Large-scale preparation of B/N co-doped graphene-like carbon as an efficient metal-free catalyst for the reduction of nitroarenes

Article abstract of DOI:10.1039/c7nj04187j

Boron and nitrogen co-doped graphene-like carbon (BNG) is a metal-free catalyst that has been synthesized by combining ball-milling with thermal treatment. Firstly, the edge-selectively-functionalized graphene nanoplatelets (EFGnPs) were prepared by ball

Full text of DOI:10.1039/c7nj04187j

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Jason B. Benedict et al.
The role of atropisomers on the photo-reactivity and fatigue of
diarylethene-based metal–organic frameworks
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Large-scale preparation of B/N co-doped graphene-like carbon as
an efficient metal-free catalyst for reduction of nitroarenes
Received 00th January 20xx,
Accepted 00th January 20xx
#
#
*
Fan Yang, Yan Cao, Zhuo Chen, Xing He, Liqiang Hou and Yongfeng Li
DOI: 10.1039/x0xx00000x
Boron and nitrogen co-doped graphene-like carbon (BNG) as metal-free catalysts are synthesized by combining with ball-
milling and thermal treatment. Firstly, the edge-selectively functionalized graphene nanoplatelets (EFGnPs) were prepared
through ball milling of the pristine graphite, which can facilitate the boron incorporation. The BNG catalysts with high
content of boron and nitrogen are obtained by pyrolysis the mixture of EFGnPs and boric acid. It is found that the
reduction of nitroarenes can be catalyzed by using a low BNG loading and a small amount of N2H4 in ethanol with high
yield. It is worth noting that the type of boron species in the BNG catalyst has an important effect on the reduction
reaction that the catalyst containing the most B/N shows the highest catalytic activity during reduction of nitroarenes,
indicating that the doped B/N in BNG is one of the key active sites in impelling this reaction. Moreover, the BNG catalyst
can be used for six times and no dehalogenation phenomenon occurs during the reduction process for halogen-substituted
nitroarenes in contrast to conventional metal catalysts.
www.rsc.org/
Keywords: metal-free catalysts, boron and nitrogen co-doped graphene-like carbon, nitroarenes, reduction
free catalysts have attracted numerous attention being a
2
2-24
Introduction
promising candidate in catalysis.
It is well known that
doping heteroatoms is an efficient way to tailor its electrical
2
Catalytic reduction of nitroarenes is one of the atomic-
efficiency methods for producing the corresponding amines,
which are intermediates or the key precursors of
pharmaceuticals, polymers, pesticides, explosives, fibers, dyes
5-28
properties and expand its applications.
The boron and
2
nitrogen can be incorporated into a sp carbon network
without significantly affecting the atomic arrangement in the
hexagonal two dimensional lattice, it is due to the fact that
they are the only two small mismatch elements in atomic sizes
1
-4
and cosmetics. A number of metal catalysts, such as Pd, Au,
Fe, Ni, Ag and Zn, have been initially developed to catalyze this
2
9
5
-13
with carbon. Actually, the conjugating carbon π electrons
with electro-deficient boron can improve the activity of the
type of reaction.
Unfortunately, low tolerance toward
substituted nitroarenes are observed in some metal-based
catalytic systems, leading to undesired byproducts and difficult
3
0
two dimensional carbon materials.
Furthermore, the
1
4-16
introduction of nitrogen into graphene can produce more
defects with twisty structure, which facilitates the boron
purification.
Recently, carbon based metal-free catalysts
that show stability, cheapness, biocompatibility and
environmental friendliness have attracted more and more
attention with respect to the catalysis of organic molecule
3
1
incorporation during the post boron doping process.
Although, numerous methods, such as chemical vapor
deposition (CVD) method, pyrolysis of charcoal, boric acid and
1
7-19
transformation reactions.
Although N-doped graphene and
urea, co-annealing GO, B
2 3 3
O vapor and NH , have been
B-doped carbon have been used as catalysts for the reduction
2
0-21
explored to synthesize boron and nitrogen co-doped
2-34
of 4-chloronitrobenzene,
the excessive use of the
3
graphene.
Some of these methods are inevitable to use GO
reductant and the large scale production of catalysts problems
remain to be solved. Therefore, the development of highly
effective and convenient preparation catalysts for the
reduction of nitroarenes is still extremely desirable.
that synthesized by large amount of oxidant and strong acid,
and these methods have difficulty in large-scale production.
