Catalytic performance of nano-SiO2-supported Preyssler heteropolyacid in esterification of salicylic acid with aliphatic and benzylic alcohols

Article abstract of DOI:10.1016/S1872-2067(10)60219-7

An efficient and environmentally benign procedure for the catalytic esterification of salicylic acid with aliphatic alcohols, C_nH _2n+1OH (n = 1-5) and benzylic alcohols, RC₆H ₄CH₂OH (R = H, NO₂, OCH₃, Br, Cl, Me) was developed using nano-SiO₂-supported Preyssler heteropolyacid both under thermal conditions and microwave irradiation. Silica nanostructures were obtained through a sol-gel method and were characterized by transmission electron microscopy and powder X-ray diffraction. The effects of various parameters such as solvent type, molar ratio of substrates, Preyssler heteropolyacid loading on silica, catalyst amount, temperature, and reaction time were studied and the optimum conditions were obtained. It has been found that the catalyst with 30 wt loading is highly active and shows high yields in esterification reactions. The use of nano-SiO₂-supported Preyssler heteropolyacid coupled with microwave irradiation allows a solvent-free, rapid (3 min), and high-yielding reaction. This catalyst can be easily recovered and reused for many times without a significant loss in its activity.

Full text of DOI:10.1016/S1872-2067(10)60219-7

CHINESE JOURNAL OF CATALYSIS
Volume 32, Issue 5, 2011
Online English edition of the Chinese language journal
Cite this article as: Chin. J. Catal., 2011, 32: 782–788.
RESEARCH PAPER
Catalytic Performance of Nano-SiO2-Supported Preyssler
Heteropolyacid in Esterification of Salicylic Acid with
Aliphatic and Benzylic Alcohols
Fatemeh F. BAMOHARRAM1,*, Majid M. HERAVI2, Javad EBRAHIMI1, Ali AHMADPOUR3,
Mojtaba ZEBARJAD4
1Department of Chemistry, Islamic Azad University, Mashhad Branch, Mashhad, Iran
2Department of Chemistry, School of Sciences, Alzahra University, Tehran, Iran
3Deptartment of Chemical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
4Department of Materials Science and Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
Abstract: An efficient and environmentally benign procedure for the catalytic esterification of salicylic acid with aliphatic alcohols,
CnH2n+1OH (n = 1–5) and benzylic alcohols, RC6H4CH2OH (R = H, NO2, OCH3, Br, Cl, Me) was developed using nano-SiO2-supported
Preyssler heteropolyacid both under thermal conditions and microwave irradiation. Silica nanostructures were obtained through a sol-gel
method and were characterized by transmission electron microscopy and powder X-ray diffraction. The effects of various parameters such
as solvent type, molar ratio of substrates, Preyssler heteropolyacid loading on silica, catalyst amount, temperature, and reaction time were
studied and the optimum conditions were obtained. It has been found that the catalyst with 30 wt% loading is highly active and shows high
yields in esterification reactions. The use of nano-SiO2-supported Preyssler heteropolyacid coupled with microwave irradiation allows a
solvent-free, rapid (3 min), and high-yielding reaction. This catalyst can be easily recovered and reused for many times without a significant
loss in its activity.
Key words: Preyssler; heteropolyacid; silica; esterification; salicylic acid
The esterification of salicylic acid with alcohols over acid
catalysts is an important reaction in organic synthesis [1]. The
increasing demand for safe industrial processes requires the
development and implementation of environmentally friendly,
solid catalysts for value-added, acid-catalyzed reactions.
Homogeneous acids such as H2SO4 and H3PO4 [2–4] rep-
resent the most commonly used catalysts for most of the im-
portant esterification reactions. However, these acids are cor-
rosive, hazardous, used in more than stoichiometric amounts,
and difficult to recover from reaction mixtures. They also
cannot be reused and lead to low selectivity for desired prod-
ucts and produce a large volume of environmentally hazardous
acidic waste. New environmental rules call for the reduction of
waste production and use of more environmentally friendly
alternative catalysts. The substitution of traditional homoge-
nous Lewis and Brönsted acid catalysts by heterogeneous ones,
e.g. solid acid catalysts such as sulfated zirconia, zeolites, and
acidified silica [5] constitutes a more environmentally friendly
alternative to the organic reactions [6].
