Microwave-assisted rapid and efficient reduction of aromatic nitro compounds to amines with propan-2-ol over Nanosized perovskite-type SmFeO 3 powder as a new recyclable heterogeneous catalyst

Article abstract of DOI:10.3184/174751911X12964930076647

Nanosized perovskite-type SmFeO₃ powder, prepared through the thermal decomposition of Sm[Fe(CN)₆].4H₂O with an average particle diameter of 28 nm and a specific surface area of 42 m² g^-1, was used as a recyclable heterogeneous catalyst for the efficient and selective reduction of aromatic nitro compounds into the corresponding amines by using propan-2-ol as a hydrogen donor (reducing agent) and KOH as a promoter under microwave irradiation. This highly regio-and chemoselective catalytic method is fast, clean, inexpensive, high yielding and also compatible with the substrates containing easily reducible functional groups. In addition, the nanosized SmFeO₃ catalyst can be reused without loss of activity.

Full text of DOI:10.3184/174751911X12964930076647

104 RESEARCH PAPER
FEBRUARY, 104–108
JOURNAL OF CHEMICAL RESEARCH 2011
Microwave-assisted rapid and efficient reduction of aromatic nitro
compounds to amines with propan-2-ol over nanosized perovskite-type
SmFeO3 powder as a new recyclable heterogeneous catalyst
Saeid Farhadi*, Firouzeh Siadatnasab and Maryam Kazem
Department of Chemistry, Lorestan University, Khoramabad 68135-465, Iran
Nanosized perovskite-type SmFeO3 powder, prepared through the thermal decomposition of Sm[Fe(CN)6].4H2O with
an average particle diameter of 28 nm and a specific surface area of 42 m2 g−1, was used as a recyclable heteroge-
neous catalyst for the efficient and selective reduction of aromatic nitro compounds into the corresponding amines
by using propan-2-ol as a hydrogen donor (reducing agent) and KOH as a promoter under microwave irradiation.
This highly regio- and chemoselective catalytic method is fast, clean, inexpensive, high yielding and also compatible
with the substrates containing easily reducible functional groups. In addition, the nanosized SmFeO3 catalyst can be
reused without loss of activity.
Keywords: reduction, nanosized SmFeO3, perovskite-type oxide, nitro compounds, aromatic amines, microwave irradiation
The reduction of aromatic nitro compounds to their corre-
sponding amines is important synthetically both in the labora-
tory and in industry, mainly due to the fact that the aromatic
amines are applied as important intermediates in the produc-
tion of many pharmaceuticals, photographic materials,
agrochemicals, polymers, dyes and rubber materials.1–3 This
important transformation is traditionally performed with
metal/acid which generates large amounts of metal waste.4
In recent years, many methods/reagents have been developed
in the literature for carrying out this transformation, including
activated metals,5,6 Al/NH4Cl/MeOH,7 Co2(CO)8/H2O,8
Mo(CO)6,9 SnCl2/ionic liquid,10 N2H4/A2O3/MWI,11 N2H4/Zn,12
NaH2PO2/FeSO4,13 B10H14/Pd/C,14 FeCl3/Zn/DMF/H2O,15
HCOONH4/Mg,16 HCOON2H5/Zn,17 N2H4/Ru(bpy)2/hν,18
inorganic solids as heterogeneous catalysts has received con-
siderable attention in recent years. In this context, solid
inorganic materials such as silicate or aluminophosphate
molecular sieve-supported transition- , poly-
metal ions 34,35
mer-supported Ni–B nanoparticles36 and silica-supported gold
nanoparticles (Au/SiO2)37 have been employed as heteroge-
neous catalysts for the reduction of aromatic nitro compounds
to their corresponding amines under catalytic transfer hydro-
genation. However, these reactions are usually conducted in
refluxing alcoholic solvents, a process that requires several
hours of reaction time. Furthermore, the activity of most of the
catalysts decreases with subsequent recycling.