The boron and nitrogen co-doped graphene are usually used in
3
5
the oxygen reduction reaction (ORR), hydrogen evolution
38
In the last few years, heteroatoms doped graphene as metal-
3
reaction (HER), Li-O
6
37
2
batteries and microwave absorption.
However, it has been rarely reported for catalytic the organic
3
9
molecular transformation reactions.
It is therefore
interesting to explore the facile large-scale production of BNG
synthetic method for efficient application in catalysis of the
reactions.
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In this work, the BNG is first time fabricated by ball milling of Synthesis of B/N co-doped graphene-like carbon
the pristine graphite followed a high temperature annealing of
The BNG was prepared by thermal treatment of EFGnPs and
the resultant edge-selectively functionalized graphene
nanoplatelets (EFGnPs) and boric acid. The merit of this
method is to avoid using of the graphene oxide that
synthesized by a large amount of strong acids and oxidants,
which has the potential large-scale production of BNG.
Moreover, the BNG is used as an efficient catalyst for catalytic
nitroarenes hydrogenation, and the utilization efficiency of
hydrazine hydrate is close to 99% under certain conditions.
The catalyst shows good tolerance to a variety of different
functional groups, exhibiting excellent yields in reduction of
various kinds of substituted nitroarenes.
boric acid. Typically, 1g EFGnPs and 5g boric acid were
dissolved in 20 ml ethanol for 30 min under constant stirring.
Successively, the mixture was dried at 80 °C in the oven
overnight to remove the ethanol. The obtained composite was
o
o
o
put in a quartz boat and annealed at 700 C, 800 C and 900 C
for 4 h in an argon atmosphere and denoted as BNG-700, BNG-
8
00 and BNG-900, respectively. After cooling to room
2 3
temperature, the residual boric acid and B O were removed
by washing with boiling water. Finally, we obtained the
o
resultant black powder BNG by filtration and drying at 80 C
overnight. For comparison, the NG-800 was synthesized by
thermal treatment of EFGnPs in the same conditions.
Catalytic reduction of nitroarene
Experimental
In a typical catalysis reaction, 4 mg BNG-800 was mixed with
Materials
0.5 mmol p-nitrochlorobenzene (80 mg) and 0.5 mL ethanol.
All the chemicals are used as received without further 1.5~4.0 equiv. of hydrazine hydrate (0.75~2.0 mmol) was
o
purification: 10000 mesh Graphite flakes (Jinrilai Graphite Co., added into the above solution under magnetic stirring at 70 C.
Ltd., Qingdao, China); boric acid (Sinopharm Chemical Regent The reaction procedure was detected by thin layer
Co., Ltd., China.); aromatic nitro compounds (Aladdin industrial chromatography (TLC). After completion of the reaction, the
corporation); Hydrazine monohydrate (85%) (China Medicine mixture was cooled to room temperature. Then, the crude
Group Shanghai Chemical Reagent Company); silica gel (Alfa product was separated from the catalyst by filtration. Finally,
Aesar, Johnson Matthey Company); Bulk boron nitride (BN) the saturated hydrochloric ethyl acetate solution was added to
(Liaoning DCEI Co. Ltd., China, with lateral size around 30 μm); the crude product solution, and
a white precipitate
Ethanol, Acetonitrile, Acetic ether, Hydrochloric acid and (aminehydrochloride) was formed instantly. To obtain the
Petroleum ether (Beijing Chemical Works).
isolated yield, the aminehydrochloride hydrochloride was
removed by filtration and washed with ethyl acetate. For the
recyclability experiment, the reactions were operated in the
same procedure as described above, except using the reused
catalyst. After the reaction, the filtered catalyst was washed
Characterization
Scanning electron microscopy (Hitachi SU8010) and
transmission electron microscopy (JEM-2100) are employed to
observe the morphology and surface structure of the
materials. HRTEM was carried out using an image spherical
aberration-corrected TEM system (Titan Cubed Themis G2 300
FEI). Chemical components are analysed by the X-ray
photoelectron spectrometer (XPS, Thermo Fisher K-Alpha
American with an Al Ka X-ray source). Crystal structure of the
o
with ethyl acetate, then, the catalysts were dried at 60 C for
the next cycles.
Result and Discussion
hybrid materials is obtained from X-ray diffraction (XRD, Characterization of BNG materials
Bruker D8 Advance Germany), and the data are collected on a The mechanochemical cracking of a large grain size graphite to
Shimadzu XD-3A diffractometer using Cu Kα radiation. BET synthesize the BNG is schematically shown in Scheme 1. The
specific surface area, pore radius and volume are analysed pristine graphite has a grain size in the range of a few to
2
with N adsorption/desorption isotherms at 77 K on a SSA4200 dozens of micrometres, as shown in a typical SEM image (Fig.
instrument (Builder, Beijing).
