Highly efficient and recyclable acetylation of phenols and alcohols by nickel zirconium phosphate under solvent-free conditions

Article abstract of DOI:10.1007/s13738-015-0711-z

Nickel zirconium phosphate nanoparticles have been used as an efficient catalyst for the acetylation of a wide range of alcohols and phenols with acetic anhydride in good to excellent yields under solvent-free conditions. The steric and electronic properties of the different substrates had a significant influence on the reaction conditions required to achieve the acetylation. The catalyst used in the current study was characterized by inductively coupled plasma optical emission spectroscopy, X-ray diffraction, N₂ adsorption-desorption, scanning electron microscopy, and transmission electron microscopy. This nanocatalyst could also be recovered and reused at least six times without any discernible decrease in its catalytic activity.

Full text of DOI:10.1007/s13738-015-0711-z

J IRAN CHEM SOC
DOI 10.1007/s13738-015-0711-z
ORIGINAL PAPER
Highly efficient and recyclable acetylation of phenols and alcohols
by nickel zirconium phosphate under solvent‑free conditions
Abdol Reza Hajipour1,2 · Hirbod Karimi1,3 · Afshin Kohi1
Received: 6 November 2014 / Accepted: 25 July 2015
©
Iranian Chemical Society 2015
Abstract Nickel zirconium phosphate nanoparticles have
been used as an efficient catalyst for the acetylation of a
wide range of alcohols and phenols with acetic anhydride
in good to excellent yields under solvent‐free conditions.
The steric and electronic properties of the different sub-
strates had a significant influence on the reaction conditions
required to achieve the acetylation. The catalyst used in
the current study was characterized by inductively coupled
Graphical abstract
O
Solvent-free
X
40 °C, 10-45 min
X
Ni2+
+
Ac O
2
O
P
Zr
O
P
+
AcOH
R
R
R=aryl, alkyl, benzyl
Zr
X=OH, SH, NH
2
plasma optical emission spectroscopy, X‐ray diffraction, N
2
Catalyst regeneration
adsorption–desorption, scanning electron microscopy, and
transmission electron microscopy. This nanocatalyst could
also be recovered and reused at least six times without any
discernible decrease in its catalytic activity.
1
. Washed with ethanol and water
o
2
. Dried at 110
C
3
. Activated at 450 oC
Keywords Nickel zirconium phosphate · Nanoparticles ·
Acylation · Solvent-free · Solid catalyst
Introduction
α‐Zirconium phosphate (ZP) is one of the most important
compounds in inorganic chemistry, and the layered struc-
ture of this material has been used in a variety of different
fields [1–3]. ZP behaves as a unique ion exchanger because
of its exceptionally poor aqueous solubility, high thermal
stability, resistance to radiation and abrasive properties [4,
+
*
Abdol Reza Hajipour
haji@cc.iut.ac.ir
5]. The H of the P–OH moiety in ZP can be exchanged
for various other ions, which results in the enlargement of
the interlayer distance [6–9]. Several studies pertaining to
the successful exchange of the H of the P–OH group in
1
Pharmaceutical Research Laboratory, Department
of Chemistry, Isfahan University of Technology,
+
8
4156 Isfahan, Islamic Republic of Iran
ZP with various divalent and trivalent cations have been
reported in the literature [10–14]. It has also been reported
2
3
Department of Neuroscience, University of Wisconsin,
Medical School, Madison, WI 53706-1532, USA
2
+
2+
that ZP possesses excellent selectivity towards Pb , Zn ,
3
+
and Fe as an ion exchanger [15–17]. Furthermore, ZP
has been reported to exhibit antibacterial activity when it
Young Researchers and Elite Club, Shahreza Branch, Islamic
Azad University, Shahreza, Iran
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J IRAN CHEM SOC
was loaded with Cu2+, Zn , or Ce [5, 6, 13, 14]. Several
reports have also appeared in the literature concerning the
catalytic activities of ion exchanged materials of this type,
including the use of zinc zirconium phosphate (ZPZn) as a
catalyst in the acetylation of alcohols and phenols and the
use of a copper zirconium phosphate (ZPCu) as catalysts in
selective oxidation of alcohols [18–24].
2+
3+
catalysts and procedures capable of promoting the acety-
lation process. With growing environmental concerns, one
of the most promising ways to achieve these goals seems
to be the use of green and insoluble catalysts or of ecof-
riendly solvent-free conditions. When an insoluble catalyst
is used, it can be easily recovered from the reaction mix-
ture by simple filtration and recycled and can be reused
several times, making the process more economically and
environmentally viable. Furthermore, the reported exam-
ples have demonstrated that heterogeneous catalysts typi-
cally require easier work-up procedures. Also, solvent-free
synthetic methods are valuable for environmental and eco-
nomical reasons [22, 24]. With this in mind, and as part of
ongoing work towards the development of efficient green
catalysts for organic transformations [64, 65], with particu-
lar emphasis on the acetylation and acylation of aromatic
compounds [52, 53], we report herein the use of nickel zir-
conium phosphate (ZPNi) as an efficient catalyst for the
mild and convenient acetylation of alcohols and phenols
under solvent‐free conditions. This new ZPNi catalyst was
characterized by inductively coupled plasma optical emis-
sion spectroscopy (ICP‐OES), X‐ray diffraction (XRD),
Protection and deprotection of organic functions are
important processes during multi-step organic synthesis.
The choice of a method for the functional group’s transfor-
mations depends on its simplicity, high yields of the desired
products, short reaction times, low cost of the process, and
ease of the work-up procedures [25, 26]. The acetylation
of alcohols, phenols, thiols, and amines is one of the most
important and frequently used transformations in organic
synthesis, especially in the synthesis of natural compounds,
biologically active compounds, and polyfunctional mol-
ecules such as nucleosides, carbohydrates, chalcones,
flavanones, naphthoquinones, pesticides, and steroids.
