Simple and efficient procedure for the friedel-crafts acylation of aromatic compounds with carboxylic acids in the presence of P2O5/AL2O3 under heterogeneous conditions

Article abstract of DOI:10.1080/00397910802663436

An efficient and chemoselective method for the Friedel-Crafts acylation of aromatic compounds using P2O5/Al2O3 and carboxylic acids. Both aromatic and aliphatic carboxylic acids reacted easily to afford the corresponding aromatic ketones in good yields.

Full text of DOI:10.1080/00397910802663436

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Simple and Efficient Procedure
for the Friedel–Crafts Acylation
of Aromatic Compounds
with Carboxylic Acids in the
Presence of P2O5/AL2O3 Under
Heterogeneous Conditions
Abdol R. Hajipour a b , Amin Zarei c , Leila Khazdooz
b & Arnold E. Ruoho a
a Department of Pharmacology , University of
Wisconsin Medical School , Madison, Wisconsin, USA
b Pharmaceutical Research Laboratory, Department
of Chemistry , Isfahan University of Technology ,
Isfahan, Iran
c Department of Science , Islamic Azad University,
Fasa Branch , Fasa, Fars, Iran
Published online: 26 Jun 2009.
To cite this article: Abdol R. Hajipour , Amin Zarei , Leila Khazdooz & Arnold E.
Ruoho (2009) Simple and Efficient Procedure for the Friedel–Crafts Acylation of
Aromatic Compounds with Carboxylic Acids in the Presence of P2O5/AL2O3 Under
Heterogeneous Conditions, Synthetic Communications: An International Journal
for Rapid Communication of Synthetic Organic Chemistry, 39:15, 2702-2722, DOI:
10.1080/00397910802663436
To link to this article: http://dx.doi.org/10.1080/00397910802663436

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Synthetic Communications1, 39: 2702–2722, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910802663436
Simple and Efficient Procedure for the
Friedel–Crafts Acylation of Aromatic
Compounds with Carboxylic Acids in the
Presence of P2O5/AL2O3 Under
Heterogeneous Conditions
Abdol R. Hajipour,1,2 Amin Zarei,3 Leila Khazdooz,2
and Arnold E. Ruoho1
1Department of Pharmacology, University of Wisconsin Medical School,
Madison, Wisconsin, USA
2Pharmaceutical Research Laboratory, Department of Chemistry, Isfahan
University of Technology, Isfahan, Iran
3Department of Science, Islamic Azad University, Fasa Branch,
Fasa, Fars, Iran
Abstract: An efficient and chemoselective method for the Friedel–Crafts
acylation of aromatic compounds using P2O5=Al2O3 and carboxylic acids. Both
aromatic and aliphatic carboxylic acids reacted easily to afford the correspond-
ing aromatic ketones in good yields.
Keywords: Carboxylic acids, Friedel–Crafts, P2O5=Al2O3
INTRODUCTION
Friedel–Crafts acylation is one of the most important methods to prepare
aromatic ketones used in manufacturing fine and specialty chemicals as
well as pharmaceuticals.[1] The disadvantages associated with the classical
procedures include the use of toxic acid chlorides or acid anhydrates as
Received October 19, 2008.
Address correspondence to Abdol R. Hajipour, Pharmaceutical Research
Laboratory, Department of Chemistry, Isfahan University of Technology,
Isfahan 84156, Iran. E-mail: haji@cc.iut.ac.ir
2702

