Greener iodination of arenes using sulphated ceria-zirconia catalysts in polyethylene glycol

Article abstract of DOI:10.1039/c3ra46537c

An environmentally benign method for the selective monoiodination of diverse aromatic compounds has been developed using reusable sulphated ceria-zirconia under mild conditions. The protocol provides moderate to good yields and selectively introduces iodine at the para/ortho position in monosubstituted arenes. SO₄^2-/Ce_0.07Zr _0.93O₂ was found to be the best choice for the synthesis of aryl iodides in high yield, presumably due to the maximum number of acid sites (4.23 mmol g^-1) among the various compositions of the catalyst system.

Full text of DOI:10.1039/c3ra46537c

RSC Advances
View Article Online
View Journal | View Issue
PAPER
Greener iodination of arenes using sulphated
ceria–zirconia catalysts in polyethylene glycol†
Cite this: RSC Adv., 2014, 4, 6267
a
a
b
Sandeep S. Kahandal, Sandip R. Kale, Manoj B. Gawande, Radek Zboril,b
*
c
a
*
*
Rajender S. Varma and Radha V. Jayaram
An environmentally benign method for the selective monoiodination of diverse aromatic compounds has
been developed using reusable sulphated ceria–zirconia under mild conditions. The protocol provides
moderate to good yields and selectively introduces iodine at the para/ortho position in monosubstituted
arenes. SO42ꢀ/Ce0.07Zr0.93O2 was found to be the best choice for the synthesis of aryl iodides in high
yield, presumably due to the maximum number of acid sites (4.23 mmol gꢀ1) among the various
compositions of the catalyst system.
Received 9th November 2013
Accepted 20th November 2013
DOI: 10.1039/c3ra46537c
www.rsc.org/advances
Halogen derivatives of hydrocarbons form an important class of nitroarenes followed by the Sandmeyer reaction. Bromination
intermediates, as they can be converted efficiently into other and chlorination easily proceed with, or sometimes without,
functionalities by simple chemical transformations. Haloge- Lewis acid catalysts, but iodination is usually more difficult
nated arenes and alkanes are precursors for organometallic owing to the low electrophilicity of iodide. Hence, efforts are
reagents1 and are widely used as intermediates for the synthesis being made towards the development of efficient, selective and
of biologically active molecules, including drugs (e.g. galanth- mild methods for the direct introduction of iodine into organic
amine), ne chemicals (e.g., iso-vanillyl sweeteners), pesticides compounds. Besides the use of volatile organic solvents as
and fungicides.2–5 The iodoarene moiety is an important struc- reaction media, most of the methods studied used harsh reac-
tural motif in biologically active molecules (e.g., thyroid tion conditions, such as the extensive use of strong acids or the
hormone) and a synthetic intermediate for a variety of ne use of heavy metal salts and the need for oxidants as activators
chemicals. The suitability of iodoarenes as synthetic interme- for iodine;11 this requires special safety precautions in experi-
diates is partly due to the fact that the iodo substituent can mental handling and generates serious concerns regarding
undergo a multitude of transition metal catalyzed cross- environmental and health issues.
coupling reactions.
PEG is a non-toxic, inexpensive, and non-volatile solvent,
Numerous Pd coupling reactions including the Heck,6 Stille,7 employed in synthetic chemistry for various organic trans-
Suzuki,8 and Sonogashira9 reactions require aromatic halides as formations.12 It also has good thermal stability, and is miscible
precursors to prepare more complex targets and aromatic with a number of organic solvents.