Acetylated groups are also commonly found in cosmetics
and foodstuffs, as well as solvents, perfumes, plasticiz-
ers, flavors, polymers, and pharmaceuticals [25–27]. One
of the most common examples of a compound containing
an acetylated group is aspirin, which is produced by the
acetylation of salicylic acid with acetic anhydride (AA) in
the presence of an acid catalyst [28]. The acetyl group is
one of the most inexpensive and commonly used protect-
ing groups in organic chemistry for the protection of –OH,
N
adsorption–desorption, scanning electron microscopy
2
(SEM), and transmission electron microscopy (TEM).
Experimental
–
SH, and –NH functional groups because the resulting
Catalyst synthesis
2
acetylated compounds are stable to various reaction con-
ditions and reagents. Furthermore, the acetyl group can be
readily introduced using inexpensive reagents and easily
removed using mild alkaline hydrolysis [29–31]. A vari-
ety of different procedures have been developed for the
acetylation of alcohols, phenols, amines, and thiols using
both homogeneous and heterogeneous catalysts such as
All of the reagents and solvents used in the current study
were purchased from Merck Chemical Company and used
without further purification. The catalyst was prepared
according to previously published procedures, with minor
modifications [2, 8–10]. ZP was prepared according to the
following procedure. ZrOCl 8H O (5 g) was heated at
2
2
IV
V (TPP)(OTf) [27], La(NO ) 6H O [29], B(C F ) [30],
reflux in a solution of H PO (50 ml, 12 mol/L) for 24 h.
2
3 3
2
6
5 3
3 4
CuSO 5H O [31], ZnCl [32], borated zirconia [33], ZnO
2
The resulting mixture was cooled to ambient temperature
to give a suspension, which was filtered, and the filter cake
was then washed with a solution of H PO (0.1 mol/L)
until the filtrate was free of chloride ions. The filter cake
was then washed several times with distilled water until the
pH of the filtrate was neutral. The solid was then collected
and dried in an oven at 110 °C for 24 h [2]. ZPNi was pre-
pared through an ion‐exchange reaction [8–10]. Briefly, ZP
(3 g) was dispersed in deionized water (50 ml) at 50 °C,
and the resulting suspension was treated with a solution of
4
2
2
[
34], Ce(OTf) [35], SiO –ZnCl [36], H PW O [37],
3 2 2 3 12 40
DMAP HCl [38], Cu(BF ) [39], silica‐bonded sulfamic
4
2
3
4
acid [40], Cp ZrCl [41], [TMBSA][HSO ] [42], [bmim]
2
2
4
[
[
OTs] [43], [MMPPA][HSO ] [44], SaSA [45], SBNPSA
4
46], SuSA [47], P(4‐VPT) [48], acylimidazolium ace-
tate [49], polyvinylpolypyrrolidoniume tribromide [50],
ZnAl O @SiO [51], P O /Al O [52], [Hmim]HSO [53],
2
4
2
2
5
2
3
4
Yttria‐zirconia [54], CoCl [55], MWCNTs–C–PO H
2
3
2
[
56], NiCl [57], Ni/SiO [58], DBSA [59], Rice husk [60]
anhydrous NiCl [61], LaFeO /SiO [62], and Fe/SBA-15
2 2
Ni(OAc) (100 ml, 0.1 mol/L) in water (excess amount of
2
3
2
2
2
+
[
63]. However, most of these catalysts have advantages
Ni ). This mixture was then heated at reflux for 4 days.
It is noteworthy that the acetate ion performed effectively
as a base to keep the hydrogen ion concentration in solu-
tion sufficiently low to achieve high loadings of the cata-
lyst [7]. A complete exchange between the cations and the
and limitations. Despite extensive interest in the develop-
ment of new methods of acetylation, there is still scope
for the development of simple, efficient, inexpensive,
widely applicable, reusable, and environmentally benign
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J IRAN CHEM SOC
completion of the reaction (as determined by GC), the cata-
lyst was separated from the reaction mixture by centrifuge,
then the supernatant was collected and diluted with 10 %
NaHCO solution (10 ml) before being extracted with Et O
3
2
(
2 × 10 ml). The combined organic extracts were washed
and then dried over anhydrous CaCl before being evapo-
2
rated to dryness under vacuum to give the desired product.
In some cases, it was necessary for the product to be puri-
fied by column chromatography over silica gel eluting with
a mixture of cyclohexane and ethyl acetate.
Scheme 1 Procedure for the preparation of ZPNi
Recyclability studies of catalyst
hydrogen ions of the P–OH groups could not be achieved
in less than 3 days or at temperatures below 80 °C [13].
The resulting slurry was filtered hot to give a light green
solid, which was washed with distilled water until no Ni2+
ions could be detected in the filtrate (i.e., until the filtrate
was colorless). The solid product was then dried at 100 °C
for 24 h before being calcined at 600 °C for 4 h to give the
final product, ZPNi, as a pale green solid (Scheme 1).
To examine the recyclability of the catalyst, the used ZPNi
was recovered from the reaction media and re-used. For
recycling, after the first use, the catalyst was separated from
the reaction mixture by centrifugation, washed sequentially
with ethanol and water before being dried at 110 °C for 2 h,
and then activated at 450 °C for 2 h.
Catalyst characterization
Results and discussion
The chemical composition of the ZPNi catalyst was evalu-
ated at different stages of the reaction (i.e., before and
after the catalytic reaction) by ICP-OES using an Optima
Catalyst characterization results
The ICP-OES analyses of ZP and ZPNi are shown in
Table 1. The results obtained in the current study for ZPNi
were compared with those reported previously in the litera-
ture [8–10]. Our results revealed that there was a negligible
leach of nickel ions into the reaction media after the reac-
tion (i.e., following the first use of the catalyst).
