Selective Synthesis of Symmetrical Secondary Amines from Nitriles with a Pt?CuFe/Fe3O4 Catalyst and Ammonia Borane as Hydrogen Donor

Article abstract of DOI:10.1002/cplu.202000028

Hydrogenation of nitriles is an efficient and environmentally friendly route to synthesize symmetrical secondary amines, but it usually produces a mixture of amines, imines, and hydrogenolysis by-products. Herein we report a magnetic quaternary-component Pt?CuFe/Fe₃O₄ nanocatalyst system for the selective synthesis of symmetrical secondary amines with ammonia borane as hydrogen donor. The catalyst with a low Pt loading (0.456 wt%) is the source of the activity, and the d-band electron transfer from Cu to Fe enhances the selectivity. This synergistic effect results in the transformation of benzonitrile to dibenzylamine with excellent conversion (up to 99 %) and nearly quantitative selectivity (up to 96 %) under mild reaction conditions, nevertheless, the reaction TOF is as high as up to 1409.9 h^?1. A variety of nitriles are suitable for the synthesis of symmetrical secondary amines. More importantly, unwanted hydrogenolysis byproducts, especially toluene, is not detected at all. In addition, the catalyst is magnetically recoverable, and it can be reused up to five times.

Full text of DOI:10.1002/cplu.202000028

A Multidisciplinary Journal Centering on Chemistry
Accepted Article
Title: Selective Synthesis of Symmetrical Secondary Amines from
Nitriles with a Pt-CuFe/Fe3O4 Catalyst and Ammonia Borane as
Hydrogen Donor
Authors: Rongxiu Guo, GuangQi He, Lei Liu, Yongjian Ai, Ze-nan Hu,
Xinyue Zhang, Haimeng Tian, Hong-bin Sun, Dun Niu, and
Qionglin Liang
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: ChemPlusChem 10.1002/cplu.202000028
Link to VoR: https://doi.org/10.1002/cplu.202000028
01/2020

10.1002/cplu.202000028
ChemPlusChem
FULL PAPER
Selective Synthesis of Symmetrical Secondary Amines from
Nitriles with a Pt-CuFe/Fe3O4 Catalyst and Ammonia Borane as
Hydrogen Donor
Rongxiu Guo,[a,b] GuangQi He,[a,b] Lei Liu,[a] Yongjian Ai,[c] Ze-nan Hu,[a] Xinyue Zhang,[a,b] Haimeng
Tian,[a] Hong-bin Sun,*[a] Dun Niu,*[a] and Qionglin Liang[c]
Dedication ((optional))
[a]
Dr.L.Liu, Dr.Z.Hu, M.Sc.H.Tian, Dr.H.Sun, Dr.D.Niu.
Department of Chemistry, Northeastern University
Shenyang 110819, People’s Republic of China
E-mail: sunhb@mail.neu.edu.cn; niudun@mail.neu.edu.cn
Dr.R.Guo, Dr.G.He, Dr.X.Zhang.
School of Materials Science and Engineering, Northeastern University
Shenyang 110819, People’s Republic of China
[b]
[c]
Dr.Y.Ai, Dr.Q.Liang.
Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University
Beijing 100084, People’s Republic of China
Supporting information for this article is given via a link at the end of the document.((Please delete this text if not appropriate))
Abstract: Hydrogenation of nitriles is an efficient and environmentally
friendly route to synthesize symmetrical secondary amines, but it
usually produces a mixture of amines, imines and hydrogenolysis by-
products. Herein we report a magnetic quaternary-component nano-
catalyst system for the selective synthesis of symmetrical secondary
amines with ammonia borane as hydrogen donor. The loading of Pt
in the catalyst is only 0.456 wt%. Due to the synergistic effect of Pt-
CuFe/Fe3O4, the benzonitrile is converted to dibenzylamine with
excellent conversion (up to 99%) and nearly quantitative selectivity
(up to 96%) under mild reaction conditions, nevertheless, the reaction
TOF is as high as up to 1409.9 h-1. A variety of nitriles are suitable for
the synthesis of symmetrical secondary amines. More importantly, the
unwanted hydrogenolysis byproduct, especially toluene, is not
detected at all. In addition, the catalyst is magneticly recoverable, and
it can be reused for five times.