iodides are among the most versatile building blocks in this
The development of mild, cost effective and environmentally
category. Although there are numerous examples (direct or benign catalytic procedures for the iodination of aromatic
indirect synthesis), where electrophilic aromatic substitution is compounds is a fertile area of research. Previously, heteroge-
used to replace an aryl hydrogen atom with a halogen group, neous metal oxides and sulfate catalysts have been deployed as
iodination still remains a difficult transformation to facilitate.10 acid or oxidative catalysts for iodination chemistry.13
Iodo compounds are oen synthesized via the reduction of
Recently, we have found that ceria–zirconia mixed oxides
can act as an efficient bifunctional catalyst system for the
sequential epoxidation–aminolysis of styrenes.14 The sulphated
aDepartment of Chemistry, Institute of Chemical Technology (Autonomous), N. Parekh form of these mixed oxides has been found to be a good catalyst
Marg, Matunga, Mumbai 400 019, India. E-mail: rv.jayaram@ictmumbai.edu.in; Fax:
for the modied Ritter reaction.15 In a continuation of research
activities on the development of benign protocols using
heterogeneous catalysts,16–18 we have now explored the catalytic
+91(22)24145614
bRegional Centre of Advanced Technologies and Materials, Faculty of Science,
ˇ
˚
Department of Physical Chemistry, Palacky University, Slechtitelu 11, 783 71
activity of these oxides for the iodination of arenes. Herein, we
report a mild and experimentally simple catalytic method for
Olomouc, Czech Republic. E-mail: mbgawande@yahoo.co.in; manoj.gawande@upol.cz
cSustainable Technology Division, National Risk Management Research Laboratory,
US Environmental Protection Agency, MS 443, 26 West Martin Luther King Drive, the synthesis of iodoarenes using sulphated ceria–zirconia as a
Cincinnati, Ohio, 45268, USA. E-mail: Varma.Rajender@epamail.epa.gov
heterogeneous, inexpensive and recyclable catalyst. The
method does not require the addition of any oxidant or acti-
† Electronic supplementary information (ESI) available: Experimental details,
catalyst characterization data and GCMS spectra of all prepared compounds.
vator, such as heavy metals (lead, mercury and chromium). The
See DOI: 10.1039/c3ra46537c
This journal is © The Royal Society of Chemistry 2014
RSC Adv., 2014, 4, 6267–6274 | 6267

View Article Online
RSC Advances
Paper
4-iodoaniline was obtained even aer 24 h under the present
reaction conditions (Table 1, entry 1).
When the same reaction was carried out in the presence of
other reported catalysts such as H2SO4, ZrSO4, low yields and
poor regioselectivity were observed (Table 1, entries 2 and 3).
Also, with single component oxides – CeO2 or ZrO2, only a
35–48% yield of 4-iodoaniline was obtained (Table 1, entries
4 and 5). However, upon sulphation, the yield of 4-iodoaniline
increased to 43–77% (Table 1, entries 6 and 7) with improved
selectivity. A physical mixture of SO42ꢀ/CeO2 and SO42ꢀ/ZrO2 (10
wt% of each) gives a 55% yield, with poor regioselectivity
towards 4-iodoaniline (Table 1, entry 8). The investigation was
further extended to several compositions of sulphated ceria–
zirconia and sulphated yttria–zirconia catalysts. It was observed
that the sulphated ceria–zirconia system gave better yields/
regioselectivity for the synthesis of iodoanilne compared to
sulphated yttria–zirconia catalysts (Table 1, entry 10–21).
As the cerium content in SO42ꢀ/CexZr1ꢀxO2 was increased
from 0.02–0.07 mol%, the total acidity and surface area of the
catalysts were also found to increase. A further increase in
cerium content resulted in a decrease in both total acidity and
surface area (see ESI†), which was also manifested in the activity
and selectivity of the reaction.
Scheme 1 Synthesis of iodoarenes catalysed by sulphated ceria–
zirconia as a catalyst in PEG-200.
mild reaction conditions and the use of PEG-200 as a green
solvent make the process environmentally benign and hazard-
free (Scheme 1).
Results and discussion
To develop a suitable catalytic protocol for the synthesis of
iodoarenes, iodination of aniline in the presence of several
surface modied metal oxides and mixed metal oxides using I2
and PEG-200 as reaction medium was chosen as the test reac-
tion (Scheme 2 and Table 1).
2ꢀ
Among the various catalysts tested in the study, SO4
/
CexZr1ꢀxO2 gave the maximum yield (97%) with preferential
para selectivity. In the absence of a catalyst only a 25% yield of
When the reaction was carried out with SO42ꢀ/Ce0.07Zr0.93O2
catalyst, 97% yield with 100% selectivity for 4-iodoaniline was
obtained, which is the highest among the various compositions
of SO42ꢀ/CexZr1ꢀxO2 studied (Table 1, entry 11). This could be
due to the maximum value in the number of acid sites (4.23
mmol gꢀ1) and acid strength as determined by potentiometric
titration using n-butylamine.19 In this method, the initial elec-
trode potential (Ei) indicates the strength of the acid sites and
Scheme 2 Synthesis of 4-iodoaniline in PEG-200 at 30 ꢁC.
