Ultrasound-promoted Friedel-Crafts acylation of arenes and cyclic anhydrides catalyzed by ionic liquid of [bmim]Br/AlCl3

Article abstract of DOI:10.1134/S107036321409031X

A simple and efficient method of Friedel-Crafts acylation of arenes with succinic anhydride, phthalic anhydride and glutaric anhydride under the action of 1-butyl-3-ethylimidazolium ([bmim]Br/AlCl₃ ([bmim]⁺) cation (ionic liquid) and ultrasound irradiation is presented. Thy purity of products was tested by GC-MS and their structures evaluated by IR and ¹H NMR spectroscopy.

Full text of DOI:10.1134/S107036321409031X

ISSN 1070-3632, Russian Journal of General Chemistry, 2014, Vol. 84, No. 9, pp. 1825–1829. © Pleiades Publishing, Ltd., 2014.
Ultrasound-Promoted Friedel-Crafts Acylation
of Arenes and Cyclic Anhydrides Catalyzed
1
by Ionic Liquid of [bmim]Br/AlCl
3
Leila Zare Fekri and Mohammad Nikpassandb
a
a
Department of Chemistry, Payame Noor University, PO Box 19395-3697 Tehran, Iran
e-mail: chem_zare@pnu.ac.ir; chem_zare@yahoo.com
b
Department of Chemistry, Rasht Branch, Islamic Azad University, Rasht, Iran
Received June 19, 2014
Abstract—A simple and efficient method of Friedel-Crafts acylation of arenes with succinic anhydride,
phthalic anhydride and glutaric anhydride under the action of 1-butyl-3-ethylimidazolium ([bmim]Br/AlCl
3
+
(
[bmim] ) cation (ionic liquid) and ultrasound irradiation is presented. Thу purity of products was tested by
1
GC-MS and their structures evaluated by IR and H NMR spectroscopy.
DOI: 10.1134/S107036321409031X
INTRODUCTION
demonstrated high selectivity and could be readily
recycled making.
Importance of the Friedel-Crafts reaction for
laboratory and industrial organic synthesis cannot be
overestimated. In most cases Friedel-Crafts acylation
upon aliphatic or aromatic acid halides or acetic
anhydrides catalysis in combination with Lewis or
Bronsted acids leading to ketones is studied in depth
To the best knowledge, this is the first report on the
Friedel-Crafts reaction of cyclic anhydrides with
arenas under the action of [bmim]Br/AlCl ionic liquid
3
promoted by ultrasound leading to ketoacids. Such
process could be an efficient rout to pharmaceutical
compounds [7, 13, 14].
[1, 2]. Synthesis of ketocarboxylic acids is of particular
importance for synthesis of lactones [3, 4] and pyri-
dazinones [5] as pharmaceutical compounds. Keto-
carboxylic acids were used as structural blocks of bio-
logically active compounds such as fenbufen, bucloxic
acid, menbutone, trepibutone, florantyrone, and some
more.
RESULTS AND DISCUSSION
According to experimental data (Table 1) the molar
fraction of AlCl in [bmim]Br/AlCl had significant
3
3
influence on the acylation reaction of m-xylene with
phthalic anhydride. Efficiency of the catalyst reached
maximum at molar fraction 0.67 and decreased at
AlCl , H SO , HF and other Lewis acids are used as
3
2
4
catalysts in conventional Friedel–Crafts reactions but
such catalysts are not environmentally friendly and
cannot be recycled. Therefore, replacement of these
highly corrosive and hazardous acidic catalysts by
alternative environmentally friendly catalysts was one
of major objectives of our research. Ultrasound enhan-
cement of the reactions is known as an efficient and
economically pronounced method [6, 7].
higher molar fractions of AlCl
3
. Depending on the rate
, acidity of the
of [bmim]Br to the Lewis acid AlCl
3
ionic liquid system can vary within wide range.
Actually Friedel–Crafts acylation was catalyzed more
efficiently by an acidic catalyst than by a basic one.
