Chromium containing Fe3O4/polyacrylonitrile-ethylenediamine as a magnetically recoverable catalyst for alcohol oxidation

Article abstract of DOI:10.1016/j.catcom.2014.11.011

A new chromium containing Fe₃O₄/polyacrylonitrile-ethylenediamine has been prepared through in situ polymerization of acrylonitrile onto the surface of magnetic nanoparticles. The polymer magnetic nanocomposite was utilized for the oxidation of a number of aromatic alcohols as a reusable catalyst. The corresponding aldehydes were obtained in high yields within short reaction time under mild conditions.

Full text of DOI:10.1016/j.catcom.2014.11.011

Chromium containing Fe3O4/polyacrylonitrile-ethylenediamine as a magneti-
cally recoverable catalyst for alcohol oxidation
Arash Heidarnezhad, Farzad Zamani
PII:
DOI:
Reference:
S1566-7367(14)00464-6
doi: 10.1016/j.catcom.2014.11.011
CATCOM 4133
To appear in:
Catalysis Communications
Received date:
Revised date:
Accepted date:
20 May 2014
30 September 2014
10 November 2014
Please cite this article as: Arash Heidarnezhad, Farzad Zamani, Chromium contain-
ing Fe3O4/polyacrylonitrile-ethylenediamine as a magnetically recoverable catalyst for
alcohol oxidation, Catalysis Communications (2014), doi: 10.1016/j.catcom.2014.11.011
This is a PDF file of an unedited manuscript that has been accepted for publication.
As a service to our customers we are providing this early version of the manuscript.
The manuscript will undergo copyediting, typesetting, and review of the resulting proof
before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that
apply to the journal pertain.

ACCEPTED MANUSCRIPT
Chromium containing Fe3O4/polyacrylonitrile-ethylenediamine as a
magnetically recoverable catalyst for alcohol oxidation
Arash Heidarnezhad a and Farzad Zamani a,b *
a Laboratory of Applied Chemistry, Central Laboratory Complex, Isfahan Science and
Technology Town, Isfahan University of Technology, Isfahan 8415683111, Iran
b Department of Chemistry, Shahreza Branch, Islamic Azad University, Shahreza 31186145,
Isfahan, Iran
Abstract
A new chromium containing Fe3O4/polyacrylonitrile-ethylenediamine has been prepared
through in situ polymerization of acrylonitrile onto the surface of magnetic nanoparticles. The
polymer magnetic nanocomposite was utilized for the oxidation of a number of aromatic
alcohols as a reusable catalyst. The corresponding aldehydes were obtained in high yields within
short reaction time under mild conditions.
Keywords: Polymer magnetic catalyst, Cr(III), Ethylenediamine, Polyacrylonitrile, Organic-
solvent-free alcohol oxidation.
*
Corresponding author: Fax: +98-311-3869714; Tel.: +98-311-3865355; E-mail: fzamani@iaush.ac.ir
1

ACCEPTED MANUSCRIPT
1. Introduction
In recent years, the use of nanoparticles as catalysts in organic transformations has
attracted considerable interest because nanoparticles provide high surface area-to-volume ratios
[1,2]. Although a significant enhancement of catalytic activity could be achieved by synthesizing
a catalyst in nanometer dimensions, recovery of the catalyst from the reaction mixture is a
problem as they cannot be efficiently filtered out from the reaction medium. Therefore, the
design of efficient and recoverable nanoparticles has become an important issue in the case of
economic and environmental aspects. In this regard, magnetic nanoparticles (MNPs) have held
out significant potential as reusable catalysts because of the ease of recovery by magnetic
separation, which prevents loss of catalyst and increases recyclability. Over the last decade,
functionalized magnetic nanoparticles have been utilized as efficient recoverable catalyst for
various organic transformations, which represent excellent catalytic activities [3-9].
Selective catalytic oxidation of benzyl alcohol to benzaldehyde is one of the most
important chemical reactions in chemistry. Benzaldehyde has been widely applied in the
manufacture of odorants, flavors, aniline dyes, plastic additives and pharmaceutical
intermediates as an important raw material [10]. Over the last few years, many studies have been
reported on the oxidation of benzyl alcohol to benzaldehyde with different catalytic systems [11–
14]. Therefore, the increasing need for efficient and selective catalysts as well as the fundamental
investigations are continuously the driving forces for synthesis of new catalysts. Furthermore,
from the point of view of environmentally benign and clean technologies, synthetic strategies
that avoid the use of any organic solvents as well as corrosive catalysts and oxidants are
becoming more attractive. Regarding sustainable systems, hydrogen peroxide is as a favorite
oxidant since it can oxidize organic compounds with water as a by-product and thus avoids the
2