Perovskite-type transition metal oxides (ABO3) constitute
an important class of materials due to their electrical, magnetic
and catalytic properties. These mixed oxides are promising
catalytic materials for organic transformations due to their
much lower cost as compared to noble metals, high thermal
and chemical stability and their insolubility in acidic and basic
aqueous or non-aqueous solutions. These properties allow
them to be used as heterogeneous catalysts for organic trans-
formations.38,39 The most significant problem for applying
perovskite-type oxides as catalysts is their low surface areas
which are usually less than 5 m2 g−1.38,39 One approach to over-
come this problem is to prepare nanosized perovskite-type
oxides. Nanosized materials can be novel catalysts because of
their large surface area and the high density of active sites.40
Thus, it is expected that nano-perovskites could exhibit high
catalytic activity for organic transformations. Furthermore,
the use of microwave irradiation (MWI) as an energy source
for organic transformations, combined with inorganic solids as
catalysts is rapidly growing due to minimal waste, efficiency
of catalyst recycling, faster reactions, increased yields and
easier set-up and work up procedures.41
In continuation of our interest in exploring nanostructured
catalysts for organic transformations,42,43 we now report the
microwave-assisted reduction of aromatic nitro compounds
with propan-2-ol as a hydrogen donor and potassium hydrox-
ide as a promoter over a nanosized SmFeO3 heterogeneous
catalyst.Catalyticresultsindicatethatthenanosizedperovskite-
type SmFeO3 is a green, highly selective and efficient
recyclable catalyst for the rapid reduction of aromatic nitro
compounds to the corresponding amines under MWI. To the
best of our knowledge, this is the first report of a catalytic
reduction of aromatic nitro compounds over a nanosized
perovskite-type oxide and under MWI.
HCOOH/Raney
nickel,19
HCOONH4/Ni[P(OPh3)4],20
N2H4·H2O/Fe2O3/MgO,21 Na2S/NEt4Br,22 Sm/NH4Cl/ultrasonic
irradiation,23 HCOON2H5/Raney Ni,24 HI,25 S8/NaHCO3,26
NaBH4/Raney nickel27 and Fe(acac)3/TMDS.28 Catalytic hydro-
genation employing H2 gas and catalysts such as Pd/C, Pd(II)
complex/Al2O3, or Raney nickel has also been reported for the
reduction of nitroarenes.29–31 However, some of these methods
show important limitations including low-yields, harsh reac-
tion conditions, expensive reagents, incompatibility with other
functional groups present in the molecule, lack of selectivity
and the need for special equipment and an inert atmosphere.
So, the development of simpler, inexpensive, widely-
applicable and environmentally-benign procedures is still an
active area of research.
Among the various methods investigated so far, catalytic
transfer hydrogenation in which hydrogen gas is replaced with
a safe, clean and stable hydrogen donor, such as hydrazine
hydrate, formic acid or propan-2-ol, is one of the most promis-
ing methods for the reduction of aromatic nitro compounds to
the corresponding aromatic amines.32 In comparison with other
reported methods, catalytic transfer hydrogenation has poten-
tial advantages, including operational simplicity, high selectiv-
ity and yield, no highly diffusible and flammable hydrogen gas
used and no special equipment required. Pt, Pd, Ru and Raney
Ni are the traditional catalysts employed in catalytic transfer
hydrogenation.33 However, expensive metals such as palladium
or platinum on carbon and Raney nickel used for this purpose
are flammable when exposed to air and, in most cases, the use
of an inert atmosphere is necessary.
To overcome the above-mentioned problems and owing to
economic and environmental considerations, the catalytic
transfer hydrogenation of aromatic nitro compounds over
Results and discussions
For the present study, firstly nanosized perovskite-type
SmFeO3 powder with an average particle diameter of 28 nm
* Correspondent. E-mail: sfarhad2001@yahoo.com

JOURNAL OF CHEMICAL RESEARCH 2011 105
and Brunauer–Emmett–Teller (BET) specific surface area of
42 m2 g−1 was easily prepared from the decomposition of the
Sm[Fe(CN)6]·4H2O complex according to our reported method
and characterised by several analytical and spectroscopic
techniques.44 Initial attempts were focused on the reduction
of nitrobenzene as a model substrate to optimise the reaction
conditions. In a typical reaction, a mixture of nitrobenzene
(5 mmol) and KOH (5 mmol) dissolved in propan-2-ol
(15 mL) was placed into the microwave cavity (2.45 GHz,
900 W maximum power) and irradiated with power 20%
(180 W) in the presence of different loadings of the nanosized
SmFeO3catalyst. As can be seen in Table 1, the yield of aniline
increased with an increase in the amount of the catalyst from
1 to 5 mol%, which is due to the proportional increase in
the number of active sites (Table 1, entries 1–3). However, no
significant improvement in the yield was observed with higher
catalyst loads (Table 1, entries 4 and 5). The optimal catalyst
load proved to be 5 mol%, which resulted in aniline as the only
product in 93% yield after 18 min of irradiation (Table 1,
entry 3) and hence all further experiments were carried out at
this catalyst loading. When other alcohols as hydrogen source
were tested for the same reaction, only ethanolwas found to be
effective and methanol, propan-1ol and butan-2-ol gave a
decreased yield of amine product after a long reaction time
(Table 1, entries 6–9). Indeed, in an experiment when tert-
butanolwhich possess no α-H atom, was used instead of
propan-2-ol, as would be expected no observable reduction
occurred and the starting nitro compound was recovered
unchanged (Table 1, entry 10). This finding confirms that the
type of alcoholplays a significant role in the reduction of nitro
compounds. Amongst alcohols, propan-2-ol was the most
suited hydrogen donor as primary alcohols dehydrogenate to
the corresponding aldehyde, which acts as a catalyst poison.
