Preparation and Characterization of an Efficient Nano-Inorganic Composite of CuO/ZnO/Al2O3 for the Catalytic Amination of Aryl Halides in Aqueous Conditions

Article abstract of DOI:10.1007/s10562-018-2567-1

In this research, an efficient recyclable nano-inorganic composite of CuO/ZnO/Al₂O₃ (CuO/ZnO/Al₂O₃ nanocatalyst) is prepared, characterized and used for the amination of aryl halides with aqueous ammonia in water. The catalyst was prepared by co-precipitation method and characterized by various techniques such as the X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy, and brunauer–Emmett–Teller surface area analysis. Various aryl halides reacted with aqueous ammonia and corresponding products were obtained in high yields. CuO/ZnO/Al₂O₃ nanocatalyst as an efficient stable catalyst is recyclable up to five consecutive runs by simple filtration. Graphical Abstract: An efficient recyclable nano-inorganic composite of CuO/ZnO/Al₂O₃ (CuO/ZnO-Al₂O₃ nanocatalyst) is prepared, characterized and used for the amination of aryl halides with aqueous ammonia in water. [Figure not available: see fulltext.].

Full text of DOI:10.1007/s10562-018-2567-1

Catalysis Letters
https://doi.org/10.1007/s10562-018-2567-1
Preparation and Characterization of an Efficient Nano-Inorganic
Composite of CuO/ZnO/Al2O3 for the Catalytic Amination of Aryl
Halides in Aqueous Conditions
Jalal albadi1 · Mehdi Jalali2 · Heshmat Allah Samimi1
Received: 9 July 2018 / Accepted: 21 September 2018
© Springer Science+Business Media, LLC, part of Springer Nature 2018
Abstract
In this research, an efficient recyclable nano-inorganic composite of CuO/ZnO/Al2O3 (CuO/ZnO/Al2O3 nanocatalyst) is
prepared, characterized and used for the amination of aryl halides with aqueous ammonia in water. The catalyst was prepared
by co-precipitation method and characterized by various techniques such as the X-ray diffraction, scanning electron micro-
scope, energy dispersive spectroscopy, and brunauer–Emmett–Teller surface area analysis. Various aryl halides reacted with
aqueous ammonia and corresponding products were obtained in high yields. CuO/ZnO/Al2O3 nanocatalyst as an efficient
stable catalyst is recyclable up to five consecutive runs by simple filtration.
Graphical Abstract
An efficient recyclable nano-inorganic composite of CuO/ZnO/Al2O3 (CuO/ZnO-Al2O3 nanocatalyst) is prepared, character-
ized and used for the amination of aryl halides with aqueous ammonia in water.
Keywords CuO/ZnO/Al2O3 nanocatalyst · Amination · Ammonia · Aryl halide
1 Introduction
Synthesis of aryl amines is an active area in organic syn-
thesis because of the occurrence of these moieties in bio-
Electronic supplementary material The online version of this
logically important natural products, pharmaceuticals, and
article (https://doi.org/10.1007/s10562-018-2567-1) contains
their applications in materials researches [1]. Aryl amines
supplementary material, which is available to authorized users.
are attractive targets for chemical synthesis because of their
utility in fine chemicals, dyes and polymers [2]. The most
common approach to prepare aryl amines generally relays
on the use of transition-metal catalysts to promote the cou-
pling reaction of aryl halides with ammonia or ammonia
derivatives [3].
* Jalal albadi
Chemalbadi@gmail.com; Albadi@sku.ac.ir
1
Department of Chemistry, Faculty of Sciences, Shahrekord
University, Shahrekord, Iran
2
National Petrochemical Company, Petrochemical Research
and Technology Company, Tehran, Iran
Vol.:(0123456789)
1 3

J. albadi et al.
Metal-catalyzed reactions are one of the most widely
used methodologies for the creating C–N bonds. and they
have been used in the C–N coupling of amines and aryl
halides. Various catalysts, including Pd, and Cu have
been shown to catalyze the amination of aryl halides with
ammonia [4–14]. Among these, the copper-catalyzed Ull-
mann reaction has been proven to be the most convenient
synthetic route for installing an N-aryl functionality [6].
