A simple, fast and excellent protocol for the synthesis of phenols using CuFe 2O 4 magnetic nanoparticles

Article abstract of DOI:10.1007/s12039-019-1624-7

Abstract: This paper describes a very mild, quick and simple protocol for the synthesis of phenols using CuFe ₂O ₄ magnetic nanoparticles as a catalyst. The nanosized catalyst has an average diameter of 17.63 nm. The magnetic nanoparticles were characterized by SEM, EDX, VSM, XRD and TEM analysis. The synthesis of phenols from phenylboronic acids using H ₂O ₂ as an oxidant proceeded very well with excellent yields. Heterogeneous catalyst, easy recyclability, mild reaction conditions, short reaction time added as an advantage for the present protocol. Graphical Abstract: A very mild, quick and efficient protocol has been designed for the preparation of phenols from phenyl boronic acids using CuFe ₂O ₄ Magnetic Nanoparticles (MNPs) as a catalyst. Heterogeneous catalyst, easy recyclability added as an advantage for the protocol.[Figure not available: see fulltext.].

Full text of DOI:10.1007/s12039-019-1624-7

J. Chem. Sci.
(2019) 131:48
© Indian Academy of Sciences
https://doi.org/10.1007/s12039-019-1624-7
REGULAR ARTICLE
A simple, fast and excellent protocol for the synthesis of phenols
using CuFe O magnetic nanoparticles
2
4
∗
RITUPARNA CHUTIA and BOLIN CHETIA
Department of Chemistry, Dibrugarh University, Dibrugarh 786 004, Assam, India
E-mail: bolinchetia@dibru.ac.in
MS received 30 January 2019; revised 22 March 2019; accepted 25 March 2019
Abstract. This paper describes a very mild, quick and simple protocol for the synthesis of phenols using
CuFe2O4 magnetic nanoparticles as a catalyst. The nanosized catalyst has an average diameter of 17.63 nm.
The magnetic nanoparticles were characterized by SEM, EDX, VSM, XRD and TEM analysis. The synthesis
of phenols from phenylboronic acids using H2O2 as an oxidant proceeded very well with excellent yields.
Heterogeneous catalyst, easy recyclability, mild reaction conditions, short reaction time added as an advantage
for the present protocol.
Keywords. Phenols; CuFe2O4 magnetic nanoparticles; short reaction time; heterogeneous catalysis; easy
recyclability.
1
. Introduction
electron-withdrawing substituents catalysed by copper,
palladium, etc. These conditions suffer from several
9
Phenolic compounds are produced as secondary
metabolites by most plants. These compounds play an
important role in the growth and reproduction of plants,
and provide protection against pathogens and preda-
drawbacks like harsh reaction condition, poor func-
tional group compatibility, less substrate scope, etc.
Among them, the synthesis of phenols from aryl-
boronic acids to phenols has received significant atten-
tion in organic synthesis, because arylboronic acids
are diverse, less toxic, and highly stable under air.
The transformations of aryl boronic acids to phenols
via ipso-hydroxylation have been reported by several
scientists using different reaction conditions. Several
research groups have reported different catalysts for
the synthesis of phenols using arylboronic acids which
1
tors, besides contributing towards the colour and sen-
2
sory characteristics of fruits and vegetables. Phenols
exhibit a wide range of physiological properties, such
as anti-allergenic, anti-atherogenic, anti-inflammatory,
anti-microbial, anti-thrombotic, cardioprotective and
vasodilatory effects.3 Phenolic compounds also have
a wide range of applications both in the industrial world
–7
8
10
11
and in nature. Antioxidant activity is a beneficial effect
includesiron(III)oxide, (NH ) S O , potassiumper-
4
2
2
8
1
2
13
14
derived from phenolic compounds.
oxymonosulfate, hydrazine hydrate, I , Amberlite
2
15
16
17
The production of phenols has begun since the 1860s.
IR 120 resin, H BO –H O , NaClO2. Recently,
3
3
2
2
th
Moreover, towards the end of the 19 century, phenols
many scientists have carried out ipso-hydroxylations
1
8
19
have been used in the synthesis of dyes, explosives i.e.,
picric acid, etc. Formaldehyde resins are the basis of
the oldest plastics and are still used in electrical equip-
ment to make low-cost thermosetting plastics such as
melamine and bakelite.
Looking at the immense value of phenols, scientists
have tried to synthesize it through various reaction path-
ways. The laboratory scale synthesis of phenols uses
nucleophilic substitution of aryl halides activated by
using CNT-chitosan, ascorbic acid, Fe O @SiO
2
3
2
20
21
nanoparticles, Cu O nanoparticles, etc. But these
2
conditions suffer one or more disadvantages like longer
reaction time and/or high amount of catalyst load-
ing. Nowadays, the use of nanoparticles as a catalyst
is growing over other catalyst systems, but because
of their nanosize, the isolation and recovery of the
nanocatalyst from the reaction mixture has been one
of the major drawbacks.
*
For correspondence
Electronic supplementary material: The online version of this article (https://doi.org/10.1007/s12039-019-1624-7) contains
supplementary material, which is available to authorized users.
0123456789().: V,-vol