The effect of the nature of the base was also investigated. A
strong inorganic base such as NaOH provided comparable
results to KOH (Table 1, entry 11). Ca(OH)2 and Na2CO3
yielded less amount of aniline due to their lower basicity while
NH3 and Me3N did not give any product (Table 1, entries
12–13). Hence, all further reactions were carried with the
propan-2-ol /KOH system. The reduction of nitrobenzene
w
as also attempted without the catalyst or in the absence of
potassium hydroxide base In both the cases, the reaction
failed completely (Table 1, entries 16 and 17) confirming that
.
,
the SmFeO3 catalyst and base are essential for this reaction.
Further, no reaction was observed in the absence of MWI
(Table 1, entry 18).
To evaluate the scope and limitations of this method, we
decided to test it on a series of aromatic nitro compounds under
the optimised conditions. The results in Table 2 indicate the
generality and efficacy of this novel catalytic system. The
reduction of various aromatic nitro compounds containing
electron-donating/withdrawing groups was investigated under
the optimised reaction conditions (Table 2). In most cases, the
corresponding amines were obtained in excellent yields
(>96%) within very short reaction times of 10–22 min. As can
be seen in Table 2, electron-donating/ withdrawing groups
do not ave significant influence on the reaction times and
h
a
yields. In all cases, amines were found to be the only product
of the reactions and the usual side products of nitro reduction
such as azoxy, azo, and hydrazo compounds were not observed
in the final product. The present method was highly chemose-
lective in the presence of other hydrogenolysable or reducible
groups. The sensitive functional groups such as halogens,
–OH, –NH2, –OCH3, –CN, –COMe, –CHO, –COOH, –COOEt
and C=C did not undergo any change under the reaction condi-
tions. Halogenated nitro compounds were reduced to the amino
compounds without losing the halogen (Table 2, entries 6–12).
The catalyst also shows promise for regioselective reduction of
dinitro compounds, so that from the dinitrobenzenes under
these conditions only one nitro function was reduced (Table 2,
entries 12–14). Nitro compounds containing carbonyl groups
were also reduced to the corresponding amino compounds and
the reduction of carbonyl groups was not observed (Table 2,
entries 21–26). Even the aldehyde group remained intact under
the reaction conditions (Table 2, entry 21). Furthermore, this
reduction was also successfully carried out on
a bulkier mol-
ecule such as 1-nitronaphthalene (entry 28) with high yield.
Table 1 The microwave-assisted reduction of nitrobenzene to aniline over a nanosized SmFeO3 catalyst under different
conditionsa
Entry
SmFeO3 /mol%
H-donor
Base
Time /min
Conversion /%b
Yield /%c
1
2
1
2.5
5
Propan-2-ol
Propan-2-ol
Propan-2-ol
Propan-2-ol
Propan-2-ol
Methanol
KOH
KOH
KOH
KOH
KOH
KOH
KOH
KOH
KOH
KOH
NaOH
Ca(OH)2
Na2CO3
NH3
35
30
18
20
18
30
20
30
30
30
22
35
35
35
35
25
25
30
18
62
100
100
100
51
93
55
39
0
14
56
93
93
93
45
88
50
34
0
3
4
7.5
10
5
5
6
7
5
Ethanol
8
5
Propan-1-ol
Butan-2-ol
Tert-Butanol
Propan-2-ol
Propan-2-ol
Propan-2-ol
Propan-2-ol
Propan-2-ol
Propan-2-ol
Propan-2-ol
Propan-2-ol
9
5
10
11
12
13
14
15
16
17
18d
5
5
92
23
21
0
88
17
15
0
5
5
5
5
Me3N
KOH
–
0
0
0
0
0
5
0
0
5
KOH
0
0
a Reaction conditions: nitrobenzene (5 mmol), KOH (5 mmol), alcohol(15 mL), under microwave heating.
b Conversions were determined with GC-MS analysis.
c Isolated yields.
d In the absence of microwave irradiation.

