Cycloaddition of Propargylic Amines and CO2 by Ni@Pd Nanoclusters Confined Within Metal–Organic Framework Cavities in Aqueous Solution

Article abstract of DOI:10.1007/s10562-019-03072-3

The bio-metal–organic framework (bio-MOF) notion along with nanoparticles catalysts of Ni@Pd core–shell magnetic for carbon dioxide conversion is made by l-glutamic acid that is the natural substitute for combinatorial ligands, and illustrated their catal

Full text of DOI:10.1007/s10562-019-03072-3

Catalysis Letters
https://doi.org/10.1007/s10562-019-03072-3
Cycloaddition of Propargylic Amines and CO2 by Ni@Pd Nanoclusters
Confned Within Metal–Organic Framework Cavities in Aqueous
Solution
Wang Zhi‑tao1,2
Received: 27 September 2019 / Accepted: 7 December 2019
© Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract
The bio-metal–organic framework (bio-MOF) notion along with nanoparticles catalysts of Ni@Pd core–shell magnetic for
carbon dioxide conversion is made by l-glutamic acid that is the natural substitute for combinatorial ligands, and illustrated
their catalytic efect, in the propargylic amines cyclization with carbon dioxide for obtaining 2-oxazolidinones, completed
to the correlation of structure–DFT. This nano Ni@Pd that consists of catalyst is detected using ICP, XRD, TGA, TEM,
FT-IR, and VSM. The zinc-glutamate-MOF or ZnGlu is properly proved as the MOF catalyst in the case of the propargylic
amines cyclization with carbon dioxide for obtaining 2-oxazolidinones, in addition, its performance is compared to those
of outstanding synthetic MOFs stated in the method. The produced catalyst done even at moist state, is thermally as well as
chemically frm; easily separable, heterogeneous, because of high selectivity of it, lack of mixture solvents, and also sim-
ple catalyst recovery using outside magnet. It is recycled until ten times. Ni@Pd/ZnGlu MNPs dramatically improves the
availability of the nanoparticle levels in comparison whit the common substrate because of its 3D hierarchical construction.
Ni@Pd/ZnGlu MNPs, because of their economic environmental and economic parameters, are considered as the future of
MOF chemistry in industry.
Graphic Abstract
Cycloaddition of propargylic amines and CO2 by Ni@Pd nanoclusters confned within metal−organic framework cavities
in aqueous solution.
Cycloaddition of Propargylic amines and CO2 by Ni@Pd
nanoclusters confined within metal−organic framework cavities
in aqueous solution
O
R3
O
N
R1
R2
Ni(ac)2·4H2
PdBr2
O
CO2
L-glutamic acid
HN R3
R2
R1
Zinc =
Ni@Pd =
Keywords Heterogeneous catalyst · One-pot synthesis · Green chemistry · CO2 · 2-Oxazolidinone
* Wang Zhi-tao
wangzhitao66@163.com
1
State Key Laboratory of Inorganic Synthesis and Preparative
Chemistry, Jilin University, Changchun 130012, China
2
School of Chemistry, Tonghua Normal University,
Tonghua 134000, China
Vol.:(0123456789)
1 3