The ionic liquid was basic at the mole fraction of AlCl
in the ionic liquid being less than 0.5 and at higher
content of the same the ionic liquid became acidic.
3
Over recent years, ionic liquids had proven to have
a distinctive potential as an alternative to conventional
catalysts and reactions media [8–12]. Such compounds
The molar ratio of ionic liquid to m-xylene equal to
2 : 1 and X(AlCl ) = 0.67 were determined to be the
3
most efficient (Table 2).
Purity of all products was tested by GC-MS.
1
1
The text was submitted by the authors in English.
Structures of those were scrutinized by IR and H
1
825

1
826
LEILA ZARE FEKRI, MOHAMMAD NIKPASSAND
Table 1. Effect of molar fraction of AlCl
3
in ionic liquid on
Table 2. Influence of molar ratio of ionic liquid to m-xylene
on the acylation reaction
the acylation reaction of m-xylene with phthalic anhydride
under ultrasound irradiation
Reaction
time, min
Yield,
%
X(AlCl
3
)
n(AlCl
3
) : n([bmim]Br) Time, min Yield, %
n{[bmim]Br/AlCl }: n(m-xylene)
3
0
.33
0.5:1.0
no
reaction
0
0.5
1.0
1.5
2.0
2.5
3.0
60
45
35
25
25
25
73
75
80
85
79
76
0
0
0
0
0
.50
.60
.67
.71
.75
1.0:1.0
1.5:1.0
2.0:1.0
2.5:1.0
3.0:1.0
120
90
25
25
25
51
63
85
80
73
NMR spectroscopy. The reactions data are presented in
Table 3.
charged into a Pyrex-glass open vessel and irradiated
in a water bath under silent condition by ultrasound
(
45 kHz) at 60°C for the 20–30 min. Progress of the
AlCl were irradiated in a water bath under silent
3
reaction was monitored by TLC (EtOAc : petroleum
ether = 1 : 4). The reaction mixture was cooled down
to room temperature and organic components extracted
by chloroform. Upon evaporation of the solvent the
residual crystalline products were collected.
condition by ultrasound (45 kHz) at 60°C for 45 min,
yield 75%.
Upon completion of the process the organic
components were extracted by chloroform and the
residual [bmim]Br/AlCl ionic liquid phase treated
3
Compound I. White solid, mp 114–116°C; FT–IR
with ether. Upon vacuum drying the latter at 80–100°C
–
1
(
KBr), ν, cm : 2400–3400, 1680, 1590, 1440, 1220.
for 30 min the recycled [bmim]Br/AlCl had high
3
1
H NMR spectrum (500 MHz, CDCl ), δ , ppm: 2.9 t
3
H
catalytic activity. Activity of the recycled [bmim]Br/
(
8
2H, J = 6.5 Hz), 3.4 t (2H, J = 6.5 Hz), 7.5 m (3H),
AlCl is listed in Table 4.
3
.00 m (2H), 11.5 s (1H).
Synthetic procedure involving [bmim]Br/AlCl and
3
Compound II. White solid, mp 122–124°C; FT–IR
following make up of the reaction mixtures were
simple and hazardous free.
–
1
(
KBr), ν, cm : 2400–3400, 1680, 1600, 1400, 1230.
1
H NMR spectrum (500 MHz, CDCl ), δ , ppm: 2.45 s
3
H
(
3H), 2.8 t (2H, J = 6.6 Hz), 3.3 t (2H, J = 6.6 Hz),
EXPERIMENTAL
7
.30 d (2H, J = 8.2 Hz), 7.92 d (2H, J = 8.2 Hz), 11.5 s
(
1H).
Materials and measurements. All chemicals
were purchased from Merck and Fluka and used
Compound III. White solid, mp 108–110°C; FT–IR
–
1
without further purification. Ultrasound apparatus (KBr), ν, cm : 2400–3400, 1690, 1600, 1440, 1257.