106 JOURNAL OF CHEMICAL RESEARCH 2011
Table 3 Comparison of the reduction of several nitro
compounds to their corresponding amines over nanosized-
SmFeO3 and bulk-SmFeO3a
This new reduction system was easily scaled-up and served
for the synthesis of aniline at a several gram scale. In an exper-
iment, a mixture of nitrobenzene (250 mmol), propan-2-ol
(450 mL) and nanosized SmFeO3catalyst (5 mol%) in a round-
bottom flask was irradiated in a microwave oven equipped
with a refluxing system for 55 min. Aniline was formed in
95% yield which is even slightly higher than the laboratory
scale yield (93%), and the high chemical purity was main-
tained.
In order to make a comparison and to show the merit of
microwave method, the reduction of substrates was also con-
ducted under conventional heating at the same conditions. In
Table 2, the results obtained were compared with the micro-
wave reaction. As expected, the conventional heating took
longer for the maximum conversion under the same reaction
conditions. From this Table, it is evident that the microwave
Entry Substrate
Nano-SmFeO3 Bulk-SmFeO3
Time Yield
Time Yield
/min /%b
/min
/%b
1
2
3
4
5
Nitrobenzene
18
21
14
18
22
93
96
94
94
90
30
30
30
35
35
55
58
60
56
38
4-Bromonitrobenzene
4-Methylnitrobenzene
3-Methoxynitrobenzene
4-Nitrophenol
a Reaction conditions: nitrobenzene (5 mmol), KOH (5 mmol),
propan-2-ol (15 mL), catalyst (5 mol%) under microwave heat-
ing.
b Isolated yields.
heating dramatically increased the reaction rate. It is, however,
noteworthy here that the corresponding amines were obtained
in high yields through both conditions. The difference in the
reaction times for two methods also shows that the heating
mechanisms differs from each other.
The reduction of several substrates was also investigated
over a bulk SmFeO3 sample prepared bya traditional solid state
reaction (specific surface area = 3.5 m2g −1 and average particle
diameter = 25 µm) under the optimised conditions. The results
in Table 3 clearly indicate that the nanosized SmFeO3 catalyst
is much more active than the bulk SmFeO3 catalyst. This can
be mainly attributed to the higher specific surface area and the
much higher density of active sites in the nanosized SmFeO3
catalyst.
(
Table 4). This observation confirms that the nanosized
SmFeO3 is stable under the reaction conditions and was not
affected by the reactants. This could be attributed to the
high stability of the perovskite-type structure of SmFeO3
ence it behaves truly as heterogeneous solid catalyst.
Although the exact mechanism for this reaction over nano-
,
h
a
sized SmFeO3 particles is not very clear, we think that it
is similar to the classical Meerwein-Pondorf-Verley (MPV)
reduction.34,35,45 At the initial stage, propan-2-ol is adsorbed on
Table 4 Reusability of the nanosized SmFeO3 catalysta
Cycle
0
1st
2nd
3rd
4th
The reusability of the catalyst was also tested for the reduc-
tion of nitrobenzene. After the completion of reaction, the
catalyst was separated from the reaction mixture washed with
acetone, dried, and reused in the next runs under the same
conditions. The results indicate that there is no appreciable
difference in the yields of product even after the fourth run
Time /min
Yield /%b
18
93
20
91
20
92
22
89
22
90
a Reaction conditions: nitrobenzene (5 mmol), KOH (5 mmol),
propan-2-ol (15 mL), catalyst (5 mol%) under microwave heat-
ing.
b Isolated yields.