W. Zhi-tao
within the core are catalytically inactive. Therefore, to
make a major percent of noble metal atoms available by
catalysis and for decreasing the utilize, the interior noble
metal atoms may be changed using diferent non-noble
metals like Ni, Co, and Fe to decrease the utilize of noble
metal but removing the total efciency of the catalyst.
Moreover, the existence of Ni, Fe, and Co in hybrid,
core–shell NPs possess proper magnetic separability, sol-
vent adaptability, stability, and catalytic activity [45–47].
Whole these characteristics greatly increase the potential
usage of considered catalysts. Hence, promising noble
metal catalysts of NPs with inactive cores, impressive
recoverable, and great catalytic activities characteristics
are acutely rare [48–51].
1 Introduction
Recently, expansion of green approaches according to
chemical consolidation of carbon dioxide is received a big
deal of concern owning to carbon dioxide can be utilized
as a cheap, renewable, and safe C1 structure block to pro-
duce proper organic materials. Diferent benefcial chem-
icals, like cyclic carbonates [1–3], polycarbonates [4],
urethanes [5], methanol [6], dimethyl carbonate [7–10],
formic acid [11], etc. are provided utilizing CO2. One of
the benefcial expansion in which carbon dioxide are used
as a layer is via the carboxylative cyclization from propar-
gylic amines with carbon dioxide for obtaining 2-oxazoli-
dinones [12–15] 2-oxazolidinones signifcant heterocyclic
chemicals that has a signifcant pattern as chemical inter-
mediates [16] as well as chiral auxiliaries [17] in the case
of organic production, and also as antibacterial medicines
[18] in green chemistry. The carboxylative cyclization in
the case of propargylic amines by carbon dioxide that uses
for a main clean economic reaction is known as one of the
most appropriate instances of carbon dioxide consolidation
to achieve 2-oxazolidinones.
The present work attained to expand new catalysts and
noble metal NPs along with proper dispersed high acces-
sibility for the procurement of 2-oxazolidinone using reac-
tion of propargylic amine and carbon dioxide at the eco
friendly states. Hereon, we select a proteinogenic amino
acid and l-glutamic acid as well as only spacer of MOF
material. ZnGluis utilized as a novel supporting substance
to avouch Ni@Pd NPs for achieving Ni@Pd/ZnGlu MNPs
with increased availability for active levels and high level
zone. ZnGlu showed not just proper rate of catalytic reac-
tion, however, great reusability for the catalytic reaction.
The great activity of it is due to its high approachability
as well as low possibility of the compression and leaching
of the Nps on the Ni@Pd/ZnGlu support approach (refer
to Scheme 1).
Metal–Organic Frameworks (MOF) are achieved great
respond from researchers because it prepares an extensive
range of usages in term of gas carbon dioxide capture,
storage, catalysis research, separation, and guest depend-
ent luminescence felds [19–26]. The eco-friendly MOFs
has been commonly for feited because of the combinato-
rial nature of ligands. Toxic ligands or organic solvents stay
in lattices of MOF; trace areas are discovered even since
activation. Bio-MOFs are anticipated as the future of MOF
materials in an environmentally safe community [27–31].
Because of richness of amino acids in amino carboxylate or
functional classes in chains, amino acids possess the herit-
age of amino acid within cycloaddition catalysis at fresh and
improved states [32–35]. Heterogeneous catalysis utilizing
MOF-supported small metal nano-particles (NPs) or nano-
carbons (NCs) are achieved growing research consideration
due to the nanopores of MOFs may not just serve as formats
to produce monodisperse metal of NPs/NCs, however, pro-
vide micro environments, which can apply selectivity con-
trol upon the enclosed NPs/NCs into catalytic reactions. The
arrangement of metal NPs/NCs within MOFs is performed
using chemical vapour evidence utilizing organometallic
precursors within the gas [36, 37]. Palladium NPs have
special importance between the noble metals due to their
premier catalytic efciency [38–40]. Palladium NP nano-
catalysts are receiving high consideration because of their
catalytic activity during the wastewaters treatment having
4-NP or 4-CP pollutants [41–44].
O
R3
O
N
R1
R2
Ni(ac)2·4H2O
PdBr2
CO2
L-glutamic acid
HN R3
R2
R1
Zinc =
Ni@Pd =
Virtually, most catalytic reactions of noble metal NPs
occur only onto the NPs level and a great atom fraction
Scheme 1 Synthesis of 2-oxazolidinone on the surfaces of Ni@Pd/
ZnGlu
1 3