7
300 V ICP-OES spectrometer (PerkinElmer). The samples
were ground into a fine powder and analyzed by XRD on
a Philips X’pert X-ray diffractometer. The specific surface
areas of the samples were determined from their N adsorp-
2
tion–desorption isotherms using the Brunauer-Emmett-
Teller (BET) method on a Quantachrome ChemBET 3000
instrument. Each sample was degassed at 400 °C for 2 h
before being analyzed to remove any adsorbed species
from their surfaces. The BET surface areas of the materi-
Figure 1 shows the powder XRD patterns of the ZP
and ZPNi materials. The results show some characteristic
reflections in the 2θ range of 5°–40°. The diffraction peak
in ZP at 2θ–12° was assigned to a d002 basal spacing of
7.5 Å between the planes, which was consistent with the
patterns previously reported for ZP and its derivatives with
a hexagonal crystal system [2]. It shows that the d-spacing
of the (002) plane of ZPNi had increased, which indicated
als were estimated from their N adsorption–desorption
2
isotherms. The surface morphologies of the ZP and ZPNi
materials were studied by SEM on a Philips XL scabbing
electron microscope (Philips). TEM images of ZPNi were
obtained on a CENTRA 100 TEM system (Zeiss).
2
+
that the Ni ions had intercalated into the interlayer of ZP
and increased the d002 basal interlamellar spacing of ZP
2
+
General experimental procedure for the acetylation
from 7.5 to 9.8 Å. It is well known that the ion radii of Ni
of substrates under solvent‐free conditions
Table 1 Element contents of ZPNi (atm. %)
ZPNi (1 mol %) was added to a mixture of alcohol
Entry
Sample
Cu
O
Zr
P
(
1 mmol) and AA (2 mmol), and the resulting mixture was
stirred at 40 °C for the specified time (Scheme 2). Upon
1
2
3
4
ZP
–
63.1
58.7
59.3
62.5
13.6
10.9
10.4
12.2
23.3
18.7
18.7
19.4
ZPNi
ZPNia
ZPNib
11.7
11.6
5.9
a
After run 1
b
Scheme 2 Summarized procedure for acetylation of phenols
After run 7
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J IRAN CHEM SOC
ZPNi shows three adsorption stages. The first of these
stages was observed at p/p < 0.37, whereas the second
0
stage was observed in the range of 0.37 < p/p < 0.93, and
0
the third stage was observed at higher relative pressures
(
p/p > 0.93). The N adsorption–desorption isotherm of
0 2
ZPNi exhibited a typical “type IV” isotherm shape with
a distinct hysteresis loop, which is characteristic of a
mesoporous material [68].
The hysteresis loop (type H3) is associated with the
occurrence of capillary condensation in the mesopores,
which indicates the presence of a mesoporous structure
in the ZPNi catalyst. The observed increase in adsorption
at the higher p/p value indicated the presence of larger
0
mesopores in the sample [9].
Fig. 1 XRD patterns of powder ZP (down), ZPNi fresh (middle) and
ZPNi after 7th run (up)
The surface area of ZPNi after the 7th run was found
2
to be 85.4 m /g. The SEM image of ZP (Fig. 3a) revealed
the presence of hexagonal plates with well-defined shapes
and very smooth surfaces. Figure 3b and c show the SEM
images of ZPNi. These images revealed that the structure
of ZPNi was much less ordered than that of ZP, and that
the ZPNi particles had aggregated to form both sheets and
spheres of different shapes and sizes [9]. Figure 4 shows
the TEM images of ZPNi. It shows that ZPNi catalyst
retained the original morphology of ZP (layered structure)
and that the particles were approximately 150 nm in size.
These images also showed nanoparticles of different sizes
on the smooth surface of the ZP. The presence of metal-
lic crystal nanoparticles on the surface of ZP indicated that
the nickel deposited on the surface of the ZP had agglomer-
ated. Similar observations have also been reported for zinc
and cerium with ZP [6, 14]. Figures 3d and 4c show the
SEM and TEM images of the catalyst following its 7th run,
respectively. Both of these images showed that the sheets
and particles had conglomerated to a much greater extent
following the 7th run because of the process used to regen-
erate the catalyst.
Fig. 2 N adsorption–desorption isotherm of ZPNi
2
(
0.69 Å) and hydrated Ni2+ (4.04 Å) are smaller than the
basal spacing of ZP (7.5 Å) [66, 67].
These results therefore indicated that Ni2 ions had
inserted into the interlayer of ZP and increased the basal
spacing of the modified ZP after the exchange [8–10].
Taken together, these data indicated that ZPNi had been
formed successfully. The XRD pattern of the ZPNi cata-
lyst after the 7th run showed that the basal spacing of ZP
was about 10.1 Å, which was only a little larger than that
of the fresh ZPNi catalyst. This increase may have occurred
+
Catalytic activity of ZPNi towards the acetylation
of phenols and its expected mechanism
The conversion of phenol (1 mmol) to phenyl acetate was
selected as a model reaction to optimize the conditions,
and the reaction was conducted in the presence of ZPNi
(1 mol %) and AA (2 mmol) in various solvents, as well as
being investigated under solvent-free conditions. As shown
in Table 2, the use of ZPNi as a catalyst under solvent-
free conditions provided higher yields and shorter reaction
times than those achieved under conventional conditions.