3
1
Astra 3D (9.5 dm , 45 kHz frequency, input power
H NMR spectrum (500 MHz, CDCl
3
), δ , ppm: 2.39 s
H
with heating, 305W) was used. Melting points (3H), 2.53 s (3H), 2.8 t (2H, J = 6.5 Hz), 3.2 t (2H, J =
6
.5 Hz), 7.11 d (1H, J = 8.0 Hz), 7.30 s (1H), 7.69 d
were measured with an Electrothermal 9100 appa-
ratus. FT–IR spectra were recorded by a Shimadzu
(
1H, J = 7.6 Hz), 10.41 s (1H).
1
FT–IR-8400S spectrometer. H NMR spectra were
Compound IV. White solid, mp 124–126°C; FT–IR
–
1
measured with a Bruker DRX-500 spectrometer
(
KBr), ν, cm : 2400–3400, 1676, 1600, 1596, 1232.
against TMS standard. 13C NMR spectra were
1
H NMR spectrum (500 MHz, CDCl ), δ , ppm: 2.8 t
3
H
measured with a Bruker DRX-125 Avance (2H, J = 6.5 Hz), 3.3 t (2H, J = 6.5 Hz), 7.49 d (2H,
spectrometer.
J = 8.5 Hz), 7.96 d (2H, J = 8.5 Hz), 10.41 s (1H).
General method for ketocarboxylic acid (I–XIV).
Compound V. White solid, mp 136–138°C; FT–IR
–
1
A mixture of an anhydride (10 mmol), an arene
(KBr), ν, cm : 2400–3400, 1695, 1660, 1600, 1565,
1
(
10 mmol), and [bmim]Br/AlCl (20 equiv) were
1240. H NMR spectrum (500 MHz, CDCl ), δ , ppm:
3
3
H
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 84 No. 9 2014

ULTRASOUND-PROMOTED FRIEDEL-CRAFTS ACYLATION OF ARENES
1827
Table 3. Resulting data of ketocarboxylic acid derivatives synthesis under optimized conditions
Substrate
Anhydride
O
Product
Yield, %a,b
Purity, %
99.5
O
OH
O
O
8
5
O
O
CH3
O
OH
O
9
8
8
5
7
3
99.6
99.9
99.4
99.5
O
H C
3
O
O
CH3
CH3
O
OH
O
O
CH3
H C
3
O
O
Cl
O
OH
O
O
Cl
O
O
OCH3
O
OH
O
O
9
5
O
H CO
3
O
O
O
8
5
99.7
98.6
O
HO C
2
CH3
O
O
O
O
9
7
H C
3
HO C
2
CH3
O
CH3 O
c
O
O
3(85)
99.5
CH3
H C
3
HO C
2
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 84 No. 9 2014

1
828
LEILA ZARE FEKRI, MOHAMMAD NIKPASSAND
Table 3. (Contd.)
Substrate
Anhydride
Product
Yield, %a,b
Purity, %
99.7
O
O
Cl
O
8
6
Cl
O
HO C
2
O
O
O
8
5
99.0
O
OH
O
O
O
O
CH3
O
OH
9
4
99.2
99.5
98
O
H C
3
O
O
O
OCH3
O
OH
9
6
O
H CO
3
O
O
O
Cl
Br
O
OH
OH
8
5
5
O
Cl
Br
O
O
O
O
8
98.8
O
a
b
1
c
Isolated yield. Identified by IR and H NMR spectroscopy. Equimolar amounts of methaxylene (10 mmol), Phthalic
anhydride (10 mmol) and 20 equiv.
Table 4. Activity data of the recycled [bmim]Br/AlCl
reaction of m-xylene with phthalic anhydride
3
in the
2.5 t (2H, J = 6.7 Hz), 3.0 t (2H, J = 6.7 Hzt), 3.7 s
(
3H), 6.78 d (2H, J = 8.9 Hz), 7.80 d (2H, J = 8.9 Hz).