Cycloaddition of Propargylic Amines and CO2 by Ni@Pd Nanoclusters Confned Within Metal–…
0.0534 g palladium(II) bromide (0.0002 mol) are mixed to
2 Experimental
18.0 mL OAm and 0.3 mL TOP under the temperature of
25 °C. The reaction is heated to 245 °C at a gentle fow of
argon for 1 h. After that the Ni@Pd/ZnGlu is separated of
the reaction compound using a magnet and then washed for
many times by deionized water as well as acetone. Eventu-
ally, Ni@Pd/ZnGlu is dried at vacuum and the temperature
of 50 °C [45].
2.1 Materials and Methods
Chemical materials were purchased from Fluka and Merck
in high purity. Melting points were determined in open
capillaries using an Electrothermal 9100 apparatus and are
uncorrected. FTIR spectra were recorded on a VERTEX 70
spectrometer (Bruker) in the transmission mode in spectro-
scopic grade KBr pellets for all the powders. The particle
size and structure of nano particle was observed by using
a Philips CM10 transmission electron microscope operat-
ing at 100 kV. Powder X-ray difraction data were obtained
using Bruker D8 Advance model with Cu ka radiation.
The thermogravimetric analysis (TGA) was carried out on
a NETZSCH STA449F3 at a heating rate of 10 °C min−1
under nitrogen. The purity determination of the products and
reaction monitoring were accomplished by TLC on silica gel
polygram SILG/UV 254 plates. Mass spectra were recorded
on Shimadzu GCMS-QP5050 Mass Spectrometer.
2.4 General Approach About the Synthesis
of 2‑Oxazolidinone
In a Schlenk-tube are properly added 1.0 mg Ni@Pd/ZnGlu
MNPs. In addition, 1 mmol propargylic amine at the pres-
ence of argon atmosphere and the within Schlenk-tube is
replaced to 1.5 MPa carbon dioxide. The carboxylative cycli-
zation of the propargylic amine in the presence of carbon
dioxide performed using the stirring of the yielded mixture
under the temperature of 25 °C at solvent-free state and also
visible light irradiation by a 15 W CFL at 2 h. Until end of
the reaction, the advance of the reaction is evaluated using
TLC while the reaction is ended, methanol as well as dichlo-
romethane are released to the reaction compound and the
catalyst is separated using a magnet. After that the solvent is
separated of solution at decreased pressure and the yielding
product cleaned using recrystallization by methanol.
2.2 General Approach About the Production
of ZnGlu
Single crystals as well as bulk powder of zinc-glutamate-
MOF are singly achieved of the similar reaction compound.
For a aqueous solution of 30 mL stirred of 0.294 g (2 mmol)
l-glutamic acid along with 0.200 g (5 mmol) NaOH is
released 0.575 g (2 mmol) zinc sulfate heptahydrate within
15 mL water using a dropping funnel. Immediate precipita-
tion resulted in the by utilizing vessel being hold in to an
oil bath under the temperature of 100 °C; thenceforward
the temperature of oil bath is enhanced increased to the
temperature of 140 °C. The solution along with the pre-
cipitate is returned within in the oil bath at 6 h as well as
the white sudden is removed of provided hot. The refne
achieved is evaporated for decreasing the volume nearly
about 10 mL and hold at stable temperature of 25 °C at a
few days for obtaining X-ray difraction modality Zn(H2O)
(C5H7NO4).H2O crystals. The precipitate achieved in the
bulk is additionally dried at the presence of air and under
the temperature of 25 °C and is defned as ZnGlu(C) and
further evaluated in the case of structural resemblance of
the bulk-produced catalyst to single crystals. The catalyst
has been dried under temperature of 25 °C [52].
3 Results and Discussion
After load ions of Ni@Pd NPs onto ZnGlu, which is like
to an eco-friendly MOF, propargylic amines cyclization to
CO2 to obtain 2-oxazolidinones is used. The results suggest
the amine groups within ZnGlu can forcefully assistance
the loading of metal NPs as stated in other diferent MOFs.
This view is just like to the production and metal NPs/NCs
encapsulation in the dendrimers of poly(PAMAM). Within
PAMAM dendrimer, the interplay among metal pioneers and
the internal amino teams of the dendrimer was reliable to be
the basis proof to load metal in the dendrimer.
Since loading of Ni@Pd in ZnGlu, the X-ray difraction
(XRD) of powder is utilized to examine that whether the
Ni@Pd NPs fraught on ZnGlu as yet protected their crys-
tal structure. The XRD schemes of the as-produced ZnGlu
(refer to Fig. 1b) matched properly to the obtained XRD
patterns (refer to Fig. 1a). Since the loading on Ni@Pd
NPs, there is no exterior disadvantage of Bio-MOF in XRD
schemes (refer to Fig. 1c). XRD evaluation may prepare situ-
ation for the Ni@Pd NPs composition. Figure 1c shows that
Ni@Pd NPs represented sharp peaks for Pd (111), Ni (111),
Pd (200) and Pd (220) as well as Pd (311) that also inquire
the existing fcc-Pd and also fcc-Ni.
2.3 General Approach About the Synthesis of Ni@
Pd/ZnGlu
Ni@Pd/ZnGlu NPs are provided using reaction of ZnGlu
to 49.7 mg nickel(II) acetate tetrahydrate (0.0002 mol) and
1 3

W. Zhi-tao
Fig. 1 XRD analysis of (a)
simulated ZnGlu; (b) ZnGlu;
and (c) Ni@Pd/ZnGlu
Fig. 2 SEM images of a ZnGlu;
and b Ni@Pd/ZnGlu; TEM
images of c ZnGlu; and d Ni@
Pd/ZnGlu
1 3