mixtures, which include some of the primary, secondary and
tertiary amines, imines and hydrogenolysis by-products due to the
high redox potentials of nitriles.[5] In the case of benzonitrile
hydrogenation, there is usually another absolutely undesired by-
product toluene.[6] Therefore, preciously controlling of the
selectivity is a huge challenge to a secondary amine-oriented
catalyst.[7]
Recently, there are some inspiring results about the
hydrogenation of nitriles to secondary amine with H2 as hydrogen
source.[8] Jiao’s group reported a 5NiO-Pd/SiC catalyst for the
hydrogenation of nitriles with H2 to secondary amines by the
modification of NiO nanodots.[8b] Direct hydrogenation usually
requires pressurized hydrogen or ultralong reaction time,[9] which
produce the hydrogenolysis by-products.[8a] Avoiding the
explosive nature of hydrogen, catalytic transfer hydrogen has the
advantages of the milder reaction condition and the more practical
operation.[10] In recent years, ammonia borane (AB, NH3·BH3) has
been considered as an extremely promising hydrogen source for
readily hydrogen transfer due to the high hydrogen capacity and
favorable solubility.[11] Ammonia borane has been successfully
Introduction
Symmetrical secondary amines, as the versatile intermediates of
various pharmaceuticals and bioactive chemicals, such as
dibenzylamine, which can be used for the synthesis of Penicillin
salt, their synthesis has received much attention.[1] The traditional
production of secondary amines is performed through typical
organic synthetic routes, including direct N-alkylation with primary
12]
used as a hydrogen source for hydrogenation of nitriles.[7a,
Sun’s group reported a series of heterogeneous catalysts, which
are bimetal NPs (NiPd or FePd) supported on the graphene or
reduced graphene oxide to catalyze the tandem AB
dehydrogenation and hydrogenation of R-NO2 and/or R-CN to R-
NH2 in aqueous methanol solutions.[13] These reaction system
invariably offered the primary amines with relatively high
selectivity.
Pd catalysts often produce primary amines in majority during the
hydrogenation of nitriles.[14] But Pt catalysts show a very different
catalytic behavior to obtain secondary amines as the major
product.[8c, 14a, 15] In 2014, Gu’s group reported an entirely new Pt
nanowire catalyzed reductive amination process for the
preparation of secondary amines from the corresponding
amines, reductive amination of carbonyl compounds and
1e, 2]
alkylative amination.[1d,
Nevertheless, these stoichiometric
methods have some disadvantages, such as harsh reaction
3]
conditions and considerable inorganic wastes.[1b,
As the
advanced alternative approach, catalytic hydrogenation of
aromatic or aliphatic nitrile compounds is an economical, green
and one-step pathway of the amines preparation.[4] This catalytic
process often shows severe selectivity issues to produce the
1
This article is protected by copyright. All rights reserved.

10.1002/cplu.202000028
ChemPlusChem
FULL PAPER
nitriles.[8c] However, the catalysis Pt nanowire still requires large
amount of noble metals. Multimetallic NPs, owing to the altered
electronic character through the strong metal–metal interactions,
[16] not only reinforce properties of catalytic kinetics and selectivity,
but also enable to minimize the loading of noble metal to a low
level.[17]
Based on our previous work in the development of magnetic
catalysts and transfer hydrogenation,[7b, 18] here we explored a
facile low-loading Pt-based quaternary component catalyst, which
was efficient to yield secondary amines with admirable
chemoselectivity in the presence of AB. Furthermore, the catalyst
could be separated by the magnets to reused for five times. The
selectivity of secondary amines can be up to 96%, and the
hydrogenolysis by-products, especially the undesired toluene,
were completely undetected in all reactions. The catalyst diagram
and preparation flowchart are shown in Scheme 1.
(Table 1, entry 1). The platinum-containing tertiary
component catalyst worked with low activity. The conversion
with the Pt-Cu/Fe3O4 catalyst reached 99%, but the
selectivity to dibenzylamine (DBA) was poor (Table 1, entries
2-3). Copper can activate the cyano-group, making the C-N
bond easier to break and hydrogenate.[7b] According to a
widely recognized reaction scheme, the intermediate imine
can form the primary amine by reacting quickly with surface
hydrogen species, or convert to the multi-substituted amines
by elimination of NH3. Thus, the selectivity of products is
intensively determined by the lifetime of the intermediate
imine. By extending the lifetime of the intermediate imines, it
is prior to obtain secondary amines.[7b, 8b] Thus, we modified
the Pt-Cu catalyst with a fourth component to weaken the
effect of copper so as to improve the selectivity of secondary
amines. Fe, Co, or Ni was used to alloy with copper (Table
S1, entries 2-3). We found that Pt-FeCu/Fe3O4 was the
optimal catalyst (Table 1, entries 5-7).