Table 2 The reduction of various aromatic nitro compounds with propan-2-ol over a nanosized SmFeO3 catalysta
Entry
Substrate
Product
Microwave method
Time /min
Yield /%b
18 93
Conventional method
Time /min
Yield /%b
1
2
C6H5NO2
p-MeC6H4NO2
C6H5NH2
p-MeC6H4NH2
240
320
300
240
180
140
150
150
180
180
180
340
210
180
120
100
110
120
330
300
240
240
270
320
300
340
300
120
94
93
91
93
91
92
90
95
92
96
94
65
94
95
96
92
90
88
70
85
87
88
86
90
85
85
87
94
14
20
18
20
18
10
21
14
20
20
22
20
19
10
14
18
18
20
22
20
20
18
20
22
20
22
10
94
90
94
90
96
95
96
94
96
92
95
93
95
95
94
94
92
66
90
90
92
88
91
88
90
94
93
3
m-MeC6H4NO2
m-MeOC6H4NO2
o-MeOC6H4NO2
m-ClC6H4NO2
m-MeC6H4NH2
m-MeOC6H4NH2
o-MeOC6H4NH2
m-ClC6H4NH2
4
5
6
7
o-ClC6H4NO2
o-ClC6H4NH2
8
p-BrC6H4NO2
p-BrC6H4NH2
9
m-BrC6H4NO2
m-BrC6H4NH2
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
2,5-(Cl)2C6H3NO2
2,3-(Cl)2C6H3NO2
3-NO2,4-ClC6H3NO2
m-NO2C6H4NO2
p-NO2C6H4NO2
p-CNC6H4NO2
2,5-(Cl)2C6H3NH2
2,3-(Cl)2C6H3NH2
3-NO2,4-ClC6H3NH2
m-NO2C6H4NH2
p-NO2C6H4NH2
p-CNC6H4NH2
p-NH2C6H4NO2
m-NH2C6H4NO2
o-NH2C6H4NO2
3,4-(NH2)2C6H3NO2
p-HOC6H4NO2
p-CHOC6H4NO2
p-MeCOC6H4NO2
p-HOOC-C6H4NO2
p-EtOOC-C6H4NO2
p-NH2CO-C6H4NO2
p-MeCONHC6H4NO2
p-CH2=CHC6H4NO2
1-Nitronaphthalene
p-NH2C6H4NH2
m-NH2C6H4NH2
o-NH2C6H4NH2
3,4-(NH2)2C6H3NH2
p-HOC6H4NH2
p-CHOC6H4NH2
p-MeCOC6H4NH2
p-HOOC-C6H4NH2
p-EtOOC-C6H4NH2
p-NH2CO-C6H4NH2
p-MeCONHC6H4NH2
p-CH2=CHC6H4NH2
1-Naphthylamine
a Reaction conditions: nitrobenzene (5 mmol), KOH (5 mmol), propan-2-ol (15 mL), under microwave and conventional heating.
b Yields are for isolated pure products.

JOURNAL OF CHEMICAL RESEARCH 2011 107
and irradiated with power 20% (180 W) for an appropriate time. The
progress of the reaction was monitored by TLC and GC-MS. After
completion of the reaction, the mixture was cooled to room tempera-
ture, the organic layer extracted with ethyl acetate or dichloromethane
(3 × 10 mL), dried over sodium sulfate and concentrated under a
reduced pressure. The pure product was isolated by silica-gel plate
using carbon tetrachloride (see Caution)-ethyl acetate or n-hexane-
ethyl acetate. The results are shown in Table 2. All products are
commercially available and were identified through the comparison of
their physical and spectroscopic data (m.p., C, H, N analysis, FT-IR,
GC-MS, 1H and 13C NMR) with those of authentic samples or reported
data.
CAUTION: Appropriate precautions must be taken because
of the toxicity and environmental unfriendliness of carbon
tetrachloride.
Scheme 1 The initial stage for the reduction of nitrobenzene
over the nanosized SmFeO3 catalyst.
Physical and spectroscopic data of some representative products:
p-Toluidine (Table 2, entry 2): m.p = 44–45°C (lit. 46 45°C). Anal.
Calcd for C7H9N: C, 78.39; H, 8.40; N, 13.06. Found: C, 78.45; H,
the catalyst followed by the formation of an alkoxide, which is
also known to be the activated H-donor in the presence of
KOH. As shown in Scheme 1, the coordinative interaction of
the substrate (nitrobenzene) with the Lewis acid centre of cata-
lyst allows the formation of a six membered transition state in
which hydride transfer takes place. Thus, the role of catalyst is
to hold both the H-donor and the H-acceptor through the Lewis
acid sites in close proximity so that direct hydrogen transfer
can take place smoothly. It is worthwhile mentioning that ace-
tone was found in all reaction mixtures by GC-MS analysis,
which is consistent with this hydride transfer pathway.