Cycloaddition of Propargylic Amines and CO2 by Ni@Pd Nanoclusters Confned Within Metal–…
The morphology along with the produced ZnGlu sizes,
and Ni@Pd/ZnGlu NPs are evaluated using TEM and SEM
analyses. The mean microspheres diameter is in the range of
100–120 nm (refer to Fig. 2a, b). It showed that the ZnGlu
is loaded to well-dispersed Ni@Pd nanoparticles (as can be
seen in Fig. 2c, d). More investigation of the TEM scheme
of the reproduced catalyst indicates that the Ni@PdNPs
fully the ZnGlu are properly scattered. It is found that when
Ni@Pd/ZnGlu NPs performs as a spatial about extremely
active and soluble Ni@Pd NPs, it can additionally act as a
nanoscafold for recapturing the Ni@Pd NPs within the tree
construction of ZnGlu, so barricading Ni@Pd compaction.
The interplay of Ni@Pd as precursors to the –NH2 mate-
rials of glutamate is additionally proved using FT-IR spectra.
As can be seen in Fig. 3 that showing the FT-IR spectra, the
peaks are shown close to 1255 cm−1 which have bright inten-
sity variations like the Ni@Pd loading on ZnGlu is enhanc-
ing. In addition, two diferent peaks are observed near 1642
and 1424 cm−1 that possess clear intensity variations like the
Ni@Pd loading is enhanced. The peak close to 1089 cm−1
may be ascribed to the –NH2 cutting as well as rocking
vibration. The intensities in the case of nitrogen–hydrogen
asymmetric stretching peak of vibration near 3640 cm−1, and
nitrogen–hydrogen symmetric stretching peak of vibration
close to 3561 cm−1 (as observed in Fig. 3a) reduce dramati-
cally with the increasing Ni@Pd loading, and red variations
to 3324 and 3219 cm−1 in the case of the former one (refer
to Fig. 3b).
The TG pattern about Ni@Pd/ZnGlu NPs is found and
illustrated in Fig. 4. In term of Ni@Pd/ZnGlu simple, among
50 °C and 280 °C to 5% lost weight relating to water physi-
cally adsorbed. The amino functionalized analogues of Ni@
Pd/ZnGlu indicated dramatic weight losses of 21% to 24%
under the temperature of 400 °C, likely because of ligand
disintegration. As can be illustrate in Fig. 4, a considerable
weight loss stage emerged under the temperatures between
of 550 and 600 °C, that is related to the material oxidizes
decomposition. Ni@Pd/ZnGlu NPs indicated a promising
thermal consistency under reaction temperature.
Figure 5 shows magnetization curves about the super
paramagnetic conduct of the Ni@Pd nanoparticles and nano-
catalyst of Ni@Pd/ZnGlu. The magnetic saturation amounts
Fig. 3 FTIR spectra of (a) ZnGlu; and (b) Ni@Pd/ZnGlu
1 3

W. Zhi-tao
Fig. 4 TGA diagram of of Ni@
Pd/ZnGlu
Fig. 5 Room-temperature mag-
netization curves of (a) Ni@Pd,
and (b) Ni@Pd/ZnGlu MNPs
related to the NPs of Ni@Pd and nanocatalyst of Ni@Pd/
ZnGlu were 43.3 and 24.7 emu g−1. Hence, the NPs of Ni@
Pd enhanced Ni@Pd/ZnGlu nanocatalyst can be properly
removed from the solution utilizing an outside magnetic
force, and can be utilized and also recycled.
l-glutamic acid indicates two parts on the core site spectrum
deconvolution at 399.4 as well as 401 eV; properties of the
C–NH2 group. ZnGlu possess N1s peaks close to 399.8 and
401.5 eV; the slight change than higher binding energy can
be due to coordination of Zn–NH2. Moreover, XPS spectrum
for Pd3d indicates a match indicative of metallic Pd.
XPS can be used for investigating the chemical parts
of the MNPs site of Ni@Pd/ZnGlu MNPs. A pattern of
XPS in the case of the as gathered catalyst are illustrated
in Fig. 6. Peaks corresponded to N, Pd, Zn, O, C, and Ni
can be observed in Fig. 6. The N1s spectrum related to
It is known that the Ni@Pd immobilization on the level
of ZnGlu NPs can cater a proper dispensation of catalyti-
cally active Ni@Pd parts upon the support and reinstates the
Ni@Pd NPs in the chemical reaction as well as supports the
1 3