Table 1 Synthesis of iodoanilne using sulphated ceria–zirconia solid acid catalystsa
Entry Catalyst
1g
BET Surface area (m2 gꢀ1
)
Acidity (mmol gꢀ1 b
)
Ei (mV)c Conversion (%)d Selectivity (%)e Yield (%)f
30
70
45
60
45
84
54
43
65
80
100
82
62
57
53
56
54
68
92
69
60
80/20
85/15
67/33
93/7
91/9
96/4
85/15
100
25
54
27
48
35
77
43
38
55
76
97
75
55
49
44
46
48
57
86
65
56
2
H2SO4
—
—
12
10
37
23
17
—
22
53
28
14
12
10
34
43
52
75
35
29
—
—
0.8
0.3
2.07
1.22
1.54
—
3.17
4.23
3.52
3.50
2.97
2.17
1.23
1.64
1.93
4.19
2.91
2.65
—
—
55
3
ZrSO4
4
ZrO2
5
6
7
CeO2
27
168
154
157
—
440
560
450
460
248
197
148
195
310
530
330
248
SO42ꢀ/ZrO2
SO42ꢀ/CeO2
8
Ce0.07Zr0.93O2
9h
10
11
12
13
14
15
16
17
18
19
20
21
SO42ꢀ/CeO2 + SO42ꢀ/ZrO2
SO42ꢀ/Ce0.02Zr0.98O2
SO42ꢀ/Ce0.07Zr0.93O2
SO42ꢀ/Ce0.10Zr0.90O2
SO42ꢀ/Ce0.15Zr0.85O2
SO42ꢀ/Ce0.20Zr0.80O2
SO42ꢀ/Ce0.25Zr0.75O2
SO42ꢀ/Y0.04Zr0.96O2
SO42ꢀ/Y0.08Zr0.92O2
SO42ꢀ/Y0.12Zr0.88O2
SO42ꢀ/Y0.16Zr0.84O2
SO42ꢀ/Y0.20Zr0.80O2
SO42ꢀ/Y0.24Zr0.76O2
88/12
100
100
100
98/2
95/5
95/5
92/8
90/10
90/10
94/6
99/1
100
a
Reaction conditions: aniline (2 mmol), I2 (2 mmol), PEG-200 (2 ml), 12 h, RT, catalyst (15 wt% w.r.t. aniline). b Surface acidity values determined
c
d
using the n-butylamine potentiometric titration method. Ei initial electrode potential (mV). Conversion determined using GC analysis.
e
f
Selectivity determined using GC analysis. Isolated yields. g 24 h. h 7.5 (wt%) of each w.r.t. aniline.
6268 | RSC Adv., 2014, 4, 6267–6274
This journal is © The Royal Society of Chemistry 2014

View Article Online
Paper
RSC Advances
the end point of the titration is related to the number of acidic entry 12), it reacted with aniline to form 2,2,4-trimethyl-1,2-
sites (mmol gꢀ1). For comparison, a test reaction was also dihydroquinoline as the exclusive product.
carried out with non-sulphated Ce0.07Zr0.93O2, which gave a 38%
As the primary goal of this study was to develop a process
yield of 4-iodoaniline (Table 1, entry 8). We also explored the that is ‘green’ and environmentally viable, the iodination reac-
effect of surface ratio of (Ce/Zr) and surface density of sulpha- tion was conducted in polyethylene glycol (PEG); (Table 3,
tion. The highest surface sulphate ratio of Ce/Zr (0.075) was entries 13–15) PEG-200 gave the highest yield (97%) of 4-
obtained with SO42ꢀ/Ce0.07Zr0.93O2, which was also found to iodoaniline (Table 3, entry 13). Hayase et al. have studied the
have maximum acid sites (ESI Table 2†).