ACCEPTED MANUSCRIPT
production of highly toxic wastes [15,16]. These advantages of hydrogen peroxide motivate
scientists to develop new catalytic systems for H2O2-mediated alcohol oxidation reactions. A
variety of different catalytic systems for the hydrogen peroxide promoted oxidation have been
developed recently [17-21].
Chromium complexes are well-known catalysts since they have many advantages such as
variable oxidation states, spin states coordination numbers and redox properties in different
chromium complexes [22]. In this case, many studies have been undertaken to investigate the
catalytic activity of various chromium-containing catalysts in the oxidation of alcohols [23-26].
As a continuation of our studies related to efficient heterogeneous magnetic catalysts
[27,28], we became interested in immobilization of ethylenediamine onto the polyacrylonitrile
coated Fe3O4 nanoparticles through its primary amine groups, which plays as a ligand for
incorporation of chromium ions. Catalytic performance of the polymer magnetic nanocomposite
was examined for alcohol oxidation.
2. Experimental
2.1. Catalyst preparation
Preparing Cr(III)-containing Fe3O4/polyacrylonitrile-ethylenediamine includes four steps
which are as follows. The schematic procedure was also illustrated in Scheme 1. First, Fe3O4
nanoparticles were synthesized by a chemical co-precipitation method [29]. Afterwards, surface
modification of the magnetic nanoparticles was carried out as reported in the literature [30], with
some modifications. Fe3O4 nanoparticles (1 g) were placed in a round bottom flask and sonicated
for 10 min. Then, a solution of acrylonitrile monomer (0.5 g) in THF (15 mL) were added
dropwise and sonicated for another 10 min. Benzoyl peroxide (0.05 g) was then added as
3

ACCEPTED MANUSCRIPT
initiator, and the mixture was heated to 60 °C for 6 h while stirring. Finally, the resulting solid
material was removed by a magnet and dried at 50 °C overnight to give Fe3O4-PAN.
Ethylenediamine was immobilized onto the surface of Fe3O4-PAN using a simple procedure as
described previously [31]. Briefly, 1 g of Fe3O4-PAN, ethylenediamine (20 mL) and deionized
water (10 mL) were added to a round bottom flask and the mixture was stirred under reflux for 5
h. Then, the sample was separated by an external magnet and washed several times with warm
deionized water until the pH was neutral. Finally, the nanocomposite was dried overnight under
vacuum at 70 °C to yield Fe3O4-PAN-ED. Finally, the incorporation of chromium ions onto the
Fe3O4-PAN-ED nanocomposite was carried out using various amounts of CrCl3.6H2O (1, 2, 3
and 4 mmol). In details, a flask containing a stirred suspension of chrome(III) chloride
hexahydrate in dry methanol (15 mL) was purged with nitrogen and heated to 40 °C under a
nitrogen atmosphere. Fe3O4-PAN-ED (1 g) was then added in one portion and the resulting
suspension was refluxed in a nitrogen atmosphere under vigorous stirring for 6 h. Afterwards, the
synthesized nanocomposite (Fe3O4-PAN-ED-Cr) was separated from the suspension by magnetic
decantation, washed several times with deionized water and dry methanol, and dried under
vacuum at room temperature.
The Cr content of the nanocomposite, as determined by atomic absorption spectroscopy
(AAS), was found to be 0.64, 1.12, 1.58 and 1.60 mmol g−1 for 1, 2, 3 and 4 mmol of chrome(III)
chloride hexahydrate, respectively.
(Space for Scheme 1)
2.2. Apparatus
The crystalline structures of the samples were evaluated by X-ray diffraction (XRD)
analysis on a Bruker D8 Advance diffractometer with CuKα radiation at 40 kV and 20 mA.
4