Hybrid nanostructures show multi-functionality with
synergistic effects between independent domains [15].
From the perspective of heterogeneous catalysis, these
mixture nanostructures could provide optimal architectures
for bifunctional catalytic systems [16]. In these catalysts,
one or two of the components acts as an active surface
for the reaction, and the other works as a support to sta-
bilize the whole structure. The inorganic border between
the components can either tailor the chemical nature of
the active component, or create new species to increase
catalytic activities. Therefore, these well-defined hybrid
nanostructures are ideal for heterogeneous catalysts [17].
In recent years, Cu-catalysts supported on ZnO–Al2O3
mixed oxides have gained special interests as industrial
catalysts. Specially, CuO/ZnO/Al2O3 has been paid more
attention, and some progresses have been reported [18,
19]. Therefore, for the preparation of CuO/ZnO/Al2O3 cat-
alyst, various approaches have been reported and different
kind of this catalyst was prepared and studied [20–25].
Previously, we have reported the amination of aryl hal-
ides in the presence of CuO–CeO2 nanocomposite and
poly(4-vinylpyridine)-supported copper iodide nanopar-
ticles catalyst (P4VPy–CuI) [26, 27]. To the best of our
knowledge, CuO/ZnO/Al2O3 nanocatalyst has not used as
catalyst in organic synthesis reactions in particular for the
amination of aryl halides. Therefore, in continuation of our
programs for the study on different nanocatalysts [28–30],
we herein, report the preparation, characterization and
catalytic activity of an efficient recyclable nano-inorganic
composite of CuO/ZnO/Al2O3 (CuO/ZnO/Al2O3 nanocata-
lyst) for the amination of aryl bromides and iodides with
aqueous ammonia in water (scheme 1).
2 Experimental
All chemical compounds were purchased from Merck
chemical companies. Products were characterized by
comparison of their spectroscopic data (1H NMR, IR) and
physical properties with those reported in the literature.
Yields refer to isolated products.
2.1 Preparation of Catalyst
The CuO/ZnO/Al2O3 nanocatalyst was prepared via a co-
precipitation method, by adding Na2CO3 solution (0.5 M)
drop-wise into a mixture of Cu(NO3)2·3H2O (0.03 M),
Zn(NO3)3·6H2O (0.03 M), and aluminium nitrate (0.03 M),
solutions under vigorous stirring. The obtained suspension
was aged at pH = 8.5 for 15 min at 50 °C, then filtered
and washed with warm deionized water (<0.05 µS cm−1).
The precipitates were dried 12 h at 100 °C followed by
calcination at 300 °C for 3 h to afford the CuO/ZnO/Al2O3
nanocatalyst.
2.2 Catalyst Characterization
The X-ray diffraction (XRD) analysis was performed using
an X-ray diffractometer, Cu–Kα monochromatized radia-
tion source and a nickel filter (Panalytical X’PertPro),
in order to investigate the structure and crystallinity of
the catalyst. Scherrer equation was used to determine
the average crystallite size of the sample. The morphol-
ogy of the CuO/ZnO/Al2O3 nanocatalyst was studied by
scanning electron microscopy (SEM) method by a JEOL
JSM-6500F instrument, equipped with an energy disper-
sive spectroscopy (EDS) analytical system to study the
presence of different components of the catalyst. The
brunauer–Emmett–Teller (BET) surface area was tested
by N2 adsorption–desorption method. The analysis was
carried out using an automated gas adsorption analyzer
(Tristar 3020, Micromeritics). The sample was purged
with nitrogen gas for 3 h at 300 °C by a VacPrep 061 degas
system (Micrometrics).