Cycloaddition of Propargylic Amines and CO2 by Ni@Pd Nanoclusters Confned Within Metal–…
Fig. 6 XPS spectra of Ni@Pd/
ZnGlu MNPs
Table 1 Synthesis of
2-oxazolidinone by Ni@Pd/
ZnGlu MNPs in diferent
solvents
activity is studied to provide 2-oxazolidinone. It is selected
like a modelled reaction in the case of optimizing the reac-
tion factor including the solvent at visible light irradiation
utilizing a 32 W CFL. In the present paper, we have found
that common heating at solvent-free states is more impres-
sive compared to utilizing organic solvents, with taking into
consideration of reaction time as well as production of the
desired 2-oxazolidinone (refer to Table 1). The capability to
utilize solvent-free states as the reaction zone signifcantly
enhances the green testimonial of the approach.
Entry Solvent
Yield (%)a
1
2
3
H2O
MeOH
EtOH
53
46
42
49
18
38
17
6
35
38
39
–
4
5
i-PrOH
THF
6
7
EtOAc
DMF
8
9
Toluene
CH2Cl2
CHCl3
DMSO
CH3CN
Dioxane
n-Hexane
We have studied the signifcant pattern of temperature in
the production of 2-oxazolidinone at the presence of Ni@
Pd/ZnGlu MNPs that is considered as a catalyst. Outcomes
obviously showed that the catalytic activity cannot change
temperature of reaction. The most appropriate temperature
about this reaction is 25 °C temperature. Higher tempera-
ture does not lead to changing the reaction efciency. The
catalyst value essential to enhance the reaction efciently
is tested. It is determined that the changing Ni@Pd/ZnGlu
MNP can have signifcant infuence. The most appropriate
value of Ni@Pd/ZnGlu MNP was 1.0 mg that acquired the
desirable product for 95% production (refer to Fig. 7). At the
proper states, the reaction advance in the attendance of an
amount of Ni@Pd/ZnGlu MNP (1.0 mg) is analysed using
GC. Utilizing this catalyst approach, proper products of
2-oxazolidinone may be obtained during 2 h (refer to Fig. 8).
No clear by-products are detected utilizing GC apparatus
in whole the experiments as well as the 2-oxazolidinone is
cleanly created by 95% production. Infuences of carbon
dioxide pressure in the attendance of propargylic amine and
MNP of Ni@Pd/ZnGlu under the temperature of 25 °C at
10
11
12
13
14
15
–
–
Solvent-free 95
Reaction conditions: propar-
gylic amine (1 mmol), CO2
2.0 MPa, Ni@Pd/ZnGlu MNPs
(2 mg), and under visible light
irradiation using a 32 W CFL,
after 3 h
aIsolated yields
Ni@Pd NPs from compression. Moreover, the hydrophilic
nature of supported ZnGlu prepares an averages of proper
dispersion of ZnGluNPs in aqueous medium to expand this
apparatus as a semi-homogeneous catalyst of Ni@Pd about
organic reactions at solvent-free like a safe and green states.
To demonstrate this, the Ni@Pd/ZnGlu MNP catalytic
1 3

W. Zhi-tao
Fig. 7 Efect of increasing
amount of Ni@Pd/ZnGlu MNPs
on the preparation of 2-oxazo-
lidinone
100
90
80
70
60
50
40
30
20
10
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Ni@Pd/ZnGlu MNPs (mg)
Fig. 8 Efect of time on yield of
100
90
80
70
60
50
40
30
20
10
0
2-oxazolidinone
0
20
40
60
80
100
120
140
Time (min)
Fig. 9 Efect of pressure on
100
90
80
70
60
50
40
30
20
10
0
yield of 2-oxazolidinone
0
0.3
0.6
0.9
1.2
1.5
1.8
CO2 pressure (Mpa)
1 3