ACCEPTED MANUSCRIPT
Fourier transform infrared (FT-IR) spectra were recorded with a Perkin Elmer 65 spectrometer in
the range of 400–4000 cm−1. Transmission electron microscopy (TEM) analysis was performed
on a Phillips CM10 microscope at an accelerating voltage of 200 kV. Magnetization
measurements were carried out on a BHV-55 vibrating sample magnetometer (VSM). DR UV–
Vis spectroscopy was carried out with a JASCO V-670.
2.3. General procedure for alcohol oxidation
In a typical reaction, a mixture of benzyl alcohol (0.2 mL, 2 mmol) and the magnetic
catalyst (0.03 g) was loaded in a two-neck round bottom flask. Hydrogen peroxide (30%, 6
mmol) was then added dropwise to the mixture and stirred under organic-solvent-free condition
at room temperature. The progress of reaction was monitored by thin layer chromatography
(TLC). After completion of the reaction, the catalyst was separated by an external magnet and
the liquid organic product was analysed by an Agilent gas chromatograph 6890 equipped with a
HP-5 capillary column. Dodecane was used as the internal standard to calculate benzyl alcohol
conversion and benzaldehyde selectivity.
3. Results and discussion
3.1. Catalyst characterization
The crystalline structures of Fe3O4 and Fe3O4/PAN–ED-Cr were evaluated by powder X-
ray diffraction (XRD). As displayed in Fig. 1, all the samples depict diffraction peaks at around
30.4°, 36.0°, 43.3°, 53.8°, 57.1° and 62.5° 2θ ascribing to the spinel structure of Fe3O4 [32],
which can be assigned to the diffractions of the (220), (311), (400), (422), (511) and (440) faces
of the crystals, respectively. Furthermore, the XRD patterns show similar diffraction peaks
5

ACCEPTED MANUSCRIPT
which indicate that the nanocomposite was synthesized without damaging the crystal structure of
the Fe3O4 core. Moreover, the broad diffraction peak in the range of 2θ between 20° and 30°
accounts for the amorphous polymer coated on the magnetic nanoparticles [33].
(Space for Fig. 1)
The FT-IR spectra of the Fe3O4, Fe3O4/PAN, Fe3O4/PAN–ED and Fe3O4/PAN–ED–Cr
samples were recorded to confirm the modification of the magnetite surface with the organic
polymer shell and metal ions (Fig. 2). The presence of magnetite nanoparticles is confirmed by
1
the strong adsorption band at about 562 cm− , corresponding to the Fe–O vibrations (Fig. 2a–d).
1
Considering the spectrum of Fe3O4/PAN (Fig. 2b), the 2248 cm− absorption band indicates the
existence of C≡N units in the nanocomposite. Moreover, the bands in the 2800-3000 cm−1 region
are attributed to the stretching of C–H bonds of the saturated alkane, which are observable in Fig.
2b-d [34]. In the case of Fe3O4/PAN–ED (Fig. 2c), it can be seen that the intensity of
characteristic absorption peak of the C≡N group decreases significantly. Instead, two strong
1
1
characteristic bands appeared at the region of 1654 cm− and 1433 cm− , which can be assigned to
the amide functional group and bending vibration absorption of the N–H bond [30]. In addition,
the peak at approximately 3400 cm−1 may be attributed the presence of the stretching vibration of
the N–H groups in the structure of Fe3O4/PAN–ED. These results demonstrate that most of the
C≡N functional groups in Fe3O4/PAN have been converted to amide groups through the
immobilization of ethylenediamine, and the Fe3O4/PAN–ED was successfully obtained. In terms
of Fe3O4/PAN–ED–Cr (Fig. 2d), a red shift of the band at 1654 сm−1 is observed (1654 сm−1 →
1628 сm−1), which is possibly due to the asymmetrical fluctuations of the carbonyl group after
interaction with the metal ions [28]. The same shift also took place for the vibration absorption
of the N–H bond, which shifts from 1433 cm−1 to 1402 cm−1 indicating the interaction between
6