2.3 General Procedure
A mixture of aryl halide (1 mmol), NH4OH (2 mmol),
Cs2CO3 (1 mmol) and CuO/ZnO/Al2O3 nanocatalyst
(0.1 g), in water was stirred at reflux condition. After reac-
tion completion, (monitored by TLC), the mixture reaction
was cooled to room temperature and catalyst filtered. Then
the residue was evaporated to dryness, the residue was
poured into a saturated NaCl solution, extracted with ethyl
acetate and dried over anhydrous MgSO4. Evaporation of
nanocatalyst
reflux
O
,
CuO/ZnO/Al2O3
NH
4OH
ArX
X=Br, I
ArNH2
s
H
C CO
,
2
3
2
Scheme 1 CuO/ZnO/Al2O3 nanocatalyst catalyzed amination of aryl
halides
1 3

Preparation and Characterization of an Efficient Nano-Inorganic Composite of…
the solvent followed by column chromatography on silica
gel gave the pure products in high yields.
3 Results and Discussion
3.1 X‑ray Diffraction
Figure 1, Shows the XRD pattern of the CuO/ZnO/Al2O3
nanocatalyst. As reported in literature [31], the diffrac-
tion peaks centered at 2θ = 31.8, 2θ = 34.82, 2θ = 56.92,
2θ=69.12 are attributed to the (100), (002), (110) and (200)
crystalline planes of ZnO crystals, respectively. The diffrac-
tion peaks centered at 2θ=36.58, 2θ=47.86 and 2θ=63.32
may be corresponded to (111), (202) and (113) planes of
CuO, respectively [32]. It is valuable to note that the peaks
centered at about 2θ = 36.58 may be related to α, δ and θ
and the peaks centered at about 2θ = 47.86 can be attrib-
uted to the γ, δ, θ, Al2O3 phases, respectively [30]. These
explanations can be stated, because the percentages of Al2O3
(10%) and CuO (5%) in the target catalyst are nearly close.
As presented, the synthesized catalyst is a mixture of three
type crystals and overlapping the characteristic peaks may
influence the detailed interpretations of the given XRD pat-
tern. Therefore, the XRD data can be a proof to indicate the
presence of three crystals in the blended catalyst.
3.2 N2 Adsorption/Desorption Analysis
As seen from Fig. 2, the isotherms of the support and cat-
alyst display thin hysteresis loops between p/p0 = 0.3–0.8
and p/p0 =0.3–0.85, respectively. However, according to the
IUPAC instructions, these N2 adsorption/desorption profiles
correspond to the approximately non-porous metal oxides’
structures and could be categorized as type III [33, 34]. As
seen, the hysteresis loop of the support is smaller than the
catalyst hysteresis loop. As demonstrated in the Fig. 2a, the
Fig. 2 The N2 adsorption/desorption and pore width distribution of
the ZnO support and catalyst
amount of adsorbed N2 gas per gram of catalyst is greater
than that of the support in each relative pressure below 0.8.
This difference may be due to the high surface area of the
CuO/ZnO/Al2O3 compared to the ZnO support. The specific
surface area and porosity of the support and the catalyst
were calculated by employing the BET and Barrett-Joyner-
Halenda (BJH) methods, respectively. The pore width dis-
tribution and structural characteristics of the support and
300
250
200
150
100
50
Table 1 Structural parameters of the support and the nanocatalyst
Catalyst
BET surface
Total pore vol-
Average
pore width
(nm)
0
area (m2 g−1
)
ume (cm3 g−1
)
0
10
20
30
40
50
60
70
80
2θ
ZnO
CuO/ZnO/Al2O3
39.13
51.11
0.164
0.179
22.69
17.68
Fig. 1 The XRD pattern of CuO/ZnO/Al2O3 nanocatalyst
1 3

J. albadi et al.
catalyst are presented in Fig. 2b and Table 1, respectively.
The Fig. 2b exhibits a wide pore size distribution for both
the ZnO support and the CuO/ZnO/Al2O3 nanocatalyst with
a maximum at about 30 and 24 nm, respectively. It is valu-
able to note that the pores size for both support and cata-
lyst varied between mesoporous to macroporous structures.