Cycles
Yield, %
Compound VI. White solid, mp 93–94°C; FT–IR
–
1
(
KBr), ν, cm : 3200–3400, 1680, 1660, 1595, 1440,
1
2
3
4
5
85
85
84
82
83
1
1
260. H NMR (500 MHz, CDCl ), δ , ppm: 7.41 t
3
H
(
2H, J = 7.3 Hz), 7.54–7.60 m (2H), 7.68 t (1H, J =
7.4 Hz), 7.73 d (2H, J = 7.3 Hz), 8.08 d (2H, J =
1
3
7
1
1
.7 Hz). С NMR (125 MHz, СDСl ), δ , ppm:
3
С
27.98, 128.59, 128.89, 129.82, 130.00, 131.18, 133.54,
33.58, 137.39, 142.99, 170.80.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 84 No. 9 2014

ULTRASOUND-PROMOTED FRIEDEL-CRAFTS ACYLATION OF ARENES
1829
1
Compound VII. White solid, mp 99–101°C; FT–IR
1590, 1490, 1408, 1286, 1185. H NMR spectrum:
–
1
(
KBr), ν, cm : 3200–3400, 1680, 1660, 1595, 1440,
(500 MHz, СDСl ), δ , ppm: 2.10–2.14 m (2H), 2.54 t
(2H, J = 7.1 Hz), 3.08 t (2H, J = 7.1 Hz), 7.64 d (2H,
J = 8.5 Hz), 7.86 d (2H, J = 8.5 Hz).
3
H
1
1
2
280. H NMR spectrum (500 MHz, CDCl ), δ , ppm:
3
H
.4 s (3H), 6.0 s (1H), 7.24 d (2H, J = 8.0 Hz), 7.38 d
1H, J = 7.5 Hz), 7.58 t (1H, J = 7.5 Hz), 7.64–7.69 m
3H), 8.10 d (1H, J = 7.8 Hz).
(
(
CONCLUSIONS
An optimized and facile protocol for acylation of
Compound VIII. White solid, mp 133–135°C; FT–IR
–
1
arenes by cyclic anhydride under the action of AlCl
3
(
1
2
KBr), ν, cm : 3200–3400, 1693, 1680, 1580, 1480,
1
and ultrasound irradiation was developed. The
mechanism of acylation reaction catalyzed by [bmim]
280. H NMR spectrum (500M Hz, CDCl ), δ , ppm:
3
H
.37 s (3H), 2.65 s (3H), 6.93 d (1H, J = 7.8 Hz), 7.09
Br/AlCl ionic liquids is not clear yet. The current
3
d (1H, J = 7.9 Hz), 7.12 s (1H), 7.44 d (1H, J = 7.5 Hz),
study indicated [bmim]Br/AlCl
as
a
novel
3
7
.58 t (1H, J = 7.5 Hz), 7.64–7.69 m (3H), 8.06 d (1H,
13
environmentally friendly catalyst and media for m-
J = 8.6 Hz), 10 s (1H). C NMR (125M Hz, CDCl ),
3
xylene’s acylation reaction.
δ , ppm: 21.79, 21.89, 126.25, 128.44, 128.54, 129.88,
C
1
1
31.19, 132.35, 133.26, 133.36, 134.34, 140.84, 142.97,
44.50, 171.72, 198.85.
ACKNOWLEDGMENTS
We thank the Research Committee of University of
Guilan for partial support given to this study.
Compound IX. White solid, mp 228–230°C; FT–IR
–
1
(
1
KBr), ν, cm : 3200–3400, 1693, 1680, 1580, 1480,
1
280, 1100. H NMR spectrum (500 MHz, СDСl ), δ ,
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3
H
ppm: 7.40 t (1H, J = 7.5 Hz), 7.44 d (1H, J = 7.7 Hz),
1
2
3
4
. Olah, G.A., Friedel-Crafts and Related Reactions, New
7
.55–7.60 m (2H), 7.68 t (1H, J = 7.5 Hz), 7.74 d (2H,
York: Wiley, 1973.