ACCEPTED MANUSCRIPT
the nitrogen donors and the metal ions. Furthermore, the characteristic band of N–H group of
PAN–ED, which is located at about 3400 cm−1, reduced in the spectrum of the Fe3O4/PAN–ED–
Cr (Fig. 2d), implying a strong interaction between the nitrogen donors and the metal ions [28].
(Space for Fig. 2)
Figure 3 depicts the TEM micrograph of the Fe3O4/PAN–ED–Cr nanocomposite. A
continuous layer of the complex (PAN–ED–Cr) was clearly observed on the outer surface of the
Fe3O4 nanoparticles. It means that after compositing with PAN–ED–Cr, the particles were fully
encapsulated by the metal-containing complex to form Fe3O4/PAN–ED–Cr, with the size of
approximately 20 nm.
(Space for Fig. 3)
The magnetic properties of the Fe3O4 and Fe3O4/PAN–ED–Cr nanocomposite were
measured by a vibrating sample magnetometer (VSM) at room temperature (Fig. 4). It can be
seen that the saturation magnetization (Ms) values of the samples are 61.2 and 42.3 emu g−1 for
the Fe3O4 and Fe3O4/PAN–ED–Cr, respectively. It is clear that the Ms of the nanocomposite
(Fig. 4b) is significantly less than that of the magnetic nanoparticles (Fig. 4a), which may be due
to the fact that the Fe3O4 nanoparticles were coated completely by an inert organic shell (PAN–
ED–Cr). These results from the magnetic properties are in accordance with the XRD, IR and
TEM analysis.
(Space for Fig. 4)
The DRS UV-Vis spectroscopy of Fe3O4-PAN-ED and Fe3O4-PAN-ED-Cr was performed
in order to investigate the electronic state of the transition metal ion. As illustrated in Fig. 5,
there is no characteristic peak in Fe3O4-PAN-ED spectrum (Fig. 5a). However, in terms of
7

ACCEPTED MANUSCRIPT
Fe3O4-PAN-ED-Cr (Fig. 5b), two absorption peaks appeared at ∼400 and ∼590 nm, which could
be attributed to the d–d transitions of the Cr complex.
(Space for Fig. 5)
3.2. Catalytic activity
The catalytic performance of Fe3O4/PAN–ED–Cr was evaluated for the oxidation of
alcohols as a new magnetic catalyst. In order to optimize the reaction conditions and obtain the
best catalytic activity, the oxidation of benzyl alcohol was chosen as a model reaction. In this
case, different reaction parameters such as solvent and amount of catalyst were investigated. The
model reactions were carried out over the catalyst with the best metal content (reported in the
experimental section, 1.58 mmol g−1) at room temperature.
As far as the effect of solvent is concerned, the model reaction was carried out in several
solvents as well as organic-solvent-free condition to investigate the efficiency of the catalyst
(Table 1). It can be seen, the best yield was obtained when the reaction was performed under
organic-solvent-free condition (67%). Also, it is obvious that the catalytic activity of the
magnetic nanocomposite significantly reduced by using water as solvent, which may be due to
the possibility of blocking active sites of the catalyst by water molecular.
Moreover, the effect of catalyst amount on the oxidation of benzyl alcohol was carried
out by different amounts of the catalyst (Table 1). It was observed that while the amount of
catalyst increased from 0.01 to 0.03 g, the product yield raised significantly from 67% to 98%,
which is probably due to the availability of more active sites (Cr3+). Since then, the percentage of
yield remained stable between 0.03 g and 0.04 g, with a reduction of about 12% in benzaldehyde
8