Thus, this distribution pattern may confirm the non-porous
structure of metal oxides which aggregate together [33].The
high surface area and total pore volume of the CuO/ZnO/
Al2O3 nanocatalyst are because of the incorporating of the
Al2O3 phases in target catalyst. It is valuable to note that
the total surface area of some Al2O3 phases can be varied
between 250 and 800 m2 g−1.
As shown in Table 1, the average pore width of the cata-
lyst is smaller than the support’s one. The reason for this
may be due to the co-formation of mesoporous Al2O3 struc-
ture with CuO and ZnO.
3.3 SEM Study
Figure 3 represents the SEM images of the CuO/ZnO/Al2O3
nanocatalyst with different magnifications. An aggregation
of the Al2O3 and CuO nanoparticles was observed on the
surface of ZnO support. The sizes of these nanoaggregates
with different shapes are less than 20 nm. As a quantitative
proof, the EDS (Fig. 3c) analysis has been performed, and
presented the content of ZnO support greater than 75% by
weight. It is valuable to note that the weight percent of Cu
and Al in nanocatalyst was lower than that of zinc and there-
fore was not appeared in EDS spectrum.
3.4 Amination of Aryl Halides
Initially, for the optimization of reaction conditions, the
reaction of iodobenzene with aqueous ammonia was cho-
sen as a model and its behavior was studied under a variety
of conditions. Influence of several factors such as tempera-
ture, CuO loading, catalyst amount and solvent were investi-
gated. Various CuO/ZnO/Al2O3 amount containing 5, 10 and
15 wt% CuO, were studied. It was found that 5CuO/ZnO/
Al2O3 showed the good activity and efficiency (Table 2).
Increase in the CuO loading did not significantly effect
on the yield and time of the reaction. Therefore, the reac-
tion was studied in the presence of different amounts of
the 5CuO/ZnO/Al2O3 nanocatalyst. Furthermore, it was
observed that using 0.1 g of 5CuO/ZnO/Al2O3 nanocata-
lyst was sufficient for the reaction completion after 3 h.
The influence of various solvents on the yield and time of
the reaction was also examined and water was preferred
as the most efficient solvent. The reaction was evaluated
in the presence of different bases. Among the bases were
selected, Cs2CO3 gave the best result (Table 2). The effect
of various amounts of NH4OH was also studied. It was
Fig. 3 SEM micrographs (a, b) and EDS analysis (c) results of CuO/
ZnO/Al2O3 nanocatalyst
found that using 2 mmol of NH4OH in refluxing water was
suitable for the reaction completion. Therefore, 2 mmol
of NH4OH, 1 mmol of Cs2CO3 and catalyst (0.1 g), in
water at reflux conditions was considered to be the most
conditions for this reaction. After this, the reaction of vari-
ous aryl iodides including electron-donating and electron-
withdrawing groups, with aqueous ammonia were explored
(Table 3). From Table 3, all aryl halides were converted to
1 3

Preparation and Characterization of an Efficient Nano-Inorganic Composite of…
Table 2 Optimization of the reaction conditionsa
time of reactions (Table 3). Moreover, reaction of various
aryl bromides with aqueous ammonia were studied. It was
found that aryl bromides converted to their correspond-
ing products and suitable results were obtained. However,
times of the reactions were increase, and products synthe-
sized in excellent yields.
Entry CuO
Catalyst
amount
(g)
Condition
Time (h) Yield (℅)b
loading
(wt%)
1
2
3
4
5
6
5
5
5
5
5
0.05
0.1
0.05
0.1
0.05
0.1
EtOH/reflux 12
EtOH/reflux 12
MeCN/reflux 12
MeCN/reflux 12
DMF/reflux 12
DMF/reflux 12
Trace
30
Trace
50
30
45
–
–
50
75
91
70
90
92
The activity of the recovered catalyst was also checked
under the optimized conditions and reaction of iodoben-
zene with aqueous ammonia was chosen as a model reac-
tion. After reaction completion, the catalyst was washed
with hot acetone, dried and stored for another successive
reaction run. This process was repeated for 5 runs and no
considerable decrease in yield was observed. The results
are revealed in Table 4.
