Sulfonated diatomite as heterogeneous acidic nanoporous catalyst for synthesis of 14-aryl-14-H-dibenzo[a,j]xanthenes under green conditions

Article abstract of DOI:10.1016/j.apcata.2014.03.012

Sulfonic acid functionalized diatomite afforded diatomite-SO₃H as an efficient heterogeneous solid acid nanoporous. The resulting immobilized catalysts have been successfully used in the synthesis of 14-aryl-14-H- dibenzo[a,j]xanthenes under so

Full text of DOI:10.1016/j.apcata.2014.03.012

Applied Catalysis A: General 477 (2014) 132–140
Contents lists available at ScienceDirect
Applied Catalysis A: General
journal homepage: www.elsevier.com/locate/apcata
Sulfonated diatomite as heterogeneous acidic nanoporous catalyst for
synthesis of 14-aryl-14-H-dibenzo[a,j]xanthenes under green
conditions
Hossein Naeimi∗, Zahra Sadat Nazifi
Department of Organic Chemistry, Faculty of Chemistry, University of Kashan, Kashan 87317, Islamic Republic of Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
Sulfonic acid functionalized diatomite afforded diatomite-SO3H as an efficient heterogeneous solid acid
nanoporous. The resulting immobilized catalysts have been successfully used in the synthesis of 14-aryl-
14-H-dibenzo[a,j]xanthenes under solvent free conditions. This procedure has a lot of advantages such
as very easy reaction conditions, recyclable heterogeneous acidic catalyst, natural catalyst, absence of
any tedious workup or purification and much milder method. The corresponding products have been
obtained in excellent yields, high purity and short reaction times.
Received 9 December 2013
Received in revised form 5 March 2014
Accepted 6 March 2014
Available online 15 March 2014
Keywords:
© 2014 Elsevier B.V. All rights reserved.
Acidic nanoporous catalyst
Diatomite-supported
␤-Naphthol
Aldehydes
One-pot
Eco-friendly
Xanthene
1. Introduction
Xanthene derivatives posses a broad range of useful biolog-
ical and pharmacological properties such as antibacterial [11],
Diatomite (SiO2·nH2O) is a kind of mineral assemblage in nat-
ural sediments. It consists of frustule, the silicified hard shell of
diatom [1]. The diatom shell, which is composed of amorphous
silica, has properties such as high porosity with strong adsorba-
bility and excellent thermal resistance [2]. Due to the extremely
porous structure, low density and high surface area of diatomite,
there is a possibility to use it for the adsorption of organic and
inorganic chemicals [3]. Hence, diatomite has been widely used as
alteration media, catalytic support as an adsorbent for pet litter and
oil spills [4]. Although diatomite has a unique combination of phys-
ical and chemical properties, its use as an adsorbent in wastewater
treatment has not been extensively investigated [5–8]. Recently,
the novel applications of diatomite as biological support, pharmic
carrier, chromatogram support, and functional filler have attracted
extensive attentions [9,10].
anti-inflammatory activities [12], antiviral [13], and photodynamic
therapy [14]. Furthermore, some other their derivatives have found
application in industry such as dyes [15], laser technology [16], and
pH sensitive fluorescent materials for visualization of biomolecules
[17]. A number of methods have been developed for the synthesis
of 14-H-dibenzo[a,j]xanthene by condensation of ␤-naphthol and
aldehydes in the presence of p-toluene sulfonic acid [18], molec-
ular iodine [19], K5CoW12O40·3H2O/silica-gel/MW [20], LiBr/MW
[21], amberlyst-15 [22], ␣-iodoacetates from alkenes/ammonium
acetate/I2 [23], cation-exchange resins [24] as catalyst, Beckmann
rearrangement products [25], isonitriles [26], silica sulfuric acid
[27] and sulfamic acid [28].