interaction of molecular iodine with PEG and proposed that the
The effect of various reaction parameters such as catalyst interatomic distance in the iodine molecule slightly increased
loading, solvent system etc. was also investigated for the model when the concentration of PEG was larger than a limiting
reaction. An increase in initial catalyst loading, up to 15 wt%, concentration, C1. It was observed that C1 decreased with an
results in an increased yield of the product while further increase in the molecular weight of PEG in the case of molecular
increase has no profound effect (Table 2, entry 1–5).
weights below 300 and was unaffected for higher molecular
The solvent plays a key role in catalyst activity and thus weights of PEG.20
choice of the proper solvent is crucial (Table 3). The synthesis of
In the iodination reaction, an increase in the interatomic
iodoanilne under solvent-free conditions gave a 35% yield of the distance would result in weakening of the I–I bond in molecular
desired product (Table 3, entry 1). It was observed that non- iodine, which in turn would favour the electrophilic aromatic
polar solvents like 1,4 dioxane, n-hexane and mildly polar substitution reaction. See ESI for UV-Vis spectra of I2+PEG-200-
solvents like chloroform, ethyl acetate, tetrahydrofuran, 600.†lmax ¼ 360 nm corresponds to diatomic I2, which is
dichloromethane, and dichloroethane gave good to moderate slightly shied by interaction with the solvent (PEG).20
yields of the product (Table 3, entries 2–8). Polar solvents such
Interestingly, when the iodination reaction was carried out
as methanol, acetonitrile and ethanol, were found to be better with ICl, poor regioselectivity was observed as evidenced by the
reaction media for iodination (Table 3, entries 9–11). Interest- presence of polyiodination products of aniline shown by GC
ingly, when the reaction was carried out in acetone (Table 3, and GC-MS analysis (m/z (%) ¼ 345 (100%) M+) (Scheme 3 and
Fig. 7 ESI†).
When different iodine sources were used for the synthesis of
4-iodoaniline, it was observed that molecular iodine gave better
yield and selectivity over iodine monochloride and N-iodo-
succinimide under similar experimental conditions (Table 4,
entries 1–3).
Table 2 Effect of catalyst loading on the yield of iodoanilinea
Entry
Catalyst loading (wt%)
Yield (%)b
1
2
3
4
5
5
10
15
20
25
61
74
97
97
97
To evaluate the applicability of the SO42ꢀ/Ce0.07Zr0.93O2
catalytic system for iodination, the reactions of structurally
varied and electronically diverse amines and phenols were
carried out with I2 and PEG-200 as a reaction medium; the
results are summarized in Table 5. Iodination of aniline pref-
erably takes place at the para position, with a high yield (97%)
a
Reaction conditions: aniline (2 mmol), I2 (2 mmol), PEG-200 (2 ml), 12
h, RT, SO42ꢀ/Ce0.07Zr0.93O2 catalyst (wt% w.r.t. aniline). b Isolated yields.
Table 3 Effect of solvent on the iodination of anilinea
Entry
Solvent
Yield (%)b
1
2
3
4
5
6
7
8
—
35
49
54
60
65
67
78
80
83
85
87
0
1,4 Dioxane
n-Hexane
Scheme 3 Reaction of aniline with ICl in PEG-200 at 30 ꢁC.
Table 4 Iodination of aniline with various iodine sourcesa
Chloroform
Ethyl acetate
Tetrahydrofuran
Dichloromethane
Dichloroethane
Methanol
Acetonitrile
Ethanol
Acetone
9
10
11
12
13
14
15
Entry
Iodinating source
Yield (%)b
1
2
3
I2
NIS
ICl
97
PEG-200
PEG-400
PEG-600
97
85
79
74
65 (60/40)c
a
a
Reaction conditions: aniline (2 mmol), iodinating source (2 mmol),
PEG-200 (2 ml), 12 h, RT, SO42ꢀ/Ce0.07Zr0.93O2 catalyst (15 wt% w.r.t.
aniline). b Isolated yields. c Polyiodination of aniline was observed.
Reaction conditions: aniline (2 mmol), I2 (2 mmol), solvent (2 ml), 12 h,
b
RT, SO42ꢀ/Ce0.07Zr0.93O2 catalyst (15 wt% w.r.t. aniline). Isolated
yields.