1a). After ball milling for 48h and thermal treatment, the
resultant BNG shows dramatically reduced grain sizes in the
range of 0.1-3 μm (Fig. 1b, Figs. S1a and 1b, ESI†). There is an
obvious size reduction due to the mechanochemical
exfoliation of graphite and in situ generation of small-sized
Synthesis of functionalized graphene nanoplatelets
EFGnPs were synthesized by ball-milling method in a planetary
ball-mill machine at 750 rpm. Typically, 6 g of pristine graphite
was placed into a stainless-steel capsule containing stainless
steel balls of 5 mm in diameter. Then, the container was fixed
in the ball-mill machine and agitated with 750 rpm for 48 h.
Oxygen functional groups and nitrogen element were
introduced by the reaction between a large number of defects
of product and the air moisture when opened the container lid
4
1
active carbon pieces, which benefits for doping of B and N.
However, no sintering phenomenon was observed during the
heat treatment with different temperatures from Fig. S1c
(ESI†). Furthermore, the thickness of the pristine graphite and
BNG-800 is estimated by the atomic force microscope (AFM)
(Figs. S2a and 2b, ESI†). It is found that the thicknesses of BNG-
4
0
in air at the end of ball milling. The resultant product was
further extracted with 1 M aqueous HCl solution to remove
metallic impurities. Final product was washed four times by
deionized water and ethanol, and then dried at 80 °C in the
oven overnight for used in the next step.
8
00 is about 4.7 nm and the pristine graphite is around 60 nm.
This result illustrates that the graphene-like carbon is obtained
after the ball milling of graphite.
2
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nanosheets of BNG-800 is obtained after ball milling and
thermal treatment (Fig. 1d). Furthermore, the high-resolution
TEM (HR-TEM) images (Fig. 1e and 1f) display that the layers of
BNG-800 decrease distinctly from multilayer to few-layer in
spite of some edge distortion. These results clearly indicate
that the pristine graphite flake can be directly exfoliated into
few-layer graphene-like carbon by ball milling and thermal
treatment.
Raman spectroscopic analysis (Fig. 2a) was carried out to
analyse the structural defects that created by the
mechanochemical exfoliation and doping. Owing to the large
grain size, the pristine graphite showed a weak D band at
-1
around 1350 cm that corresponding to the topological
defects, while the relatively high intensity of G and 2D bands
-1
was observed at 1577 and 2712 cm , respectively. The ratio of
the D- to G-band intensities (I /I ) was 0.22. In contrast, the
D
G
EFGnPs, BNG-700, BNG-800 and BNG-900 showed strong D
-1
bands around 1350 cm , and their I /I ratios were 1.16, 1.14,
D
G
1.16 and 1.26, respectively. These results indicate that a
significant size reduction and edge distortion were produced
by mechanochemical cracking. Comparing with EFGnPs, the
slight decrease of the I /I ratio of BNG-700 is probablely due
Scheme 1. A schematic illustration of the fabrication of BNG
D
G
to that the reduced defects are more than the increased
defects by B doping procedure. However, the ratios I /I of
D
G
BNG-700, BNG-800 and BNG-900 are gradually increased with
the increasing of doping content.
Fig. 2. (a) Raman spectra, (b) XPS survey spectra, High-resolution XPS spectra (c) B1s
spectra of BNG-800 and (d) N1s spectra of BNG-800.
The element analysis of the pristine graphite and BNG samples
has been further achieved by XPS (Fig. 2b). The survey
spectrum of the BNG-700, BNG-800 and BNG-900 samples
indicates that the O, N and B are incorporated into these
materials. The oxygen functional groups increase from 8.80
Fig. 1. SEM images of (a) the pristine graphite and (b) BNG-800, TEM images of (c) the at% to 11.46 at% after ball milling. Notably, the N content of
pristine graphite and (d) BNG-800, HRTEM images of (e) the pristine graphite and (f)
3
2
.88 at% is observed in EFGnPs samples due to that N in air
BNG-800.
has been incorporated into the structure of carbon by ball
milling. After B doping, the N contents in the BNG-700, BNG-
The TEM image (Fig. 1c) shows that the pristine graphite has
the large and thickness sheet, and the small and thin
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4
2, 45
800 and BNG-900 are 3.21, 3.31 and 4.46 at%, respectively pyridinic N-oxide substitution, respectively.