Different Fe/Cu ratio of the catalyst had significant influence
on the selectivity of BA hydrogenation (Table 1, entries 6-10).
The selectivity of DBA increased from 66% to 97% when the
Fe/Cu ratio increased from 1:4 to 4:1. Meanwhile, the
conversion decreased from 99% to 67%. Pt-Fe50Cu50/Fe3O4
showed the best performance for the selective
hydrogenation of BA to DBA among the catalysts with
different Fe/Cu compositions. According to inductively
coupled plasma mass spectrometry (ICP-MS), the Pt content
was 0.456 wt% and the Cu content was 7.24 wt% in Pt-
Scheme 1. Brief schematic illustration of the synthesis of the Pt-CuFe/ Fe3O4.
Results and Discussion
The catalysts with different components were used to test the
performance of the reduction of benzonitrile, which is the
model reaction. The conversion of BN and the selectivity of
products over different catalysts are shown in Table 1. It is
worth noting that toluene was completely not obtained in the
series of reactions. When the support Fe3O4 nanospheres
were loaded with only Pt NPs, the reaction hardly proceeded
Table 2. Hydrogenation of nitriles with various functionalities.[a]
Table 1. Hydrogenation of nitriles to secondary amines over different
component catalysts.[a]
2
This article is protected by copyright. All rights reserved.

10.1002/cplu.202000028
ChemPlusChem
FULL PAPER
Fe50Cu50/Fe3O4. The turnover frequencies (TOFs) revealed
that the Pt-Fe50Cu50/Fe3O4 exhibited the highest TOF of
hydrogenate acetonitrile to the corresponding secondary amine in
95% yield (entry 12). Phenyl acetonitrile also underwent the
transfer hydrogenation successfully, providing the corresponding
secondary amine product with 93% selectivity (entry 11), which
can be attributed to the excellent activation of the cyano-group by
the catalyst. Importantly, hydrogenolysis by-products were
completely undetected in the substrate exploration.
1409.9 h-1 at full conversion
, which is significantly higher than
the reactions with H2 in the literatures (Table S1).
The effect of the support also was discussed. Pt-Fe50Cu50
NPs without a support was less active than the Pt-
Fe50Cu50/Fe3O4 catalyst (Table 1, entry 5), since the Fe3O4
support provides the workshops to disperse the Pt-FeCu
NPs to avoid agglomeration. Other supports loading with Pt-
FeCu NPs for the reaction were also used in the model
reaction, but both their conversion and selectivity were lower
than Fe3O4 support (Table S2, entries 4-5).
In addition, different hydrogen sources were tested in the
hydrogenation of nitriles showed in Table S2. Especially, the
conversion of the Pt-Fe50Cu50/Fe3O4 catalyst was only 15%
with atmospheric H2 (Table S2, entry 5). Because the content
of Pt in the catalyst (0.456 wt%) was too small to decompose
a sufficient amount of active hydrogen for reaction.
The general applicability of the Pt-FeCu/Fe3O4 catalyst is
investigated using different substrates. From Table 2, the
aromatic nitriles containing different groups, such as -CH3, -OCH3,
-Cl and -F were selectively hydrogenated to the corresponding
symmetrical secondary amines under mild conditions in short
reaction time. The substrates bearing the electron donating
groups give the corresponding secondary amine product with up
to 96% selectivity (Table 2, entries 2-7). The only slightly lower
selectivity of bis(2-methylbenzyl) amine may be due to steric
hindrance (Table 2, entry 4). Substrates bearing electron-
withdrawing groups also have terrific selectivity up to 94% (Table
2, entry 9). Noticeably, no dehalogenation was detected in the
catalytic system (Table 2, entries 8-10). This is probably because
of the ultralow Pt loading that cannot active the C-X bond
efficiently. It is worth noting that aliphatic nitriles are usually hard
to be hydrogenated to amines due to the instability of the aliphatic
imine. However, this catalytic system can also selectively
In order to investigate the interaction of the components in the
quaternary component catalyst, a series of characterizations of
the Pt-Fe50Cu50/Fe3O4 catalyst are performed. XRD and FTIR are
used to confirm the synthesis of Fe3O4 microspheres by
solvothermal method, as shown in Figure S1 and Figure S2. The
morphologies of Fe3O4 microspheres and the Pt-Fe50Cu50/Fe3O4
catalyst are investigated by transmission electron microscopy
(TEM) and high-resolution transmission electron microscopy
(HRTEM). The Fe3O4 microspheres are spherical in shape and
have the uniform particle size (Figure 1a). After Pt-FeCu NPs are
loaded by the conventional impregnation method, the catalyst
could maintain the morphology without any change. From the
Figure 1g, we find the (111) plane of ferric oxide. And in Figure
1h, the crystal lattice of 0.301 nm can be indexed to (220) planes
of the typical FeCu alloy nanoparticle, which demonstrates the
formation of FeCu alloy nanoparticles on the catalyst. The
selected area electron diffraction (SAED) characterization is used
to demonstrate the formation of active site. From Figure 1i, the
lattice spacing of 0.148, 0.161, and 0.209 nm can be indexed to
the (440), (511), and (400) planes of the cubic phase of Fe3O4
(JCPDS No. 19-0629). Moreover, the lattice spacing of 0.111,
0.258, and 0.301 nm can be indexed to the (553), (311), and (220)
planes of the cubic phase of FeCu alloy (JCPDS No. 49-1399),
indicating the electronic modulation between FeCu. And the
lattice spacing of 0.226 nm correspond to the (111) plane of
platinum, which confirms the existence of metallic platinum in the
catalyst. There is no detectable platinum alloy, proving that Pt did
not form alloy with Fe or Cu.