5
7
8
9
10
11
12
13
14
15
5
10
5
5
5
10
10
15
15
0.05
0.1
0.05
0.07
0.1
0.07
0.1
0.07
0.1
H2O/r.t.
H2O/r.t.
24
24
8
5.5
3
5
3
H2O/reflux
H2O/reflux
H2O/reflux
H2O/reflux
H2O/reflux
H2O/reflux
H2O/reflux
The XRD pattern and SEM image with of the catalyst
after five cycle was recorded. As seen from Fig. 4, the
intensity of some peaks was reduced but the crystal struc-
ture of the catalyst was remained. Comparison of the SEM
image of the used catalyst with fresh catalyst shown more
agglomeration of the catalyst particles in used catalyst.
The possible mechanism for the amination of aryl hal-
ides in the presence of CuO/ZnO/Al2O3 nanocatalyst is as
shown in Scheme 2. Initially, addition of CuO/ZnO/Al2O3
nanocatalyst to aryl iodide gives the ZnO/Al2O3CuO(Ar)
(I) that co-ordination of it with the amine followed by
deprotonation and CsX elimination provides the desired
product.
3
3
91
aReaction conditions: iodobenzene (1 mmol), Cs2CO3 (1 mmol),
NH4OH (2 mmol), conditions
bIsolated pure products
their corresponding amines in high yields. Electron-with-
drawing groups such as nitro on aromatic ring increased
the yield of reactions, while the electron-releasing groups
such as methoxy decreased the yield and increased the
Table 3 CuO/ZnO/Al2O3 nanocatalyst catalyzed amination of aryl halides
Entry
Aryl halide
Product
Time (h)
Yield (%)a
1
2
3
4
5
6
7
8
C6H5I
4-NO2C6H4I
4-ClC6H4I
4-CF3C6H4I
4-OMeC6H4I
3,4,5-(OMe)3C6H2I
C6H5Br
4-MeC6H4Br
4-OMeC6H4Br
4-NO2C6H4Br
C6H5NH2
3
1
2.5
1
5
7
4.5
6
7.5
2
4
91
93
92
92
88
87
90
88
88
92
89
4-NO2C6H4NH2
4-ClC6H4NH2
4-CF3C6H4NH2
4-OMeC6H4NH2
3,4,5-(OMe)C6H2NH2
C6H5NH2
4-MeC6H4NH2
4-OMeC6H4NH2
4-NO2C6H4NH2
9
10
11
NH2
I
12
13
4
5
88
88
Me
NH2
Me
I
MeO
I
MeO
NH2
aIsolated pure products. Reaction conditions: aryl halide (1 mmol), NH4OH (2 mmol), Cs2CO3 (1 mmol), catalyst amount (0.1 g), in water at
reflux conditions
1 3

J. albadi et al.
Table 4 Recyclability study of CuO/ZnO/Al2O3 nanocatalyst upon
4 Conclusion
the reaction of iodobenzene with aqueous ammoniaa
In summary, we have reported the catalytic activity of an
efficient nano inorganic composite of CuO/ZnO/Al2O3
(CuO/ZnO/Al2O3 nanocatalyst) as a competent recycla-
ble catalyst for the amination of aryl halides with aqueous
ammonia in water. This catalyst easy to handle and can be
recovered five runs simply by filtration. Moreover, ease of
work-up, heterogeneous reaction conditions, high yields
of products, short reaction times, and clean procedure will
make this procedure useful.
Run
1
2
3
4
5
Time (h)
3
3
3
3.5
88
4.5
87
Yield (%)b
91
91
90
aReaction conditions: iodobenzene (1 mmol), NH4OH (2 mmol),
Cs2CO3 (1 mmol), catalyst amount (0.1 g), in water at reflux condi-
tions
bIsolated pure products
Fig. 4 The XRD pattern and
SEM image of the catalyst after
the recyclability study
Scheme 2 The probable mecha-
nism for the amination of aryl
halides
CuO
ArX
-
CsX+ HCO
3
CuO
CuO
NH3
Cs2CO3
Ar-NH2
Ar-X
Ar-X
NH3
CuO/ZnO/Al2O3:
CuO
1 3

Preparation and Characterization of an Efficient Nano-Inorganic Composite of…
18. Takeguchi T, Yanagisawa K, Inui T, Inoue M (2000) Appl Catal
A Gen 192:201
Acknowledgements We are grateful to the research council of Shah-
rekord university, for the support of this research.