As known, solid heteropolyacids (HPAs) and their deriva-
tives have been intensively studied because they can be used as
excellent acidic, redox, and bifunctional catalysts in catalytic
reactions [7–9]. In this area, increasing attention has been paid
to search for preparing supported HPA catalysts. Efforts have
also been made to study the support of HPAs on suitable nano
supports [10,11]. The use of supported HPAs increases the
specific surface area of the catalysts and modifies their cata-
lytic properties. Catalytic properties can increase using nano
supports. Thus, immobilization of HPAs on a number of sup-
ports was extensively studied. Silica, alumina, and active car-
Received 15 November 2010. Accepted 21 February 2011.
*Corresponding author. Tel: +98-511-8435000; Fax: +98-511-8424020; E-mail: abamoharram@yahoo.com; fbamoharram@mshdiau.ac.ir
This work was supported by Islamic Azad University, Mashhad Branch.
Copyright © 2011, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier BV. All rights reserved.
DOI: 10.1016/S1872-2067(10)60219-7

Fatemeh F. BAMOHARRAM et al. / Chinese Journal of Catalysis, 2011, 32: 782–788
bon were the most investigated supports [12–16]. It has been
flow under the influence of gravity.
found that HPAs supported on SiO2 are most stable. It is due to
their high thermal stability, unique pore system, and numerous
possibilities to modify their composition, morphology, and
sorption properties.
1.2 Catalyst preparation
H14[NaP5W30O110] was prepared according to our earlier
work [18]. For the preparation of supported catalyst, the syn-
thesized nano-silica was suspended in 20 ml of water and then
the heteropolyacid with different loadings of tungsten was
added to this suspension. After stirring the heterogeneous
solution-support mixture, the solvent was evaporated, samples
were dried at 120oC and the catalysts were calcined at 250oCin
a furnace prior to use.
The objective of this paper is to enhance the catalytic prop-
erties of Preyssler catalyst, with formula of H14[NaP5W30O110],
via supporting it on nano-SiO2 for esterification of salicylic
acid with aliphatic and benzylic alcohols.
14–
The structure of the anion [NaP5W30O110
]
is formed by a
cyclic assembly of five {PW6O22} groups. The unusual 5-fold
symmetry of this anion is achieved by fusion of five {PW6O22}
groups. The central sodium ion lies not on the equator of the
anion but in a plane roughly defined by oxygen atoms of the
phosphate groups [17]. Our research group has developed
catalysis with Preyssler HPA for a broad range of organic
syntheses and environmentally benign catalysis during the past
few years [18–27]. Good yields, high selectivity, economical
convenience, ease of work up, high hydrolytic and thermal
stability, and high catalytic activity of Preyssler HPA [28–34]
have indicated high potential for nano-catalysis in organic
synthesis and environmentally benign catalysis.
1.3 Catalyst characterization
Infrared (IR) spectra were recorded on a Buck scientific 500
spectrometer (KBr pellets). The particle size and shape of
nanostructures of SiO2 were studied by transmission electron
microscopy (TEM, LEO 912 AB). The X-ray diffraction
(XRD) patterns of the samples were obtained using a
PW3710-Philips powder diffractometer (Cu KĮ irradiation).
BET specific surface areas, pore sizes, and pore volumes were
calculated from nitrogen adsorption isotherms using an Auto-
sorb-1 Quantachrome instrument.
To the best of our knowledge there is no literature report on
the use of nano-silica supported Preyssler HPA as catalyst in
esterification of salicylic acid. Recently, we systematically
investigated the catalytic behavior of Preyssler HPA for many
acid-catalyzed reactions and found that this catalyst is more
active than the other catalysts [35–40]. In order to perform a
new contribution to the field of eco-friendly, acid-catalyzed
reactions coupled with nanotechnology, we report here on the
results of esterification of salicylic acid with aromatic and
aliphatic alcohols using Preyssler HPA supported on
nano-silica under thermal and microwave conditions.
