Supported bismuth(III) nitrate on silica sulfuric acid as useful reagent for nitration of aromatic compounds under solvent-free conditions

Article abstract of DOI:10.1007/s11178-005-0372-y

A number of aromatic compounds were nitrated to the corresponding nitroaromatic derivatives with the use of supported bismuth(III) nitrate on silica sulfuric acid under solvent-free conditions.

Full text of DOI:10.1007/s11178-005-0372-y

Russian Journal of Organic Chemistry, Vol. 41, No. 10, 2005, pp. 1493–1495. From Zhurnal Organicheskoi Khimii, Vol. 41, No. 10, 2005, pp. 1524–1526.
Original English Text Copyright © 2005 by Hajipour, Zarei, Ruoho.
Supported Bismuth(III) Nitrate on Silica Sulfuric Acid
as Useful Reagent for Nitration of Aromatic Compounds
under Solvent-Free Conditions*
1
,2
2
1
A. R. Hajipour , A. Zarei , and A. E. Ruoho
1
Department of Pharmacology, University of Wisconsin, Medical School,
300 University Avenue, Madison, 53706-1532, WI, USA
1
2
Pharmaceutical Research Laboratory, College of Chemistry, Isfahan University of Technology,
Isfahan 84156, IR Iran;
fax: +1(608)2621257; e-mail: arkajipour@facstaff.wisc.edu; haji@cc.iut.ac.ir
Received March 24, 2004
Abstract—A number of aromatic compounds were nitrated to the corresponding nitroaromatic derivatives with
the use of supported bismuth(III) nitrate on silica sulfuric acid under solvent-free conditions.
Conventional methods for the nitration of aromatic
compounds utilize a mixture of nitric and sulfuric acids
or nitronium tetrafluoroborate [1]. In the latter case,
the nitration is accompanied by liberation of HF and
heated for a time indicated in table. The reaction was
fast, and the product was readily isolated by extraction
and purified by chromatography.
Activated aromatic compounds were converted into
the corresponding nitro derivatives in excellent yields
by the action of 1.2 equiv of the reagent in 1–4 min
at room temperature. Reactions with less active sub-
strates were carried out with 1.5 equiv of the reagent
under stirring at 50–70°C; in these cases, the reaction
time was 120–180 min, and the products were isolated
in good yields (see table). The nitration of aromatic
compounds containing readily oxidizable groups, e.g.,
benzenethiol and benzaldehyde, was accompanied by
oxidation to afford diphenyl disulfide and benzoic
acid, respectively. The regioselectivity in the nitration
with supported Bi(III) nitrate on silica sulfuric acid
was the same as in the conventional procedures [1–3].
BF [1]. Nitro derivatives necessary for the preparation
4
of azido-substituted aromatic compounds as photo-
affinity ligands [2] were obtained by usual nitric–
sulfuric acid and nitronium tetrafluoroborate methods
[
3]. In the recent time, reactions occurring under sol-
vent-free conditions attract much attention [4–6]. The
main advantages of such methods, as compared to
classical procedures, are cleaner reactions, reduced
reaction time, and easy isolation of the products.
In continuation of our studies on the development
of ecologically friendly procedures for carrying out
chemical reactions in the absence of a solvent [7], the
present communication describes an extremely con-
venient method for nitration of aromatic compounds
with supported bismuth(III) nitrate on silica sulfuric
acid under solvent-free conditions. The nitrating agent
was prepared by grinding 2 mmol (0.8 g) of silica
sulfuric acid [8] with 0.33 mmol (0.13 g) of anhydrous
bismuth(III) nitrate in a mortar until a homogeneous
mixture was obtained. Appropriate aromatic substrate
was added to the reagent prepared in such a way
so that the substrate-to-reagent molar ratio was
In order to estimate the efficiency of nitration under
solvent-free conditions in comparison to the reaction in
solution, we performed nitration of toluene in several
solvents: methanol, acetone, diethyl ether, methylene
chloride, tetrahydrofuran, and 1,4-dioxane. Tetrahydro-
furan turned out to be the best among the above
solvents. When toluene was treated with silica sulfuric
acid-supported Bi(NO ) at a ratio of 1:1.2, the con-
3 3
version was only 40% in 24 h under reflux. The yield
of the product did not increase in the presence of
1
:(1.2–1.5), and the mixture was thoroughly ground in
2
equiv of the reagent.
a mortar and was left to stand at room temperature or
We can conclude that the proposed procedure for
*
The text was submitted by the authors in English.
the nitration of aromatic compounds with supported
1
070-4280/05/4110-1493 © 2005 Pleiades Publishing, Inc.