This journal is © The Royal Society of Chemistry 2014
RSC Adv., 2014, 4, 6267–6274 | 6269

View Article Online
RSC Advances
Paper
Table 5 Iodination of arenes with I2 using sulphated ceria–zirconiaa
Entry
Substrate
Product
Time (h)
12
Yield (%)b
97
1
2
3
12
12
95
52
4
5
6
7
12
12
12
12
70
61
95
60
8
9
12
12
85
35
10
12
99
6270 | RSC Adv., 2014, 4, 6267–6274
This journal is © The Royal Society of Chemistry 2014

View Article Online
Paper
RSC Advances
Table 5 (Contd.)
Entry
Substrate
Product
Time (h)
Yield (%)b
11
12
13
12
96
12
12
85
95
14
15
12
12
82
75
16
15
75
17
18
15
15
70
45
This journal is © The Royal Society of Chemistry 2014
RSC Adv., 2014, 4, 6267–6274 | 6271

View Article Online
RSC Advances
Paper
Table 5 (Contd.)
Entry
Substrate
Product
Time (h)
Yield (%)b
19
20
15
30
24
24
NR
NR
21
a
Reaction conditions: Arene (2 mmol), I2 (2 mmol), PEG-200 (2 ml), RT, SO42ꢀ/Ce0.07Zr0.93O2 catalyst (15 wt% w.r.t. arene). b Isolated yields, NR – no
reaction.
of the product (Table 5, entry 1). When reaction of 4-iodoaniline
was carried out with I2, 2,4-diiodoaniline was obtained also
Experimental
with an excellent yield of 95% (Table 5, entry 2). The iodination
reaction of various arenes exhibited a strong dependency on the
electron withdrawing and donating nature of the substituents
present in the aromatic ring. Reactions of substituted anilines
containing a strong electron withdrawing nitro group (–NO2) at
the ortho, meta and para positions gave moderate yield of the
products (Table 5, entries 3–5). 3-Chloroaniline, gave 4-iodo-3-
chloroaniline in an excellent yield, whereas with 4-chloroani-
line under the same reaction conditions, only a moderate yield
of 2-iodo-4-chloroaniline was obtained (Table 5, entries 6
and 7). Interestingly, it was found that when the reaction of
diphenylamine and diphenyl ether was carried out with two
equivalents of I2, only monoiodination occurred at one of the
aromatic rings (Table 5, entries 8 and 9). The present reaction
system was also applicable for the iodination of N,N-dimethy-
laniline, 4-methylaniline, 3-methoxyanisole and anisole (Table
5, entries 10–13).
To further expand the generality of the protocol, iodination
of several phenols were carried out under the optimized reac-
tion conditions (Table 5, entries 14–19). The reaction of phenol
gave good yields of 4-iodophenol (Table 5, entry 14). The pres-
ence of electron donating and withdrawing substituents such as
–CH3, –C(CH3)3, –CHO and –Cl (ortho and ortho, para), which
strongly inuence the substitution reaction gave moderate to
good yields of the products (Table 5, entries 15–19). Iodination
of benzene and benzoic acid did not take place even when the
reaction was conducted for 24 h (Table 5, entries 20 and 21).
All commercial reagents were used as received unless otherwise
mentioned. For analytical and preparative thin-layer chroma-
tography, Merck (0.2 mm) and Kieselgel GF 254 (0.5 mm) pre-
coated plates were used. The catalysts were characterized using
XRD, FT-IR, TGA-DSC, BET surface area, total acidity by
n-butylamine potentiometric titration method and SEM/EDAX.