19. Zhang YL, Sun Q, Deng JF, Wu D, Chen SY (1997) Appl Catal
A Gen 158:105
20. Agrell J, Birgersson H, Boutonnet M (2002) J Power Sources
106:249
References
21. He L, Cheng H, Lianga G, Yu Y, Zhao F (2013) Appl Catal A Gen
452:88
1. Schlummer B, Scholz U (2004) Adv Synth Catal 346:1599
2. Evano G, Blanchard N, Toumi M (2008) Chem Rev 108:3054
3. Aubin Y, Fischmeister C, Thomas CM, Renaud JL (2010) Chem
Soc Rev 39:4130
22. Chen CS, Lin JH, You JH, Chen CR (2006) J Am Chem Soc
128:15950
23. Behrens M, Kissner S, Girsgdies F, Kasatkin I, Hermerschmidt F,
Mette K, Ruland H, Muhler M, Schlogl R (2011) Chem Commun
47:1701
4. Shen Q, Hartwig JF (2006) J Am Chem Soc 128:10028
5. Surry DS, Buchwald SL (2007) J Am Chem Soc 129:10354
6. Li Y, Zhu X, Meng F, Wan Y (2011) Tetrahedron 67:5450
7. Noori N, Nikoorazm M, Ghorbani-Choghamarani A (2017) Catal
Lett 147:204
24. Catillon-Mucherie S, Ammari F, Krafft JM, Lauron-Pernot H,
Touroude R, Louis C (2007) J Phys Chem C 111:11619
25. Fu M, Li YL, Wu SW, Lu P, Liu J, Dong F (2011) Appl Surf Sci
258:1587
8. Islam M, Mondal S, Mondal P, Roy AS, Tuhina K, Mobarok M,
Paul S, Salam N, Hossain D (2011) Catal Lett 141:1171
9. Wang X, Meng F, Zhang J, Xie J, Dai B (2018) Catal Lett
148:1142
26. Albadi J, Mansournezhad A (2014) Chin J Chem 32:396
27. Albadi J, Shiran JA, Mansournezhad A (2014) Acta Chim Slov
61:900
28. Albadi J, Alihoseinzadeh A, Razeghi A (2014) Catal Commun
49:1
10. Chavan SS, Sawan SK, Sawant VA, Lahiri GK (2010) Inorg Chem
Acta 363:3359
29. Albadi J, Jalali M, Momeni A (2018) Res Chem Intermed 44:2395
30. Albadi J, Alihosseinzadeh A, Jalali M, Shahrezaei M, Mansourn-
ezhad A (2017) Mol Catal 440:133
11. Chavan SS, Sawan SK, Sawant VA, Lahiri GK (2011) Inorg Chem
Commun 14:1373
12. Komati R, Jursic BS (2014) Tetrahedron Lett 55:1523
13. Yang B, Liao L, Zeng Y, Zhu X, Wan Y (2014) Catal Commun
45:100
31. Albadi J, Alihosseinzadeh A, Mansournezhad A (2015) Synth
Commun 45:877
32. Chauhan J, Shrivastav N, Dugaya A, Pandey D (2017) J Nanomed
Nanotechnol 8:429
14. Nair RN, Niekerk CV, Erdogan G, Grotjahn DB (2014) Top Catal
57:1539
33. Chiang C-L, Lin K-S (2017) Int J Hydrog Energy 42:23526
34. Jalali M, Aliakbar A (2015) Int J Environ Anal Chem 96:542
15. Gao J, Gu H, Xu B (2009) Acc Chem Res 42:1097
16. Somorjai GA, Park JY (2008) Top Catal 49:126
17. Arnal PM, Comotti M, Schüth F (2006) Angew Chem Int Ed
45:8224
1 3