The contents
(Table 1). As of all N species are summarised in Table 3.
Table 1. Special content of typical graphite, EFGnPs, BNG-700, BNG-800 and BNG-900
From the XRD patterns of EFGnPs and BNG along with the
pristine graphite as reference (Fig. 3a), it can be found that the
pristine graphite shows a strong and sharp peak at 26.5°,
which correspond to (002) lattice plane with interlayer d
spacing of 0.34 nm. Compared with the pristine graphite, the
main peaks of EFGnPs and BNG are shifted to the left with
negligible low intensity, indicating full delamination of most
graphite layers via edge selective functionalization during ball-
samples by XPS
Samples
Graphite
EFGnPs
C (at%)
91.20
84.66
86.85
82.51
81.18
O (at%)
8.80
N (at%)
-
B (at%)
-
11.46
8.34
3.88
3.21
3.31
4.46
-
BNG-700
BNG-800
BNG-900
1.60
3.09
4.71
4
6
milling process. Unlike graphite oxide (GO) that shows a large
shift of lattice plane (002) to 10.2° due to random oxidation of
lattice plane, the EFGnPs and BNG show the corresponding
peak at 25.6°. It is demonstrated that the edges of EFGnPs and
BNG are mainly exfoliated, and the distance between basal
planes becomes broad due to grafted atoms and oxygen
functional groups, while the graphitic structure of the basal
plane is well maintained during ball milling and thermal
treatment process.
11.10
9.64
Table 2. B special content of BNG-700, BNG-800 and BNG-900 samples by XPS
B
Samples
Content
B-C
B-N
B-CO2
B-O
1
.60
BNG-700
BNG-800
BNG-900
18.04%
20.56%
39.71%
21.69%
at%
3
.09
21.21%
24.42%
31.68%
19.17%
24.83%
46.47%
22.28%
9.94%
at%
4
.46
at%
Table 3. N special content of BNG-700, BNG-800 and BNG-900 samples by XPS
Fig. 3. (a) XRD diffraction patterns and (b) N
7K.
2
adsorption-desorption isotherms obtained
7
N
Samples
In N
2
adsorption-desorption isotherms of EFGnPs and BNG
Content
N-6
N-5
N-Q
N-X
(
Fig. 3b), it can be observed that EFGnPs and BNG have similar
micropores and mesoporous structure due to that type I curve
at low-relative pressures and type IV with a hysteresis at high
pressures. Due to the highly ordered graphitic structure of the
3
.21
BNG-700
BNG-800
BNG-900
33.30%
29.61%
21.86%
15.23%
at%
3
.31
33.40%
41.75%
31.96%
34.34%
19.69%
12.73%
14.95%
11.18%
pristine graphite, the porosity parameters obtained from N
sorption analysis show that it has very low specific surface area
2
at%
2
-1
4
.71
2
(SSA, BET-N -method, 17.8 m g ), however, after ball milling
at%
and thermal treatment, the SSA of EFGnPs, BNG-700, BNG-800
and BNG-900 are increase to 678.7, 861.7, 884.4 and 848.7
2
m g , respectively (Table 4). This is because of extensive
-1
summarized in Table 1, the high B contents of the BNG-700,
BNG-800 and BNG-900 are obtained in 1.60, 3.09 and 4.71
at%, respectively, which due to the fact that the initial N
doping can facilitate the boron incorporation. The high
resolution B1s XPS spectra of BNG-700, BNG-800 and BNG-900
are shown in Fig. 2c and Fig. S3 (ESI†), which the binding
energies around 193.8, 191.8, 190.7 and 190.1 eV are
4
2-44
attributed to B-O, B-CO
2
, B-N, and B-C, respectively.
The
contents of all the B species are summarised in Table 2. The
high resolution N1s peak (Fig. 2d) can be deconvoluted into N-
6
(398.2 eV), N-5 (399.6 eV), N-Q (400.7 eV) and N-X (401.7
eV), which are corresponding to pyridinic substitution, pyrrolic
substitution and/or B-N bonding, graphitic substitution and
4
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Table 4. Porosity measurement data for the pristine graphite, EFGnPs, BNG-700, BNG- proceed well with prolonging the reaction time to 4.5 h when
8
00 and BNG-900
the reducing of the catalyst dosage to 3 mg (entries 4 and 5).