Figure 2. Pt 4f XPS spectrum of the Pt-Fe50Cu50/Fe3O4 (a). Fe 2p XPS
spectrums of the Pt-Fe80Cu20/Fe3O4 (b), Pt-Fe50Cu50/Fe3O4 (c), Pt-
Fe20Cu80/Fe3O4 (d).
To further prove the electronic modulation in Pt-FeCu NPs of the
catalyst, X-ray photoelectron spectroscopy (XPS) is carried out on
Pt-FeCu/Fe3O4 with different Fe/Cu ratios. The Pt 4f (62–88 eV)
and Fe 2p (705–735 eV) regions are also analyzed. From the
Figure 2a, the Pt 4f spectrum shows the peak at 71.0 eV and 74.7
Figure 1. Transmission electron microscopic (TEM) image of the Fe3O4 carriers
(a). TEM image (b-c), high-resolution TEM (HRTEM) image (g), SEAD
characterization (i), and EDS elemental mappings (d-f) of the Pt-
Fe50Cu50/Fe3O4 catalyst. HRTEM image of Pt-FeCu NPs (h).
3
This article is protected by copyright. All rights reserved.

10.1002/cplu.202000028
ChemPlusChem
FULL PAPER
eV consistent with the standard value which can be identified to
ordinary metallic Pt. In addition, it also indirectly proves that there
is no electron transfer between Pt and CuFe. The ordinary binding
energy of the metallic Fe 2p1/2 is 724.5 eV. When Fe and Cu are
combined with Pt to form a quaternary component catalyst, the
2p1/2 binding energy of Fe in Pt-FeCu/Fe3O4 had negative shift.
From the Figure 2, the binding energy of Fe 2p1/2 for the
quaternary component catalysts shift from 724.39 eV (Fe:Cu=4:1)
to 723.7 eV (Fe:Cu= 1:4), indicating that there were electron
transfer between Fe and Cu. The valence shell electron
configuration of Cu is 3d104S1, while Fe is 3d64S2, therefore we
deduce that d-electron of Cu may transfer to Fe to fill the
unsaturated d-band. This deduction is supported by the XPS
results. Then the d-band electron may underfill Cu strongly to
stable the intermediate imine. Meanwhile, it also helps to adsorb
the primary amine then promote the selective conversion of
nitriles to the corresponding secondary amines. From the Fig 2b-
d, the component with binding energies of 2p1/2 at 727.9
eV ,726.63 eV and 726.52 eV were attributable to the oxidation
state of Fe. Because Fe2+/Fe3+ can show Lewis acidity, the
oxidation states of Fe may improve the ability of the catalyst to
coordinate with the primary amine, which make it easier for imines
to react with primary amines to form secondary amines.
The production of hydrogen gas from decompositing ammonia
borane was used to evaluate the catalytic performance of the
catalysts. The hydrogen release over PtFe50Cu50/Fe3O4 and
Fe50Cu50/Fe3O4 catalysts is significantly higher than that of Pt-
catalysts, demonstrating better ability to decompose the ammonia
borane with iron and copper catalysts (Figure 4). However, due to
the low Pt content in the catalyst, there is no significant difference
in the amount of hydrogen released from the PtFeCu/Fe3O4 and
FeCu/Fe3O4 catalysts, indicating that the FeCu NPs is the main
factor to promote the decomposition of AB.
The Fe3O4 carrier offers the catalyst with excellent magnetic
recovery performance. The recoverability of the catalyst is
investigated by Vibrating Sample Magnetometer (VSM) to
demonstrate magnetism of the catalyst. The magnetic properties
of Fe3O4 and PtFe50Cu50/Fe3O4 at an applied field of 10000 Oe
are shown in Figure 3a. The magnetization saturation (Ms) value
of Fe3O4 and PtFeCu/Fe3O4 are 80.8 emu·g-1 and 49.3 emu·g-1,
respectively, which demonstrates that the Ms of Pt-
Fe50Cu50/Fe3O4 is lower than that of unsupported Fe3O4
microspheres. The Pt-Fe50Cu50/Fe3O4 has good dispersibility in
solution. The Fe3O4 also prevents the active PtFeCu from
leaching via the magnetic immobilization. Furthermore, the
catalyst can be easily separated by an external magnetic field.
The recyclability of Pt-Fe50Cu50/Fe3O4 was also verified (Figure
3b). The catalyst was used for the model reaction under the
optimized reaction conditions. The catalyst was collected with a
magnet after the reaction was completed. The catalyst was then
washed with methanol and directly charged to the next reaction.
In five cycles, the selectivity kept above 95%, and the conversion
did not change significantly in the first three runs, but decreased
slightly in the fourth run, and the conversion in the fifth run was
85%. The decrease of activity may be caused by the leaching of
Cu, which is not a magnetic element.
Figure 4. Curves for the volume of hydrogen versus time during the hydrolysis
of AB catalyzed by different catalysts.
Based on the above experiments, the mechanism of the catalytic
system was proposed in Scheme 2. Firstly, H· is produced by
PtFeCu-catalyzed decomposition of ammonia borane, and some
H· is adsorbed on the surface of Pt to form Pt-H·, which
subsequently hydrogenates nitrile to produce the imine
intermediate and primary amines by hydrogen transfer. Due to the
electronic modulation between Cu and Fe, the lifetime of imine is
extended. Secondly, the imine intermediate is then subjected to a
nucleophilic attack by the primary amine. After deamination, the
secondary imine is obtained. Finally, the secondary imine is
reduced by Pt-H· to generate the secondary amine. In addition,
the coordination ability of secondary amine is not strong enough
so that the secondary amine dissociates from the catalyst soon
after it is formed. It is difficult for the secondary amine to condense
with the imine to further form the tertiary amine.
Figure 3. Magnetization curves of the Fe3O4 and Pt-Fe50Cu50/Fe3O4 (a) and
cycle test of Pt-Fe50Cu50/Fe3O4 catalyzed selective synthesis of symmetrical
secondary amines using AB as hydrogen donor (b).Reaction conditions: 1 mmol
of benzonitrile, 1.5 mL MeOH+0.5 mL H2O, 10 mg of catalysts, 0.1 g AB, 40 oC,
3 h.
Scheme 2 Schematic representation of hydrogenation using Pt-Cu50Fe50/Fe3O4.
Conclusion
4
This article is protected by copyright. All rights reserved.

10.1002/cplu.202000028
ChemPlusChem
FULL PAPER
In summary, we have designed a quaternary component
catalyst for the direct hydrogen transfer of nitriles to
secondary amines with high conversion and selectivity
applying AB as the hydrogen donor. Importantly, the
Acknowledgements ((optional))
This work was financially supported by the National Natural
Science Foundation of China (Nos. 21872020, 81872835 and
21621003), and the China Scholarship Council (No.
201806085012).
hydrogenolysis
by-product
completely
undetected,
especially toluene, demonstrating the great potentials for
practical applications. During the reaction, Cu activates the
C-N multibond, making it easier to break. The role of Fe is to
alloy with Cu to generate its d-electron unsaturation, thereby
extending the lifetime of the mine intermediate as well as
adsorbing the produced primary amine. The Fe3O4
microspheres supply the workshop for the dispersion and the
immobilization of active sites. Therefore, the selective
synthesis of symmetrical secondary amines requires the
quaternary component synergistic effect of PtFeCu/Fe3O4,
and the absence of either one leads to inefficiency of the
reaction.
Keywords: amines • heterogeneous catalysis • hydrogen
transfer • iron oxide • transition metals
[1]
a) C. Su, R. Tandiana, J. Balapanuru, W. Tang, K. Pareek, C. T. Nai, T.
Hayashi, K. P. Loh, J. Am. Chem. Soc. 2015, 137, 685-690; b) K. Rajesh,
B. Dudle, O. Blacque, H. Berke, Adv. Synth. Catal. 2011, 353, 1479-
1484; c) S. M. Nanavati, R. B. Silverman, J. Am. Chem. Soc. 1991, 113,
9341-9349; d) R. N. Salvatore, C. H. Yoon, K. W. Jung, Tetrahedron
2001, 57, 7785-7811; eT. E. Mueller, K. C. Hultzsch, M. Yus, F. Foubelo,
M. Tada, Chem. Rev. 2008, 108, 3795-3892, f) S. Wang, J. Dai, Z. Shi,
Z. Xiong, Z. Zhang, S. Qiu, R. Wang, Chempluschem 2020; g) J. W.
Daniel, M. J. Johnson, J. Bacteriol. 1954, 67, 321-328.
a) R. N. Salvatore, A. S. Nagle, S. E. Schmidt, K. W. Jung, Org. Lett.
1999, 1, 1893-1896; b) S. Hoffmann, M. Nicoletti, B. List, J. Am. Chem.
Soc. 2006, 128, 13074-13075.
[2]
Experimental Section
[3]
[4]
Y. Zhao, S. W. Foo, S. Saito, Angew. Chem., Int. Ed. 2011, 50, 3006-
3009.
a) C. Bornschein, S. Werkmeister, B. Wendt, H. Jiao, E. Alberico, W.
Baumann, H. Junge, K. Junge, M. Beller, Nat. Commun. 2014, 5; b) A.
Mukherjee, D. Srimani, S. Chakraborty, Y. Ben-David, D. Milstein, J. Am.
Chem. Soc. 2015, 137, 8888-8891; c) R. Reguillo, M. Grellier, N.
Vautravers, L. Vendier, S. Sabo-Etienne, J. Am. Chem. Soc. 2010, 132,
7854-+; d) S. Elangovan, C. Topf, S. Fischer, H. Jiao, A. Spannenberg,
W. Baumann, R. Ludwig, K. Junge, M. Beller, J. Am. Chem. Soc. 2016,
138, 8809-8814.
D. B. Bagal, B. M. Bhanage, Adv. Synth. Catal. 2015, 357, 883-900.
A. J. McMichael, IARC Sci. Publ. 1988, 3-18.
a) Z. Shao, S. Fu, M. Wei, S. Zhou, Q. Liu, Angew. Chem., Int. Ed. 2016,
55, 14653-14657; b) L. Liu, Y. Liu, Y. Ai, J. Li, J. Zhou, Z. Fan, H. Bao,
R. Jiang, Z. Hu, J. Wang, K. Jing, Y. Wang, Q. Liang, H. Sun, iScience
2018, 8, 61-73.
a) H. W. Wang, Q. Q. Luo, W. Liu, Y. Lin, Q. Q. Guan, X. S. Zheng, H. B.
Pan, J. F. Zhu, Z. H. Sun, S. Q. Wei, J. L. Yang, J. L. Lu, Nat. Commun.
2019, 10; b) Z.-F. Jiao, J.-X. Zhao, X.-N. Guo, X.-L. Tong, B. Zhang, G.-
Q. Jin, Y. Qin, X.-Y. Guo, Catal. Sci. Technol. 2019, 9, 2266-2272; c) S.
Lu, J. Wang, X. Cao, X. Li, H. Gu, Chem. Commun. 2014, 50, 3512-3515;
d) S. Lu, P. Xu, X. Cao, H. Gu, RSC Adv. 2018, 8, 8755-8760.
C. Schafer, C. J. Ellstrom, H. Cho, B. Torok, Green Chem. 2017, 19,
1230-1234.
Materials: Sodium borohydride (NaBH4), iron chloride hexahydrate
(FeCl3·6H2O), Copper nitrate hydrate (Cu(NO3)2·3H2O), iron nitrate
nonahydrate (Fe(NO3)3·9H2O), cobaltous nitrate hexahydrateall
(Co(NO3)2·6H2O), nickel nitrate hexahydrate (Ni(NO3)2·6H2O) and all of
the nitriles were purchased from Sinopharm Chemical Reagent Co., Ltd.,
China. H2PtCl6·6H2O were provided by Eybridge Reagent Co., Ltd., China.
Ammonia was provided by Aladdin Reagent Co., Ltd., China. All the
chemicals were of analytical grade and were used without any further
purification.
[5]
[6]
[7]
Preparation of magnetic Fe3O4 nanosphere: In a beaker, 1.35 g ferric
chloride hexahydrate, 3.6 g anhydrous sodium acetate, and 1 g PEG-200
were weighted, and 40 mL ethylene glycol was poured into the beaker.
The mixture was stirred vigorously for 30 min, then transferred to a 50 mL
Teflon-lined stainless-steel autoclave. The autoclave was heated at a
constant temperature of 200 °C for 8 h, then naturally cooled to room
temperature. The magnetic Fe3O4 nanospheres were collected by magnet
and respectively washed three times with deionized water and ethanol,
and dried at 60 °C over night.
[8]
[9]
[10] a) S. Gladiali, E. Alberico, Chem. Soc. Rev. 2006, 35, 226-236; b) H.-U.
Blaser, H. Steiner, M. Studer, Chemcatchem 2009, 1, 210-221.
[11] a) B. Peng, J. Chen, Energy Environ. Sci. 2008, 1, 479-483; b) A. Rossin,
M. Peruzzini, Chem. Rev. 2016, 116, 8848-8872; c) J. C. Koepke, J. D.
Wood, Y. F. Chen, S. W. Schmucker, X. M. Liu, N. N. Chang, L. Nienhaus,
J. W. Do, E. A. Carrion, J. Hewaparakrama, A. Ranaarajan, I. Datye, R.
Mehta, R. T. Haasch, M. Gruebele, G. S. Girolami, E. Pop, J. W. Lyding,
Chem. Mater. 2016, 28, 4169-4179.
[12] a) C. Yu, J. Fu, M. Muzzio, T. Shen, D. Su, J. Zhu, S. Sun, Chem. Mater.
2017, 29, 1413-1418; b) Y.-F. Zen, Z.-C. Fu, F. Liang, Y. Xu, D.-D. Yang,
Z. Yang, X. Gan, Z.-S. Lin, Y. Chen, W.-F. Fu, Asian J. Org. Chem. 2017,
6, 1589-1593.
[13] a) O. Metin, A. Mendoza-Garcia, D. Dalmizrak, M. S. Gultekin, S. Sun,
Catal. Sci. Technol. 2016, 6, 6137-6143; b) H. Goksu, S. F. Ho, O. Metin,
K. Korkmaz, A. M. Garcia, M. S. Gultekin, S. Sun, ACS Catal. 2014, 4,
1777-1782.
[14] a) J. J. W. Bakker, A. G. van der Neut, M. T. Kreutzer, J. A. Moulijn, F.
Kapteijn, J. Catal. 2010, 274, 176-191; b) L. Hegedus, T. Mathe, Appl.
Catal., A 2005, 296, 209-215; c) L. McMillan, L. F. Gilpin, J. Baker, C.
Brennan, A. Hall, D. T. Lundie, D. Lennon, J. Mol. Catal. A: Chem. 2016,
411, 239-246.
Preparation of magnetic PtFeCu/Fe3O4 catalyst: 100 mg of Fe3O4
nanospheres was pretreated with 60 mL of 0.1 mol/L HCl for 30 minutes
under sonification. 100 mg Fe(NO3)3·9H2O, 60.4 mg Cu(NO3)2·3H2O and
100 mg Fe3O4 were weighted into a 250 mL round-bottom flask. 0.5 mg of
H2PtCl4 was dissolved in deionized water, and transfered into the round-
bottom flask. Subsequently, 80 mL methanol-deionized water solvent (1:1)
were added. The mixture was vigorously stirred under an Ar atmosphere
for 1 hour. Then 10 mL methanol containing 0.1 g NaBH4 was quickly
transferred to the round-bottom flask under vigorous stirring, and
maintained for 4 h. The PtFeCu/Fe3O4 catalyst was collected by magnet
and respectively washed three times with deionized water and ethanol,
and dried at 60 °C over night. For comparison, the PtFeCu/Fe3O4 catalysts
with different non-precious metal contents (Co or Ni) were prepared in the
similar process.
[15] H. Greenfield, Ind. Eng. Chem. Prod. Res. Dev. 1976, 15, 156-158.
[16] a) S. E. Habas, H. Lee, V. Radmilovic, G. A. Somorjai, P. Yang, Nat.
Mater. 2007, 6, 692-697; b) D. Xu, Z. Liu, H. Yang, Q. Liu, J. Zhang, J.
