, and then NaH (20 mmol)
was dispersed into the mixture by ultrasonication. 1,3‐
Bis(trimethoxysilylpropyl)imidazolium iodide (22 mmol)
was added at room temperature and stirred for another 16 h
at 60°C. The resultant products were collected and washed
successively with ethanol and deionized water, and then dried
under vacuum at 60°C for 2 h for further use.
2
2
| EXPERIMENTAL
.1 | Materials and methods
Chemical materials of high purity were purchased from Fluka
and Merck. Melting points were determined in open capil-
laries using an Electrothermal 9100 apparatus and are uncor-
rected. Fourier transform infrared (FT‐IR) spectra were
2
.4 | General procedure for preparation of
KCC‐1/IL/Ni@Pd NPs
KCC‐1/IL/Ni@Pd structures were prepared by the reaction of
KCC‐1/IL with 49.7 mg of nickel(II) acetate tetrahydrate
(
Ni(ac) ⋅4H O; 0.2 mmol) and 53.4 mg of palladium(II) bro-
2
2
SCHEME 1 Synthesis of 2‐oxazolidinone catalysed by KCC‐1/IL/
mide (PdBr ; 0.2 mmol) which were mixed with 18.0 ml of
2
Ni@Pd NPs
OAm and 0.3 ml of TOP at room temperature. The reaction

SADEGHZADEH ET AL.
3 of 10
1
3
was heated to 245°C under a gentle argon flow for 1 h. Then
the KCC‐1/IL/Ni@Pd was separated from the reaction mix-
ture using an external magnet and washed several times with
deionized water and acetone. Finally, KCC‐1/IL/Ni@Pd was
dried under vacuum at 50°C.
J = 6.7 Hz, 1H), 4.60 (qt, J = 7.0 Hz, 1H). C NMR (δ,
ppm): 9.9, 19.7, 42.9, 44.8, 97.3, 142.1, 155.3.
3‐Methyl‐5‐benzylidene‐1,3‐oxazolidin‐2‐one
White powder; m.p. 139–141°C. H NMR (δ, ppm): 2.94
(s, 3H), 4.30 (d, J = 2.1 Hz, 2H), 5.49 (t, J = 2.1 Hz, 1H),
(2f).
1
7
2
5
.19 (t, J = 7.3 Hz, 1H), 7.30 (dd, J = 7.3 Hz, J = 7.6 Hz,
H), 7.54 (d, J = 7.6 Hz, 1H). C NMR (δ, ppm): 30.5,
0.9, 102.9, 127.0, 128.2, 128.7, 133.5, 141.7, 155.6.
13
2
.5 | General procedure for preparation of 2‐
Oxazolidinones
5
‐(4′‐Methylbenzylidene)‐3‐methyl‐1,3‐oxazolidin‐2‐one
1
To a Schlenk tube were successively added KCC‐1/IL/Ni@Pd
NPs (0.1 mg) and propargylic amine (1 mmol) under an argon
atmosphere, and the inside of the Schlenk tube was then
replaced with CO (1 MPa). The carboxylative cyclization of
the propargylic amine with CO proceeded by the stirring of
(2 g). White powder; m.p. 134–136°C. H NMR (δ, ppm):
7.47 (d, J = 8.1 Hz, 2H), 7.15 (d, J = 8.0 Hz, 2H), 5.50 (t,
J = 2.0 Hz, 1H), 4.30 (d, J = 2.0 Hz, 2H), 3.00 (s, 3H),
2.31 (s, 3 H). C NMR (δ, ppm): 155.6, 140.6, 136.3,
130.5, 129.0, 127.9, 102.9, 50.8, 30.2, 21.0.
13
2
2
the resulting mixture at room temperature under solvent‐free
conditions and visible light irradiation using a 15 W compact
fluorescent lamp (CFL) for 1 h. The progress of the reaction
was monitored by TLC, and when the reaction was completed,
methanol and dichloromethane were added to the reaction
mixture and the catalyst was separated using an external mag-
net. Then the solvent was removed from solution under
reduced pressure and the resulting product purified by recrys-
tallization using methanol.
5‐Benzylidene‐3‐butyl‐4‐ethyloxazolidin‐2‐one (2 h).
Yellow oil. H NMR (δ, ppm): 1.09 (m, 6H), 1.31–1.40 (m,
1
2H), 1.52–1.59 (m, 2H), 1.73–1.75 (m, 1H), 1.97–2.01 (m,
1H), 3.01–3.06 (m, 1H), 3.54–3.65 (m, 1H), 4.54 (s, 1H),
5.50 (s, 1H), 7.20 (dd, J = 6.8 Hz, J = 12.8 Hz, 1H), 7.34
(dd, J = 7.2 Hz, J = 12.8 Hz, 2H), 7.61 (d, J = 7.6 Hz,
13
2H). C NMR (δ, ppm): 6.3, 13.5, 20.1, 25.0, 29.1, 41.0,
58.9, 102.2, 126.5, 128.1, 133.8, 146.6, 155.3. GC–MS m/z
(%) = 259 (14), 230 (100), 174 (51), 118 (26), 90 (22).
2
.5.1 | Spectral data for synthesized
3
| RESULTS AND DISCUSSION
compounds
1
3
‐Butyl‐5‐methyleneoxazolidin‐2‐one (2a). Yellow oil. H
NMR (δ, ppm): 0.90 (t, J = 7.2 Hz, 3H), 1.31–1.22 (m,
H), 1.50–1.44 (m, 2H), 3.20 (t, J = 7.2 Hz, 2H), 4.14 (d,
J = 2.4 Hz, 2H), 4.22 (d, J = 2.4 Hz, 2H), 4.64 (d,
The KCC‐1/IL/Ni@Pd NPs were prepared through conden-
sation of 1,3‐bis(trimethoxysilylpropyl)imidazolium iodide
with KCC‐1 as a template. The material was then reacted
with a substoichiometric amount of nickel(II) acetate
tetrahydrate and palladium(II) bromide to yield the KCC‐1/
IL/Ni@Pd NP catalyst.
FT‐IR spectroscopy was employed to determine the sur-
face modification of the synthesized catalyst (Figure 1). The
Si─O─Si symmetric and asymmetric stretching vibrations
2
13
J = 2.4 Hz, 1H). C NMR (δ, ppm): 13.6, 19.5, 28.9, 43.5,
7.4, 85.9, 150.0, 155.2. GC–MS m/z (%) = 155 (90), 113
27), 112 (100), 98 (11), 84 (37).
‐Methyl‐5‐methylene‐1,3‐oxazolidin‐2‐one (2b). Yel-
low oil. H NMR (δ, ppm): 2.89 (s, 3H), 4.14 (dd,
J = 2.4 Hz, 2H), 4.30 (dt, J = 3.1 Hz, 1H), 4.72 (dt,
J = 3.1 Hz, 1H). C NMR (δ, ppm): 30.4, 50.8, 86.5,
49.0, 156.1.
‐Methyl‐5‐ethylidene‐1,3‐oxazolidin‐2‐one (2c). White
powder; m.p. 74–76°C. H NMR (δ, ppm): 1.64 (dt,
J = 7.0 Hz, 3H), 2.89 (s, 3H), 4.10 (dq, J = 2.2 Hz, 2H),
4
(
3
1
1
3
1
3
1
1
3
4
5
.60 (qt, J = 7.0 Hz, 1H). C NMR (δ, ppm): 9.6, 30.3,
0.0, 97.3, 141.3, 156.0.
3
‐Benzyl‐5‐ethylidene‐1,3‐oxazolidin‐2‐one (2d). White
1
powder; m.p. 40–42°C. H NMR (δ, ppm): 1.65 (dt,
J = 7.0 Hz, 3H), 3.92 (dq, J = 2.2 Hz, 2H), 4.42 (s, 2H),
13
4
.53 (qt, J = 7.0 Hz, 1H), 7.24–7.40 (m, 5H, Ar).
NMR (δ, ppm): 9.9, 47.4, 47.9, 97.9, 128.0, 128.8, 135.2,
41.6, 156.3.
‐Isopropyl‐5‐ethylidene‐1,3‐oxazolidin‐2‐one (2e). Yel-
C
1
3
1
low oil. H NMR (δ, ppm): 1.15 (d, J = 6.5 Hz, 6H), 1.69
FIGURE 1 FT‐IR spectra of (a) KCC‐1 NPs and (b) KCC‐1/IL/
(dt, J = 6.9 Hz, 3H), 4.02 (dq, J = 2.2 Hz, 2H), 4.12 (septet,
Ni@Pd NPs

4
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SADEGHZADEH ET AL.
−
1
at 802 and 1103 cm and the O─H stretching vibration at
1
3
(
444 cm− were observed in the spectrum of KCC‐1
−
1
Figure 1a). The O─H stretching vibration at 3444 cm ,
Si─O stretching at 1110 cm , C═N stretching at 1635 cm
and CH stretching at 2905 cm were observed in the spec-
−
1
−1
−
1
2
trum of KCC‐1/IL/Ni@Pd NPs (Figure 1b). These results
indicated that the imidazolium IL had been successfully intro-
duced onto the surface of KCC‐1.
The structures of the synthesized KCC‐1 NPs, KCC‐1/IL
and KCC‐1/IL/Ni@Pd nanocatalyst were analysed using
TEM. The as‐prepared KCC‐1 microspheres with fibrous
structure were uniform and monodispersed (Figure 2a). The
average diameter of the microspheres was about
150–170 nm. Figure 2(a) further clarifies that the distance
between two fibres was about 10–15 nm. Subsequently, 1,3‐
bis(trimethoxysilylpropyl)imidazolium iodide was coated on
KCC‐1 to form KCC‐1/IL core–shell particles (Figure 2b).
The image of the catalyst revealed that the fibrous nanosilica
KCC‐1 was loaded with well‐dispersed Ni@Pd NPs
(Figure 2c). Further inspection of the TEM micrograph of
the recovered catalyst demonstrates that the Ni@Pd NPs
throughout the regular mesofibres of the parent KCC‐1/IL
are well distributed. This observation shows that while
KCC‐1/IL/Ni@Pd acts as highly active and soluble Ni@Pd
species, it may also operate as a nanoscaffold to recapture
the Ni@Pd NPs inside the mesofibres, thus preventing
Ni@Pd agglomeration.
To confirm the thermal stability of the KCC‐1/IL/
Ni@Pd material, TGA was performed at temperatures
ranging from room temperature to 1000°C (Figure 3). As
can be seen, two weight loss stages were observed in air
flow. About 5 wt% weight loss was observed in the first
stage (40–250°C) corresponding to the loss of small mole-
cules such as physically absorbed water. In the second
stage (400–600°C), the weight loss was about 11 wt%,
which can be attributed to the pyrolysis of cross‐linking
organic group derivatives. These data are in good agree-
ment with the results of FT‐IR analysis and confirmed
the incorporation of IL groups into the material framework
as well as their high stability during preparation and puri-
fication stages.
XRD patterns and FT‐IR spectra of KCC‐1/IL/Ni@Pd
NPs have been measured in order to obtain more information
about their crystallographic features and molecular struc-
tures. The XRD pattern of as‐prepared KCC‐1/IL/Ni@Pd
NPs catalyst is shown in Figure 4. The broad peak between
2
0° and 30° corresponds to amorphous silica. The XRD pat-
FIGURE 2 TEM images of (a) KCC‐1, (b) KCC‐1/IL and (c) KCC‐
tern can easily indexed to the cubic phase of Ni@Pd NPs.
Figure 4 reveals that Ni@Pd NPs exhibit sharp peaks of Pd
1
/IL/Ni@Pd.
(111), Ni (111), Pd (200), Pd (220) and Pd (311), which also
The nitrogen adsorption–desorption isotherms of KCC‐1/
verify the existence of face‐centred cubic Pd and face‐centred
cubic Ni, again confirming the successful growth of metal
particles on the surface of KCC‐1/IL.
IL/Ni@Pd showed characteristic type IV curves (Figure 5).
which is consistent with literature reports of standard fibrous
silica spheres. For KCC‐1, the Brunauer–Emmett–Teller

SADEGHZADEH ET AL.
5 of 10
and uniform mesostructure with a decrease in surface area,
pore diameter and pore volume parameters in comparison
with pristine KCC‐1. With the functionalization by IL, the
corresponding pore volumes are markedly reduced. This
could be ascribed to increased loading with the sensing
probe, which occupies a large volume inside the silica
spheres (Figure 5 and Table 1).
X‐ray photoelectron spectroscopy (XPS) was used to
investigate the chemical elements on the surface of KCC‐1/
IL/Ni@Pd. A full‐scan XPS spectrum for the as‐prepared cat-
alyst is illustrated in Figure 6. Peaks corresponding to Si, O,
C, N, I, Ni and Pd can be clearly observed, and the presence
of N 1 s and I 3d further confirmed that KCC‐1 had been suc-
cessfully functionalized by the IL. Also, the XPS elemental
survey scan of the surface of KCC‐1/IL/Ni@Pd nanocatalyst
microspheres revealed the presence of Ni and Pd elements.