1.4 Catalytic test
In a typical reaction, 1-pentanol, salicylic acid, and nano-
catalyst were put in a glass reactor and the reaction mixture was
stirred and refluxed at the boiling point of solvents for 3 h. At
room temperature (25 oC) reactions were carried out with stir-
ring for 6 h. At regular intervals, Karl-Fischer- titration was
performed for determination of the produced water. The
products were characterized by comparison of their spectro-
scopic data with those of authentic samples. Yields were de-
termined by gas chromatography (Pu 4500 gas chromatograph
with an FID detector; HP-5 column, 30 m × 0.32 mm i.d. ×
0.25 ȝm film thickness). The GC process started at 70 ºC and
the temperature was raised with a rate of 15 ºC/min. Under
microwave irradiation a solution of salicylic acid, alcohol, and
nanocatalyst was irradiated for 3 min. A MILESTONE
1 Experimental
1.1 Synthesis of SiO2 nanoparticles
The material used in this work as the SiO2 precursor is tet-
raethyl orthosilicate (TEOS, Merck, 98%). Besides the main
precursor, nitric acid (Arman Sina, 65%) and double distilled
water were used for peptization and as solvent, respectively.
The sol-gel precursor solution was obtained by mixing of
TEOS and ethanol with EtOH/TEOS molar ratio of 4. The
mixture was stirred using magnetic stirring. At a pH value of 2
forms a clear solution. The molar ratio of water to TEOS was
12. After the specified solution was obtained for 20 min, it was
poured in a clean container and left at ambient temperature for
gelation. After the gel had formed, the gelation time was cal-
culated for the sample. The final step in the process consisted
o
APC-55E microwave (450 W, 80 C) was used in all of the
experiments.
2 Results and discussion
2.1 Characterization results
In our previous work, we investigated performance and ca-
pability of sodium-30-tungstopentaphosphate, the so-called
Preyssler’s anion, for highly selective and efficient esterifica-
tion of salicylic acid with some aliphatic and benzylic alcohols
[18] in the presence of different forms of Preyssler catalyst, i.e.
o
of drying the sample at 220 C for 6 h. The gelation time is
defined as the time between pouring the solution in the con-
tainer and the time at which the solution ceases to discernibly

Fatemeh F. BAMOHARRAM et al. / Chinese Journal of Catalysis, 2011, 32: 782–788
in pure form, as mixed addendum, and silica-supported. The
100
80
60
40
20
results of the comparison between supported and
non-supported Preyssler HPA have shown that in all cases the
supported polyacid is less active than the non-supported one.
Therefore, it is of great interest to know what occurs if the
nano-SiO2-supported Preyssler HPA is used in this esterifica-
tion reaction. Interestingly, we have found that the
nano-SiO2-supported Preyssler catalyst renders the esterifica-
tion reaction more effective in an organic solvent than
SiO2-supported Preyssler catalyst.
(2)
(1)
Silica nanostructures were obtained through a sol-gel
method. All of the conditions are shown in the experimental
section. The BET surface area, pore volume, and average pore
size of nanosized SiO2 were obtained as 287 m2/g, 0.28 cm3/g,
and 0.25 nm, respectively. After the impregnation of HPA (with
30% being the best loading), the BET surface area, pore vol-
ume, and average pore size were obtained as 201 m2/g, 0.10
cm3/g, and 0.21 nm, respectively. The BET surface area and
pore volume decreased, indicating that the pores of nanosized
silica are being filled and the supported HPA blocked some
pores of the support.
1800
1600
1400
1200
1000
800
600
Wavenumber (cmꢀ1)
Fig. 2. IR spectra of Preyssler heteropolyacid in bulk form (1) and nano
form (2).
since the heteropolyacid does not react with SiO2 or with water,
but it can remain in the silica nanoparticles without appreciable
change of the structure.
2.2 Catalytic activity
The obtained nano structures were characterized by TEM as
shown in Fig. 1. This figure shows 40 nm spheres. The XRD
pattern of nano-SiO2 with sharp peaks in the 2ș range from 7º
to 36º confirmed the crystalline nature of SiO2. In addition, lack
of an XRD peak centered at 2ș angle 22º (typical for amor-
phous SiO2) confirmed the crystallinity. The patterns of the
spherical products confirm the SiO2 structure.