With the optimized conditions in hand, we proceeded
to evaluate the scope and generality of the method using
various alcohols and phenols (Table 3). Pleasingly, the
hydroxyl groups of the all of different alcohols and phe-
nols tested were converted to the corresponding acetates in
2
+
because of the presence of less Ni on the surface of ZP,
and an increase in the number of water molecules between
2
+
the layers following the seventh run (i.e., Ni ions may
have been washed off during the regeneration of the cata-
lyst, see “General experimental procedure for the acety-
lation of substrates under solvent-free conditions” and
Table 1). Figure 2 shows the N2 adsorption–desorption
isotherm of ZPNi, as a representative example, in the rela-
tive pressure range (p/p ) of 0.1–1.0. The surface area of
0
2
ZPNi was determined to be 103.1 m /g. The isotherm for
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J IRAN CHEM SOC
Fig. 3 SEM images of regular morphology of prepared ZP (a), ZPNi fresh (b, c), and after 7th run (d)
Fig. 4 TEM images of regular morphology of prepared ZPNi fresh (a, b) (different magnification) and after the 7th run (c)
good yields and short reaction times using 3 or 4 equiva-
lents of AA (Table 3, entries 8–10, 20). Furthermore, the
products were readily isolated from the reaction mixtures
by a simple filtration followed by a standard work-up pro-
cedure. Phenols reacted smoothly under the optimized
conditions (Table 3, entries 1–15), with the correspond-
ing acetates being formed in yields of 83–96 %. Further-
more, no by-products (such as those resulting from a Fries
rearrangement) were observed with the substituted phe-
nols. The presence of electron-donating substituents (i.e.,
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J IRAN CHEM SOC
Table 2 Conversion of phenol to phenylacetate in different solvents
and under solvent-free conditions in the presence of ZPNi (1 mol %)
group in the para-position is faster than those with electron-
withdrawing groups. The acetylation of primary amines
was significantly faster than that of secondary amines
Entry
Solventa
Yield (%)b
Time (min)
(
Table 3, entries 31, 32). In contrast, the rate of acetylation
1
2
3
4
5
Dichloromethane
Diethylether
Acetonitrile
Trace
Trace
Trace
47
120
120
120
75
of thiols is lower than that of phenols and amines.
A schematic representation of the ZPNi-mediated acety-
lation process is shown in Scheme 3. To develop a deeper
understanding of the role of the ZPNi catalyst in the acety-
lation reaction, we investigated the acetylation of phenol,
4-hydroxyphenol, and benzyl alcohol in the absence of the
catalyst. As expected, no products were formed in any of
these reactions, which demonstrated the importance of the
catalyst in the acetylation process.
Cyclohexane
Solvent-freec
91
15
a
The reaction was carried out in 5 ml of solvents at reflux condi-
tions
b
The yields refer to isolated pure products
The reaction was carried out at 40 °C
c
All of the acetylated products formed in the current
study were characterized by GC–MS (Agilent 5975C spec-
trometer), FT-IR (JASCO FT-IR 680 plus spectrophotome-
–
CH , –OCH , –OH) on the phenol ring led to a significant
3
3
1
increase in the rate of the acetylation reaction (Table 3,
entries 2–10), with shorter reaction times being observed
in these cases. In contrast, the presence of electron-with-
drawing groups (i.e., carboxyl, nitro, and halo groups) on
the phenol ring led to a decrease in the rate of the acetyla-
tion reaction (Table 3, entries 11–15), with longer reaction
times being observed. The optimized reaction conditions
were also successfully applied to the acetylation of ben-
zylic alcohols bearing an electron-withdrawing or electron-
donating group without the formation of any by-products
resulting from oxidation reactions (Table 3, entries 17–22).
For deactivated aromatic rings (Table 3, entries 21 and 22),
the acetylated products were obtained in much lower yields
and required longer reaction times than the corresponding
activated aromatic systems (Table 3, entries 18–20). The
reaction times required for the acetylation of the phenols
were longer than those required for the benzylic alcohols.
This difference in the reaction times was attributed to the
low nucleophilicity of phenols compared to benzylic alco-
hols because of the delocalization of the lone pairs of elec-
trons on the phenolic oxygen throughout the benzene ring
ter; JASCO), and H NMR (Bruker-Avance AQS 400 MHz
spectrometer) analyses and a comparison of these data with
those of standard samples or data from the literature [28,
44, 45, 47–53]. The reusability of the ZPNi catalyst was
investigated under the optimum reaction conditions for the
acetylation of phenol, and the results are shown in Table 4.
The elemental composition of the catalyst remained largely
unchanged following its 7th run, although the amount of
nickel in the catalyst was reduced by almost 50 % com-
pared with the first run (Table 1). The recycled ZPNi cat-
alyst gave a similar product yield to the freshly prepared
catalyst up until the sixth cycle.
The catalytic efficiency of ZPNi was compared with
several previously reported catalysts and protocols, and
the results are shown in Table 5. Phenol was converted
to acetylphenol in 91 % yield following a reaction time
of less than 15 min at 40 °C using the current protocol
(Table 5, entry 18). Although some of the other catalysts
performed well for the same reaction (Table 5, entries 2,
6, 10), they invariably required longer reaction times to
reach completion (Table 5, entries 3, 6, 7, 9, 11, 13, 14) or
required the use of a solvent (Table 5, entries 4, 6, 7, 9, 12).
It is noteworthy that the more reactive acetyl chloride was
required in one case, where it was used at room tempera-
ture (Table 5, entry 5). Furthermore, this reaction required
a longer reaction time to reach afford a similar yield of the
acetylated product to the current protocol.
[
43, 49, 51]. To further extend the scope of the ZPNi cata-
lyst, we also investigated the acetylation of several aliphatic
alcohols, including 1-hexanol, cyclohexanol, 3-methyl-
1
-butanol, and tert-butanol, under the optimized condi-
tions (Table 3, entries 23–26). The acetylation reactions
of 1-hexanol cylohexanol, 3-methyl-1-butanol proceeded
much more rapidly than the acetylation of tert-butanol,
most likely because of the steric hindrance provided by the
tert-butyl group.