As shown in Figure 6, the peaks observed in the XPS spec-
trum of Pd 3d at binding energies of 335.1 and 340.2 eV
are characteristic of metallic Pd.
FIGURE 3 TGA curve of KCC‐1/IL/Ni@Pd NPs
Magnetization curves (Figure 7) show the
superparamagnetic behaviour of the Ni@Pd NPs and
KCC‐1/IL/Ni@Pd nanocatalyst. The magnetic saturation
values of Ni@Pd NPs and the KCC‐1/IL/Ni@Pd
−
1
nanocatalyst are 4.45 and 0.91 emu g , respectively.
Therefore, the KCC‐1/IL/Ni@Pd nanocatalyst could be
efficiently separated from a solution using an external
magnetic force, and thus could be reused and recycled.
KCC‐1/IL NPs can provide a good immobilization of
Ni@Pd on their surface, which protects the Ni@Pd NPs from
aggregation and the support stabilizes the Ni@Pd NPs during
a chemical reaction. KCC‐1/IL has a hydrophilic character
that provides an advantage of great dispersion of KCC‐1/IL
NPs for developing this system as a semi‐homogeneous
Ni@Pd catalyst for organic reactions under green conditions.
To investigate this, the catalytic activity of the KCC‐1/IL/
Ni@Pd NPs was investigated in the preparation of 2‐
oxazolidinone under visible light irradiation using a 32 W
CFL. In this study, it was found that conventional heating
under solvent‐free conditions is more efficient than using
organic solvents which creates green conditions for the syn-
thesis of 2‐oxazolidinone (Table 2).
FIGURE 4 Powder XRD pattern of KCC‐1/IL/Ni@Pd.
We also studied the decisive role of temperature in the
synthesis of 2‐oxazolidinone in the presence of KCC‐1/IL/
Ni@Pd NPs as a catalyst. The best temperature for this reac-
tion was room temperature and temperatures greater than
room temperature do not cause changes in the efficiency of
FIGURE 5 Nitrogen adsorption–desorption isotherms of KCC‐1 and
KCC‐1/IL/Ni@Pd.
(
BET) surface area, total pore volume, and Barrett–Joyner–
TABLE 1 Structural parameters of KCC‐1 and KCC‐1/IL/Ni@Pd
materials determined from nitrogen sorption experiments
2
−1
Halenda (BJH) pore diameter are obtained as 439 m g ,
1
sponding parameters of KCC‐1/IL/Ni@Pd are decreased to
2
3
−1
.49 cm g and 14.78 nm, respectively, whereas the corre-
2
(cm g−1)
3
Catalyst
S
BET (m g−1)
V
t
D
BJH (nm)
14.78
2
−1
3
−1
KCC‐1
KCC‐1/IL/Ni@Pd
439
298
1.52
98 m g , 1.02 cm g and 14.25 nm. The nitrogen sorp-
1.02
14.25
tion analysis of KCC‐1/IL/Ni@Pd also confirms a regular

6
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SADEGHZADEH ET AL.
FIGURE 6 XPS spectra of KCC‐1/IL/
Ni@Pd.
TABLE 2 Synthesis of 2‐oxazolidinone catalysed by KCC‐1/IL/
a
Ni@Pd NPs in various solvents
Entry
Solvent
EtOH
Yield (%)b
1
2
3
4
5
6
7
8
9
44
51
—
23
31
32
15
19
17
40
38
42
16
59
94
2
H O
CH
THF
CH Cl
3
CN
2
2
EtOAc
DMF
Toluene
n‐hexane
10
11
12
13
14
15
CHCl
3
DMSO
FIGURE 7 Room temperature magnetization curves of nanocatalysts
MeOH
Dioxane
i‐PrOH
Solvent‐free
the reaction, showing that the catalytic activity is not suscep-
tible to reaction temperature. Then the amount of catalyst
necessary to promote the reaction efficiently was examined,
the variation of KCC‐1/IL/Ni@Pd NPs having an effect. An
amount of 0.1 mg of KCC‐1/IL/Ni@Pd NPs was the best
amount for the synthesis of 2‐oxazolidinone which afforded
the desired product in 94% yield (Figure 8). Under the opti-
mal conditions, the shortest time necessary for reaction in
the presence of 0.1 mg of KCC‐1/IL/Ni@Pd NPs was moni-
tored using GC, and excellent yield of 2‐oxazolidinone can
a
Reaction conditions: propargylic amine (1 mmol), KCC‐1/IL/Ni@Pd NPs
0.2 mg) and CO (1.5 MPa), under visible light irradiation using a 32 W CFL,
(
2
after 4 h.
b
Isolated yield.