In order to evaluate the catalytic activity of
nano-SiO2-supported Preyssler catalyst for the esterification of
salicylic acid, the reaction was optimized for the esterification
with 1-pentanol. The effects of various parameters such as
solvent type, amount of the catalyst, temperature, loading
percentage, and time of reaction were studied. The esterifica-
tion reaction in various solvents with low boiling points, such
as dichloroethane, dichloromethane, chloroform, and carbon
tetrachloride has been explored. We have found that dichloro-
ethane is the best solvent. All of the reactions were carried out
in dichloroethane as the solvent of choice.
The heteropolyacid H14[NaP5W30O110] in the SiO2 nano par-
ticles was confirmed by IR spectroscopy as shown in Fig. 2.
The asymmetric stretching frequency of the terminal oxygen is
observed at 960 cm–1 and the P–O asymmetric stretching fre-
quency is noted at 1080 and 1165 cm–1. The prominent P–O
bands at 960, 1080, and 1165 cm–1 are consistent with a C5v
The influence of molar ratio on yield in dichloroethane as
solvent was investigated. Various molar ratios of salicylic acid
to alcohol were used. The molar ratio of salicylic acid:alcohol
was varied as 1:1 to 1:6. The results are shown in Fig. 3. The
results show that the yield increases with the molar ratio up to
symmetry
H14[NaP5W30O110] is preserved in the HPA/SiO2 nano particles.
In addition, the protonated water band of H14[NaP5W30O110
also remained noticeable in the nanoparticles at 1730 cm–1. It
could be confirmed that the heteropolyacid H14[NaP5W30O110
anion.
These
bands
demonstrate
that
]
]
90
80
70
60
50
40
30
20
10
0
was successfully immobilized within the SiO2 nanoparticles
1:1
1:2
1:3
1:4
1:5
1:6
Molar ratio
Fig. 3. Esterification of salicylic acid with 1-pentanol with various
molar ratios of acid:alcohol. Other conditions: catalyst amount 0.05 g,
solvent dichloroethane, time 3 h, reflux.
Fig. 1. TEM image of the synthesized nano-SiO2.

Fatemeh F. BAMOHARRAM et al. / Chinese Journal of Catalysis, 2011, 32: 782–788
90
80
70
60
50
40
30
Table 1 Yields of esterification of salicylic acid with 1-pentanol using
various amounts of the nanocatalyst
Catalyst amount (g)
Yield (%)
0.01
0.02
0.03
0.04
0.05
0.06
49
67
73
80
89
89
Reaction conditions: molar ratio of acid:alcohol 1:5, solvent dichloro-
ethane, time 3 h, reflux.
10
20
30
40
50
Catalyst loading (%)
Fig. 4. Esterification of salicylic acid with 1-pentanol with various
loadings of catalyst. Other conditions: catalyst amount 0.05 g, molar ratio
of acid:alcohol 1:5, solvent dichloroethane, time 3 h, reflux.
any appreciable effect on the reaction yield. It is important to
note that the esterification reaction is an equilibrium reaction
and due to this, the ester yield increases with time till it reaches
the equilibrium value, and there is no further increase beyond
equilibrium value with further raise of reaction time.
1:5. The mechanism involves protonation of the acid on the
Brönsted acid site of the catalyst followed by addition of al-
cohol and elimination of a water molecule. During the reaction,
the protonated acid interacts with alcohol and a too large al-
cohol fraction may hinder access of the acid to the catalytic
site. In view of this, the optimum ester yield was obtained with
acid:alcohol molar ratio of 1:5.
The esterification reactions were carried out at two tem-
peratures including room temperature (RT, lowest temperature)
and reflux temperature (highest temperature). The maximum
yield of ester is reached at the reflux temperature. This was
expected since increasing the temperature is apparently fa-
vorable for the acceleration of the forward reaction. In general,
the yields are lower when the reactions are carried out at room
temperature. Also this can be attributed to the fact that the
esterification is an endothermic reaction. Hence the reaction
product yield increases with temperature enhancement.
After optimizing the conditions, we examined the generality
of these conditions to other alcohols with different initial
Preyssler catalyst loadings (10%–50%) on nano-silica. Under
these conditions, a series of experiments were tested (Table 2).
Interestingly, in all cases the observed yields were highest with
30% loading.