Moreover, we have compared the BNG-800 with other
catalysts reported in the literatures, as summarized in Table S1
(ESI†). It is obvious that the BNG-800 catalyst prepared in this
work is much more active than other catalysts under
comparable reaction conditions. Furthermore, our strategy of
synthesis of NG-800 is to avoid using of the graphene oxide
that synthesized by a large amount of strong acids and
oxidants, which has the potential large-scale production. The
GO is needed for the preparation of NG-800 and RGO catalysts,
whose synthetic process produce plenty of waste acid.
Therefore, the BNG-800 has distinct advantages relative to
other carbon metal-free catalysts both from the catalytic
performance and synthesis methods. However, the oxidative
BET surface area
Pore volume
Pore size
(nm)
2
-1
3 -1
Samples
(m g )
(cm g )
Graphite
EFGnPs
17.8
0.14
0.76
0.85
0.97
0.85
32
4.5
3.9
4.4
4
678.7
861.7
884.4
848.7
BNG-700
BNG-800
BNG-900
exfoliation of graphite layers by shear force as well as wedging
effect of heteroatoms grafted at the edge of EFGnPs by
thermal treatment. The large surface area and edge defects
can be beneficial for catalytic activity of BNG.
o
reaction cannot proceed completely when using 60 C (entry
6
). For the purpose of comparison, a series of control
experiments, such as without catalyst, using Graphite, EFGnPs,
NG-800, boric acid, phenylboronic acid, BN and B have
2 3
O
Catalytic performance
been performed. Among these experiments, the reaction
cannot proceed by using Graphite, boric acid, phenylboronic
The as-prepared BNG catalysts are used to catalyze the
hydrogenation of 4-chloronitrobenzene to 4-chloroaniline, as
shown in Table 5.
acid, NB and
B
2
O
3
as catalysts and without catalyst,
respectively (entries 7-12), demonstrating that the small
molecular B compounds are not the catalytic species in current
reaction systems. Although, the N doped catalysts EFGnPs and
NG-800 show some catalytic activities (entries 13-14), they
show much inferior catalytic activities compared with that of
the BNG-800. These results demonstrate that the coexistence
of B and N atoms in the network would tune the electronic
structure and form the different charge sites on the surface of
graphene-like carbon that contributes to the catalytic
a
Table 5. Evaluation of reaction conditions for the reduction of 4-chloronitrobenzene
b
Entry
Catalyst
BNG-700
BNG-800
BNG-900
BNG-800
BNG-800
BNG-800
Graphite
Time
3
Usage
Yield
79
1
2
3
4
5
6
7
8
9
4
4
4
3
3
4
4
4
4
4
4
0
4
4
3
99
3
85
3
76
reduction
reactions.
4.5
3
95
The possible reaction mechanism is that when nitroarenes
substrates get close enough to the benzene ring of the catalyst
c
79
3
trace
a
Boric acid
phenylboronic acid
BN
3
-
-
2 4
Table 6. Catalytic reduction of nitroarenes into amines by N H catalyzed by BNG-800
3
1
1
1
1
1
0
1
2
3
4
3
-
B
2
O
3
3
-
-
3
-
EFGnPs
NG-800
3
25
d
3
39
a
o
b
c
reaction conditions: 0.5 mmol substrate, 4 mg catalyst, 70 C; isolated yield;
o
d
0
.5 mmol substrate, 4 mg catalyst, 60 C; catalyst prepared with heating the
o
EFGnPs at 800 C.
The 4mg of BNG-700, BNG-800 and BNG-900 catalysts is
initially investigated with respect to the hydrogenation of 0.5
o
mmol 4-chloronitrobenzene at 70 C for 3 h in ethanol,
producing 4-chloroaniline in 79%, 99% and 85% yield,
respectively (entries 1-3). These results indicate that the fine
structures of the BNG catalysts play a key role to impel the
reaction. Through the deep analysis, we find that the ratio of
B-N in total B content of BNG-700, BNG-800 and BNG-900 are
20.56%, 31.28% and 19.17%, respectively (Table 2). Thus, we
propose that the B-N active specie plays one of key roles to
impel the reaction due to the highest B-N content in the BNG-
800 catalyst. It should be noticed that the reaction can
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b
Entry
Reactant
Product
T (h)
3
Yield
97
yields, which indicates that the current catalytic system shows
high chemoselectivity (entries 11-12).
c
1
2
3
4
5
3
5
7
7
99
94
90
98
Fig. 4. The catalyst reusability for the reduction 4-chloronitrobenzene and TEM image
of BNG-800 after the catalyst repetition six times.