ACCEPTED MANUSCRIPT
selectivity, which may be due to over-oxidation of the substrate at the high amount of the
catalyst.
(Space for Table 1)
In order to investigate the role Cr3+ in the catalyst, the model reaction was carried out
under the optimized reaction conditions in the presence of Fe3O4/PAN–ED as catalyst. No
reaction yield was obtained even after four hours. As a result, it can be concluded that Cr3+
incorporated onto the magnetic nanocomposite plays a pivotal role in the oxidation of alcohols.
Based on the experimental results, a proposed mechanism for the oxidation of alcohols by
hydrogen peroxide under Fe3O4/PAN–ED-Cr could be summarized as the following, which is
similar to the previous reported literature [35].
(1) Cr(ІІI) + 2H2O2 → Cr(VI) + 2HO• + 2HO¯
(2) HO• + RCH2OH → RC•HOH + H2O
(3) RC•HOH + Cr(VI) → RCHO + Cr(ІIІ) + H+
In the case of industrial aspects, reusability of the catalyst was tested by carrying out
repeated runs of the reaction on the same batch of the catalyst in the case of the model reaction.
In order to regenerate the catalyst, after each cycle, it was separated by a magnet and washed
several times with deionized water and ethanol. Then, it was dried in oven at 60 °C and used in
the oxidation reaction. The results showed that this polymer magnetic catalyst could be reused
six times with no significant loss of activity/selectivity (7% in yield).
The Fe3O4/PAN–ED–Cr catalyst also represented good activity and selectivity in the
oxidation of different aromatic and aliphatic alcohols (Table 2). All the investigated alcohols
9

ACCEPTED MANUSCRIPT
were converted to their corresponding aldehydes in high yields with excellent selectivity. It can
also be observed that the catalyst had high activity for the oxidation of secondary alcohols (Table
2, Entries 11 and 12).
(Space for Table 2)
4. Conclusion
A facile procedure for the synthesis of Cr(III)-containing Fe3O4/polyacrylonitrile-
ethylenediamine nanocomposite (Fe3O4/PAN–ED–Cr) was reported. This new magnetic organic-
inorganic nanocomposite containing Cr3+ represented high catalytic activity/selectivity in the
oxidation of alcohols. The magnetic catalyst also showed excellent level of reusability, which
make it a good candidate for industrial catalytic purposes in different oxidation reactions.
Acknowledgements
The authors thank the Isfahan Science and Technology Town (Isfahan University of
Technology) for the support of this work.
References
[1] D. Astruc, F. Lu, J.R. Aranzaes, Angew. Chem. Int. Ed. 44 (2005) 7852.
[2] M.T. Reetz, M. Maase, Adv. Mater. 11 (1999) 773.
[3] V.V. Costa, M.J. Jacint, L.M. Rossi, R. Landers, E.V. Gusevskaya, J. Catal. 282 (2011) 209.
[4] M. Zhang, Q. Sun, Z. Yan, J. Jing, W. Wei, D. Jiang, J. Xie, M. Chen, Aust. J. Chem. 66 (2013) 564.
[5] B. Li, L. Gao, F. Bian, W. Yu, Tetrahedron Lett. 54 (2013) 1063.
[6] M. Beygzadeh, A. Alizadeh, M.M. Khodaei, D. Kordestani, Catal. Commun. 32 (2013) 86.
[7] M. Esmaeilpour, A.R. Sardariana, J. Javidi, Appl. Catal. A: Gen. 445–446 (2012) 359.
[8] N.T.S. Phan, C.W. Jones, J. Mol. Catal. A: Chem. 253 (2006) 123.
[9] X. Jin, K. Zhang, J. Sun, J. Wang, Z. Dong, R. Li, Catal. Commun. 26 (2012) 199.
10