In order to examine the effect of Preyssler anion loading on
silica, catalysts with different initial Preyssler HPA loadings
(10%–50%) on nano-silica were prepared. The results are
shown in Fig. 4. The results show that the highest yield can be
achieved with 30% loading. The yield increases with an in-
crease in Preyssler HPA loading on silica from 10% to 30%. It
is attributed to the increase in the total number of available
active catalytic sites for the reaction. Higher Preyssler anion
loadings on silica (> 30%) affected yields and gave lower yield
of esters, which can be likely attributed to side reactions cata-
lyzed by the excess amount of acidic sites. The fall of the yield
at high catalyst loading was also attributed to competitive
adsorption between the additives and the substrates at the ac-
tive sites on the catalyst surface or physically blocking of the
catalyst pores by excessive amounts of additives. Thus 30%
loading is the optimum condition for the esterification reaction.
After optimizing the percentage loading, we endeavored to
optimize the amount of the catalyst. The observations are pre-
sented in Table 1. The esterification reaction was conducted by
varying the catalyst amount from 0.01 to 0.06 g by keeping all
of the other parameters constant. The results in Table 1 indicate
that the yield increases with the catalyst amount up to 0.05 g.
Any further increasing does not have any appreciable effect on
the reaction yield. It is suggested that the ester yield reaches a
steady value with increase in catalyst amount, which can be
attributed to reaching the equilibrium value of the ester yield.
The effect of reaction time on the esterification reaction of
salicylic acid was also studied (Fig. 5). The results indicate that
there is an increase in the amount of product with increase of
reaction time. The optimum reaction time has been found to be
3 h at reflux temperature and any further increase did not have
2.3 Microwave irradiation
Esterification under microwave irradiation, besides being
environmentally friendly, is also marked by a considerable
90
80
70
60
50
40
30
20
10
0
0.5
1.0
1.5
2.0
2.5
3.0
Time (h)
Fig. 5. Esterification of salicylic acid with 1-pentanol at different times.
Other conditions: catalyst amount 0.05 g, molar ratio of acid:alcohol 1:5,
solvent dichloroethane, reflux.

Fatemeh F. BAMOHARRAM et al. / Chinese Journal of Catalysis, 2011, 32: 782–788
Table 2 Yields of esterification of salicylic acid with aliphatic and benzylic alcohols under room temperature and reflux conditions
Yield of ester (%)
Alcohol
10% catalyst loading 20% catalyst loading 30% catalyst loading 40% catalyst loading 50% catalyst loading
RT
45
46
48
26
46
24
48
43
28
29
35
32
26
25
Reflux
60
RT
48
49
51
30
50
27
52
47
31
42
38
35
29
28
Reflux
72
RT
53
56
58
36
57
31
59
43
35
49
44
39
34
32
Reflux
82
RT
46
49
50
33
52
28
54
28
30
42
38
33
28
27
Reflux
74
RT
41
44
45
28
48
24
50
25
27
37
34
29
24
23
Reflux
58
Methanol
Ethanol
62
74
85
78
62
1-Propanol
74
76
86
79
64
2-Propanol
30
43
53
46
30
Butanol
66
78
87
70
55
t-Butanol
25
39
44
42
26
1-Pentanol
68
80
89
85
79
2-Pentanol
45
56
67
60
45
Benzyl alcohol
4-Metoxy benzyl alcohol
2-Methyl benzyl alcohol
2-Chloro benzyl alcohol
4-Bromo benzyl alcohol
3-Nitro benzyl alcohol
44
54
63
56
36
55
67
77
70
55
57
64
73
65
40
50
60
59
52
39
34
43
53
47
32
32
40
49
42
30
Reaction conditions: catalyst amount 0.05 g, molar ratio of acid:alcohol 1:5, solvent dichloroethane, time 3 h (for reflux condition) or 6 h (for room tem-
perature).
reduction of reaction time in comparison to conventional es-
terification [41,42]. Furthermore, to the best of our knowledge,
esterification of salicylic acid with silica-supported
nano-Preyssler catalyst has not yet been achieved under mi-
crowave irradiation. To determine the potential of this new
catalytic system, the esterification reactions were carried out
under the optimized conditions under microwave irradiation.
The results are shown in Table 3. As we can see, this catalyst
afforded excellent yields in very short time (3 min). Since we
had high yields of products and recyclable catalysts, we can tell
that the reactants should absorb microwave irradiation for
conversion while the catalyst and products were stable.
crowave-based process lies not only in the reduction of reac-
tion time from hours to minutes, but it is also known to reduce
side reactions, enhance yields, and improve reproducibility.