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To overcome all these difficulties, the use of magnetic to it and stirred at room temperature. 5 mL of 0.1 M NaOH
nanoparticles (MNPs) as a catalyst is preferred over was added to the stirring solution. After 30 min 0.1 M NaBH4
was added to the solution and stirred for about 1 h. The result-
choosing other catalysts because of their stability, easy
ing solution was centrifuged at 1200 rpm for 10 min and
synthesis, better selectivity, excellent surface area to the
washed with ethanol. The centrifuged product was dried and
the desired product of CuFe2O4 MNPs was obtained.
volume ratio, and easy recyclability. Various magnetic
nanoparticles have been synthesized in the laboratory
22,23
24
which include Fe O ,
Cu/SB-Fe O , etc.
3
4
3 4
2.2 General procedure for the Ipso-Hydroxylation
HereinwehavesynthesizedCuFe O MNPsbyavery
2
4
convenient and simple procedure and used it as a catalyst
in the production of phenols from aryl boronic acids.
In a round bottom flask 1 mmol of phenylboronic acid, 0.03
mmol (3 mol%) of CuFe2O4 MNPs, 200 µL of H2O2 (30%)
were added and stirred at room temperature. The desired prod-
uct was obtained after about 2 min which was monitored by
TLC. The reaction mixture was diluted with 20 mL of diethyl
ether and the combined organic layer was washed with brine
and dried over by anhydrous Na2SO4 and evaporated in a
2
. Experimental
2.1 Preparation of the catalyst using Coprecipitation
Method
1
rotary evaporator. The products were confirmed by H NMR
1
3
0
.5 g of FeCl3 and 0.5 g of copper acetate were added in a and C NMR spectroscopy without any further purification.
round bottom flask and 70 mL of deionised water was added
3
. Results and Discussion
3.1 Characterization of the catalyst
The powder XRD diffraction pattern of the prepared
CuFe O MNPs is shown in Figure 1. The various
2
4
diffraction peaks at 2ꢀ = 18.3, 30.3, 35.6, 42.8, 57.1,
2.95 corresponds to the planes (110), (111), (200),
220), (311), (222) respectively. The sharp diffraction
6
(
peaks clearly shows the highly crystalline nature of
CuFe O MNPs.
2
4
The SEM images showed the structure and morphol-
ogy of the nanoparticles (Figure 2). The SEM images
Figure 1. Powder XRD pattern of CuFe2O4 MNPs.
Figure 2. (a) SEM image; (b) EDX image of CuFe2O4MNPs.

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Page 3 of 6
48
Figure 3. (a) TEM images of the synthesized nanoparticles; (b) the SAED pattern of one nanoparticle
(inset) and; (c) grain size distribution of the nanoparticles.
1
5
0
5
0
5
Table 1. Optimization of H2O2.
Sl. No Oxidant (H2O2)µL Time (min)
1
1
2
3
4
5
50
30
5
3
2
2
100
150
200
300
-20000 -15000 -10000 -5000
0
5000 10000 15000 20000
-
Reaction conditions: phenyl boronic acid (1
mmol), CuFe2O4(3 mol%), rt.
-
-
10
15
crystalline nature of the nanoparticles (Figure 3b). The
average diameter of the nanoparticle was found to be
Applied Magneꢀc Field
1
7.636 nm (Figure 3c).
Furthermore, to observe the magnetic behaviour
Figure 4. VSM study of the CuFe2O4 MNPs.
the VSM analysis of the nanoparticles was studied
depicted the structure of nanoparticles to be spherical (Figure 4). From the VSM study, the coercivity (Hci)
with slight aggregation. The purity of the nanoparticles was found to be 53.387 G.
was observed from the Energy Dispersive X-ray (EDX)
spectrum which shows the presence of copper, iron and
oxygen element.
3.2 Application of the Catalyst
The morphology of the nanoparticles was determined The prepared catalyst was used for the synthesis of
from the TEM images (Figure 3a). The selected area various substituted phenols from arylboronic acids. We
electron diffraction (SAED) pattern of the CuFe O
began our experiment with the optimization parameter
2
4
MNPs showed bright fringes, which indicated the for which we took phenyl boronic acid (1 mmol) as the
OH
H O , CuFe O MNPs
2
2
2
4
B
OH
rt
OH
Scheme 1. Synthesis of phenol using CuFe2O4 MNPs.