Some of the previously reported protocols used ace-
tic acid as the acetylating agent, representing a much
greener choice than acetyl chloride (Table 5, entries 4, 8,
15), although these reactions required long reaction times
(3–15 h), high temperatures (70–110 °C), and a large
excess of acid acetic in almost all cases. The acetylation of
phenol was also investigated using ZrOCl 8H O, and ZP
Also, we extended the use of ZPNi for direct acetyla-
tion of some thiols (Table 3, entries 27–30) and amines
(
Table 3, entries 31–36) with AA. Excellent results were
obtained with one equivalent of AA in the presence of
ZPNi. It is obvious that the acetylation rate was influenced
by the electronic factors associated with the substrates. The
acetylation of thiols and amines with the electron-donor
2
2
under our optimized reaction conditions (Table 5, entries
19 and 20). ZrOCl 8H O gave an excellent yield of the
2
2
desired product, but was much more difficult to recover
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J IRAN CHEM SOC
Table 3 Acetylation of phenols, thiols, and amines with AA catalyzed by ZPNi under solvent-free conditions
Entry
Substrate
C H OH
Producta
Time (min)
Temperature (°C)
Mole ratiob
Yield (%)c
1
2
3
4
5
6
7
8
9
C H OAc
15
15
10
30
10
10
10
15
15
30
45
45
45
35
30
15
15
15
10
10
15
15
10
10
10
20
20
15
15
45
10
45
10
10
30
45
40
40
40
40
40
40
40
40
40
40
60
60
60
60
60
40
40
40
40
40
40
40
40
40
40
40
40
40
40
60
40
60
40
40
40
60
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:3
1:3
1:4
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:3
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
91
93
96
88
95
95
95
92
89
90
83
85
83
90
92
92
91
92
94
92
88
85
94
93
95
89
87
89
90
86
90
82
93
95
85
81
6
5
6
5
2-Me–C H OH
2-Me–C H OAc
6 4
6
4
4-Me–C H OH
4-Me–C H OAc
6 4
6
4
2,6-(Me) –C H OH
2,6-(Me) –C H OAc
2 6 3
2
6
3
2,4-(Me) –C H OH
2,4-(Me) –C H OAc
2 6 3
2
6
3
4-(CH ) C–C H OH
4-(CH ) C–C H OAc
3 3 6 4
3
3
6
4
4-MeO–C H OH
4-MeO–C H OAc
6 4
6
4
4-OH–C H OH
4-AcO–C H OAc
6 4
6
4
3-OH–C H OH
3-AcO–C H OAc
6 4
6
4
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
2,3-di-OH–C H OH
2,3-di-AcO–C H OAc
6
3
6
3
4-Cl–C H OH
4-Cl–C H OAc
6
4
6
4
4-Br–C H OH
4-Br–C H OAc
6 4
6
4
4-NO –C H OH
4-NO –C H OAc
2 6 4
2
6
4
2-OH–C H CO H
2-AcO–C H CO H
6 4 2
6
4
2
4-OH–C H CO H
4-AcO–C H CO H
6 4 2
6
4
2
2-Naphthol
2-Naphthyl acetate
C H CH OAc
C H CH OH
6
5
2
6
5
2
2-MeO–C H CH OH
2-MeO–C H CH OAc
6 4 2
6
4
2
4-MeO–C H CH OH
4-MeO–C H CH OAc
6 4 2
6
4
2
4-OH–C H CH OH
4-AcO–C H CH OAc
6 4 2
6
4
2
4-Cl–C H CH OH
4-Cl–C H CH OAc
6 4 2
6
4
2
4-NO –C H CH OH
4-NO –C H CH OAc
2 6 4 2
2
6
4
2
1-Hexanol
Cyclohexanol
1-Hexyl acetate
Cyclohexyl acetate
3-Methyl-1-butanol
(CH ) C–OH
3-Methylbutyl acetate
(CH ) C–OAc
3
3
3 3
C H SH
C H SAc
6
5
6
5
C H –CH SH
C H –CH SAc
6 5 2
6
5
2
4-Me–C H SH
4-Me–C H SAc
6 4
6
4
4-Cl–C H SH
4-Cl–C H SAc
6 4
6
4
C H NH
C H NHAc
6 5
6
5
2
(C H ) NH
(C H ) NAc
6 5 2
6
5 2
C H –CH NH
C H –CH NHAc
6 5 2
6
5
2
2
4-Me–C H NH
4-Me–C H NHAc
6 4
6
4
2
4-Br–C H NH
4-Br–C H NHAc
6 4
6
4
2
4-NO –C H NH
4-NO –C H NHAc
2 6 4
2
6
4
2
a
b
c
1
All products were characterized by GC–MS, IR, and H NMR spectral data and comparison with those of authentic samples or reported data
Substrate AA mole raio
Isolated yield
and reuse than the ZPNi catalyst. ZP gave a lower yield
70 %) than ZPNi. The use of ZPZn as a catalyst, however,
provided a similar result to that of ZPNi (Table 5, entry
), with a 20 mol % loading of ZPZn providing the acetyl
phenol product in 89 % yield following a reaction time of
5 min [22]. Moreover, ZPNi was compared with two other
Ni-containing catalyst, NiCl and Ni/SiO as well (Table 5,
was identified the best catalyst for this transformation in
terms of the reaction time and the loading of the catalyst.
Benzyl alcohol was also acetylated under the optimized
conditions to give the acetylated product in 91 % yield fol-
lowing a reaction time of 15 min at 40 °C (Table 5, entry
35). This protocol was also compared with a variety of dif-
ferent previously reported procedures for the same trans-
formation, and the results are shown in Table 5. When the
(
1
4
2
2
entries 16 and 17). Based on this comparison process, ZPNi
1
3

J IRAN CHEM SOC
1
4
-Cl–C H OAc (Table 3, entry 9). H NMR (400 MHz,
6 4
CDCl ): δ = 7.43 (d, J = 8.4 Hz, 2H) 6.75 (d, J = 8.4 Hz,
3
2
1
7
H), 2.24 (s, 3H); IR (KBr): υ = 3075, 2939, 1765, 1641,
591, 1488, 1370, 1200, 1163, 1014, 941, 845, 798,
−1
20 cm
.
2
-AcO–C H CO H (Table 3, entry 12). 1H NMR
6
4
2
(
2
1
400 MHz, CDCl ): δ = 10.4 (s, 1H), 7.95–7.12 (m, 4H),
3
.35 (s, 3H); IR (KBr): υ = 3426–2996, 2872, 1752, 1687,
−
1
607, 1458, 1306, 1188, 917, 753, 706 cm
.