Besides the efficient energy input that microwaves can provide
to the reaction mixtures, a chemical activation effect cannot be
discounted. During the irradiation, there is a total or partial
alignment of dipolar molecules and/or ionic species with the
direction of the electrical field. Such an alignment may then
favor interactions between reactants and may lead to shorter
and more efficient reactions.
2.4 Reusability of the catalyst
A dramatic change in the way of chemical synthesis can be
achieved by microwave irradiation. The efficiency of the mi-
In order to further evaluate the performance of the catalyst,
Table 3 Yields of esterification in the presence of nano-SiO2-supported Preyssler HPA under microwave irradiation
Yield of ester (%)
10% catalyst loading 20% catalyst loading 30% catalyst loading 40% catalyst loading 50% catalyst loading
Alcohol
Methanol
70
74
77
56
77
51
87
70
57
71
68
63
57
55
80
83
85
61
84
57
96
77
64
78
75
69
62
60
89
91
92
98
92
63
89
72
74
85
82
75
68
66
81
84
85
63
85
58
81
66
66
80
77
71
64
62
72
76
79
58
79
53
79
64
59
73
70
66
60
57
Ethanol
1-Propanol
2-Propanol
Butanol
t-Butanol
1-Pentanol
2-Pentanol
Benzyl alcohol
4-Metoxy benzyl alcohol
2-Methyl benzyl alcohol
2-Chloro benzyl alcohol
4-Bromo benzyl alcohol
3-Nitro benzyl alcohol
Reaction conditions: catalyst amount 0.05 g, molar ratio of acid:alcohol 1:5, solvent dichloroethane, time 3 min, power 450 W, temperature 80 ºC.

Fatemeh F. BAMOHARRAM et al. / Chinese Journal of Catalysis, 2011, 32: 782–788
263
reuse experiments of the catalyst were carried out. The catalyst
was filtered at the end of the reaction. The obtained precipitate
was washed with water and dried. The catalyst was reused for
the next run under the same conditions. The results indicated
that the activity of the catalyst was not affected even at the third
run with the reused catalyst. This phenomenon implied that the
catalyst can be efficiently recovered and recycled without any
significant loss of activity, as the catalyst remained active even
after the third cycle (86% yield). Thus there is not leaching. By
this token, the catalyst possesses application potential in in-
dustry.
13 Fricke R, Jerschkewitz H G, Ohlmann G. J Chem Soc, Faraday
Trans I, 1986, 82: 3491
14 Kasztelan S, Moffat J B. J Catal, 1987, 106: 512
15 Moffat J B, Kasztelan S. J Catal, 1988, 109: 206
16 Brückman K, Che M, Haber J, Tatibouet, J M. Catal Lett, 1994,
25: 225
17 Alizadeh M H, Harmalker S P, Jeannin Y, Martin-Free J, Pope M
T. J Am Chem Soc, 1985, 107: 2662
18 Bamoharram F F, Heravi M M, Roshani M, Jahangir M, Gharib
A. Appl Catal A, 2006, 302: 42
19 Bamoharram F F, Heravi M M, Roshani M, Gharib A, Jahangir
M. J Mol Catal A, 2006, 252: 90
20 Bamoharram F F, Heravi M M, Roshani M, Tavakoli N. J Mol
Catal A, 2006, 252: 219
3 Conclusions
21 Bamoharram F F, Heravi M M, Roshani M, Akbarpour M. J Mol
Catal A, 2006, 255: 193
Nano-sized SiO2 with different loading of Preyssler HPA has
been synthesized and the catalytic behavior of it has been
studied in the esterification of salicylic acid with different
aromatic and aliphatic alcohols. The catalyst with 30 wt%
loading showed good catalytic activity with a maximum con-
version of salycilic acid as compared with other loadings.
Esterification reactions were found to occur faster with mi-
crowave irradiation than with conventional heating. The molar
ratio of acid to alcohol, temperature, catalyst amount, and
reaction period influenced the ester yield during the reaction.