6
7
4
2
3
8
8
4
94
95
96
85
90
93
The heterogeneous catalyst is superior to a homogenous one
due to its reusability feature. To assess recyclability of BNG-
8
00 catalyst, multiple 4-chloronitrobenzene reduction
d
reactions have been carried out. It is found that the catalytic
activity is not changed obviously after the catalyst repetition
six times, giving excellent yields with all cycles with prolonging
the reaction time to 6 hours (Fig. 4a). We have analyzed the
BNG-800 that has been used six cycles by the TEM image (Fig.
8
e
9
e
1
0
4b). It can be found that some organic substances covered on
1
1
2
the surface of the used BNG-800 leading to the active sites
decreasing on the catalyst. This result reveals the reasons that
the yield decreases slightly after six cycles.
1
5
91
a
o
reaction conditions: 0.5 mmol substrate, 4 mg catalyst, 1.5 equiv N
2
H
4
, 70 C,
Conclusions
b
c
ethanol as solvent; isolated yield; 1 mmol substrate, 1 mg catalyst, 4 equiv
o
d
o
N
2
H
4
, 100 C; 0.5 mmol substrate, 8 mg catalyst, 1.5 equiv N
2
H
4
, 70 C, ethanol In summary, BNG catalysts were prepared by
H , 80 C, ethanol as
2 4
a
mechanochemical cracking method that combining ball-milling
and thermal treatment. In the process, the introduction of
nitrogen into graphene-like carbon by ball-milling can
introduce more defects and twisty structure, which facilitate
the boron incorporation. The incorporation of N and B into the
grahenen-like carbon framework show striking promotional
effect on the catalytic reduction of nitroarenes, which can
produce the corresponding anilines by using a low catalyst
loading and a small amount of N H in ethanol. Under the
e
o
as solvent; 0.5 mmol substrate, 8 mg catalyst, 4 equiv N
solvent.
through π-π interactions, the oxygen atoms of nitro group
4
would abstract the active hydrogen atoms, and finally obtain
the high selectivity for desired products and achieve the
7
2 4
efficient utilization of N H .
We extended BNG-800 catalyst to various substituted
nitroarenes for demonstrating the generality of this reaction
under the optimized conditions, and the results are
summarized in Table 6. For reduction of nitrobenzene, aniline
is formed in 97% yield (entry 1). It is note that the chloro-,
bromo- and iodo-substituted nitroarenes can also proceed
smoothly to afford the corresponding anilines in high yields
with no discernible dehalogenation (entries 2-4). The
nitroarenes with bearing an electrondonating group at R
produce are quantitatively transformed into the corresponding
amines in excellent yields (entries 5-7). Substrate 4-
nitroanisole with a strong electro-donating group afforded the
desired products in high yield by increasing the catalyst using
amount to 8 mg (entry 8). In addition, the electron-
withdrawing groups, such as carboxyl and cyano functionalities
in nitroarenes, remain intact in the presence of the BNG
catalyst (entries 9-10). When the 4-nitroacetophenone and 4-
nitrobenzaldehyde have been used as substrates for such
reduction reaction system. We found that the corresponding
formyl and ketone arylamines was selectivity obtained in high
2
4
optimized reaction conditions, the present reduction of
various nitroarenes affords the corresponding anilines in high
chemical yields. In addition, the BNG-800 catalyst can be
simply and efficiently used for six consecutive runs. It is worth
noting that no dehalogenation phenomenon was observed in
the current catalytic system during the reduction process for
halogen-substituted nitroarenes, which was superior to the
conventional metal catalytic systems. Further work is in
progress to extend BNG catalysts for a wide range of reactions
.
Conflicts of interest
There are no conflicts to declare.
Acknowledgements
6
| J. Name., 2012, 00, 1-3
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Pl Ne ae swe Jd oo u nr no at l aod fj Cu sh te mm ai sr tgr iyn s
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ARTICLE
We gratefully thank for the National Natural Science 15 C. Lian, H. Liu, C. Xiao, W. Yang, K. Zhang, Y. Liu and Y. Wang,
Solvent-free selective hydrogenation of chloronitrobenzene
Foundation of China (No. 21776302), the Science Foundation
3 4
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863 Program, No. 2015AA034603).
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(
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New Journal of Chemistry
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DOI: 10.1039/C7NJ04187J
A graphic abstract
Boron and nitrogen co-doped graphene-like carbon catalysts are fabricated by
mechanochemistry, which shows excellent activity in catalysis of reduction of
nitroarenes.