4
-MeO–C H CH OAc (Table 3, entry 17). 1H NMR
6
4
2
(
400 MHz, CDCl ): δ = 7.15 (d, J = 8.5 Hz, 2H), 6.78 (d,
3
Scheme 3 Summarized procedure for acetylation of phenols
J = 8.5 Hz, 2H), 5.0 (s, 2H), 3.65 (s, 3H), 2.2 (s, 3H); IR
(
KBr): υ = 3011, 2943, 2826, 1729, 1613, 1518, 1460,
−1
reaction was conducted at room temperature in the pres-
ence of a different catalyst, it generally required longer
reaction times to reach completion (Table 5, entries 23,
1363, 1243, 1176, 1120, 1031, 960, 823 cm
.
3-Methylbutyl acetate (Table 3, entry 23). 1H NMR
(400 MHz, CDCl ): δ = 4.18 (t, J = 6.6 Hz, 2H), 2.1 (s,
3
2
7–29, 33). The use of ZPZn, ZrOCl 8H O, or ZP as a cat-
3H), 1.58–1.67 (m, 1H), 1.43–1.5 (m, 2H), 0.96 (d, J = 3.4,
6H); IR (KBr): υ = 2962, 2935, 1743, 1465, 1430, 1249,
2
2
alyst under the optimized conditions provided the desired
product in yields of 91, 90, and 75 %, respectively (Table 5,
entries 21, 36, 37). However, large excesses of the catalyst
were required in all three of these cases, and significant
difficulties were encountered during the recovery of these
catalysts. These reactions also resulted in lower yields of
the product. There were, however, some benefits to using
these catalysts, in that they used acid acetic as an acetylat-
ing agent instead AA, but they all required longer reaction
times, higher temperatures, and a large excess of acid ace-
tic to reach completion (Table 5, entries 24 and 32).
−1
1172, 1136, 1065, 962, 857 cm
.
1
4-Cl–C H SAc (Table 3, entry 30). H NMR (400 MHz,
6
4
CDCl ): δ = 8.24 (d, J = 8.9 Hz, 2H). 7.61 (d, J = 8.9 Hz,
3
2H), 2.49 (s, 3H); IR (KBr): υ = 1745, 1503, 1222, 1198,
−1
980, 750 cm
.
4-NO –C H NHAc (Table 3, entry 34). 1H NMR
2
6
4
(400 MHz, CDCl ): δ = 7.43 (br s, 1H), 7.37 (d,
3
J = 8.4 Hz, 2H), 7.12 (d, J = 8.2 Hz, 2H), 2.32 (s, 3H),
2.16 (s, 3H).; IR (KBr): υ = 3361, 2916, 2849, 1702, 1685,
1610, 1597, 1443, 1408, 1368, 1314, 1253, 1175, 1118,
1
−1
H NMR and FT-IR spectral data of the selected com-
1000, 856, 768 cm
.
pounds from Table 3 are as follows:
C H OAc (Table 3, entry 1). 1H NMR (400 MHz,
6
5
CDCl ): δ = 7.2 (t, J = 7.9 Hz, 2H), 7.1 (t, J = 7.5 Hz, 1H),
Conclusions
3
7
2
7
.0 (t, J = 7.9 Hz, 2H), 2.3 (s, 3H); IR (KBr): υ = 3055,
915, 1753, 1581, 1485, 1364, 1179, 1014, 916, 876, 804,
ZPNi is an inexpensive, noncorrosive, and environmen-
tally benign catalyst that can be readily prepared from
simple starting materials. This catalyst was characterized
using various analytical methods and the results were in
agreement with those reported previously in the literature.
In this study, we have developed a simple and efficient
procedure for the acetylation of a variety of different alco-
hols in good yields over short reaction times. There are
several notable advantages to this methodology, including
a broad substrate scope, the use of AA as an acetylating
agent, excellent product yields, and easy work-up proce-
dure resulting from the heterogeneous conditions.
−1
39, 675 cm
.
1
4
-Me–C H OAc (Table 3, entry 3). H NMR (400 MHz,
6
4
CDCl ): δ = 7.04 (d, J = 7.9 Hz, 2H), 6.82 (d, J = 7.9 Hz,
3
2
1
9
H), 2.35 (s, 3H), 2.27 (s, 3H); IR (KBr): υ = 3045, 2936,
773, 1608, 1515, 1442, 1378, 1207, 1187, 1173, 1014,
−
1
47, 915, 832, 816 cm
.
4
-(CH ) C–C H OAc (Table 3, entry 6). 1H NMR
3
3
6
4
(
(
400 MHz, CDCl ): δ = 7.37 (d, J = 8.25 Hz, 2H), 7.18
3
d, J = 8.25 Hz, 2H), 2.27 (s, 3H), 1.24 (s, 9H); IR (KBr):
υ = 3052, 2971, 2918, 1759, 1600, 1517, 1448, 1373,
−
1
1
279, 1211, 1116, 1026, 924, 841, 686 cm .
Table 4 The catalyst re-used under the optimum reaction conditions for acetylation of phenol
Substratea
Fress
91
Run 1
91
Run 2
89
Run 3
88
Run 4
87
Run 5
84
Run 6
81
Run 7
71
Phenol
a
Reaction conditions: phenol (1 mmol), AA (2 mmol), catalyst (1 mol %), 40 °C
1
3

J IRAN CHEM SOC
Table 5 Comparison of protocols for the acylation of phenol and benzyl alcohol
Entry
Catalyst
T (°C)
Time (min)
AA (equiv.)