Acylation of Aromatic Compounds
2703
acylating agents and an excess amount of aluminum trichloride as a
Lewis acid, which entails environment pollution and tedious workup.
To minimize this problem, some catalytic Friedel–Crafts acylations have
been developed recently.[2] Using carboxylic acids as acylating agents is a
superior method with respect to the procedures utilizing acyl chlorides
and anhydrides for the synthesis of aryl ketones. Carboxylic acids are
stable, less toxic, and more available compounds, and their handling is
much easier than that of their corresponding acyl chlorides and anhydri-
des. Zeolites,[3] heteropolyacids and their salts,[4] clay,[5] alumina=
trifluoroacetic anhydride (TFAA),[6] MeSO3H=graphite,[7] and Lewis
acids[8] are reported to catalyze Friedel–Crafts acylation using carboxylic
acids as acylating agents. However, the catalytic efficiency and=or applic-
able substrate range are very limited. For instance, a methodology of
acylation of anisole with carboxylic acids over HZSM-5 zeolite, although
environmentally safe, has limitations with regard to generality (no
reaction with higher acids) and efficiency (reaction time of 48 h and
concomitant O-acylation).[3c] Thus, a reliable general method for this
useful reaction involving nonhazardous reagents is in demand.
RESULTS AND DISCUSSION
Recently, the use of catalysts and reagents on solid supports was devel-
oped because such reagents not only simplify purification processes but
also help to prevent release of reaction residues into the environment.
This has led to growth in the field of solid supported on alumina.[9]
Although there are many reports of using phosphorus pentoxide as a
reagent in organic reactions,[10] P2O5 is difficult to handle because of
its moisture sensitivity at room temperature. P2O5 on alumina (P2O5=
Al2O3) is easy to prepare and handle and also is a useful reagent that
could be removed from the reaction mixture by simple filtration.[11]
Herein, we report an efficient, convenient, and chemoselective procedure
for the conversion of carboxylic acids to the corresponding aryl ketones
in the presence of P2O5=Al2O3. These reactions are easily carried out
under heterogeneous and reflux conditions (Scheme 1).
The acylation reactions were carried out by heating a stirring mixture
of the corresponding carboxylic acids, P2O5=Al2O3, and aromatic com-
pounds such as toluene, p-xylene, m-xylene, mesitylene, thiophene,
bromobenzene, chlorobenzene, and nitrobenzene under reflux conditions.
However, for the compounds such as anisole, 1,3-dimethoxybenzene,
2-methoxynaphtalene, naphthalene, anthracene, 2-methylthiophene, thio-
anisole, and biphenyl, the acylation reactions were carried out in
1,2-dichloroethane under reflux conditions. The products were isolated

2704
A. R. Hajipour et al.
Scheme 1. Friedel–Crafts acylation of aromatic compounds.
by simple filtration of the reaction mixture and then by usual workup.
Different structures of aromatic rings underwent acylation with a wide
rang of carboxylic acids. These reaction conditions were successfully
applied for the preparation of different aryl ketones from electron-rich
and electron-poor aromatic compounds. The results of this study are pre-
sented in Table 1. The reactions are remarkably clean, convenient, and no
chromatographic separation is necessary to get the spectra-pure com-
pounds except in few cases (Table 1, entries 26, 28, 29). By using this
reagent, acylation occurs at the para position with high selectivity. How-
ever, in cases where the para positions are blocked (Table 1, entries 2, 14),
the acyl group is introduced ortho to the substituted groups on aromatic
rings. This procedure is also good enough for the acylation of hetero-
cyclic aromatic compounds such as thiophene and 2-methyltiophene
(Table 1, entries 8, 17), as well as polycyclic aromatic hydrocarbons
(Table 1, entries 7, 9, 25, 26), producing the corresponding acylated pro-
ducts in good yields. These reactions are rather fast even with the higher
carboxylic acids. However, for deactivated aromatic rings such as bromo-
benzene and chlorobenzene (Table 1, entries 11, 22), the corresponding
4-acylated products were obtained in poor yields. Using nitrobenzene,
no product was obtained (Table 1, entry 12). It is notable that the acyl-
ation reaction between 3-phenylpropionic acid and anisole in the
presence of P2O5=Al2O3 produces the corresponding 4-acylated product
in good yield (Table 1, entry 27). However, the reaction between 3-
phenylpropionic acid and toluene or the reaction between 3-phenylpropionic
acid and m-xylene produces 2,3-dihydro-30H-[1,20]biindenyliden-10-one as
a major product (Table 1, entries, 28, 29). These results show that at first
intramolecular Friedel–Crafts acylation occurs and then the aldol
condensation reaction is carried out consequently.
To evaluate the role of Al2O3, we studied the acylation of toluene
with 4-nitrobenzoic acid in the absence of Al2O3. This reaction was
carried out under reflux conditions for 5 h in the presence of P2O5 alone.
The yield of (4-nitrophenyl) (p-tolyl)methanone was obtained in 42%.