1
8.38; N, 13.12%. IR (KBr) (νmax/cm−1): 3335 (N–H). H NMR (300
MHz, CDCl3) δ 6.72 (d, J = 8.15 Hz, 2H), 6.65 (d, J = 8.14 Hz, 2H),
3.41 (broad signal, 2H), 2.25 (s, 3H). 13C NMR (75 MHz, CDCl3)
δ 144, 130, 127.3, 116.5, 20. MS, m/z: 107 (M+).8,19
p-Bromoaniline (Table 2, entry 8): m.p = 65–66°C (lit.46 66 °C).
Anal. Calcd for C6H6BrN: C, 41.85; H, 3.49; N, 8.14. Found: C, 41.80;
H, 3.52; N, 8.10%. IR (KBr) (νmax/cm−1): 3350 (N–H).1H NMR (300
MHz, CDCl3) δ 7.25–7.15 (m, 2H), 6.62–6.50 (m, 2H), 3.64 (broad
signal, 2H). 13C NMR (75 MHz, CDCl3) δ 145.2, 130, 117.5, 111. MS,
m/z: 171(M+, 79Br), 173 (M+, 81Br).
p-Aminobenzonitrile (Table 2, entry 15): m.p = 84–85°C (lit.46 83–
85°C). Anal. Calcd for C7H6N2: C, 71.17; H, 5.12; N, 23.71. Found:
C, 70.97; H, 5.02; N, 23.53%. IR (KBr) (νmax/cm−1): 3370 (N–H), 2250
(C≡N ).1H NMR (300 MHz, CDCl3) δ 7.45 (d, J = 8.6 Hz, 2H), 6.70
(d, J = 8.6 Hz, 2H), 4.15 (s, 2H). 13C NMR (75MHz, CDCl3) δ 150.9,
133.8, 120.5, 114.4, 99.5. MS, m/z: 118 (M+).8,19
p-Aminoacetophenone (Table 2, entry 22): m.p = 103–106°C
(lit.51 104–105 °C). Anal. Calcd for C8H9NO: C, 71.02; H, 6.66; N,
10.36. Found: C, 71.12; H, 6.72; N, 10.41%. IR (KBr) (νmax/cm−1):
3300 (N–H), 1680 (C=O ).1H NMR (300 MHz, CDCl3) δ 7.75 (d, J =
8.60 Hz, 2H), 6.61 (d, J = 8.59 Hz, 2H), 4.20 (broad signal, 2H), 2.45
(s, 3H). 13C NMR (75 MHz, CDCl3) δ 196.2, 151.5, 130.2, 126, 113.5,
25. MS, m/z: 135 (M+).8,19
According to the above mechanism, since the nitro group
can withdraw electron density more strongly from the aro-
matic ring compared to other functional groups, it can easily
be adsorbed on the catalyst surface leading to the amine
products. This may
b
e
the reason for
the chemoselective
reduction of nitro group ahead of
a
a
carbonyl group.
In conclusion, we have developed a novel and efficient cata-
lytic system for the reduction of aromatic nitro compounds
to the corresponding aromatic amines by using propan-2-ol/
microwave irradiation over a recyclable nanosized SmFeO3
catalyst. The advantages of this method are: highly selective
reduction of nitro compounds in the presence of other reduc-
ible or hydrogenolysable groups, ready availability and ease of
operation, rapid reduction, high yields of substituted amines,
avoidance of strong acid media, no equipment of pressure
apparatus and cost effectiveness. The present method offers
an economical, safe, and environmentally benign alternative to
available procedures.
The authors gratefully acknowledge the Lorestan University
and Iran Nanotechnology Initiative Council (INIC) for their
financial support.
Received 1 October 2010; accepted 7 December 2010
Paper 1000383 doi: 10.3184/174751911X12964930076647
Published online: 10 February 2011
Experimental
All chemicals and solvents were purchased from Merck or Fluka and
used as received. Melting points were obtained on an Electrothermal-
9200 instrument and are uncorrected. Elemental analysis was per-
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for solutions in CDCl3 with TMS as an internal standard. IR spectra
were recorded in KBr pellets on a Shimadzu FT-IR 8400 spectropho-
tometer. Mass spectra were measured on a Shimadzu QP 5050 GC–
MS. Microwave irradiation was carried out using a modified domestic
oven (LG, 2.45 GHz, 900W maximum power). As a domestic micro-
wave oven has been used it should be noted that when others attempt
the procedures, the microwave conditions may have to be modified
to obtain similar results. Analytical TLC was carried out on plates
precoated with silica gel GF254. The nanosized SmFeO3 catalyst was
synthesised by the previously reported method.44
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