Yield%
Solvent
Ref
1
2
3
4
5
6
7
8
9
ZPZn
60
R T
R T
110
R T
R T
80
45
15
150
14 (h)
60
150
210
180
10 (h)
30
180
10
120
180
15 (h)
240
30
15
15
2
1.2
1
89
92
40
10
90
98
83
3
99
97
-
97
99
-
77
90
95
91
92
70
-
[22]
[30]
B(C
6
F
5
)
3
-
ZnCl
2
-
[32]
a
Borate zirconia
5
Toluene
-
[33]
b
ZnO
1.2
[34]
Ce(OTf)
SiO -ZnCl
3
1.5
1.2
CH
CH
3
CN
[35]
2
2
3
CN
[36]
a
H
3
PW12
O
40
70
5
-
[37]
DMAP·HCl
Cu(BF4)
R T
R T
R T
50
R T
R T
110
65
R T
40
1.1
1
3 ml
Toluene
[38]
10
11
12
13
14
15
16
17
18
19
2
-
-
[39]
c
silica sulfamic acid
[40]
[bmim][OTs]
2
[bmim][BF
4
]
[43]
[MMPPA][HSO
SBNPSA
4
]
1.5
3 ml
-
-
-
[44]
c
[46]
a
Yttria–zirconia
5
[54]
Ni/SiO
NiCl
ZPNi
2
1.5
4
CH
3
CN
[58]
2
-
-
-
[61]
2
2
This work
This work
This work
ZrOCl
2
ZP
·8H
2
O
40
40
2
0
15
2
-
2
2
2
2
2
2
1
2
3
4
5
6
ZPZn
60
R T
R T
110
80
30
2
180
14 (h)
180
15
600
120
120
120
45
240
240
30
15
15
2
1.2
1a
91
98
63
25
90
93
93
99
99
85
91
94
98
98
91
90
-
-
[22]
[30]
B(C
6
F
5 3
)
ZnCl
borated zirconia
SiO -ZnCl
silica sulfamic acid
Cp ZrCl
2
[32]
5
Toluene
CH CN
[34]
2
2
1.2
3
[36]
c
R T
R T
R T
R T
reflux
R T
110
R T
R T
40
3ml
-
-
-
-
[40]
27
28
29
30
31
32
33
34
35
36
2
2
1
[41]
[TMBSA][HSO
4
]
4
1.1
1.1
1.2
[42]
[MMPPA][HSO
SaSA
]
[44]
CH
2
Cl
2
[45]
c
SBNPSA
3 ml
-
[46]
a
Yttria–zirconia
5
-
-
-
-
-
[54]
CoCl
NiCl
ZPNi
2
2
4
2
2
[55]
2
[61]
This work
40
40
This work
ZrOCl
2
ZP
·8H
2
O
3
7
15
2
75
-
This work
R T room temperature
a
Acetic acid as the acetylating agent
Acetyl chloride as the acetylating agent
Ethyl formate as the acetylating agent
b
c
1
3

J IRAN CHEM SOC
Acknowledgments We gratefully acknowledge the funding support
received for this project from the Isfahan University of Technology
31. M.M. Heravi, F.K. Behbahani, V. Zadsirjan, H.A. Oskooie, J.
Braz. Chem. Soc. 17, 1045 (2006)
(
IUT), IR Iran.
32. P. Yadav, R. Lagarkha, Z.A. Balla, Asian J. Chem. 22, 5155
(
2010)
3. L. Osiglio, G. Romanelli, M. Blanco, J. Mole. Catal. A Chem.
16, 52 (2010)
4. F. Tamaddon, M.A. Amrollahi, L. Sharafat, Tetrahedron Lett. 46,
841 (2005)
3
3
3
References
7
1
.
.
F. Li, M. Wei, J. He, Y. Du, P. Sun, D.G. Evans, X. Duan, Chin. J.
Catal. 20, 514 (1999)
L. Sun, W.J. Boo, H.J. Sue, A. Clearfield, New J. Chem. 31, 39
35. R. Dalpozzo, A. De Nino, L. Maiuolo, A. Procopio, M. Nardi, G.
Bartoli, R. Romeo, Tetrahedron Lett. 44, 5621 (2003)
36. R. Gupta, V. Kumar, M. Gupta, S. Paul, R. Gupta, Indian J.
Chem. Sec. B 47, 1739 (2008)
2
(2007)
3
4
.
.
A.R. Hajipour, H. Karimi, Mater. Lett. 116, 356 (2014)
V.I. Pet’kov, A.V. Markin, I.A. Shchelokov, M.V. Sukhanov,
N.N. Smirnova, Russ. J. Phys. Chem. 81, 1728 (2007)
Q. Shi, S. Tan, Y. Ouyang, Q. Yang, A. Chen, W. Li, X. Shu, J.
Feng, J. Fang, Y. Chen, Adv. Matter. Sci. 150–151, 852 (2011)
X. Cai, G.J. Dai, S.Z. Tan, Y. Ouyang, Y.S. Ouyang, Q.S. Shi,
Mater. Lett. 67, 199 (2012)
37. R. Tayebee, F. Cheravi, Bull. Korean Chem. Soc. 30, 2899
(2009)
38. Z. Liu, Q. Ma, Y. Liu, Q. Wang, Org. Lett. 16, 236 (2014)
39. A.K. Chakraborti, R. Gulhane, Shivani, Synthesis 111 (2004)
40. K. Niknam, D. Saberi, Appl. Catal. A 366, 220 (2009)
41. M. Lakshmi Kantam, K. Aziz, P.R. Likhar, Catal. Commun. 7,
484 (2006)
42. W. Wang, W. Cheng, L. Shao, J. Yang, Catal. Lett. 121, 77 (2008)
43. Y. Liu, L. Liu, Y. Lu, Y.Q. Cai, Monatsh. Chem. 139, 633 (2008)
44. C. Yue, Q. Liu, T. Yi, Y. Chen, Monatsh. Chem. 141, 975 (2010)
45. F. Shirini, M.A. Zolfigol, M. Abedini, Monatsh. Chem. 140,
1495 (2009)
5
6
7
8
.
.
.
.
A. Clearfield, J.M. Kalnins, J. Inorg. Nuc. Chem. 40, 1933
(1978)
S. Allulli, C. Ferragina, A. La Ginestra, M.A. Massucci, N.
Tomassini, A.A.G. Tomlinson, J. Chem. Soc. Dalton Trans. 2115
(1976)
9
.