Cycloaddition of Propargylic Amines and CO2 by Ni@Pd Nanoclusters Confned Within Metal–…
Table 2 Efect of visible light intensity on course of the reaction
information is presented in Table 3. In the frst step, one
separated reaction is tested at the attendance of ZnGlu. The
outcome of this works proved that any value of the proper
yield is not created (refer to Table 3, entries 1). According
to this disappoint outcomes, we conduct another study to
enhance the product ion by adding the NPs in catalyst. NPs
that acts as a cocatalyst is known as a essential compound
for activating propargylic amines enhancing their catalytic
functions. The catalytic behavior of these distinct NPs is
determined to be of the discipline Pd~Ni@Pd>Au>Cu>
Ag>ZnO>Pt>RuO2 >TiO2 >FeNi3 >Ni. As a result, Ni@
Pd/ZnGlu MNPs was used in the subsequent investigations
because of its high reactivity, high selectivity and easy sepa-
ration by simple magnet.
Entry
Visible light intensity (W)
Yield (%)a
1
2
3
4
5
6
–
8
15
20
22
32
–
69
95
95
95
95
Reaction conditions: propargylic amine (1 mmol), CO2 1.5 MPa, and
Ni@Pd/ZnGlu MNPs (1 mg) under visible light irradiation at room
temperature under solvent-free conditions for 2 h
aIsolated yields
The carboxylative cyclization in the case of a diversity
of propargylic amines is after wards chosen for exploring
the scope of this expanded Ni@Pd/ZnGlu MNP catalytic
method. As can be observed in Table 4, aromatic as well as
aliphatic propargylic amines done smoothly for giving the
relating 2-oxazolidinones in great products.
2 h (refer to Fig. 9). The catalyst compound attains an mean
conversion more than 95% under pressure of 1.5 Mpa.
In the present paper, a set of experiments is performed by
utilizing light of distinct intensities to detect the optimized
visible light intensity required to this reaction. In addition,
the activity is indicated that when Ni@Pd/ZnGlu MNP is
utilized like a catalyst without considering the visible light
radiation (refer to Table 2, entries 1). It is showed that the
product is identical while 15 W CFL is utilized. Neverthe-
less, while CFL’s of lower intensities are utilized, marginal
reduce in production and reaction rate is detected (refer to
Table 2, entries 2). Utilizing a CFL of higher wattage upon
the other hand not possess any sensible infuence on produc-
tion or time of reaction.
In comparison to previously reported methods, our
method was milder, greener from viewpoint for propargylic
amines cyclization with carbon dioxide, support, and metal
and costly efective with higher conversion and selectiv-
ity towards production of 2-oxazolidinones [53–55]. This
comparison clearly exhibits that how powerful our proposed
catalyst plays the role of catalyst. It should be noted that in
our research, unlike most other reports, a simple nano-metal
is used instead of a metal complex. This makes it easy to
separate of catalyst from the reaction mixture and reuse it
(Table 5).
To more investigation of the performance of the cata-
lyst, various control experiments are done and the achieved
The reusability state of a catalyst is known as a signif-
cant property in the case of the green chemistry. Hence,
reusability state MNPs of the Ni@Pd/ZnGlu MNP is
Table 3 Comparison of the catalytic efciency of Ni@Pd/ZnGlu
MNPs with various catalysts
Entry
Catalyst
Yield (%)a
Table 4 Synthesis of 2-oxazolidinone derivatives catalyzed by Ni@
1
2
3
4
5
6
7
8
ZnGlu
Ni@Pd/ZnGlu
Pd/ZnGlu
–
Pd/ZnGlu MNPs
95
95
16
83
87
78
66
57
50
61
34
Entry R1
R2
H
R3
Product Yield (%)b
Ni/ZnGlu
1
H
CH3CH-
2a
88
Cu/ZnGlu
Au/ZnGlu
Ag/ZnGlu
ZnO/ZnGlu
RuO2/ZnGlu
TiO2/ZnGlu
Pt/ZnGlu
2CH2CH2
2
3
4
5
6
7
8
H
CH3
CH3
CH3
C6H5
4-CH3C6H4
C6H5
H
|H
H
H
H
H
CH3
CH3
C6H5CH2
(CH3)2CH
CH3
2b
2c
2d
2e
2f
2 g
2 h
92
85
91
90
94
97
91
9
10
11
12
CH3
FeNi3/ZnGlu
CH3CH2 CH3CH-
2CH2CH2
Reaction condition: propargylic amine derivatives (1 mmol), Ni@Pd/
ZnGlu MNPs (1.0 mg), and CO2 1.5 MPa, under solvent-free condi-
tions and visible light irradiation at room temperature under solvent-
free conditions after 2 h
Reaction condition: propargylic amine derivatives (1 mmol), Ni@Pd/
ZnGlu MNPs (1.0 mg), and CO2 1.5 MPa, under solvent-free condi-
tions and visible light irradiation at room temperature after 2 h
aIsolated yield
aYield refers to isolated product
1 3