2705

2706

2707

2708

2709

2710

2711

2712
A. R. Hajipour et al.
However, by using the combination of P2O5=Al2O3, the yield of (4-nitrophe-
nyl) (p-tolyl)methanone was greater (21%) than that with P2O5 alone under
the same conditions (Table 1, entry 1). The effect of Al2O3 may be due to
good dispersion of P2O5 on the surface of alumina, leading to significant
improvements in its reactivity. Al2O3 as a support may also minimize cross
contamination between inorganic and organic components.[12]
EXPERIMENTAL
General
All reagents were purchased from Merck and Aldrich and used without
further purification. All yields refer to isolated products after purifica-
tion. Products were characterized by comparison with authentic samples
and by spectroscopic data [Fourier transform–infrared (FTIR, 1H NMR,
1
13C NMR, mass spectra (MS), CHNS, and melting point]. H NMR
spectra were recorded at FT 300 MHz. The spectra were measured in
CDCl3 unless otherwise stated, relative to tetramethylsilane (TMS)
(0.00 ppm). P2O5=Al2O3 (w=w 50%) was prepared according to previous
works.[11a]
General Procedure for Acylation of Aromatic Compounds Using
Carboxylic Acids and P2O5/Al2O3 in Reflux of Aromatic Rings
P2O5=Al2O3 (w=w 50%, 0.6 g) was added to a mixture of a carboxylic acid
(1.5 mmol) and an aromatic compound (5 mL). The reaction mixture was
stirred under reflux conditions for the appropriate reaction times
(Table 1). After completion of the reaction (monitored by thin-layer
chromatography, TLC), the mixture was diluted with Et2O and filtered.
The organic layer was washed with 10% NaHCO3 solution and then dried
over anhydrous Na2SO4. The solvent was evaporated under reduced
pressure to give the corresponding pure aryl ketone.
Typical Procedure for Acylation of Toluene Using 4-Nitrophenylacetic
Acid and P2O5/Al2O3
P2O5=Al2O3 (w=w 50%, 0.6 g) was added to a mixture of 4-nitrophenyl-
acetic acid (1.5 mmol, 0.27 g) and toluene (5 mL), and the reaction
mixture was stirred under reflux conditions for 3 h. After cooling, the
mixture was diluted with Et2O (15 mL) and filtered. The organic layer

Acylation of Aromatic Compounds
2713
was washed with 10% NaHCO3 solution and then dried over anhydrous
Na2SO4. The solvent was evaporated under reduced pressure to give
1-((p-tolyl)-2-(4-nitrophenyl)ethanone in 78% yield.
Typical Procedure for Acylation of 1,3-Dimethoxybenzene Using
4-Nitrobenzoic Acid and P2O5/Al2O3 in 1,2-Dichloroethane
Under Reflux Conditions
P2O5=Al2O3 (w=w 50%, 0.6 g) was added to a mixture of 4-nitrobenzoic
acid (1.5 mmol, 0.25 g), 1,3-dimethoxybenzene (3 mmol, 0.4 mL), and
1,2-dichloroethane (5 mL), and the reaction mixture was stirred under
reflux conditions for 3 h. After cooling, the mixture was diluted with
CH2Cl2 (15 mL) and filtered. The organic layer was washed with 10%
NaHCO3 solution and then dried over anhydrous Na2SO4. The solvent
was evaporated under reduced pressure. The crude product was washed
with cold n-hexane to give (2,4-dimethoxyphenyl)(4-nitrophenyl)-
methanone in 75% yield.
1H NMR and IR Spectral Data for Some Products
Compound 1b
Mp 118–120ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 8.6 (2H, d,
J ¼ 9.1 Hz), 8.2 (2H, d, J ¼ 9.1 Hz), 8 (2H, d, J ¼ 8.6 Hz), 7.55 (2H, d,
J ¼ 8.6 Hz), 2.55 (3H, s). IR (KBr) cmꢁ1: 3080, 1645, 1595, 1525, 1340,
1305, 1260, 910, 840, 825, 730, 700. Anal. calcd. for C14H11NO3: C,
69.7; H, 4.56; N, 5.81%. Found: C, 69.78; H, 4.61; N, 5.77%.
Compound 3b
Mp 96–98ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 8.33 (2H, d,
J ¼ 8.89 Hz), 7.92 (2H, d, J ¼ 8.89 Hz), 7.64 (2H, d, J ¼ 8.35 Hz), 7.37
(2H, d, J ¼ 8.35 Hz), 3 (1H, septed, J ¼ 7.3 Hz), 1.3 (6H, d, J ¼ 7.3 Hz).
IR (KBr) cmꢁ1: 3060, 2973, 1660, 1600, 1515, 1340, 1265, 925, 850,
700. Anal. calcd. for C16H15NO3: C, 71.37; H, 5.57; N, 5.2%. Found:
C, 71.25; H, 5.68; N, 5.31%.
Compound 4b
Mp 122–124ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 8.3 (2H, d,
J ¼ 8.92 Hz), 7.96 (2H, d, J ¼ 8.92 Hz), 6.92 (2H, s), 2.38 (3H, s), 2.1