ACCEPTED MANUSCRIPT
[10] M.P. Chaudhari, S.B. Sawant, Chem. Eng. J. 106 (2005) 111.
[11] T. Punniyamurthy, S. Velusamy and J. Iqbal, Chem. Rev. 105 (2005) 2329.
[12] I.W.C.E. Arends and R.A. Sheldon, “Modern Oxidation of Alcohols Using Environmentally Benign Oxidants,”
In: J.-E. Blackvall, Ed., Modern Oxidation Methods, 2nd Edition, Wiley-VCH, Weinheim, 2010.
[13] V.R. Choudhary, P.A. Chaudhari, V.S. Narkhede, Catal. Commun. 4 (2003) 171.
[14] V. Mahdavi, M. Mardani, M. Malekhosseini, Catal. Commun. 9 (2008) 2201.
[15] Y. Ishii, K. Yamawaki, T. Ura, H. Yamada, T. Yoshida, M. Ogawa, J. Org. Chem. 53 (1988) 3587.
[16] R. Noyori, M. Aoki, K. Sato, Chem. Commun. (2003) 1977.
[17] E.I. Solomon, R.K. Szilagyi, S.D. George, L. Basumallick, Chem. Rev. 104 (2004) 419.
[18] P. Gamez, P.G. Aube, W.L. Driessen, J. Reedijik, Chem. Soc. Rev. 30 (2001) 376.
[19] R. Borthakur, M. Asthana, A. Kuamr, A. Koch, R.A. Lal, RSC Adv. 3 (2013) 22957.
[20] R. Borthakur, M. Asthana, M. Saha, A. Kuamr, A.K. Pal, RSC Adv. 4 (2014) 21638.
[21] R. Borthakur, M. Asthana, A. Kuamr, R.A. Lal, Inorg. Chem. Commun. 46 (2014) 198.
[22] J.E. Huheey, E.A. Keiter, R.D. Keiter, O.K. Medhi, Inorganic Chemistry, 4th edn, Pearson Education, South
Asia, 2008.
[23] X. Wang, G. Wu, J. Li, N. Zhao, W. Wei, Y. Sun, J. Mol. Catal. A: Chem. 276 (2007) 86.
[24] S.P. Mardur, G.S. Gokavi, J. Iran. Chem. Soc. 7 (2010) 441.
[25] A.F. Shojaei, M.D. Rafie, M.H. Loghmani, Bull. Korean Chem. Soc. 33 (2012) 2748.
[26] Z. Lounis, A. Riahi, F. Djafri, J. Muzart, Appl. Catal. A. 309 (2006) 270.
[27] F. Zamani, S. Kianpour, Catal. Commun. 45 (2014) 1.
[28] F. Zamani, S.M. Hosseini, S. Kianpour, Dalton Trans. 43 (2014) 3618.
[29] G.Y. Liu, H. Wang, X.L. Yang, L.Y. Li. Eur. Polym. J. 45 (2009) 2023.
[30] R.J. Kalbasi, M. Kolahdoozan, M. Rezaei, Mater. Chem. Phys. 125 (2011) 784.
[31] G. Li, J. Xiao, W. Zhang, Green. Chem. 14 (2012) 2234.
[32] L. Cabrera, S. Gutierrez, M. P. Morales, N. Menendez, P. Herrasti, J. Magn. Magn. Mater. 321 (2009) 2115.
[33] H. Deng, Z. Lei, Composites Part B 54 (2013) 194.
[34] Y. Chen, Z. Qian, Z.C. Zhang, Colloid. Surf. A. 312 (2008) 209.
11