Therefore, the synthesis of these class heterocyclic compounds
is particularly significant and interest researches. Hence the syn-
thesis of heterocycles under solvent free conditions has attracted
much attention in synthetic organic chemistry.
In this research, we hope to report a simple, efficient method for
the synthesis of 14-aryl-14-H-dibenzo[a,j]xanthenes by reaction of
␤-naphthol and aromatic aldehydes in the presence of diatomite-
SO3H as heterogeneous acidic catalyst. In this reaction, the catalyst
∗
Corresponding author. Tel.: +98 3615912388; fax: +98 3615912397.
E-mail address: naeimi@kashanu.ac.ir (H. Naeimi).
http://dx.doi.org/10.1016/j.apcata.2014.03.012
0926-860X/© 2014 Elsevier B.V. All rights reserved.

H. Naeimi, Z.S. Nazifi / Applied Catalysis A: General 477 (2014) 132–140
133
could be recycled several times without significant loss of activity
and high purity.
NMR (CDCl3, 400 MHz)/ı ppm: 6.50 (s, 1H, CH), 6.98–7.01 (t, 1H,
J = 7.6, Ar), 7.13–7.17 (t, 2H, J = 7.6, Ar), 7.40–7.43 (t, 2H, J = 7.6, Ar),
7.48–7.54 (m, 4H, Ar), 7.56–7.60 (t, 2H, J = 7.2, Ar), 7.81–7.92 (d, 2H,
J = 8.8, Ar), 7.82–7.85 (d, 2H, J = 8.0, Ar), 8.39–8.41 (d, 2H, J = 8.8, Ar);
13C NMR/(CDCl3, 100 MHz)/ı ppm: 148.74, 145.03, 131.48, 131.07,
128.88, 128.82, 128.5, 128.29, 126.81, 126.42, 124.26, 122.72,
118.04, 117.34, 38.07, UV (CH2Cl2)/ꢁmax (nm): 244, 232.
2. Experimental
2.1. Materials
14-(4-Chlorophenyl)14H-dibenzo[a,j]xanthenes (3b): yellow
solid, m.p. = 289–290 ◦C, (m.p. = 287–288 ◦C) [36]; IR (KBr)/ꢀ
(cm−1): 3067, 1624, 1591, 1514, 1585, 1431, 1243, 1085, 961, 808,
743; 1H NMR (CDCl3, 400 MHz)/ı ppm: 6.48 (s, 1H, CH), 7.10–7.12
(d, 2H, J = 8.4, Ar), 7. 41–7.47 (m, 4H, Ar), 7.48–7.50 (d, 2H, J = 8.8, Ar),
7.57–7.61 (t, 2H, J = 7.6, Ar), 7.80–7.82 (d, 2H, J = 8.8, Ar), 7.84–7.86
(d, 2H, J = 8.0, Ar), 8.32–8.34 (d, 2H, J = 8.4, Ar); 13C NMR/(CDCl3,
100 MHz)/ı ppm: 148.51, 145.01, 131.39, 131.31, 131.20, 130.19,
129.83, 129.19, 128.91, 127.60, 125.14, 123.77, 118.21, 117.50,
39.87; UV (CH2Cl2)/ꢁmax (nm): 244, 230.
14-(2-Chlorophenyl)14H-dibenzo[a,j]xanthenes (3c): white
solid, m.p. = 212–213 ◦C, (m.p. = 214–215 ◦C) [36]; IR (KBr)/ꢀ
(cm−1): 3059, 1625, 1591, 1462, 1402, 1243, 1032, 959, 808; 1H
NMR (CDCl3, 400 MHz)/ı ppm: 6.81 (s, 1H, CH), 6.92 (m, 2H, Ar),
7.40–7.44 (m, 3H, Ar), 7.48–7.51 (d, 2H, J = 8.8, Ar), 7.61–7.64 (m,
5H, Ar), 8.74–8.76 (d, 2H, J = 8.4, Ar); 13C NMR/(CDCl3, 100 MHz)/ı
ppm: 148.95, 143.59, 131.83, 130.92, 130.15, 129.61, 129.06,
128.67, 127.96, 127.88, 126.94, 124.45, 123.49, 118.12, 118.02,
34.65; UV (CH2Cl2)/ꢁmax (nm): 246, 230.