2714
A. R. Hajipour et al.
(6H, s). IR (KBr) cmꢁ1: 3050, 2875, 1670, 1600, 1520, 1440, 1345, 1260,
910, 870, 845, 720. Anal. calcd. for C16H15NO3: C, 71.37; H, 5.57; N,
5.2%. Found: C, 71.26; H, 5.68; N, 5.28%.
Compound 5b
Mp 122–123ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 8.35 (2H, d,
J ¼ 9.12 Hz), 7.9 (2H, d, J ¼ 9.12 Hz), 7.83 (2H, d, J ¼ 9.2 Hz), 7 (2H,
d, J ¼ 9.2 Hz), 3.92 (3H, s). IR (KBr) cmꢁ1: 3080, 2960, 1630, 1590,
1510, 1350, 1320, 1260, 1170, 1010, 935, 845. Anal. calcd. for
C14H11NO4: C, 65.37; H, 4.28; N, 5.44%. Found: C, 65.48; H, 4.37; N,
5.36%.
Compound 6b
Mp 119–121ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 8.27 (2H, d,
J ¼ 8.8 Hz), 7.86 (2H, d, J ¼ 8.8 Hz), 7.55 (1H, d, J ¼ 8.7 Hz), 6.62 (1H,
dd, J1 ¼ 8.7 Hz, J2 ¼ 1.74 Hz), 6.5 (1H, d, J ¼ 1.74 Hz), 3.9 (3H, s), 3.65
(3H, s). 13C NMR (75 MHz, CDCl3, TMS) d ¼ 196, 165, 160.3, 147.7,
145, 133.3, 130.2, 123.5, 120.3, 105.4, 98.8, 55.8, 55.5. IR (KBr) cmꢁ1
:
3075, 2930, 1640, 1600, 1515, 1465, 1345, 1275, 1200, 1155, 1120, 945,
850, 815, 730. Anal. calcd. for C15H13NO5: C, 62.71; H, 4.53; N,
4.88%. Found: C, 62.61; H, 4.63; N, 4.81%.
Compound 7b
Mp 172–174ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 8.25 (2H, d,
J ¼ 8.82 Hz), 7.98 (3H, m), 7.74 (1H, d, J ¼ 7.35 Hz), 7.52 (1H, d,
J ¼ 9.1 Hz), 7.4 (2H, m), 7.32 (1H, d, J ¼ 9.1 Hz), 3.8 (3H, s). 13C
NMR (75 MHz, CDCl3, TMS) d ¼ 196.6, 155.5, 151.2, 143.3, 133.2,
132.3, 131, 129.6, 129.2, 128.7, 125.2, 124.6, 124.2, 122, 113.5, 57.2. EIMS
m=z (%): 307 (Mþ, 56), 290 (16), 276 (13), 260 (12), 185 (100), 142 (25),
127 (21), 120 (27), 114 (26), 106 (15), 92 (14), 76 (14), 43 (34). IR
(KBr) cmꢁ1: 3040, 2920 1675, 1600, 1530, 1340, 1235, 1080, 890, 840,
800. Anal. calcd. for C18H13NO4: C, 70.03; H, 4.23; N, 5.56%. Found:
C, 70.16; H, 4.21; N, 4.51%.
Compound 8b
Mp 173–174ꢀC; 1H NMR (500 MHz, CDCl3, TMS) d ¼ 8.39 (2H, d,
J ¼ 8.62 Hz), 8.22 (1H, d, J ¼ 4.16 Hz), 8.06 (2H, d, J ¼ 8.62 Hz), 7.75

Acylation of Aromatic Compounds
2715
(1H, d, J ¼ 2.85 Hz), 7.33 (1H, t, J ¼ 3.95 Hz). EIMS m=z (%): 233 (Mþ,
27), 187 (2), 150 (5), 111 (100), 83 (10), 76 (12), 50 (9), 44 (4). IR (KBr)
cmꢁ1: 3062, 1630, 1600, 1510, 1410, 1355, 1300, 1050, 875, 840, 725. Anal.
calcd. for C11H7NSO3: C, 56.65; H, 3; N, 6; S, 13.73%. Found: C, 56.71;
H, 3.1; N, 5.95; S, 13.8%.
Compound 9b
1
Mp 89–91ꢀC; mp 89–91ꢀC; H NMR (300 MHz, CDCl3, TMS) d ¼ 8.32
(2H, d, J ¼ 8.66 Hz), 8.05–7.91 (5H, m), 7.62–7.51 (4H, m). EIMS m=z
(%): 277 (Mþ, 80), 230 (12), 202 (15), 155 (100), 127 (93), 101 (28), 76
(15), 43 (8). IR (KBr) cmꢁ1: 3060, 1675, 1600, 1520, 1340, 1270, 1240,
910, 850, 790, 720. Anal. calcd. for C17H11NO3: C, 73.6; H, 3.97; N,
5.05%. Found: C, 73.51; H, 3.88; N, 4.96%.
Compound 10b
Mp 163–165ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 8.37 (2H, d,
J ¼ 9.1 Hz), 7.97 (2H, d, J ¼ 9.1 Hz), 7.88 (2H, d, J ¼ 8.65 Hz), 7.74
(2H, d, J ¼ 8.65 Hz), 7.66 (2H, d, J ¼ 8.4 Hz) 7.5 (3H, m). EIMS m=z
(%): 303 (Mþ, 70), 181 (100), 153 (30), 152 (53), 76 (15). IR (KBr) cmꢁ1
:
3060, 1650, 1600, 1515, 1355, 1280, 935, 845, 755, 730, 700. Anal. calcd.
for C19H13NO3: C, 75.24; H, 4.29; N, 4.62%. Found: C, 75.34; H, 4.22;
N, 4.51%.
Compound 11b
Mp 124–126ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 8.38 (2H, d,
J ¼ 8.71 Hz), 7.95 (2H, d, J ¼ 8.71 Hz), 7.72 (4H, s). EIMS m=z (%):
307 (Mþ þ 2, 40), 305 (Mþ, 40), 277 (8), 275 (8), 185 (100), 183 (100),
157 (35), 155 (35), 150 (36), 120 (37), 76 (56). IR (KBr) cmꢁ1: 3070,
1660, 1600, 1580, 1510, 1340, 1275, 1060, 990, 930, 845, 720. Anal. calcd.
for C13H8BrNO3: C, 51.14; H, 2.62; N, 4.59%. Found: C, 51.03; H, 2.71;
N, 4.51%.
Compound 13b
Mp 110–112ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 8.17 (2H, d,
J ¼ 8.4 Hz), 7.88 (2H, d, J ¼ 8.1 Hz), 7.4 (2H, d, J ¼ 8.4 Hz), 7.27 (2H,
d, J ¼ 8.1 Hz), 4.38 (2H, s), 2.4 (3H, s). 13C NMR (75 MHz, CDCl3,

2716
A. R. Hajipour et al.
TMS) d ¼ 195.5, 145, 143, 136, 134, 131, 130, 129, 124.5, 45.5, 20.5. IR
(KBr) cmꢁ1: 3020, 2875, 1680, 1595, 1510, 1345, 1320, 1290, 995, 845,
800, 725. Anal. calcd. for C15H13NO3: C, 70.58; H, 5.1; N, 5.49%. Found:
C, 70.49; H, 5.18; N, 5.41%.
Compound 14b
Mp 86–88ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 8.2 (2H, d,
J ¼ 8.5 Hz), 7.55 (1H, s), 7.4 (2H, d, J ¼ 8.5 Hz), 7.22 (1H, d, J ¼ 8.05 Hz),
7.15 (1H, d, J ¼ 8.05 Hz), 4.37 (2H, s), 2.42 (3H, s), 2.39 (3H, s). IR (KBr)
cmꢁ1: 3065, 2890, 1680, 1600, 1510, 1340, 1170, 985, 960, 820, 720. Anal.
calcd. for C16H15NO3: C, 71.37; H, 5.57; N, 5.2%. Found: C, 71.3; H, 5.5;
N, 5.28%.
Compound 15b
Mp 114–116ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 8.3 (2H, d,
J ¼ 8.65 Hz), 8.1 (2H, d, J ¼ 8.7 Hz), 7.55 (2H, d, J ¼ 8.65 Hz), 7.06
(2H, d, J ¼ 8.7 Hz), 4.43 (2H, s), 4 (3H, s). 13C NMR (75 MHz, CDCl3,
TMS) d ¼ 195, 165, 143.2, 131.5, 131.1, 130, 124.4, 115, 110.6, 56, 46.
IR (KBr) cmꢁ1: 3055, 2930, 1680, 1600, 1510, 1450, 1350, 1340, 1270,
1175, 990, 825, 730. Anal. calcd. for C15H13NO4: C, 66.4; H, 4.79; N,
5.16%. Found: C, 66.38; H, 4.85; N, 5.09%.
Compound 16b
Mp 119–121ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 8.18 (2H, d,
J ¼ 8.7 Hz), 7.85 (1H, d, J ¼ 8.65 Hz), 7.38 (2H, d, J ¼ 8.7 Hz), 6.55
(1H, dd, J1 ¼ 8.65 Hz, J2 ¼ 2.48 Hz), 6.48 (1H, d, J ¼ 2.48 Hz), 4.4 (2H,
s), 3.92 (3H, s), 3.88 (3H, s). IR (KBr) cmꢁ1: 3045, 2920, 1660, 1600,
1515, 1355, 1310, 1270, 1140, 990, 830, 735. Anal. calcd. for
C16H15NO5: C, 63.78; H, 4.98; N, 4.65%. Found: C, 63.71; H, 5.08; N,
4.72%.
Compound 17b
Mp 104–106ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 8.2 (2H, d,
J ¼ 8.9 Hz), 7.63 (1H, d, J ¼ 3.83 Hz), 7.47 (2H, d, J ¼ 8.9 Hz), 6.85
(1H, d, J ¼ 3.85 Hz), 4.28 (2H, s), 2.57 (3H, s). IR (KBr) cmꢁ1: 3050,
1650, 1600, 1515, 1445, 1340, 1230, 930, 810, 730. Anal. calcd. for

Acylation of Aromatic Compounds
2717
C13H11NSO3: C, 59.77; H, 4.21; N, 5.36; S, 12.26%. Found: C, 59.68; H,
4.26; N, 5.42; S, 12.19%.
Compound 18b
Mp 183–185ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 8.16 (2H, d,
J ¼ 8.96 Hz), 7.96 (2H, d, J ¼ 8.6 Hz), 7.52 (2H, d, J ¼ 8.9 Hz), 7.32
(2H, d, J ¼ 8.6 Hz), 4.5 (2H, s), 2.53 (3H, s). IR (KBr) cmꢁ1: 3055,
2910, 1675, 1590, 1515, 1340, 1225, 1175, 1080, 980, 800, 700. Anal. calcd.
for C15H13NSO3: C, 62.71; H, 4.53; N, 4.87; S, 11.15%. Found: C, 62.64;
H, 4.61; N, 4.96; S, 11.21%.
Compound 19b
1
Mp 51–53ꢀC; H NMR (300 MHz, CDCl3, TMS) d ¼ 8.1–7.8 (7H, m),
7.45 (2H, d, J ¼ 8.25 Hz), 2.45 (3H, s). IR (KBr) cmꢁ1: 3030, 2920,
1660, 1600, 1580, 1460, 1330, 1280, 925, 780, 710.
Compound 20b
1
Thick oil; H NMR (300 MHz, CDCl3, TMS) d ¼ 7.8 (2H, m), 7.55 (1H,
m), 7.45 (2H, m), 7.23 (1H, dd, J1 ¼ 6.8 Hz, J2 ¼ 3.07 Hz), 7.1 (1H, s), 7.03
(1H, d, J ¼ 6.8 Hz), 2.38 (3H, s), 2.27 (3H, s). IR (KBr) cmꢁ1: 3060, 2916,
1660, 1610, 1595, 1445, 1375, 1265, 1160, 940, 885, 825, 700.
Compound 21b
Mp 34–35ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 7.8 (2H, d,
J ¼ 8.57), 7.56 (1H, t, J ¼ 7.8 Hz), 7.43 (2H, t, J ¼ 7.8 Hz), 6.9 (2H, s),
2.33 (3H, s), 2.08 (6 H, s). 13C NMR (75 MHz, CDCl3, TMS) d ¼ 201,
138.6, 137.5, 137, 134.3, 133.75, 129.6, 128.9, 128.3, 21.4, 19.4. IR
(KBr) cmꢁ1: 3045, 2895, 1670, 1610, 1595, 1580, 1450, 1375, 1310,
1265, 1170, 920, 850, 700.
Compound 24b
Mp 85–87ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 7.78 (2H, d,
J ¼ 8.2), 7.53 (1H, t, J ¼ 7 Hz), 7.4 (2H, t, J ¼ 7 Hz), 6.55 (1H, dd,
J1 ¼ 8.2 Hz, J2 ¼ 2.1 Hz), 6.5 (1H, d, J ¼ 2.1 Hz), 3.88 (3H, s), 3.7 (3 H,

2718
A. R. Hajipour et al.
s). IR (KBr) cmꢁ1: 3020, 2920, 1640, 1600, 1440, 1370, 1285, 1100, 1020,
935, 830, 810, 690. Anal. calcd. for C15H14O3: C, 74.38; H, 5.78%. Found:
C, 74.29; H, 5.82%.
Compound 25b
Mp 125–127ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 8–7.85 (4 H, m),
7.6–7.35 (7H, m), 3.85 (3H, s). EIMS m=z (%): 262 (Mþ, 62), 245 (16), 185
(100), 142 (15), 105 (15), 77 (30). IR (KBr) cmꢁ1: 3060, 2916, 2830, 1660,
1590, 1500, 1450, 1250, 1070, 880, 780, 690. Anal. calcd. for C18H14O2: C,
82.44; H, 5.34%. Found: C, 82.38; H, 5.45%.
Compound 27b
Mp 96–98ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 7.95 (2H, d,
J ¼ 8.87 Hz), 7.37–7.2 (5 H, m), 6.92 (2H, d, J ¼ 8.87 Hz), 3.86 (3H, s),
3.25 (2H, t, J ¼ 8.05 Hz), 3.05 (2H, t, J ¼ 8.05 Hz). 13C NMR (75 MHz,
CDCl3, TMS) d ¼ 198, 163.2, 141.5, 130.5, 130.2, 128.5, 126.3, 113.7,
55.5, 40.5, 30.5. IR (KBr) cmꢁ1: 3040, 2915, 1670, 1600, 1570, 1500,
1450, 1420, 1255, 1170, 1020, 980, 840, 780, 745, 700. Anal. calcd. for
C16H16O2: C, 80; H, 6.66%. Found: C, 79.94; H, 6.78%.
Compound 28b
Mp 144–146ꢀC; 1H NMR (500 MHz, CDCl3, TMS) d ¼ 7.9 (1H, d,
J ¼ 8 Hz), 7.72 (1H, d, J ¼ 7.44 Hz), 7.67 (2H, s), 7.51–7.04 (4 H, m),
4.1 (2H, s), 3.44 (2H, d, J ¼ 5.64 Hz), 3.11 (2H, t, J ¼ 5.63). IR (KBr)
cmꢁ1: 3040, 2875, 1675, 1625, 1600, 1580, 1470, 1325, 1280, 980,
740. Anal. calcd. for C18H14O: C, 87.8; H, 5.69%. Found: C, 87.88; H,
5.75%.
Compound 30b
Mp 100–102ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 8.04 (2H, d,
J ¼ 8.68 Hz), 7.8 (1H, d, J ¼ 15.1 Hz), 7.62 (2H, m), 7.55 (1H, d,
J ¼ 15.1 Hz), 7.4 (3H, m), 6.97 (2H, d, J ¼ 8.68 Hz), 3.88 (3H, s). EIMS
m=z (%): 238 (Mþ, 100), 237 (72), 223 (22), 135 (92), 131 (22), 107 (18),
103 (36), 92 (30), 77 (77). IR (KBr) cmꢁ1: 3045, 2875, 1650, 1600,
1575, 1440, 1420, 1260, 1230, 1180, 1015, 980, 830, 765, 700. Anal. calcd.
for C16H14O2: C, 80.67; H, 5.88%. Found: C, 80.54; H, 6%.