XRD patterns of the catalysts were recorded using a Bruker AXS
˚
diffractometer with Cu–Ka radiation (l ¼ 1.540562 A) over a 2q
range of 0–80ꢁ. SEM-EDAX data were obtained using a Tungsten
source and a JEOL (model JSM-6390) instrument. Thermograms
were recorded on an SDT Q 600V 8.2 Build 100 model from TA
instruments. Potentiometric titrations were carried out using
an Equiptronics digital potentiometer (EQ-614A) instrument
tted with a double junction electrode. The percentage
conversion, selectivity and relative yields of the nal products
were determined using a Thermosher gas chromatograph (GC-
1000) tted with a capillary column (30 m ꢂ 0.32 mm ID –
0.25 mm BP-10) and FID detector. The products were identied
by GC-MS using a Shimadzu (GCMS-QP 2010) E.I. mode
instrument with high purity helium as the carrier gas. All the
products obtained and discussed in this work have been
previously reported and representative products were charac-
terized by suitable technique such as GC and GC-MS (Shimadzu
QP 2010) analysis.
Reusability of SO42ꢀ/Ce0.07Zr0.93O2
This indicates that the present process requires the presence of A set of experiments were carried out to examine the reusability
an electron donating group on the aromatic ring to facilitate the of the SO42ꢀ/Ce0.07Zr0.93O2 catalyst in the iodination reaction.
electrophilic aromatic substitution reaction.
The catalyst was separated aer each run by ltration, washed
6272 | RSC Adv., 2014, 4, 6267–6274
This journal is © The Royal Society of Chemistry 2014

View Article Online
Paper
RSC Advances
both aniline and phenol gave good to excellent yields with high
regioselectivity. Among the various compositions studied,
SO42ꢀ/Ce0.07Zr0.93O2 was found to be the best candidate in
terms of activity, selectivity and reusability. Salient features
such as an easy workup procedure, avoiding the use of an
oxidant, an environmentally viable solvent and a recyclable
catalyst renders the protocol environmentally benign.
Acknowledgements
This work was supported by the Operational Program Research
and Development for Innovations; European Regional Devel-
opment Fund (CZ.1.05/2.1.00/03.0058). SSK and SRK are
thankful to CSIR, Government of India for nancial assistance.
Fig. 1 Reusability of SO42ꢀ/Ce0.07Zr0.93O2 for iodination of aniline.
Reaction conditions: aniline (10 mmol), I2 (10 mmol), PEG-200 (10 ml),
12 h, 30 ꢁC, SO42ꢀ/Ce0.07Zr0.93O2 catalyst: 15 wt% w.r.t. aniline, iso-
lated yield.
References
with acetone and dried at 100 ꢁC for 2 h in an oven before use in
the next catalytic cycle. The SO42ꢀ/Ce0.07Zr0.93O2 catalyst was
found to be reusable for ve times without any signicant loss
in activity (Fig. 1).
1 (a) H. Normat, Adv. Org. Chem., 1960, 2, 1; (b) B. J. Wakeeld,
The Chemistry of Organolithium Compounds, Pergamon,
Oxford, 1976; (c) S. G. Davies, in Organotransition Metal
Chemistry, Applications to Organic Synthesis, Pergamon,
Oxford, 1982; (d) K. C. Cannon and G. R. Krow, in
Handbook of Grignard Reagents, ed. G. S. Silverman and
P. E. Rakita, M. Dekker, NewYork, 1996, ch. 25, p. 497.
2 S. Patai and Z. Rappoport, The Chemistry of Halides, Pseudo-
Halides and Azides, John Wiley and Sons, Chichester, UK,
1995, suppl. D2.
3 D. M. Burland, R. D. Miller and C. A. Walsh, Chem. Rev.,
1994, 94, 31–75.
4 A. B. Naidu, D. Ganapathy and G. Sekar, Synthesis, 2010, 20,
3509–3519.
5 J. H. Chang, H.-U. Kang, I.-H. Jung and C.-G. Cho, Org. Lett.,
2010, 12(9), 2016–2018.
Catalyst preparation
All chemicals of analytical grade were used without any further
purication.
A
series of SO42ꢀ/CexZr1ꢀxO2 catalysts were
prepared by the method described by Lee et al.21,22 A precipitate
of Zr(OH)4 was obtained by adding aqueous ammonia to 0.25 M
solution of zirconium oxychloride at room temperature with
vigorous stirring until the pH reached 8.0. To this, an acidic
aqueous solution of cerium sulphate, Ce(SO4)2$4H2O, was
added and the ensuing precipitate was dried at 110 ꢁC for 24 h
and calcined at 650 ꢁC for 2 h. A series of catalysts were prepared
by varying the mol % of cerium (0.02–0.25) added.