J = 7.5 Hz), 8.09 d (1H, J = 7.8 Hz).
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Compound X. White solid, mp 126–128°C; FT–IR
vol. 256, p. 3.
–
1
(
1
1
KBr), ν, cm : 2400–3400, 1695, 1674, 1596, 1412,
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Zarrabi, S., Chin. Chem. Lett., 2008, vol. 12, p. 1431.
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287. H NMR spectrum (500 MHz, СDСl ), δ , ppm:
3
H
.90–1.97 m (2H), 2.31 t (2H, J = 7.2 Hz), 2.97 t (2H,
J = 7.2 Hz), 7.34 t (2H, J = 7.8 Hz), 7.45 t (2H, J =
2001, p. 1467.
7
.5 Hz), 7.83 d (2H, J = 7.8 Hz).
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mann, A., Van Slingerland, M., Sterk, G.J., and Tim-
merman, H., J. Med. Chem., 2003, vol. 46, p. 2008.
Compound XI. White solid, mp 122–124°C; FT–IR
–
1
(
KBr), ν, cm : 2400–3400, 1698, 1676, 1606, 1451,
1
6. Xin, Y., Zang, Z.H., and Chen, F.L., Synth. Commun.,
1
1
2
286. H NMR spectrum (500 MHz, CDCl ), δ , ppm:
3
H
2
009, vol. 39, p. 4062.
.80–1.85 m (2H), 2.19 t (2H, J = 7.2 Hz), 2.22 s (3H),
.84 t (2H, J = 7.2 Hz), 7.06 d (2H, J = 7.9 Hz), 7.65 d
7
8
9
. Nikpassand, M., Mamaghani, M., Shirini, F., and
Tabatabaeian, K., Syn. Commun., 2010, vol. 17, p. 301.
. Howarth, J., James, P., and Dai, J.F., Tetrahedron Lett.,
(
2H, J = 8.1 Hz).
Compound XII. White solid, mp 144–146°C;
2000, vol. 41, p. 10319.
–
1
FT–IR (KBr), ν, cm : 2400–3400, 1705, 1668, 1601,
. Xie, X.G., Lu, J.P., Chen, B., et al., Tetrahedron Lett.,
1
1
510, 1413, 1264. H NMR spectrum (500 MHz,
2004, vol. 45, p. 809.
CDCl ), δ , ppm: 1.93–1.99 m (2H), 2.33 t (2H, J =
3
H
10. Yadav, J.S., Reddy, B.V.S., Basak, A.K., et al.,
7
(
.1 Hz), 2.94 t (2H, J = 7.2 Hz), 3.80 s (3H), 6.85 d
Tetrahedron Lett., 2003, vol. 44, p. 2217.
2H, J = 8.8 Hz), 7.87 d (2H, J = 8.8 Hz).
11. Baleizao, C., Pires, N., Gigante, B., et al., Tetrahedron
Lett., 2004, vol. 45, p. 4375.
Compound XIII. White solid, mp 112–114°C;
–
1
12. Xiao, Y. and Malhotra, S.V., Tetrahedron Lett., 2004,
FT–IR (KBr), ν cm : 2400–3400, 1705, 1684, 1601,
1
vol. 45, vol. 8339-8342.
1
(
(
590, 1490, 1403, 1283, 1195. H NMR spectrum
1
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ghani, M., and Tabatabaeian, K., Chin. Chem. Lett.,
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500 MHz, CDCl ), δ , ppm: 2.10–2.16 m (2H), 2.56 t
3
H
2H, J = 7.1 Hz), 3.09 t (2H, J = 7.1 Hz), 7.47 d (2H,
J = 8.4 Hz), 7.94 d (2H, J = 8.5 Hz).
1
Compound XIV. White solid, mp 112–114°C;
–
1
FT–IR (KBr), ν cm : 2400–3400, 1684, 1676, 1606,
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 84 No. 9 2014