14-(2-Nitrophenyl)14H-dibenzo[a,j]xanthenes (3d): yellow
solid, m.p. = 213–214 ◦C, (m.p. = 214–215 ◦C) [36]; IR (KBr)/ꢀ
(cm−1): 3057, 1625, 1591, 1500, 1395, 1346, 1305, 817, 751; 1H
NMR (CDCl3, 400 MHz)/ı ppm: 7.08 (t, 1H, J = 8.0, CH), 7.23–7.27
(t, 1H, J = 7.2, Ar), 7.42–7.46 (t, 2H, J = 7.2, Ar), 7.42–7.49 (m, 3H,
Ar), 7.57–7.63 (m, 3H, Ar), 7.81–7.84 (m, 4H, Ar), 8.53–8.55 (d,
2H, J = 8.4, Ar); 13C NMR/(CDCl3, 100 MHz)/ı ppm: 149.4, 147.03,
140.87, 134.14, 132.26, 131.72, 130.97, 129.47, 128.73, 127.59,
127.41, 124.92, 124.67, 122.58, 118.03, 117.58; UV (CH2Cl2)/ꢁmax
(nm): 244, 230.
All commercially available reagents were used without further
purification and purchased from the Merck Chemical Company in
high purity. The used solvents were purified by standard procedure.
2.2. Apparatus
IR spectra were obtained as KBr pellets on a Perkin-Elmer 781
spectrophotometer and on an impact 400 Nicolet FT-IR spectropho-
tometer. 1H NMR and 13C NMR were recorded in CDCl3 solvents on
a Bruker DRX-400 spectrometer with tetramethylsilane as inter-
nal reference. UV–vis spectra were obtained with a Perkin-Elmer
550 was recorded in CDCl3 solvents. XRF analysis was recorded
on X-ray fluorescence, Bruker, S4. Nanostructures were character-
ized using a Holland Philips Xpert X-ray powder diffraction (XRD)
diffractometer (Cu K␣, radiation, k = 0.154056 nm), at a scanning
speed of 2◦/min from 10◦ to 100◦ (2Ø). Thermo gravimetric anal-
yses (TGA) were conducted on a Rheometric Scientific Inc. 1998
thermal analysis apparatus under a N2 atmosphere at a heating rate
of 10 ◦C/min. Scanning electron microscope (SEM) of diatomite was
performed on a FESEM Hitachi S4160. The Bandelin ultrasonic HD
3200 with probe model KE 76, 6 mm diameter, was used to produce
ultrasonic irradiation and homogenizing the reaction mixture. The
N2 adsorption/desorption analysis (BET) was performed by using an
automated gas adsorption analyzer (Tristar 3020, V1.03). Melting
points obtained with a Yanagimoto micro melting point appara-
tus are uncorrected. The purity determination of the substrates
and reaction monitoring were accomplished by TLC on silica-gel
polygram SILG/UV 254 plates (from Merck Company).
2.3. Preparation of diatomite-SO3H
14-(3-Nitrophenyl)14H-dibenzo[a,j]xanthenes (3e): yellow
solid, m.p. = 212–213 ◦C, (m.p. = 210–211 ◦C) [36]; IR (KBr)/ꢀ
(cm−1): 3075, 1592, 1527, 1500, 1397, 1346, 1252, 1080, 958,
812, 748; 1H NMR (CDCl3, 400 MHz)/ı ppm: 6.62 (s, 1H, CH),
7.28–7.32 (t, 1H, J = 7.6, Ar), 7.43–7.47 (t, 2H, J = 7.6, Ar), 7.51–7.53
(d, 2H, J = 8.8, Ar), 7.60–7.64 (t, 2H, J = 7.2, Ar), 7.81–7.87 (m, 6H,
Ar), 8.30–8.32 (d, 2H, J = 8.4, Ar), 8.42 (s, 1H, Ar); 13C NMR/(CDCl3,
100 MHz)/ı ppm: 148.77, 148.21, 146.94, 134.27, 131.04, 129.58,
129.49, 129.07, 127.25, 124.58, 122.71, 122.04, 121.69, 118.13,
115.87, 37.71; UV (CH2Cl2)/ꢁmax (nm): 246, 228.