Fang, S. Zou, K. Sun, Angew. Chem., Int. Ed. 2009, 48, 4217-4221; c)
M. Sankar, N. Dimitratos, P. J. Miedziak, P. P. Wells, C. J. Kiely, G. J.
Hutchings, Chem. Soc. Rev. 2012, 41, 8099-8139.
[17] a) I. N. Francesco, F. Fontaine-Vive, S. Antoniotti, Chemcatchem 2014,
6, 2784-2791; b) S. Guo, S. Zhang, S. Sun, Angew. Chem., Int. Ed. 2013,
52, 8526-8544.
[18] a) J. Zhou, Y. Li, H.-b. Sun, Z. Tang, L. Qi, L. Liu, Y. Ai, S. Li, Z. Shao,
Q. Liang, Green Chem. 2017, 19, 3400-3407; b) Y. Ai, Z. Hu, Z. Shao, L.
Qi, L. Liu, J. Zhou, H. Sun, Q. Liang, Nano Res. 2018, 11, 287-299; c) H.
Bao, Y. Li, L. Liu, Y. Ai, J. Zhou, L. Qi, R. Jiang, Z. Hu, J. Wang, H. Sun,
Q. Liang, Chem. - Eur. J. 2018, 24, 14418-14424; d) Z. Hu, J. Zhou, Y.
General procedure for the hydrogen transfer of nitriles: Generally, 1
mmol of nitrile compound, 10 mg of catalyst, 0.1 g AB and 2 mL of solvent
were added to a sealed tube. The reaction was carried out at the 40 °C for
3 h and the yield was monitored by GC using biphenyl as the internal
standard. After the reaction, the catalyst was separated by a magnet,
respectively washed three times with deionized water and ethanol, and
used for the next reaction. The obtained crude product was separated,
purified, then determined by 1H and 1C NMR.
5
This article is protected by copyright. All rights reserved.

10.1002/cplu.202000028
ChemPlusChem
FULL PAPER
Ai, L. Liu, L. Qi, R. Jiang, H. Bao, J. Wang, J. Hu, H.-b. Sun, Q. Liang, J.
Catal. 2018, 368, 20-30; e) Z. N. Hu, Y. J. Ai, L. Liu, J. J. Zhou, G. Zhang,
H. Q. Liu, X. Y. Liu, Z. B. Liu, J. S. Hu, H. B. Sun, Q. L. Liang, Adv. Synth.
Catal. 2019, 361, 3146-3154; f) L. Liu, J. Li, Y. Ai, Y. Liu, J. Xiong, H.
Wang, Y. Qiao, W. Liu, S. Tan, S. Feng, K. Wang, H. Sun, Q. Liang,
Green Chem. 2019, 21, 1390-1395; g) Y. Ai, M. He, Q. Lv, L. Liu, H.-b.
Sun, M. Ding, Q. Liang, Chem. - Asian J. 2018, 13, 89-98; h) Y. Ai, L. Liu,
C. Zhang, L. Qi, M. He, Z. Liang, H.-b. Sun, G. Luo, Q. Liang, ACS Appl.
Mater. Interfaces 2018, 10, 32180-32191; i) J. Li, L. Liu, Y. Ai, Z. Hu, Z.
Liu, R. Guo, C. Zhang, H. Tian, J. Wu, M. Ruan, H. Sun, ChemistrySelect
2019, 4, 7346-7350; j) Z. N. Hu, Y. J. Ai, L. Liu, Y. X. Chen, X. Song, J.
F. Li, J. H. Yu, H. M. Tian, R. X. Guo, H. B. Sun, J. S. Hu, Q. L. Liang,
Chemistryselect 2019, 4, 8960-8967.
6
This article is protected by copyright. All rights reserved.

10.1002/cplu.202000028
ChemPlusChem
FULL PAPER
Entry for the Table of Contents
1. The selective synthesis of symmetrical secondary amines via transfer hydrogenation of nitrile with excellent conversion and
selectivity.
2. The quaternary component catalyst contains platinum, copper, and iron, which are supported on the magnetite Fe3O4
nanospheres.
3. The catalyst with low-loading Pt (0.456 wt%) guarantees the activity, and the d-band electron transfer from Cu to Fe enhances the
selectivity.
4. A variety of nitriles are suitable for the synthesis of symmetrical secondary amines, and no hydrogenolysis byproducts were
detected.
Institute and/or researcher Twitter usernames: ((optional))
7
This article is protected by copyright. All rights reserved.