The catalyst mixture leads to >94% conversion at a pressure
of 1 MPa. No apparent by‐products were observed using GC
in any of the experiments and 2‐oxazolidinone was obtained
cleanly in 94% yield.
be achieved in 3 h (Figure 9). The effects of CO pressure
2
in the presence of propargylic amine and KCC‐1/IL/Ni@Pd
NPs at room temperature for 3 h are shown in Figure 10.
We then conducted a series of tests using light of different
intensities in order to identify the optimal intensity of visible

SADEGHZADEH ET AL.
7 of 10
a
TABLE 3 Effect of visible light intensity on course of reaction
b
Entry
Visible light intensity (W)
Yield (%)
1
2
3
4
5
6
—
8
—
70
94
94
94
94
15
20
22
32
a
Reaction conditions: propargylic amine (1 mmol), KCC‐1/IL/Ni@Pd (0.2 mg)
and CO (1 MPa), under visible light irradiation at room temperature under sol-
2
vent‐free conditions for 3 h.
b
Isolated yield.
FIGURE 8 Effect of increasing amount of KCC‐1/IL/Ni@Pd NPs on
yield of 2‐oxazolidinone
CFL was used. However, when lower intensity was used, a
marginal reduction in yield and rate of reaction were
observed (Table 3, entry 2). Use of a CFL of higher wattage
on the other hand did not have any appreciable effect on yield
or reaction time. In the light of the experimental observations
[
67–69]
and literature reports,
the reaction appears to proceed
through mechanochemical activation, although visible light
may be imparting additional energy, speeding up the reaction.
Also photochemical activation seems to have a definite role.
To further study the efficiency of different parts of the
catalyst, various control experiments were performed and
the obtained data are summarized in Table 4. Firstly, reac-
tion was examined in the presence of KCC‐1, and no
amount of the desired product was formed (Table 4, entry
1
). When KCC‐1/IL was used as the catalyst, a reaction
FIGURE 9 Effect of reaction time on yield of 2‐oxazolidinone
was observed, although the yield of the desired product
was average (Table 4, entry 2). The ILs could not give
TABLE 4 Comparison of catalytic efficiency of KCC‐1/IL/Ni@Pd
a
NPs with that of various other catalysts
Entry
Catalyst
KCC‐1
KCC‐1/Il
KCC‐1/IL/au
KCC‐1/IL/TiO
KCC‐1/IL/ZnO
KCC‐1/IL/Pd
KCC‐1/IL/ag
KCC‐1/IL/cu
KCC‐1/IL/FeNi3
KCC‐1/IL/Pt
Yield (%)b
1
2
3
4
5
6
7
8
9
—
68
84
58
68
95
87
81
41
70
52
94
2
FIGURE 10 Effect of pressure on yield of 2‐oxazolidinone
1
0
1
1
KCC‐1/IL/RuO
KCC‐1/IL/Ni@Pd
2
light needed for the synthesis of 2‐oxazolidinone in the pres-
ence of KCC‐1/IL/Ni@Pd NPs as a catalyst. The activity was
12
a
Reaction conditions: propargylic amine derivatives (1 mmol), catalyst (0.1 mg)
almost nothing when Ni@Pd/UiO‐66‐NH NP was used as a
2
and CO2 (1 MPa), under solvent‐free conditions and visible light irradiation at
room temperature under solvent‐free conditions after 3 h.
catalyst without visible light radiation (Table 3, entry 1). It
was observed that the yield was the same when a 15 W
b
Isolated yield.

8
of 10
SADEGHZADEH ET AL.
a satisfactory catalytic activity under mild conditions.
Based on these frustrating results, we continued the
research to improve the yield of the product by adding
NPs to the catalyst as a co‐catalyst is necessary to activate
propargylic amine thus raising the catalytic activity. The
catalytic activity of these various NPs was found to be
IL/Ni@Pd and KCC‐1/Ni@Pd NPs was determined using
inductively coupled plasma mass spectrometry (ICP‐MS).