6 (a) R. F. Heck, Acc. Chem. Res., 1979, 12, 146–151; (b)
J. H. Clark, D. J. Macquarrie and E. B. Mubofu, Green
Chem., 2000, 2, 53–56; (c) R. K. Arvela, S. Pasquini and
M. Larhed, J. Org. Chem., 2007, 72, 6390–6396; (d)
A. Cassez, N. Kania, F. Hapiot, S. Fourmentin, E. Monier
and A. Ponchel, Catal. Commun., 2008, 9, 1346–1351.
7 (a) M. Cai, G. Zheng and G. Ding, Green Chem., 2009, 11,
1687–1693; (b) D. P. Sweat and C. E. Stephens, Synthesis,
2009, 3214–3218.
8 (a) S. S. Pawar, M. S. Shingare and S. N. Thore, Lett. Org.
Chem., 2007, 4, 486–490; (b) N. E. Leadbeater and
M. Marco, J. Org. Chem., 2003, 68, 888–892.
9 P. Li, L. Wang and H. Li, Tetrahedron, 2005, 61, 8633–
8640.
General procedure for the iodination reaction
In a typical reaction procedure, 2 mmol of aniline and 2 mmol
of molecular iodine were taken in a 25 ml round bottom ask.
SO42ꢀ/CexZr(1ꢀx) O2 (15 wt%) with 2 ml PEG-200 were added to
the ask and the reaction mixture was stirred for 12 h at room
temperature (30 ꢁC). The reaction was continuously monitored
by TLC and gas chromatography. Aer completion of the reac-
tion, 10 ml of ethyl acetate was added to the reaction mixture
and the catalyst was separated by simple ltration. The result-
ing reaction mass was treated with Na2S2O3 solution (10 ml) and
extracted with ethyl acetate (10 ml). It was then passed through
a bed of anhydrous Na2SO4. Evaporation of the solvent yielded
the iodo compound, which was puried by column chroma-
tography on silica gel using a mixture of hexane–EtOAc (80 : 20)
as the eluent. All the reaction products were compared with
known samples and conrmed by GC-MS.
10 M. E. Mowery and P. DeShong, J. Org. Chem., 1999, 64, 1684–
1688.
11 (a) L. Kraszkiewicz, M. Sosnowski and L. Skulski,
Tetrahedron, 2004, 60, 9113–9119; (b) H. Suzuki,
K. Nakamura and R. Goto, Bull. Chem. Soc. Jpn., 1966, 39,
128–131; (c) B. R. Patil, S. R. Bhusare, R. P. Pawar and
Y. Vibhute, Tetrahedron Lett., 2005, 46, 7179–7181; (d)
G. A. Olah, Q. Wang, G. Sandford and G. K. S. Prakash,
J. Org. Chem., 1993, 58, 3194–3195; (e) A. Bachki,
F. Foubelo and M. Yus, Tetrahedron, 1994, 50, 5139–5146;
Conclusion
Sulphated ceria–zirconia was successfully employed as a
heterogeneous catalyst with good activity for the synthesis of
aryl iodides using molecular iodine in PEG-200 as a solvent.
Various electron donating and withdrawing substituents on
This journal is © The Royal Society of Chemistry 2014
RSC Adv., 2014, 4, 6267–6274 | 6273

View Article Online
RSC Advances
Paper
(f) K. Orito, T. Hatakeyama, M. Takeo and H. Suginome,
Synthesis, 1995, 1273–1277; (g) B. Krassowska-Swiebocka,
P. Lulinski and L. Skulski, Synthesis, 1995, 926–928.
1899; (d) M. B. Gawande, P. S. Branco, I. D. Nogueira,
C. A. A. Ghumman, N. Bundaleski, A. Santos,
O. M. N. D. Teodoro and R. Luque, Green Chem., 2013, 15,
682–689.