14-(4-Nitrophenyl)14H-dibenzo[a,j]xanthenes (3f): pale yel-
low solid, m.p. = 308–309 ◦C, (m.p. = 310–311 ◦C) [36]; IR (KBr)/ꢀ
(cm−1): 3068, 1593, 1516, 1341, 1245, 824, 745; 1H NMR (CDCl3,
400 MHz)/ı ppm: 6.61 (s, 1H, CH), 7.43–7.47 (t, 2H, Ar), 7.50–7.53
(d, 2H, Ar), 7.59–7.63 (t, 2H, Ar), 7.68–7.70 (d, 2H, Ar), 7.84–7.89 (t,
4H, Ar), 8.00–8.02 (d, 2H, Ar), 8.28–8.31 (d, 2H, Ar); 13C NMR/(CDCl3,
100 MHz)/ı ppm: 152.01, 148.77, 146.29, 131.06, 129.6, 129.07,
128.97, 127.19, 124.60, 123.87, 122.04, 118.07, 115.76, 37.87; UV
(CH2Cl2)/ꢁmax (nm): 248, 228.
14-(4-Chloro-3-nitrophenyl)14H-dibenzo[a,j]xanthenes (3g):
yellow solid, m.p. = 232–234 ◦C, (m.p. = 232–234 ◦C) [37]; IR (KBr)/ꢀ
(cm−1): 3055, 1623, 1592, 1530, 1463, 1351, 1246, 952, 811, 742;
1H NMR (CDCl3, 400 MHz)/ı ppm: 7.27 (s, 1H, CH), 7.29–7.31
(d, 1H, J = 8.4, Ar), 7.45–7.52 (m, 4H, Ar), 7.62–7.65 (m, 3H, Ar),
7.84–7.89 (t, 4H, J = 9.2, Ar), 8.02–8.04 (d, 1H, J = 2.0, Ar), 8.24–8.26
(d, 2H, J = 8.4, Ar); UV (CH2Cl2)/ꢁmax (nm): 246, 232.
14-(2,4-Dichlorophenyl)14H-dibenzo[a.j]xanthenes (3h): pale
yellow solid, m.p. = 229–230 ◦C, (m.p. = 227–228 ◦C) [36]; IR (KBr)/ꢀ
(cm−1): 3060, 1622, 1590, 1514, 1464, 1430, 1401, 1247, 1103,
1072, 960, 864, 836, 807, 743; 1H NMR (CDCl3, 400 MHz)/ı ppm:
In a typical experiment, diatomite was activated in vacuum at
100 ◦C and then after cooling to room temperature, diatomite (2 g)
was dispersed in dry CH2Cl2 at room temperature under contin-
uous stirring. After 2 h, 1 ml chlorosulfonic acid was added to the
mixture of dispersion and stirred overnight. Then the solution was
filtered under reduced pressure and the obtained materials thor-
oughly washed with dry CH2Cl2 then dried at 120 ◦C for 12 h. In
this step, the modified diatomite-SO3H was obtained as a solid acid
catalyst in the organic synthesis.