The amount of Ni@Pd moieties in KCC‐1/IL/Ni@Pd
was almost equal to that in KCC‐1/Ni@Pd NPs. But it
is interesting what this amount is after ten consecutive
cycles of catalysis: the amount of Ni@Pd moieties in
KCC‐1/IL/Ni@Pd was about double that in KCC‐1/
Ni@Pd NPs. This remarkable ability of the KCC‐1/IL/
Ni@Pd mesostructure may be attributed to the IL units
that effectively manage the reaction through preventing
Ni@Pd agglomeration and releasing and recapturing
Ni@Pd NPs during the reaction process (Table 5). The
carboxylative cyclization for a variety of propargylic
amines was then undertaken to explore the scope of this
well‐developed KCC‐1/IL/Ni@Pd NP catalytic system.
As evident from Table 6, both aromatic and aliphatic
propargylic amines reacted smoothly to give the corre-
sponding 2‐oxazolidinones in excellent yields.
intheorder Pd~Ni@Pd>Ag>Au>Cu>Pt>ZnO>TiO >
2
RuO > FeNi . Therefore, we chose Ni@Pd as a co‐cat-
2
3
alyst for the synthesis of our catalyst.
To assess the exact impact of the presence of IL in the
catalyst, KCC‐1/IL/Ni@Pd was compared with KCC‐1/
Ni@Pd NPs. The loading amount of Ni@Pd in KCC‐1/
TABLE 5 Loading amount of nano‐Ni@Pd in KCC‐1/IL/Ni@Pd and
KCC‐1/Ni@Pd NPs
Entry
Catalyst
KCC‐1/Ni@Pd
KCC‐1/IL/Ni@Pd
KCC‐1/Ni@Pd after ten re‐uses
KCC‐1/IL/Ni@Pd after ten re‐uses
Amount (wt%)
1
2
3
4
9.1
9.4
3.9
9.3
It is important to note that the heterogeneous property
of KCC‐1/IL/Ni@Pd NPs facilitates their efficient recovery
from the reaction mixture during the work‐up procedure.
a
TABLE 6 Synthesis of 2‐oxazolidinone derivatives catalysed by KCC‐1/IL/Ni@Pd NPs
b
Yield (%)
Product
2a
R
3
R
2
R
1
Entry
88
91
83
92
89
94
96
95
CH
CH
CH
3
3
3
CH
2
CH
2
CH
2
H
H
1
2
3
4
5
6
7
8
2b
H
|H
H
H
H
H
H
2c
CH
CH
CH
3
3
3
2d
C
6
H
5
CH
2
2e
(CH
3
)
2
CH
2f
CH
CH
CH
3
C
6
H
5
2 g
2 h
3
3
3 6 4
4‐CH C H
CH
2
CH
2
CH
2
CH
3
CH
2
6 5
C H
a
Reaction conditions: propargylic amine derivatives (1 mmol), catalyst (0.1 mg) and CO
2
(1 MPa), under solvent‐free conditions and visible light irradiation at room tem-
perature after 3 h.
b
Refers to isolated product.
FIGURE 11 Recycling performance of
catalyst

SADEGHZADEH ET AL.
9 of 10
The activity of the recycled catalyst was also examined
under the optimized conditions. After completion of the
reaction, the catalyst was separated by filtration, washed
with methanol and dried at the filtration pump. The recov-
ered catalyst was reused for ten consecutive cycles without
any significant loss in catalytic activity (Figure 11). Also, in
order to know whether the reaction takes place at the sur-
face of KCC‐1/IL/Ni@Pd NPs or any Ni@Pd species,
ICP‐MS analysis of the remaining mixture after catalyst
and product separation was conducted upon reaction com-
pletion. The amount of Ni@Pd after ten repeat cycles was
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4
| CONCLUSIONS
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cient, visible light‐activated KCC‐1/IL/Ni@Pd‐catalysed
green synthetic strategy for the cyclization of propargylic
amines with CO to provide 2‐oxazolidinones. This combina-
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2
environmental point of view, this protocol represents good
atom economy, i.e. the expended KCC‐1/IL/Ni@Pd NPs
can be recycled and reused to mediate this reaction. The
results should be helpful in understanding the advantageous
combination of the properties of homogeneous and heteroge-
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How to cite this article: Sadeghzadeh SM, Zhiani R,
Emrani S. Ni@Pd nanoparticles supported on ionic
liquid‐functionalized KCC‐1 as robust and recyclable
nanocatalysts for cycloaddition of propargylic amines
2
3
and CO . Appl Organometal Chem. 2017;e3941.
2
https://doi.org/10.1002/aoc.3941
2
3