ACCEPTED MANUSCRIPT
[35] C. Walling, Account Chem. Res. 8 (1975) 125.
Figure captions
Fig. 1. XRD patterns of (a) Fe3O4 and (b) Fe3O4/PAN–ED-Cr.
Fig. 2. FT-IR spectra of (a) Fe3O4, (b) Fe3O4/PAN, (c) Fe3O4/PAN–ED and (d) Fe3O4/PAN–ED-Cr.
Fig. 3. TEM image of the Fe3O4/PAN–ED-Cr nanocomposite.
Fig. 4. Room temperature magnetization curves of (a) Fe3O4 and (b) Fe3O4/PAN–ED–Cr.
Fig. 5. DR UV–Vis spectra of (a) Fe3O4/PAN–ED and (b) Fe3O4/PAN–ED–Cr.
Scheme 1. Proposed schematic figure for the structure of prepared magnetic catalyst.
12

ACCEPTED MANUSCRIPT
Fig. 1
13

ACCEPTED MANUSCRIPT
Fig. 2
14

ACCEPTED MANUSCRIPT
Fig. 3
15

ACCEPTED MANUSCRIPT
Fig. 4
16

ACCEPTED MANUSCRIPT
Fig. 5
17

ACCEPTED MANUSCRIPT
H2N
Cr3+
H2N
NH2
NH
NH
CN
H2N
O
O
OH
C
NC
O
NH
C
HO
CN
CN
CN
CN
OH
OH
OH
HN
C
H
HN
NH2
NH2
C
N
NC
Benzoyl peroxide
C
O
NH2
Cr3+
HO
NC
C
CrCl3.6H2O
CN
H2N
NH2
Fe3O4
Fe3O4
Fe3O4
CN
O
Fe3O4
O
H
C
O
H2O
N
H
N
H
O
C
NC
HO
NH2
N
C
O
C
NC
CN
HO
OH
O
C
H2N
CN
O
N
3+
NH2 Cr
H
NH
H2N
Fe3O4-PAN-ED-Cr
Fe3O4
Fe3O4-PAN
Fe3O4-PAN-ED
Scheme 1
18

ACCEPTED MANUSCRIPT
Table 1. Effects of different solvents and amount of catalyst on the benzyl alcohol oxidation in the presence of
Fe3O4/PAN–ED–Cr.a
Solvent
Catalyst (g)
Selectivity to benzaldehyde (%)
Yield (%) b
Water
0.01
>99
>99
>99
>99
>99
>99
87
49
55
44
67
85
98
98
Acetonitrile
n-Hexane
Solvent-free
Solvent-free
Solvent-free
Solvent-free
0.01
0.01
0.01
0.02
0.03
0.04
a Reaction conditions: benzyl alcohol (2 mmol), H2O2 (6 mmol), reaction time= 10 min, room temperature.
b The main byproduct was benzoic acid.
b GC yield.
19

ACCEPTED MANUSCRIPT
Table 2. Organic-solvent-free oxidation of various aromatic and aliphatic alcohols over Fe3O4/PAN-ED-Cr.a
Entry
1
Substrate
Product
Time (min)
10
Yield (%)b
98
HO
CH2OH
CHO
Br
Br
CH2OH
CHO
2
10
93
Cl
Cl
CH2OH
CHO
3
4
10
90
93
59
O2N
O2N
CH2OH
CHO
HO
MeO
CHO
5
10
84
CH2OH
MeO
CH2OH
6
7
10
10
90
98
CHO
O
CHO
CH2OH
O
8
9
10
88
75
78
CHO
OH
110
110
OH
CHO
10
11
12
60
60
80
82
20

ACCEPTED MANUSCRIPT
a Reaction conditions: substrate (2 mmol), H2O2 (6 mmol), catalyst (0.03 g), room temperature, selectivity = >99.
b GC yield.
21

ACCEPTED MANUSCRIPT
Highlights
1. The synthesized nanocomposite has an excellent chemical stability.
2. This polymer magnetic catalyst could be prepared by a cheap and simple method.
3. The catalyst exhibited high catalytic activity/selectivity in the oxidation of alcohols.
4. The catalyst has an excellent level of reusability.
22