W. Zhi-tao
Table 5 An overview of some
methods for synthesis of
2-oxazolidinone
Entry
Catalyst
Solvent
T (°C)
Time (h)
Yield (%)
Ref
1
2
3
4
5
6
7
8
PtCl2
CuI
Cu(OAc)2
AgOAc
AgOAc
Ag2O
AgNO3
AuCl
AuCl(IPr)
AuCl(IMes)
AuCl(ItBu)
AuCl[P(C6H5)3]
AuCl[P(OC2H5)3]
AuCl[P(C2H5)3]
AuBr(IPr)
AuI(IPr)
AgCl(IPr)
DMSO/H2O
DMSO/H2O
DMSO/H2O
DMSO/H2O
DMSO
DMSO
DMSO
CH3OH
CH3OH
CH3OH
CH3OH
CH3OH
CH3OH
CH3OH
CH3OH
CH3OH
CH3OH
CH3OH
CH3OH
2-Propanol
CH3CN
THF
CH2Cl2
Toluene
iPrOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
60
60
60
60
60
60
60
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
40
110
60
60
60
60
60
60
60
60
60
60
60
90
90
90
90
90
r.t
240
120
114
24
18
16
17
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
24
20
20
20
20
20
20
20
20
20
20
20
21
21
21
21
21
2
69
63
78
86
90
92
95
0
91
89
83
41
61
70
84
71
52
19
0
55
15
0
0
0
89
0
0
43
67
68
95
66
18
16
45
43
72
88
67
58
85
95
[53]
[53]
[53]
[53]
[53]
[53]
[53]
[54]
[54]
[54]
[54]
[54]
[54]
[54]
[54]
[54]
[54]
[54]
[54]
[54]
[54]
[54]
[54]
[54]
[54]
[55]
[55]
[55]
[55]
[55]
[55]
[55]
[55]
[55]
[55]
[55]
[13]
[13]
[13]
[13]
[13]
–
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
CuCl(IPr)
ItBu–CO2
AuCl(IPr)
AgCl(IPr)
AgCl(IPr)
AgCl(IPr)
AgCl(IPr)
ItBu
(nC7H15)4NBr
K8[α-SiW11O39]
K6[SiW11O39Cu]
CuCl2
CuCl2 +(nC7H15)4NBr
[(nC7H15)4 N]6[α-SiW11O39Cu]
[(nC7H15)4 N]6[α-SiW11O39Co]
[(nC7H15)4 N]6[α-SiW11O39Fe]
[(nC7H15)4 N]6[α-SiW11O39Ni]
[(nC7H15)4 N]6[α-SiW11O39Zn]
[(nC7H15)4 N]6[α-SiW11O39Mn]
SiO2–(CH2)3–NEt2
SiO2–TBD
EtOH
EtOH
EtOH
EtOH
–
–
–
–
Hydrotalcite MG30
Hydrotalcite MG70
Al2O3
–
Ni@Pd/ZnGlu MNPs
Solvent-free
investigated at optimal states for synthesis of 2-oxazoli-
dinones. After performing the reaction, the solid MNPs
of Ni@Pd/ZnGlu are directly separated from the liquid
reaction zone, magnetically, as while nearing a magnet,
the solid readily separates from the solution under a few
seconds. After solvent cleaning, it may quickly be reused.
Figure 10 indicated that the catalyst is reused for tenth
consecutive runs. Synthesis of 2-oxazolidinone obtained
92% at the ten run that means only a 3% drop in perfor-
mance is seen in comparison to the related fresh catalyst
(95%). In addition, the value of Palladium leached within
the solution for synthesis of 2-oxazolidinone after each run
is evaluated using ICP. The catalyst indicated very little
leaching in each turn that 0.4% metal leaching discovered
1 3