B. Shpeizer, D.M. Poojary, K. Ahn, C.E. Runyan Jr, A. Clear-
field, Science 266, 1357 (1994)
46. K. Niknam, D. Saberi, Tetrahedron Lett. 50, 5210 (2009)
47. F. Shirini, N.G. Khaligh, Chin. J. Catal. 34, 695 (2013)
48. M. Hajjami, A. Ghorbani-Choghamarani, M. Norouzi, Chin. J.
Catal. 33, 1661 (2012)
49. N. Nowrouzi, S.Z. Alizadeh, Chin. J. Catal. 34, 1787 (2013)
50. A. Ghorbani-Choghamarani, N. Pourbahar, Chin. J. Catal. 33,
1470 (2012)
51. S. Farhadi, K. Jahanara, Chin. J. Catal. 35, 368 (2014)
52. A. Zarei, A.R. Hajipour, L. Khazdooz, Synth. Commun. 41,
1772 (2011)
53. A.R. Hajipour, L. Khazdooz, A.E. Ruoho, J. Chin. Chem. Soc.
56, 398 (2009)
54. P. Kumar, R.K. Pandey, M.S. Bodas, S.P. Dagade, M.K. Don-
gare, A.V. Ramaswamy, J. Mole. Catal. A Chem. 181, 207 (2002)
55. J. Iqbal, R.R. Srivastava, J. Org. Chem. 57, 2001 (1992)
56. F. Dehghani, A.R. Sardarian, M.M. Doroodmand, J. Iran. Chem.
Soc. 11, 673 (2014)
57. V. Constantinou-Kokotou, A. Peristeraki, Synth. Commun. 34,
4227 (2004)
58. M. Alam, A. Rahman, N.M. Alandis, M.R. Shaik, Arabian J.
Chem. 7, 53 (2014)
1
1
1
1
1
1
1
0. B.G. Shpeizer, P. Sylvester, R.A. Cahill, A. Clearfield, Chem.
Mater. 11, 1201 (1999)
1. G. Alberti, M.G. Bernasconi, U. Costantino, J.S. Gill, J. Chroma-
togr. A 132, 477 (1977)
2. G. Alberti, M. Casciola, U. Costantino, R. Vivani, Adv. Mater. 8,
2
91 (1996)
3. Y. Yang, G. Dai, S. Tan, Y. Liu, Q. Shi, Y. Ouyang, J. Rare Earths
9, 308 (2011)
4. G. Dai, A. Yu, X. Cai, Q. Shi, Y. Ouyang, S. Tan, J. Rare Earths
0, 820 (2012)
5. Q.R. Zhang, W. Du, B.C. Pan, B.J. Pan, W.M. Zhang, Q.J.
Zhang, Z.W. Xu, Q.X. Zhang, J. Hazard. Mater. 152, 469 (2008)
6. U. Costantino, L. Szirtes, E. Kuzmann, J. Megyeri, K. Lázár,
Solid State Ionics 141–142, 359 (2001)
2
3
1
1
1
2
7. S. Khare, R. Chokhare, J. Mole. Catal. A: Chem. 344, 83 (2011)
8. Y. Izumi, Y. Mizutani, Bull. Chem. Soc. Jpn 52, 3065 (1979)
9. M. Iwamoto, Y. Nomura, S. Kagawa, J. Catal. 69, 234 (1981)
0. A.I. Pylinina, I.I. Mikhalenko, Russ. J. Phys. Chem. 87, 372
(
2013)
1. A.I. Pylinina, I.I. Mikhalenko, Russ. J. Phys. Chem. 85, 2109
2011)
2. A. Hajipour, H. Karimi, M. Karimzadeh, Monatsh. Chem. 145,
461 (2014)
2
2
59. M. Esmaeilpour, A.R. Sardarian, Iran. J. Sci. Technol. Trans. A
(
Sci. 38, 175 (2014)
60. F. Shirini, S. Akbari-Dadamahaleh, A. Mohammad-Khah, A.R.
Aliakbar, C. R. Chim. 17, 164 (2014)
1
2
2
3. A.R. Hajipour, H. Karimi, Chin. J. Catal. 35, 1529 (2014)
4. A.R. Hajipour, H. Karimi, Chin. J. Catal. (2014). doi:10.1016/
S1872-2067(14)60185-6
61. G. Meshram, V.D. Patil, Synth. Commun. 39, 4384 (2009)
62. S. Farhadi, K. Jahanara, A. Sepahdar, J. Iran. Chem. Soc. 11,
1103 (2014)
2
2
2
5. H.J. Yoon, S.M. Lee, J.-H. Kim, H.J. Cho, J.W. Choi, S.H. Lee,
Y.S. Lee, Tetrahedron Lett. 49, 3165 (2008)
6. H. Sharghi, M. Jokar, M.M. Doroodmand, Adv. Synth. Catal.
63. F. Rajabi, R. Luque, Catal. Commun. 45, 129 (2014)
64. A.R. Hajipour, H. Karimi, Appl. Catal. A 482, 99 (2014)
65. A.R. Hajipour, H. Karimi, Chin. J. Catal. 35, 1136 (2014)
66. T.A. Egerton, F.S. Stone, J. Chem. Soc. Faraday Trans. 1. 69, 22
(1973)
67. J. Sneddon, Biochem. Pharmacol. 36, 3723 (1987)
68. R. Pierotti, J. Rouquerol, Pure Appl. Chem. 57, 603 (1985)
3
53, 426 (2011)
7. S.A. Taghavi, M. Moghadam, I. Mohammadpoor-Baltork, S.
Tangestaninejad, V. Mirkhani, A.R. Khosropour, Inorg. Chim.
Acta 377, 159 (2011)
2
2
3
8. I. Montes, D. Sanabria, M. García, J. Castro, J. Fajardo, J. Chem.
Educ. 83, 628 (2006)
9. T.S. Reddy, M. Narasimhulu, N. Suryakiran, K.C. Mahesh, K.
Ashalatha, Y. Venkateswarlu, Tetrahedron Lett. 47, 6825 (2006)
0. S.K. Prajapti, A. Nagarsenkar, B.N. Babu, Tetrahedron Lett. 55,
1
784 (2014)
1
3