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Table 2. Optimization of the catalysta.
model substrate and the reaction was carried out at room
temperature(Scheme1). Theproductwasformedwithin
Sl. No
Catalyst (mol %)
Time (min)
Yield (%)b
2
min with 96% yield.
Initially, we optimized our reaction using different
1
2
3
4
5
6
7
-
1
1.5
2
2.5
3
3.5
60
30
25
20
10
2
45
80
80
85
90
95
95
amounts of H
O . The reaction preceded very smoothly
2
2
using only 200 µL of H O within 2 min (Table 1, entry
2
2
4
). After the identification of the proper amount of H O2
2
the reaction was further optimized for different amount
of the catalyst (Table 2). Moreover, with the use of H O2
2
2
only as an oxidant, trace amount of yields was obtained
aReaction conditions: phenylboronic acid (1 mmol), H2O2 after 1 h (Table 2, entry 1). The yield of the product was
(
200µL), rt.
Yields are isolated yields.
further increased by using only 3 mol% of the catalyst
without the use of any solvent.
b
Table 3. CuFe2O4 MNPs catalysed ipso-hydroxylation of aryl boronic acids to phenolsa.
OH
OH
OH
OH
OH
OCH3
CH3
9
6%, 2 min
93%, 5 min
91%, 8 min
OCH3
5%, 5 min
CH
3
1%, 8 min
9
9
OH
OH
OH
OH
OH
NO2
94%, 4 min
Cl
NO
COCH3
2%, 4 min
F
2
9
2%, 8 min
9
4%, 4 min
9
9
2%, 8 min
OH
OH
O
S
OH
OH
9
1%, 8 min
86%, 5 min
CHO
94%, 8 min
9
3%, 5 min
aReaction conditions: phenyl boronic acid (1 mmol), H2O2 (200µL), rt, CuFe2O4 MNPs (3
mol%) Yields are isolated yields.

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Page 5 of 6
Ref.
48
Table 4. Comparison efficiency with other catalysts.
Catalyst
H2O2 (mL) Catalyst loading (mg) Time (min)
Ag-NP Mont-K
Bio-silica
Acidic alumina
Cu2O NP
0.5
0.2
1.5
0.2
0.2
5
5
20
15
5
10
10
2
25
26
27
2 (3 mol%)
1.05 (3 mol %)
28
CuFe2O4 MNPs
This work
th
Figure 5. (a) Recyclability of CuFe2O4 MNPs; (b) XRD of the recycled catalyst after the 5 cycle.
Using the optimized conditions provided in the previ- completion of the reaction the catalyst was extracted
ous section, the scope of the reaction was studied for a with the help of an external magnet, centrifuged and
number of phenyl boronic acids to phenols (Table 3). washed properly with ethanol. It was then dried and
It was observed that both electron withdrawing and reused for a fresh batch of reaction.
th
electron donating groups had little effect on the reactiv-
The sharp XRD peaks taken after the 5 cycle
ity conditions. Moreover, hetero arylboronic acids also (Figure 5b) proved the crystallinity of the nanoparticles.
gave high yields in less time. There was no filtration required for the recyclability of
We compared the use of CuFe O MNPs as a cat- the catalyst.
2
4
alyst for the ipso-hydroxylation of aryl boronic acids
to phenols with other reported catalyst,2
5–28
which
showed the better catalytic efficiency of our catalyst.
The easy recyclability, less amount of catalyst load-
ing, less reaction time, easy preparation of the catalyst
proved to be the advantages of the present proto-
col. The comparison efficiency of phenylboronic acid
to phenol with other reported catalyst is shown in
Table 4.
4
. Conclusions
Herein we have synthesized phenols using a very mild
procedure using a heterogeneous, recyclable CuFe O4
2
MNPs catalyst for the first time. The easy formation of
the product in less reaction time proved to be a very
significant procedure for the synthesis of phenols. The
magnetic nature of the catalyst added as an advantage
for the protocol as the product formation required less
amount of catalyst.
3.3 Recyclability
Recyclability is one of the main advantages of a hetero-
geneous catalyst. To test the recyclability, we observed
Supplementary Information (SI)
the ipso-hydroxylation of phenyl boronic acid to phenol
th
1
(Figure 5). The catalyst was easily recycled up to 5
Characterization methods and H NMR of the compunds are
cycle without any loss in the catalytic cycle. After the available at www.ias.ac.in/chemsci.

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(2019) 131:48
Acknowledgements
14. Gogoi A and Bora U 2012 An iodine-promoted, mild
and efficient method for the synthesis of phenols from
arylboronic acids Synlett. 23 1079
BC gratefully acknowledges DST-SERB (project No.SB/FT/
CS-161/2012) UGC-SAP for financial assistance, and SAIF,
NEHU Shillong for spectral data, CSIC Dibrugarh University
for XRD, SEM, EDX analysis.
1
5. Mulakayala N, Ismail Kumar K M, Rapolu R K, Kanda-
gatla B, Rao P, Oruganti S and Pal M 2012 Catalysis by
AmberliteIR-120resin:Arapidandgreenmethodforthe
synthesis of phenols from arylboronic acids under metal,
ligand, and base-free conditions Tetrahedron Lett. 53
6004
1
6. Gogoi K, Dewan A, Gogoi A, Borah G and Bora U 2014
Boric Acid as Highly Efficient Catalyst for the Syn-
thesis of Phenols from Arylboronic Acids Heteroatom
Chem. 25 127
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