12 (a) D. Sun and H. Zhai, Catal. Commun., 2007, 8, 1027–1030;
(b) J. Chen, S. K. Spear, J. G. Huddleston and R. D. Rogers, 17 (a) M. B. Gawande, P. S. Branco, I. D. Nogueira,
Green Chem., 2005, 7, 64–82; (c) V. V. Namboodiri and
R. S. Varma, Green Chem., 2001, 3, 146–148.
C. A. A. Ghumman, N. Bundaleski, A. Santos,
O. M. N. D. Teodoro and R. Luque, Green Chem., 2013, 15,
682–689; (b) M. B. Gawande, P. S. Branco and R. S. Varma,
Chem. Soc. Rev., 2013, 42, 3371–3393; (c) M. B. Gawande,
A. Rathi, P. S. Branco, I. D. Nogueira, A. Velhinho,
J. J. Shrikhande, U. U. Indulkar, R. V. Jayaram,
13 (a) W. W. Sy, B. A. Lodge and A. W. By, Synth. Commun., 1990,
20, 877–880; (b) W. W. Sy, Synth. Commun., 1992, 22, 3215–
3219; (c) W. W. Sy, Synth. Commun., 1990, 20, 3391–3394;
(d) P. Lulinski and L. Skulski, Bull. Chem. Soc. Jpn., 1997,
70, 1665–1669; (e) S. G. Yang and Y. H. Kim, Tetrahedron
Lett., 1999, 40, 6051–6054; (f) P. Zhang, D. Sun, M. Wen,
C.
A.
A.
Ghumman,
N.
Bundaleski
and
O. M. N. D. Teodoro, Chem.–Eur. J., 2012, 18, 12628–12632.
J. Yang, K. Zhou and Z. Wang, Adv. Synth. Catal., 2012, 18 (a) M. B. Gawande, D. B. Bonifacio Vasco, R. Luque,
354, 720–729; (g) C. Chiappe and D. Pieraccini, ARKIVOC,
2002, 249–255; (h) W. W. Sy, Tetrahedron Lett., 1993, 34,
6223–6224.
P. S. Branco and R. S. Varma, Chem. Soc. Rev., 2013, 42,
5522–5551; (b) M. B. Gawande, D. B. Bonifacio Vasco,
R. Luque, P. S. Branco and R. S. Varma, ChemSusChem,
2013, DOI: 10.1002/cssc.201300485d; (c) M. B. Gawande,
A. Rathi, I. D. Nogueira, C. A. A. Ghumman, N. Bundaleski,
O. M. N. D. Teodoro and P. S. Branco, ChemPlusChem,
2012, 77, 865–871.
14 K. D. Parghi, S. R. Kale, S. S. Kahandal, M. B. Gawande and
R. V. Jayaram, Catal. Sci. Technol., 2013, 3, 1308–1313.
15 (a) S. S. Kahandal, S. R. Kale, S. T. Disale and R. V. Jayaram,
Chem. Lett., 2012, 41, 738–740; (b) S. S. Kahandal, S. R. Kale,
S. T. Disale and R. V. Jayaram, Synfacts, 2012, 8(10), 1161; (c) 19 K. M. Reddy, N. Lingaiah, P. S. S. Prasad and
S. S. Kahandal, S. R. Kale, S. T. Disale and R. V. Jayaram,
ChemInform, 2012, 49, 43.
16 (a) S. S. Kahandal, S. R. Kale, S. T. Disale and R. V. Jayaram,
I. Suryanarayana, J. Solid State Chem., 2006, 35, 407–423.
20 N. Kaneniwa, A. Ikekawa and H. Hayase, Chem. Pharma.
Bull., 1974, 22(11), 2635–2641.
Catal. Sci. Technol., 2012, 2, 1493–1499; (b) M. B. Gawande, 21 J. R. Sohn, S. H. Lee and J. S. Lim, Catal. Today, 2006, 116,
R. K. Pandey and R. V. Jayaram, Catal. Sci. Technol., 2012, 143–150.
2, 1113–1125; (c) M. B. Gawande, A. Rathi, I. D. Nogueira, 22 J. R. Sohn, J. S. Lim and S. H. Lee, Chem. Lett., 2004, 33, 1490–
R. S. Varma and P. S. Branco, Green Chem., 2013, 15, 1895– 1491.
6274 | RSC Adv., 2014, 4, 6267–6274
This journal is © The Royal Society of Chemistry 2014