Cycloaddition of Propargylic Amines and CO2 by Ni@Pd Nanoclusters Confned Within Metal–…
catalyst activity. Conducted experiment is proof of the het-
100
80
60
40
20
0
erogeneous catalyst. This test has been performed with the
aforesaid model of reaction under optimal states. After 1 h
of the reaction, about 300 molar mercury is released to the
reaction compound. The reaction zone is stirred for above
2 h. In this reaction, no further conversion is seen after 2 h
from the catalyst being poisoned. A kinetics scheme of the
reaction under the attendance of Hg(0) is demonstrated in
Fig. 12. The negative outcomes obtained from the whole
heterogeneity experiments (Hg(0) poisoning as well as hot
fltration) proposed that the solid catalyst is really heteroge-
neous and no acquirable Palladium leaching performed upon
synthesis of 2-oxazolidinones.
1
2
3
4
5
6
7
8
9
10
Reuse
Fig. 10 The reusability of catalysts for synthesis of 2-oxazolidinones
Eventually, for ensuring whether the structure of the
recovered catalyst is maintained, we have investigated after
the passage of the 10th in the case of photocatalytic synthe-
sis of 2-oxazolidinones at the determined premium states
using some investigation as seen in Fig. 13. XPS pattern
demonstrated that the Pd elements show in the catalyst
fatigued entire after passage of the 10th run then their oxi-
dation condition was same to the fresh catalyst. As seen in
Fig. 13a, no other oxidation conditions are detected in the
catalyst. As seen in Fig. 13b XRD, pattern of the reproduced
catalyst proved that the catalyst structure fatigued totally
intact within recycling. The recovered catalyst guaranteed
to the outside magnetic zone and can be easily prepared
by the reaction mixture like as the fresh catalyst (refer to
Fig. 13c). Noted that the nanocatalyst has not indicated any
morphological variations that is proved by the FE-SEM pic-
tures, which captured from the recovered catalyst (refer to
Fig. 13d). The TEM picture indicated that the a black nano-
particle placed on the structure of ZnGlu were Ni@Pd after
the 10th run (refer to Fig. 13e).
after the ten run, so showing its consistency at the reaction
states as illustrated in Fig. 11.
In addition, a complete study is performed to clarify the
catalyst heterogeneous nature. Firstly, we done the hot fl-
tration experiment for synthesis of 2-oxazolidinones at pre-
mium states and determined that the catalyst is magnetically
deleted in situ after 64% for 1 h removal. In addition, the
reactants are permissible to tolerate more reaction. The out-
comes demonstrated that, after removing the heterogeneous
catalyst, the free catalyst remnant is feeble active, and the
conversion about 66% is obtained after 2 h of the synthesis
of 2-oxazolidinones. It proved that the catalyst worked het-
erogeneously during the reaction and resentful just slight
leaching done in the reaction. Secondly, for ensuring the
heterogeneous pattern of the catalyst, the mercury poisoning
examine is additionally performed. Mercury (0) is imbibed
as a metal or using synthesis and dramatically deactivated
the metal catalyst on active surface and so tranquilized the
Fig. 11 Recyclability of the
catalyst for synthesis of 2-oxa-
zolidinones
0.4
0.3
0.2
0.1
0
0
1
2
3
4
5
6
7
8
9
10
Reuse
1 3

W. Zhi-tao
Fig. 12 Reaction kinetics, Hg
(0) poisoning, and hot fltration
studies for synthesis of 2-oxazo-
lidinones
Fig. 13 a XPS, b XRD, c VSM, d TEM, and e FE-SEM images of the recovered Ni@Pd/ZnGlu MNPs after the tenth run for synthesis of 2-oxa-
zolidinones
1 3

Cycloaddition of Propargylic Amines and CO2 by Ni@Pd Nanoclusters Confned Within Metal–…
24. Corma A, Garcia H, Llabres I, Xamena FX (2010) Chem Rev
4 Conclusions
110:4606–4655
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26. Schröder F, Esken D, Cokoja M, Berg MWE, Lebedev OI, Van
Tendeloo G, Walaszek B, Buntkowsky G, Limbach HH, Chaudret
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In the present paper, we expanded a simple that is highly
efcient, obvious light activated and Ni@Pd/ZnGlu, green
synthetic method in the case of the cyclization of propar-
gylic amines to carbon dioxide for present 2-oxazolidinones.
This visible light and Ni@Pd/ZnGlu compound prepares a
simple as well as straight path for chemical stabilization of
CO2. The conditions of reaction show a vast area of func-
tional group to tolerance. This procedure shows proper atom
economy (the spent Ni@Pd/ZnGlu MNPs) may be recycled
and also reused for mediating task. They have to be helpful
for understanding the advantageous mixing of the character-
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and also the expansion of simple catalytic methods. How-
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and economical conducts and can assist for minimizing the
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