The above catalyst was recyclable, cost effective, and envi-
ronment friendly and could be used in similar reactions. This
research reports a new solid acid catalyst for the replacement of
traditional liquid acids in important reactions and introduces a
new catalyst for organic chemistry. This catalytic study may
explore the wide application of Preyssler solid acid catalyst in
industry.
22 Bamoharram F F, Heravi M M, Roshani M, Jahangir M, Gharib
A. J Mol Catal A, 2007, 271: 126
23 Bamoharram F F, Heravi M M, Roshani M, Gharib A, Jahangir
M. J Chin Chem Soc, 2007, 54: 1017
24 Bamoharram F F, Heravi M M, Mehdizadeh S. Synth React
Inorg M, 2009, 39: 746
25 Bamoharram F F, Heravi M M, Heravi H M, Dehghan M. Synth
React Inorg Met-Org Chem, 2009, 39: 394
26 Bamoharram F F. Molecules, 2010, 15: 2509
27 Bamoharram F F, Heravi M M, Ardalan P, Ardalan T. React Ki-
net Mech Catal, 2010, 100: 71
28 Bamoharram F F, Heravi M M, Sane Charkhi M J, Tavakoli N.
Synth React Inorg Met-Org Chem, in press
29 Bamoharram F F, Heravi M M, Roshani M,Toosi M, Jodeyre L.
Green Chem Lett Rev, 2009, 2: 35
30 Bamoharram F F, Heravi M M, Heravi M M, Meraji M. Inter J
Green Nanotech: Phys Chem, 2009, 1: 26
31 Heravi M M, Sadjadi S, Oskooie H, Bamoharram F F. Synth
Commun, in press
References
32 Heravi M M, Sadjadi S, Oskooie H A, Bamoharram F F.
Ultrason Sonochem, 2009, 16: 708
1
2
Kirumakki S. R, Nagaraju N, Chary K V R, Narayanan S. Appl
Catal A, 2003, 248: 161
33 Heravi M M, Sadjadi S, Oskooie H A, Bamoharram F F.
Ultrason Sonochem, 2009, 16: 718
Williamson K L. Macroscale and Microscale Organic Experi-
ments. 2nd Ed. Boston: Houghton Mifflin, 1994
Olmsted J. J Chem Educ, 1998,75: 1261
34 Heravi M M, Rasmi V, Bamoharram F F, Sadjadi S, Fotouhi L,
Sadjadi S, Bakavoli M. Synth Commun, 2009, 39: 4109
35 Sawant D P, Halligudi S B. J Mol Catal A, 2005, 237: 137
36 Sawant D P, Devassy B M, Halligudi S B. J Mol Catal A, 2004,
217: 211
3
4
Oluwaniyi O O, Ibiyemi S A. J Appl Sci Environ Manag, 2003,
7(1): 15
5
6
7
8
9
Kuriakose G, Nagaraju N. J Mol Catal A, 2004, 223: 155
Khatri C, Rani A. Fuel, 2008, 87: 2886
37 Devassy B M, Shanbhag G V, Mirajkar S P, Böhringer W B,
Fletcher J, Halligudi S B. J Mol Catal A, 2005, 233: 141
38 Devassy B M, Shanbhag G V, Lefebvre F, Halligudi S B. J Mol
Catal A, 2004, 210: 125
Yamase T. Chem Rev, 1998, 98: 307
Yadav G D, Mistry C K. J Mol Catal A, 2001, 172: 135
Alekar N A, Halligudi S B, Rajani R, Gopinathan S, Gopinathan
C. React Kinet Catal Lett, 2001, 72: 169
39 Devassy B M, Halligudi S B. J Catal, 2005, 236: 313
40 Devassy B M, Lefebvre F, Halligudi S B. J Catal, 2005, 231: 1
41 Major B, Kelemen-Horvth I, Csandi Z, Bélafi-BakóK,Gubicza L.
Green Chem, 2009, 11: 614
10 Baronetti G, Thomas H, Querini C A. Appl Catal A, 2001, 217:
131
11 Park G I, Lim S S, Song I K, Lee W Y. React Kinet Catal Lett,
2002, 75: 157
42 Liao X J, Raghavan G S V, Yaylayan V A. Tetrahedron Lett,
2002, 43: 45
12 Fricke R, Ohlmann G. J Chem Soc Faraday Trans I, 1986, 82: