Molybdate sulfonic acid: Preparation, characterization, and application as an effective and reusable catalyst for octahydroxanthene-1,8-dione synthesis

Article abstract of DOI:10.2478/s11696-012-0263-y

Molybdate sulfonic acid (MSA) as a highly efficient catalyst was synthesized and employed for the synthesis of octahydroxanthene-1,8-dione derivatives. MSA efficiently catalyzed condensation of a wide range of aryl aldehydes and cyclohexane-1,3-diones to

Full text of DOI:10.2478/s11696-012-0263-y

Chemical Papers 67 (2) 145–154 (2013)
DOI: 10.2478/s11696-012-0263-y
ORIGINAL PAPER
Molybdate sulfonic acid: preparation, characterization,
and application as an effective and reusable catalyst
for octahydroxanthene-1,8-dione synthesis
Bahador Karami*, Zahra Zare, Khalil Eskandari
Department of Chemistry, Yasouj University, 75918–74831 Yasouj, Iran
Received 14 April 2012; Revised 26 June 2012; Accepted 27 June 2012
Molybdate sulfonic acid (MSA) as a highly efficient catalyst was synthesized and employed for the
synthesis of octahydroxanthene-1,8-dione derivatives. MSA efficiently catalyzed condensation of a
wide range of aryl aldehydes and cyclohexane-1,3-diones to obtain octahydroxanthene-1,8-diones. It
was characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), and FT-IR spectroscopy.
This catalyst can be recovered and reused several times in other reactions maintaining its high
activity. This novel and green method is very cheap and has many advantages such as excellent
yields, the use of recoverable and eco-friendly catalysts, and a simple work-up procedure.
c
ꢀ 2012 Institute of Chemistry, Slovak Academy of Sciences
Keywords: molybdate sulfonic acid, catalyst, cyclic 1,3-diketone, condensation reaction, solvent-
free
Introduction
ological and therapeutic properties (El-Brashy et al.,
2004; Chibale et al., 2003). The importance of xan-
thene derivatives was clearly realized from their us-
age as dyes (Bhowmik & Ganguly, 2005), sensitizers
in photodynamic therapy destroying tumor cells (Ion
et al., 1998), pH-sensitive fluorescent materials for
biomolecules visualization (Knight & Stephens, 1989),
and in laser technologies (Ahmad et al., 2002). More-
over, some xanthene based compounds have found
application as antagonists paralyzing the action of
zoxalamine as well as in the photodynamic therapy
(Saint-Ruf et al., 1975). Several polycyclic compounds
containing the xanthene skeleton can be isolated from
natural sources (Kinjo et al., 1995). Xanthene and its
derivatives are prepared by different methods, includ-
ing the reaction of aryloxymagnesium halides with tri-
ethylorthoformate (Casiraghi et al., 1973), cyclodehy-
dration (Bekaert et al., 1992), trapping of benzynes
by phenols (Knight & Little, 2001), intramolecular
phenyl carbonyl coupling reactions of benzaldehydes
and acetophenones (Kuo & Fang, 2001), and the cy-
clocondensation of 2-hydroxy aromatic aldehydes and
2-tetralone (Jha & Beal, 2004). In view of the impor-
Preparation and use of eco-friendly catalysts to im-
prove the efficiency of reactions or provide a higher
yield has been the subject of interests especially in the
synthesis of organic compounds (Clark & Macquarrie,
1996; Prakash et al., 2004; Martins et al., 2004; Belet-
skaya & Tyurin, 2010). Therefore, preparing and em-
ploying an effective and eco-friendly catalyst can be
extremely valuable in chemical syntheses (Veverková
& Toma, 2005). Solid acids play a significant role in
green chemistry, especially in chemical manufactur-
ing processes (Movassaghi & Jacobsen, 2002; Qi et
al., 2010; Wedge & Hawthorne, 2003; Stone & An-
derson, 2007). Solid acids as catalysts have generally
high turnover numbers and they play a significant role
in the synthesis of heterocyclic compounds (Chen et
al., 2002; Kafuku et al., 2010; Kidwai & Bhatnagar,
2010; Karami et al., 2012a, 2012b, 2012c). Further-
more, they can be easily separated from organic com-
ponents (Clark, 2002). Among organic compounds,
xanthene, and its derivatives have received significant
attention in recent years due to their wide range of bi-
*Corresponding author, e-mail: karami@mail.yu.ac.ir

146
B. Karami et al./Chemical Papers 67 (2) 145–154 (2013)
Fig. 1. Preparation of MSA (I); i – hexane, 0◦C.
tance of xanthene derivatives, many methods for the
synthesis of these compounds were reported including
condensation of β-naphthol and aldehydes or acetals
catalyzed by silica sulfuric acid, HCl/CH3COOH, or
H3PO4 (Seyyedhamzeh et al., 2008). However, some
of these methods involve long reaction times, harsh
reaction conditions, or unsatisfactory yields. There-
fore, improvement of these syntheses has been contin-
uously sought for. In the current study, a new route of
xanthene derivatives preparation by molybdate sul-
fonic acid (MSA) as an eco-friendly, high efficient,
and reusable catalyst is presented. This method not
only affords the products in excellent yields but also
avoids problems associated with catalyst costs, han-
dling, safety, and pollution.
stirred for 1.5 h. The reaction mixture was gradually
poured into 25 mL of chilled distilled water under ag-
itation. The bluish solid which separated out was fil-
tered. Then, the catalyst was washed with distilled
water five times until the filtrate showed a negative
test for the chloride ion, and it was dried at 120◦C for
5 h. The catalyst was obtained in a 90 % yield as a
bluish solid which decomposed at 354◦C.
General procedure for the preparation of 9-
aryl-substituted octahydroxanthene-1,8-diones
using MSA
A mixture of 1,3-diketone (2 mmol), aldehyde
(1 mmol), and MSA (I ) (16 mg, 0.05 mmol) was me-
chanically stirred under solvent-free conditions in a
glass tube at 100◦C for 1 h. The progress of the re-
action was monitored by TLC (hexane/ethyl acetate,
ϕr = 3 : 2). After the reaction completion, the reac-
tion mixture was cooled to laboratory temperature,
washed with CHCl3 (10 mL), and filtered to remove
the catalyst, the filtrate was concentrated in vacuum
to afford the crude product which was recrystallized
from ethanol to afford the crystalline pure product.
The catalyst was washed with ethanol, dried at 120◦C
for 1 h, and reused five times in other reactions.
Experimental
Chemicals were purchased from Sigma–Aldrich
(USA), and Merck (Germany) chemical companies.
Hexane was dried prior use by distillation from cal-
cium hydride (10 g L−1). X-ray diffraction (XRD)
pattern was obtained using a Philips X Pert Pro X
diffractometer (PANalytical, The Netherlands) oper-
ated with an Ni-filtered CuKα radiation source. X-
ray fluorescence (XRF) spectroscopy was recorded
by an X-ray fluorescence analyzer, Bruker, S4 Pio-
neer (Bruker, Germany). Melting points were mea-
sured on an electrothermal KSB1N apparatus (Kru¨ss,
Germany). IR spectra were recorded in the KBr ma-
trix on a Jasco FT-IR-680 plus spectrometer (Jasco,
Results and discussion
More recently, pressure from environmentalists has
induced a search for more environmentally friendly
forms of catalysis. Also, development of practical
methods, reaction media, conditions, and/or the use of
materials based on the idea of green chemistry is one of
the important issues in the scientific community (Mar-
tins et al., 2009). Silica sulfuric acid and Nafion-Hꢀ
have been applied in a wide variety of reactions (Olah
et al., 1978; Zolfigol, 2001; Prakash et al., 2004). Ac-
cordingly, it was found that anhydrous sodium molyb-
date reacts with chlorosulfonic acid (1 : 2 mole ratio)
to give (I ). The reaction is easy and clean without any
gas production (Fig. 1).
1
Japan) at the scanning range of 400–4000 cm−1. H
NMR and 13C NMR spectra were determined on a
FT-NMR Bruker Avance Ultra Shield Spectrometer
(Bruker, USA) at 400.13 MHz (for 1H NMR) and
100.62 MHz (for 13C NMR) in CDCl3 as the solvent
in the presence of tetramethylsilane as the internal
standard. TLC was performed on TLC-Grade silica
gel-G/UV 254 nm plates (Merck, Germany) (eluent:
hexane/ethyl acetate ϕr = 3 : 2).
Preparation of MSA
Fig. 2 shows the XRD patterns of I. It was reported
that high-degree mixing of Mo–S in chlorosulfonic acid
often leads to the absence of the XRD pattern for
anhydrous sodium molybdate.
XRD patterns of sodium molybdate (Na2MoO4)
(Ding et al., 2006) show broad peaks at around 2θ
17.0◦, 27.0◦, 32.0◦, 48.0◦, 53.0◦, 57.5◦, 78.5◦, 82.0◦,
Firstly, dry hexane (25 mL) was inserted into a
100 mL round bottom flask equipped with an ice bath
and an overhead stirrer; anhydrous sodium molybdate
(4.118 g, 20 mmol) was added followed by chloro-
sulfonic acid (0.266 mL, 40 mmol) which was added
dropwise to the flask for 30 min. This solution was

B. Karami et al./Chemical Papers 67 (2) 145–154 (2013)
147
molybdate and the –OSO3H group.
In addition, titration of the catalyst with NaOH
(0.1 M) was done for a more detailed characterization
of the catalyst. First, 1 mmol of the catalyst was dis-
solved in 100 mL of water and titrated with NaOH
(0.1 M) in the presence of phenolphthalein as an in-
dicator. In the equivalent point, it can be seen that
for 1 mmol of the catalyst, 2 mmol of NaOH had to
be used. The catalyst titration showed that for the
acid–base reaction two protons are available, which is
in agreement with the proposed structure of the cat-
alyst. XRF data of I indicate the presence of MoO3
and SO3 in the catalyst (Table 1).
Fig. 2. Powder X-ray diffraction pattern of I.
Table 1. XRF data of I
MSA has a number of structural features, e.g. it
contains an acidic proton and it is efficient under
solvent-free conditions, which make it an attractive
catalyst for organic transformations. This reagent has
good thermal and mechanical stability and it can be
filtered from the reaction mixture to be subsequently
reused. In connection with our studies on new cat-
alyzed organic reactions (Karami et al., 2012a, 2012b,
2012c; Karami & Kiani, 2011), MSA was found to
be applicable as a powerful, safe and recyclable cat-
alyst for the condensation reaction between cyclic
1,3-diketones (II ) with aryl aldehydes (III ) (Fig. 3).
At first, the synthesis of 2,2ꢀ-(arylmethylene)bis(3-
hydroxycyclohex-2-enone) (IV ) from the reaction of II
with several aromatic aldehydes (III ), was expected;
however, as it can be seen from Fig. 3, under the
given conditions, IV was not formed and II with
III were effectively cyclized to give 9-aryl-substituted
octahydroxanthene-1,8-diones (V ). Structures of the
Entry
Compound
Content/mass %
1
2
3
4
5
6
7
8
9
SO3
49.52
1.150
39.02
0.150
0.064
0.019
0.012
0.010
10.03
99.98
Na2O
MoO3
Cl
K2O
Nb2O5
Fe2O3
CuO
LOIa
Total
10
a) Loss on ignition.
some of which are absent in the XRD pattern of MSA
due to high-degree mixing of Mo with sulfonic acid.
Broad peaks around 2θ 23◦, 29◦, and 34◦ from the
smaller inset can be attributed to the linking of Mo
to sulfonic acid. Furthermore, FT-IR spectrum of an-
hydrous sodium molybdate and MSA shows charac-
teristic bonds of anhydrous sodium molybdate and
chlorosulfonic acid. Absorption at 3459 cm−1, 2110
1
products (V ) were deduced from their IR, H NMR,
and 13C NMR spectroscopic data.
In another variation of the process, aromatic di-
aldehyde substrate was used instead of benzaldehyde
derivatives which led to the condensation with II
(1 : 4 mole ratio) to afford bisxanthene products.
In this case, four 1,3-diketones (II ) with a dialde-
hyde were effectively cyclized to obtain bis(9-aryl-
substituted octahydroxanthene-1,8-diones) (Fig. 4).
cm−1, 1635 cm−1, 1129 cm−1, 909 cm−1, 771 cm−1
,
637 cm−1, 616 cm−1, and 451 cm−1 in the catalyst
spectrum reveals both bonds in anhydrous sodium
Fig. 3. Synthesis of octahydroxanthene-1,8-diones catalyzed by MSA (I) as an effective catalyst; i – solvent free, 100◦C, MSA 5
mole %.

148
B. Karami et al./Chemical Papers 67 (2) 145–154 (2013)
Fig. 4. Catalyzed synthesis of bis(octahydroxanthene-1,8-diones) using MSA (I); i – solvent free, 100◦C, MSA 5 mole %.
Table 2. Optimization of molar ratio of the catalyst for the model reaction
Product
Mole %
Time/min
Yield/%
1
5
180
60
55
96
88
70
10
20
60
90
Table 3. Optimization of temperature for the model reaction
Product
Temperature/◦C
Time/min
Yield/%
r.t.
50
80
180
180
90
70
60
60
75
82
90
96
92
85
90
100
110
120
60
60
r.t. – room temperature.
Solvent-free conditions or the use of a solid re-
action catalyst reduce the pollution and costs due
to the simplification of the experimental and work-
up procedures and savings in labor. Recently, inter-
est in the environmental control of chemical processes
has increased remarkably as a response to public
concern about the pollution of environment by haz-
ardous chemical materials. Also, it is important to
know which reaction process is the most economic
and eco-friendly one, with the shortest reaction time
and highest yield of the product. Therefore, finding
optimal conditions of the reaction is inevitable. For
this purpose, the amount of catalyst and the tem-
perature of the process were optimized. First, con-
densation of dimedone (II, R1, R2 = Me; Fig. 3)
and benzaldehyde (III, Ar = Ph; Fig. 3) was cho-
sen as a model reaction (preparation of compound
Va). It was found that in the absence of a cat-
alyst, there is no appreciable progress in the con-
densation reaction even at high temperatures, and
thus, the catalyst plays a crucial role in the reac-
tion. Required amount of the catalyst in the syn-
thesis of octahydroxanthene-1,8-dione derivatives for
the model reaction is shown in Table 2. As can be
seen from this table, when 5 mole % of MSA as
an effective catalyst was added to the reaction mix-
ture, maximum yield of the product (96 %) was ob-
tained.

B. Karami et al./Chemical Papers 67 (2) 145–154 (2013)
149
Table 4. MSA catalyzed synthesis of 9-aryl substituted octahydroxanthene-1,8-diones
M.p./◦C
Reported
Aldehyde III
Product
Time/min
Yielda/%
Found
60
96
202–204
201–202b
230–232b
45
90
90
88
230–232
215–217
216–217c
30
60
60
95
89
93
219–221
226–227
209–211
221–223c
226–228d
210–212e
35
92
223–225
224–226d
50
90
86
250–252
189–191
249–252c
110
190–191f

150
B. Karami et al./Chemical Papers 67 (2) 145–154 (2013)
Table 4. (continued)
M.p./◦C
Reported
Aldehyde III
Product
Time/min
Yielda/%
Found
90
88
238–239
236–239g
60
90
245–247
–
75
86
238–240
–
45
65
95
89
271–273
260–262
272–273h
262–263b
30
55
92
88
224–227
250–252
224–226i
249–252j
60
86
170–172
169–171k

B. Karami et al./Chemical Papers 67 (2) 145–154 (2013)
151
Table 4. (continued)
Aldehyde III
M.p./◦C
Reported
Product
Time/min
Yielda/%
Found
50
92
252–255
–
a) Refers to isolated yield; b) Kantevari et al. (2007); c) Venkatesan et al. (2008); d) Fan et al. (2005); e) Zhang and Lui (2008);
f ) Horning and Horning (1946); g) Bekaert et al. (1992); h) Das et al. (2006); i) John et al. (2006); j ) Casiraghi et al. (1973); k)
Tavakoli et al. (2009).
Table 5. Synthesis of Va (model reaction) using different catalysts
Catalyst
Mole % Solvent
Temperature/◦C
Time/min
Yield/%
Reference
MSA
p-TsOH
DBSA
TMSCl
TBAHS
DBSA
SelectfluorTM
PPA–SiO2
HClO4–SiO2
SbCl3–SiO2
5
5
Solvent free
100
80
60
20
60
420
210
180
60
30
180
50
96
80
89
84
88
91
95
92
32
93
This paper
Venkatesan et al. (2008)
Jin et al. (2006)
Kantevari et al. (2006)
Karade et al. (2007)
Bin et al. (2006)
Poor Heravi (2009)
Kantevari et al. (2007)
Kantevari et al. (2007)
Zhang and Lui (2008)
MeOH/H2O
H2O, ultrasonic
CH3CN
Dioxane, H2O
H2O
Solvent free
Solvent free
Solvent free
Solvent free
10
100
10
20
10
10
10
10
25–30
Reflux
Reflux
Reflux
120
140
140
120
p-TSOH – p-Toluenesulfonic acid, DBSA – p-dodecylbenzenesulfonic acid; TMSCl – trimethylsilyl chloride, TBAHS – tetrabutylam-
monium hydrogen sulfate, SelectfluorTM – 1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2,2,2]octane bis(tetrafluoroborate), PPA–
SiO2 – polyphosphoric acid supported on silica.
As can be seen from Table 2, the best mole ratio of
the catalyst for this reaction was found to be 5 mole %,
whereas adding higher amounts of the catalyst did not
improve the catalysis results.
In the following study on the model reactions, the
reactions were examined at various temperatures in
the presence of 5 mole % of MSA to determine the
effect of temperature on the progress of the reaction
(Table 3). This observation revealed that the maxi-
mum yield of the product in the shortest reaction time
was obtained at 100◦C.
According to the archived optimal conditions, the
synthesis of xanthene derivatives under solvent-free
condition in the presence of 5 mole % of MSA and
at 100◦C was attempted.
Under these conditions, several aromatic aldehy-
des (III ) containing electron donating as well as elec-
tron withdrawing groups with different substitution
patterns were effectively condensed to give 9-aryl sub-
stituted octahydroxanthene-1,8-dione derivatives (V ).
In all cases, the corresponding xanthene derivatives
were obtained in good to excellent yields (Table 4).
Comparison of the presented method with oth-
ers for the synthesis of 3,3,6,6-tetramethyl-9-phenyl-
3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-dione (Va)
is shown in Table 5. These results show that the used
catalysts created good to excellent conditions for the
synthesis of xanthene derivatives compared to other
catalysts and methods reported previously.
All the prepared products (V ) were characterized
by their IR, 1H NMR, and 13C NMR spectroscopic
data. Spectral data of the newly prepared products
are summarized in Tables 6 and 7.
At the end of the reactions, the catalysts were fil-
tered, washed with ethanol, dried at 120◦C for 1 h, and
reused in another reaction. MSA showed high catalytic
activity with very short reaction times. Moreover, it
can be recovered and reused five times without a sig-
nificant loss of activity. Results of these observations
for the model reaction are shown in Table 8.
Fig. 5 shows the proposed mechanism for the
preparation of 9-aryl-substituted octahydroxanthene-
1,8-diones in the presence of I.
MSA is a strong solid acid able to activate the
carbonyl group of aldehydes (III ) and decrease the
energy of their transition state. Nucleophilic attack
of β-diketone (II ) on the activated carbonyl group
of aldehydes results in the formation of intermediate

152
B. Karami et al./Chemical Papers 67 (2) 145–154 (2013)
Table 6. Characterization data of newly prepared compounds
wi(calc.)/%
wi(found)/%
Compound
Formula
Mr
C
H
Vk
Vl
C40H46O6
C40H46O6
C32H30O6
622.79
622.79
510.58
77.14
77.26
77.14
77.21
75.28
75.32
7.44
7.28
7.44
7.32
5.92
5.86
Vr
Table 7. Representative spectral data of newly synthesized products
Product
Spectral data
IR, ν˜/cm−1: 808, 1003, 1162, 1200, 1365, 1425, 1462, 1620, 1666, 2957, 3040
Vk
1H NMR (CDCl3), δ: 0.97 (s, 12H, 4 × CH3), 1.07 (s, 12H, 4 × CH3), 2.18 (s, 8H, 4 × CH2), 2.44 (dd, 8H, 1J =
36.4 Hz, 4J = 17.6 Hz, 4 × CH2), 4.71 (s, 2H, 2 × CH), 7.08 (s, 2H, Ar-H), 7.27 (s, 2H, Ar-H)
13C NMR (CDCl3), δ: 25.0, 27.7, 29.0, 30.7, 32.2, 40.9, 50.6, 115.7, 127.9, 141.7, 162.4, 196.4
Vl
Vr
IR, ν˜/cm−1: 769, 1158, 1203, 1462, 1629, 1659, 2957, 3095
1H NMR (CDCl3), δ: 1.03 (s, 12H, 4 × CH3), 1.08 (s, 12H, 4 × CH3), 2.15 (dd, 8H, 2J = 24.0 Hz, 4J = 16.0 Hz,
4 × CH2), 2.48 (dd, 8H, 2J = 45.2 Hz, 4J = 17.6 Hz, 4 × CH2), 4.72 (s, 2H, 2 × CH), 7.07–7.09 (m, 3H, Ar-H),
7.15 (1H, s, Ar-H)
13C NMR (CDCl3), δ: 28.0, 29.6, 31.8, 32.6, 41.3, 51.3, 116.0, 126.8, 128.2, 144.0, 162.7, 196.7
IR, ν˜/cm−1: 802, 1001, 1165, 1210, 1425, 1460, 1623, 1665, 2950, 3038
1H NMR (CDCl3), δ: 2.29 (m, 8H, 4 × CH2), 2.39 (m, 8H, 4 × CH2), 2.57 (4H, m, 2 × CH2), 2.67 (m, 4H, 2 × CH2),
4.74 (s, 2H, 2 × CH), 7.18 (d, 4H, J = 7.6 Hz, Ar)
13C NMR (CDCl3), δ: 20.1, 27.1, 30.8, 36.9, 116.9, 128.0, 141.9, 164.0, 196.7
Fig. 5. Suggested mechanism for the synthesis of octahydroxanthene-1,8-diones derivatives; catalyst H2A–MSA.

B. Karami et al./Chemical Papers 67 (2) 145–154 (2013)
Table 8. Reusability of MSA in the reaction process for the model reaction
153
Product
Total reusability
Time/min
Yield/%
1
2
3
4
5
60
60
60
90
90
96
92
88
85
80
VI followed by a nucleophilic attack of the second β-
diketone on intermediate VI which is activated by the
acidic proton of MSA giving intermediate VII. From
the cyclization of intermediate VII and its subsequent
dehydration, the corresponding octahydroxanthene-
1,8-diones V are produced.
Chen, B. H., Fan, Y. S., Ma, Y. X., Li, P. R., & Liu, W. M.
(2002). Lewis acids-catalyzed nucleophilic addition of allyl-
stannane to aroylhydrazone. Chemical Papers, 56, 247–249.
Chibale, K., Visser, M., van Schalkwyk, D., Smith, P. J., Sar-
avanamuthu, A., & Fairlamb, A. H. (2003). Exploring the
potential of xanthene derivatives as trypanothione reductase
inhibitors and chloroquine potentiating agents. Tetrahedron,
59, 2289–2296. DOI: 10.1016/s0040-4020(03)00240-0.
Clark, J. H. (2002). Solid acids for green chemistry. Accounts of
Chemical Research, 35, 791–797. DOI: 10.1021/ar010072a.
Clark, J. H., & Macquarrie, D. J. (1996). Environmentally
friendly catalytic methods. Chemical Society Reviews, 25,
303–310. DOI: 10.1039/cs9962500303.
Das, B., Thirupathi, P., Mahender, I., Reddy, V. S., & Rao, Y.
K. (2006). Amberlyst-15: An efficient reusable heterogeneous
catalyst for the synthesis of 1,8-dioxo-octahydroxanthenes
and 1,8-dioxo-decahydroacridines. Journal of Molecular
Catalysis A: Chemical, 247, 233–239. DOI: 10.1016/j.molcata.
2005.11.048.
Conclusions
A new application of MSA as a catalyst for the
preparation of 9-aryl substituted octahydroxanthene-
1,8-diones derivatives is presented. All products were
obtained in excellent yields in the presence of the
catalytic amount of MSA. The presence of MSA in
the condensation of cyclic 1,3-diketones with aromatic
aldehydes is a key factor of the reaction progress. This
catalyst not only provides cheap and facile process, it
is also considered to be a green catalyst. Other ad-
vantages of this method are its simple experimental
procedure, utilization of a clean and recyclable cata-
lyst, the use of ready available starting materials, and
the short period of the reaction.
El-Brashy, A. M., Metwally, M. E. S., & El-Sepai, F. A. (2004).
Spectrophotometric determination of some fluoroquinolone
antibacterials by binary complex formation with xanthene
dyes. Il Farmaco, 59, 809–817. DOI: 10.1016/j.farmac.2004.
07.001.
Ding, Y., Hou, N., Chen, N.,
& Xia, Y. (2006). Phase
diagrams of Li2MoO4-Na2MoO4 and Na2MoO4-K2MoO4
systems. Rare Metals, 25, 316–320. DOI: 10.1016/s1001-
0521(06)60060-0.
Fan, X., Hu, X., Zhang, X., & Wang, J. (2005). InCl3·4H2O-
promoted green preparation of xanthenedione derivatives in
ionic liquids. Canadian Journal of Chemistry, 83, 16–20.
DOI: 10.1139/v04-155.
Horning, E. C., & Horning, M. G. (1946). Methone derivatives
of aldehydes. Journal of Organic Chemistry, 11, 95–99. DOI:
10.1021/jo01171a014.
Ion, R. M., Planner, A., Wiktorowicz, K., & Frackowiak, D.
(1998). The incorporation of various porphyrins into blood
cells measured via flow cytometry, absorption and emission
spectroscopy. Acta Biochimica Polonica, 45, 833–845.
Jha, A., & Beal, J. (2004). Convenient synthesis of 12H-
benzo[a]xanthenes from 2-tetralone. Tetrahedron Letters, 45,
8999–9001. DOI: 10.1016/j.tetlet.2004.10.046.
Jin, T. S., Zhang, J. S., Wang, A. Q., & Li, T. S. (2006).
Ultrasound-assisted synthesis of 1,8-dioxo-octahydroxanth-
ene derivatives catalyzed by p-dodecylbenzenesulfonic acid
in aqueous media. Ultrasonics Sonochemistry, 13, 220–224.
DOI: 10.1016/j.ultsonch.2005.04.002.
John, A., Yadav, P. J. P., & Palaniappan, S. (2006). Clean
synthesis of 1,8-dioxo-dodecahydroxanthene derivatives cat-
alyzed by polyaniline-p-toluenesulfonate salt in aqueous me-
dia. Journal of Molecular Catalysis A: Chemical, 248, 121–
125. DOI: 10.1016/j.molcata.2005.12.017.
References
Ahmad, M., King, T. A., Ko, D. K., Cha, B. H., & Lee,
J. (2002). Performance and photostability of xanthene and
pyrromethene laser dyes in sol-gel phases. Journal of Physics
D: Applied Physics, 35, 1473–1476. DOI: 10.1088/0022-
3727/35/13/303.
Bekaert, A., Andrieux, J., & Plat, M. (1992). New total syn-
thesis of bikaverin. Tetrahedron Letters, 33, 2805–2806. DOI:
10.1016/s0040-4039(00)78863-0.
Beletskaya, I., & Tyurin, V. (2010). Recyclable nanostructured
catalytic systems in modern environmentally friendly organic
synthesis. Molecules, 15, 4792–4814. DOI: 10.3390/molecules
15074792.
Bhowmik, B. B., & Ganguly, P. (2005). Photophysics of xan-
thene dyes in surfactant solution. Spectrochimica Acta Part
A: Molecular and Biomolecular Spectroscopy, 61, 1997–2003.
DOI: 10.1016/j.saa.2004.07.031.
Bin, L. L., Shou, J. T., Sha, H. L., Meng, L., Na, Q., & Shuang,
L. T. (2006). The reaction of aromatic aldehydes and 1,3-
cyclohexanedione in aqueous media. E-Journal of Chemistry,
3, 117–121.
Casiraghi, G., Casnati, G., & Cornia, M. (1973). Regiospecific
reactions of phenol salts: reaction-pathways of alkylphenoxy-
magnesiumhalides with triethylorthoformate. Tetrahedron
Letters, 14, 679–682. DOI: 10.1016/s0040-4039(00)72432-4.
Kafuku, G., Lee, K. T., & Mbarawa, M. (2010). The use of sul-
fated tin oxide as solid superacid catalyst for heterogeneous

154
B. Karami et al./Chemical Papers 67 (2) 145–154 (2013)
transesterification of Jatropha curcas oil. Chemical Papers,
(2009). Solvent-free route to β-enamino dichloromethyl ke-
tones and application in the synthesis of novel 5-dichlorome-
thyl-1H-pyrazoles. Journal of Heterocyclic Chemistry, 46,
1247–1251. DOI: 10.1002/jhet.227.
Movassaghi, M., & Jacobsen, E. N. (2002). A direct method
for the conversion of terminal epoxides into γ-butanolides.
Journal of the American Chemical Society, 124, 2456–2457.
DOI: 10.1021/ja025604c.
Olah, G. A., Molhotra, R., & Narang, S. C. (1978). Aromatic
substitution. 43. Perfluorinated resinsulfonic acid catalyzed
nitration of aromatics. The Journal of Organic Chemistry,
43, 4628–4630. DOI: 10.1021/jo00418a019.
Poor Heravi, M. R. (2009). SelectfluorTM promoted synthe-
sis of 9-aryl-1,8-dioxooctahydroxanthane derivatives under
solvent-free conditions. Journal of the Iranian Chemical So-
ciety, 6, 483–488.
Prakash, G. K. S., Mathew, T., Mandal, M., Farnia, M., &
Olah, G. A. (2004). Aroylation of aromatics with aryl car-
boxylic acids over Nafion-H (polymeric perfluoroalkanesul-
fonic acid), an environmentally friendly solid acid catalyst.
Arkivoc, 2004(viii), 103–110.
Qi, X., Rice, G. T., Lall, M. S., Plummer, M. S., & White,
M. C. (2010). Diversification of a β-lactam pharmacophore
via allylic C–H amination: accelerating effect of Lewis acid
co-catalyst. Tetrahedron, 66, 4816–4826. DOI: 10.1016/j.tet.
2010.04.064.
Saint-Ruf, G., Hieu, H. T., & Poupelin, J. P. (1975). The ef-
fect of dibenzoxanthenes on the paralyzing action of zoxa-
zolamine. Naturwissenschaften, 62, 584–585. DOI: 10.1007/
bf01166986.
Seyyedhamzeh, M., Mirzaei, P., & Bazgir, A. (2008). Solvent-
free synthesis of aryl-14H-dibenzo[a,j]xanthenes and 1,8-
dioxo-octahydro-xanthenes using silica sulfuric acid as cata-
lyst. Dyes and Pigments, 76, 836–839. DOI: 10.1016/j.dyepig.
2007.02.001.
64, 734–740. DOI: 10.2478/s11696-010-0063-1.
Kantevari, S., Bantu, R., & Nagarapu, L. (2006). TMSCl medi-
ated highly efficient one-pot synthesis of octahydroquinazoli-
none and 1,8-dioxo-octahydroxanthene derivatives. Arkivoc,
2006(xvi), 136–148.
Kantevari, S., Bantu, R., & Nagarapu, L. (2007). HClO4–
SiO2 and PPA–SiO2 catalyzed efficient one-pot Knoeve-
nagel condensation, Michael addition and cyclo-dehydration
of dimedone and aldehydes in acetonitrile, aqueous and
solvent free conditions: Scope and limitations. Journal
of Molecular Catalysis A: Chemical, 269, 53–57. DOI:
10.1016/j.molcata.2006.12.039.
Karade, H. N., Sathe, M., & Kaushik, M. P. (2007). An efficient
synthesis of 1,8-dioxo-octahydroxanthenes using tetrabuty-
lammonium hydrogen sulfate. Arkivoc, 2007(xiii), 252–258.
Karami, B., & Kiani, M. (2011). ZrOCl2.8H2O/SiO2: An effi-
cient and recyclable catalyst for the preparation of coumarin
derivatives by Pechmann condensation reaction. Catalysis
Communications, 14, 62–67. DOI: 10.1016/j.catcom.2011.07.
002.
Karami, B., Eskandari, K., Farahi, M., & Barmas, A. (2012a).
An effective and new method for the synthesis of polysubsti-
tuted imidazoles by the use of CrCl3.6H2O as a green and
reusable catalyst: synthasis of some novel imidazole deriva-
tives. Journal of the Chinese Chemical Society, 59, 473–479.
DOI: 10.1002/jccs.201100555.
Karami, B., Ghashghaee, V., & Khodabakhshi, S. (2012b).
Novel silica tungstic acid (STA): Preparation, characteriza-
tion and its first catalytic application in synthesis of new
benzimidazoles. Catalysis Communications, 20, 71–75. DOI:
10.1016/j.catcom.2012.01.012.
Karami, B., Khodabakhshi, S., & Haghighijou, Z. (2012c).
Tungstate sulfuric acid: preparation, characterization, and
application in catalytic synthesis of novel benzimidazoles.
Chemical Papers, 66, 684–690. DOI: 10.2478/s11696-012-
0152-4.
Stone, M. T., & Anderson, H. L. (2007). A cyclodextrin-
insulated anthracene rotaxane with enhanced fluorescence
and photostability. Chemical Communications, 2007, 2387–
2389. DOI: 10.1039/b700868f.
Tavakoli, H. R., Zamani, H., Ghorbani, M. H., & Etedali
Habibabadi, H. (2009). Solvent-free synthesis of 14-aryl(al-
kyl)-14H-dibenzo[a,j]xanthene, 9-aryl(alkyl)-3,3,6,6-tetrame-
thyl-3,4,5,6,7,9-hexahydro-2H-xanthene-1,8-dione and 2-
amino-5,6,7,8-tetrahydro-5-oxo-4-aryl-7,7-dimethyl-4H-
benzo-[b]-pyran derivatives using InCl3 as catalyst. Iranian
Journal of Organic Chemistry, 2, 118–126.
Kidwai, M., & Bhatnagar, D. (2010). Polyethylene glycol-
mediated synthesis of decahydroacridine-1,8-diones catalyzed
by ceric ammonium nitrate. Chemical Papers, 64, 825–828.
DOI: 10.2478/s11696-010-0070-2.
Kinjo, J., Uemura, H., Nohara, T., Yamashita, M., Marubaya-
shi, N.,
& Yoshihira, K. (1995). Novel yellow pigment
from Pterocarpus santalinus: Biogenetic hypothesis for san-
talin analogs. Tetrahedron Letters, 36, 5599–5602. DOI:
10.1016/0040-4039(95)01071-o.
Knight, C. G., & Stephens, T. (1989). Xanthene-dye-labelled
phosphatidylethanolamines as probes of interfacial pH. Stud-
ies in phospholipid vesicles. Biochemical Journal, 258, 683–
687.
Knight, D. W., & Little, P. B. (2001). The first efficient
method for the intramolecular trapping of benzynes by phe-
nols: a new approach to xanthenes. Journal of the Chemi-
cal Society, Perkin Transactions 1, 2001, 1771–1777. DOI:
10.1039/b103834f.
Venkatesan, K., Pujari, S. S., Lahoti, R. J., & Srinivasan,
K. V. (2008). An efficient synthesis of 1,8-dioxo-octahydro-
xanthene derivatives promoted by
a room temperature
ionic liquid at ambient conditions under ultrasound ir-
radiation. Ultrasonics Sonochemistry, 15, 548–553. DOI:
10.1016/j.ultsonch.2007.06.001.
Veverková, E., & Toma, Š. (2005). Microwave-assisted method
for conversion of alcohols into N-Substituted amides using
ꢀ
envirocat EPZG as a catalyst. Chemical Papers, 59, 8–10.
Wedge, T. J., Hawthorne, M. F. (2003). Multidentate
&
carborane-containing Lewis acids and their chemistry: mer-
curacarborands. Coordination Chemistry Reviews, 240, 111–
128. DOI: 10.1016/s0010-8545(02)00259-x.
Zhang, Z. H., & Lui, Y. H. (2008). Antimony trichloride/SiO2
promoted synthesis of 9-ary-3,4,5,6,7,9-hexahydroxanthene-
1,8-diones. Catalysis Communications, 9, 1715–1719. DOI:
10.1016/j.catcom.2008.01.031.
Zolfigol, M. A. (2001). Silica sulfuric acid/NaNO2 as a novel
heterogeneous system for production of thionitrites and disul-
fides under mild conditions. Tetrahedron, 57, 9509–9511.
DOI: 10.1016/s0040-4020(01)00960-7.
Kuo, C. W.,
& Fang, J. M. (2001). Synthesis of xan-
thenes, indanes, and tetrahydronaphthalenes via intramolec-
ular phenyl-carbonyl coupling reactions. Synthetic Commu-
nications, 31, 877–892. DOI: 10.1081/scc-100103323.
Martins, M. A. P., Teixeira, M. V. M., Cunico, W., Scapin, E.,
Mayer, R., Pereira, C. M. P., Zanatta, N., Bonacorso, H.
G., Peppe, C., & Yuan, Y. F. (2004). Indium(III) bromide
catalyzed one-pot synthesis of trichloromethylated tetrahy-
dropyrimidinones. Tetrahedron Letters, 45, 8991–8994. DOI:
10.1016/j.tetlet.2004.10.048.
Martins, M. A. P., Peres, R. L., Frizzo, C. P., Scapin, E., Mor-
eira, D. N., Fiss, G. F., Zanatta, N., & Bonacorso, H. G.