Acylation of Aromatic Compounds
2719
Compound 31b
Mp 83–85ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 7.8 (2H, d,
J ¼ 9 Hz), 7.67 (2H, d, J ¼ 8.4 Hz), 7.25 (2H, d, J ¼ 8.4 Hz), 6.95 (2H,
d, J ¼ 9 Hz), 3.85 (3H, s), 2.4 (3H, s). 13C NMR (75 MHz, CDCl3,
TMS) d ¼ 193.9, 161.4, 141.4, 133.9, 131, 128.9, 128.5, 127.5, 112, 53.9,
20. IR (KBr) cmꢁ1: 3055, 2960, 1665, 1590, 1495, 1405, 1345, 1250,
1160, 1020, 940, 825. Anal. calcd. for C15H14O2: C, 79.64; H, 6.19%.
Found: C, 79.55; H, 6.15%.
Compound 33b
Mp 62–63ꢀC; 1H NMR (300 MHz, CDCl3, TMS) d ¼ 7.55 (1H, d,
J ¼ 7.5 Hz), 7.08(2H, s), 4.6 (2H, s), 2.56 (3H, s), 2.38 (3H, s). IR
(KBr) cmꢁ1: 3050, 2935, 1685, 1610, 1565, 1440, 1390, 1290, 1135, 990,
815, 790, 735. Anal. calcd. for C10H13ClO: C, 65.75; H, 6.02%. Found:
C, 65.64; H, 6.13%.
Compound 34b
1
Mp 68–70ꢀC; H NMR (300 MHz, CDCl3, TMS) d ¼ 6.88 (2H, s), 4.4
(2H, s), 2.3 (3H, s), 2.22 (6 H, s). EIMS m=z (%): 198 (Mþ þ 2, 3), 196
(Mþ, 8), 160 (5), 147 (100), 119 (50), 91 (27), 77 (17), 43 (27). IR (KBr)
cmꢁ1: 2890, 1715, 1615, 1390, 1210, 1150, 980, 860, 765, 715. Anal. calcd.
for C11H13ClO: C, 67.17; H, 6.61%. Found: C, 67.08; H, 6.66%.
Compound 35b
Mp 100–102ꢀC; 1H NMR (500 MHz, CDCl3, TMS) d ¼ 7.97 (2H, d,
J ¼ 8.53 Hz), 7 (2H, d, J ¼ 8.53 Hz), 5.1 (2H, s), 3.88 (3H, s). IR (KBr)
cmꢁ1: 3045, 2875, 1640, 1600, 1500, 1450, 1310, 1250, 1160, 1140, 1020,
925, 850, 750. Anal. calcd. for C9H9ClO2: C, 58.22; H, 4.85%. Found:
C, 58.31; H, 4.91%.
CONCLUSION
P2O5=Al2O3 is an inexpensive, easily available, noncorrosive, and envir-
onmentally benign compound. In this work, we have reported a simple
and efficient procedure for the preparation of aryl ketones in good yields
and short reaction times. The notable advantages of this methodology

2720
A. R. Hajipour et al.
are direct use of a wide variety of carboxylic acids, operational simplicity,
generality, high regioselectivity, availability of reactants, and easy
workup as a result of the heterogeneous conditions. Further investigation
on new applications of P2O5=Al2O3 is ongoing in our laboratories.
ACKNOWLEDGMENTS
We gratefully acknowledge the funding support received for this project
from the Isfahan University of Technology (IUT), IR Iran (A. R. H.) and
Grant GM 33138 (A. E. R.) from the National Institutes of Health, USA.
Further financial support from Center of Excellency in Sensor and Green
Chemistry Research (IUT) is gratefully acknowledged.
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