1
494
HAJIPOUR et al.
a
Nitration of aromatic compounds with silica sulfuric acid-supported bismuth(III) nitrate in the absence of a solvent
b
Temperature, Reaction time,
c
Initial compound
Benzene
Toluene
Product (ortho:meta:para ratio)
Yield, %
°C
min
003
003
003
004
004
004
002
004
003
002
007
010
008
010
010
010
010
120
120
180
040
Nitrobenzene
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
50
65
70
70
65
090
090
090
090
090
080
100
090
095
090
080
080
085
080
080
090
095
080
060
080
090
Nitrotoluene (25:0:75)
2,5-Dimethyl-1-nitrobenzene
2,4-Dimethyl-1-nitrobenzene
1-Bromo-4-nitrobenzene
Chloronitrobenzene (20:0:80)
4-Nitro-N,N-dimethylaniline
4-Nitro-N,N-diethylaniline
Diphenyl disulfide
1
1
,4-Dimethylbenzene
,3- Dimethylbenzene
Bromobenzene
Chlorobenzene
N,N-Dimethylaniline
N,N-Diethylaniline
Benzenethiol
Anisole
Nitroanisole (15:0:85)
4-Bromo-2-nitroanisole
4-Methoxy-3-nitrobenzaldehyde
Nitrophenol (15:0:85)
5-Chloro-2-nitrophenol
Nitrohydroquinone
4
4
-Bromoanisole
-Methoxybenzaldehyde
Phenol
-Chlorophenol
Hydroquinone
,6-Dimethylpyridine N-oxide
3
2
2,6-Dimethyl-4-nitropyridine N-oxide
1-Nitronaphthalene
Naphthalene
Biphenyl
4-Nitrobiphenyl
2
-Naphthol
1-Nitro-2-naphthol
Benzoic acid
Benzaldehyde
3-Nitrobenzoic acid
Benzoic acid
a
b
c
Reactant molar ratio 1:2 (1:1).
The products were identified by comparing their IR and H NMR spectra and TLC data with those of authentic samples.
Isolated product after purification.
1
bismuth(III) nitrate on silica sulfuric acid under sol-
vent-free conditions is effective for both activated and
deactivated substrates.
over a period of 40 min at room temperature. Gaseous
hydrogen chloride immediately began to evolve. When
the addition of chlorosulfonic acid was complete, the
mixture was shaken for 30 min at room temperature to
obtain 76.0 g of silica sulfuric acid as a white solid [8].
EXPERIMENTAL
General procedure for nitration of aromatic
compounds with supported bismuth(III) nitrate on
silica sulfuric acid. Nitration of anisole. The nitrating
agent was prepared by mixing 0.16 g (0.36 mmol) of
bismuth(III) nitrate with 0.8 g (2.4 mmol) of silica
sulfuric acid in a mortar. The mixture was ground until
a fine homogeneous white powder was obtained. A mix-
ture of 1.16 g (1.2 mmol) of the reagent and 0.11 g
The products were identified by comparing their
spectral (IR and H NMR), chromatographic (TLC),
1
and physical parameters (melting and boiling points)
1
with those of authentic samples [1–3]. The H NMR
spectra (300 MHz) were recorded from solutions in
chloroform-d relative to tetramethylsilane as internal
reference. All reactions were carried out in the absence
of a solvent in a hood with strong ventilation.
(
1 mmol) of anisole was ground in a mortar until the
Silica sulfuric acid. A 500-ml flask equipped with
a constant-pressure dropping funnel and a gas-outlet
tube (which was connected to a gas-washing bottle
filled with water to absorb liberated hydrogen chlo-
ride) was charged with 60.0 g of silica gel. Chloro-
sulfonic acid, 23.3 g (0.2 mol), was added dropwise
initial compound disappeared (2–3 min, according to
the TLC data; see table). The mixture was treated with
methylene chloride (2×15 ml, each time under vigor-
ous stirring) and filtered through a sintered glass
funnel, and the solvent was removed under reduced
pressure. The crude product was purified by column
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 41 No. 10 2005

SUPPORTED BISMUTH(III) NITRATE ON SILICA SULFURIC ACID
1495
chromatography on silica gel using cyclohexane–ethyl
acetate (8:2) as eluent. The yield of 4-nitroanisole was
Duncan, S.M., and Majetich, G., Tetrahedron Lett., 1986,
vol. 27, p. 4945.
0
.13 g (85%).
5. Abramovitch, A., Org. Prep. Proced. Int., 1991, vol. 23,
p. 685.
The authors gratefully acknowledge financial sup-
6
. Loupy, A., Petit, A., Ramdiani, M., Yvanaeff, C.,
Majdoud, M., Labiad, B., and Villemin, D., Can. J.
Chem., 1993, vol. 71, p. 90; Varma, R.S., Chatterjee, A.K.,
and Varma, M., Tetrahedron Lett., 1993, vol. 34, p. 3207.
port for this project from the Isfahan University of
Technology (IUT), IR Iran (A.R. Hajipour), and Grant
no. GM 33138 (A.E. Ruoho) from the National In-
stitutes of Health, USA, as well as from the Center of
Excellency in Chemistry Research (IUT).
7
. Hajipour, A.R., Mallakpour, S.E., and Imanzadeh, G.,
J. Chem. Res., Synop., 1999, p. 223; Hajipour, A.R.,
Mallakpour, S.E., and Adibi, H., Chem. Lett., 2000,
p. 460; Hajipour, A.R., Mallakpour, S.E. and Af-
rousheh, A., Tetrahedron, 1999, vol. 55, p. 2311;
Hajipour, A.R. and Islami, F., Indian J. Chem., Sect. B,
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