2.4. A typical procedure for the synthesis of
14-aryl-14-H-dibenzo[a,j]xanthenes
A mixture of aldehyde (1 mmol), ␤-naphthol (2 mmol, 0.288 g)
and diatomite-SO3H (0.05 g) was heated at 90 ◦C under solvent
free conditions at 110 ◦C for the appropriate time according to
Table 3. The progress of the reactions was monitored by TLC (ethyl
acetate/petroleum ether 3/7). After completion of the reaction,
the mixture was cooled to room temperature and 10 ml CH2Cl2
was added. The catalyst was filtered off by simple filteration. The
obtained liquid was heated by evaporation on a rotary evaporator.
The obtained product was purified by recrystallization from ethanol
to afford the pure products. All of the pure products were charac-
terized by comparison of their physical and spectral data with those
of authentic samples [36,32,37,38].
14-(Phenyl)14H-dibenzo[a,j]xanthenes (3a): pale yellow solid,
m.p. = 183–184 ◦C, (m.p. = 182–183 ◦C) [36]; IR (KBr)/ꢀ (cm−1):
3061, 1624, 1592, 1513, 1459, 1410, 1248, 1078, 962, 805, 744; 1
H

134
H. Naeimi, Z.S. Nazifi / Applied Catalysis A: General 477 (2014) 132–140
6.77 (s, 1H, CH), 6.90–6.92 (d, 1H, Ar), 7.28–7.33 (m, 2H, Ar),
7.43–7.50 (m, 4H, Ar), 7.61–7.65 (t, 2H, J = 7.6, Ar), 7.81–7.85 (t,
4H, J = 9.0, Ar), 8.65–8.67 (d, 2H, J = 8.0, Ar); 13C NMR/(CDCl3,
100 MHz)/ı ppm: 148.9, 142.25, 132.8, 132.71, 132.6, 130.92,
130.59, 129. 4, 128.78, 128.41, 127.06, 124.57, 123.17, 118.11,
117.46, 34.24; UV (CH2Cl2)/ꢁmax (nm): 248, 230.
14-(2,3-Dichlorophenyl)14H-dibenzo[a.j]xanthenes (3i): white
solid, m.p. = 251–253 ◦C, (m.p. = 250–253 ◦C) [37]; IR (KBr)/ꢀ
(cm−1): 3057, 1625, 1593, 1515, 1459, 1405, 1401, 1252, 1107,
1070, 962, 869, 813, 807, 746; 1H NMR (CDCl3, 400 MHz)/ı ppm:
6.85 (s, 1H, CH), 6.87–6.89 (d, 1H, J = 8.0, Ar); 7.09–7.11 (d, 2H, J = 8.8,
Ar), 7.32–7.34 (d, 1H, J = 9.2, Ar), 7.44–7.51 (m, 4H, Ar), 7.62–7.85 (t,
4H, J = 9.2, Ar), 8.69–8.67 (d, 2H, J = 8.4, Ar); UV (CH2Cl2)/ꢁmax (nm):
248, 231.
14-(3-Hydroxyphenyl)14H-dibenzo[a,j]xanthenes (3j): Pale
Pink solid, m.p. = 172–173 ◦C, (m.p. = 174–176 ◦C) [38]; IR (KBr)/ꢀ
(cm−1): 3068, 1593, 1513, 1402, 1251, 1242, 810; 1H NMR (CDCl3,
400 MHz)/ı ppm: 3.58 (s, 3H), 6.42 (s, 1H), 6.47 (d, 1H, J = 8.2 Hz),
7.05 (t, 2H, J = 8.4 Hz), 7.13 (d, 1H, J = 7.5 Hz), 7.39 (t, 2H, J = 7.2 Hz),
7.43 (d, 2H, J = 9.0 Hz), 7.53 (t, 2H, J = 7.6 Hz), 7.72–7.82 (m, 4H),
8.36 (d, 2H, J = 8.7 Hz).
Si
Si
O
OH
OH
O
OH
Si
Si
Si
O
O
O
O
O
Si
Si
OH
OH
O
OSO3H
OSO3H
O
Si
Si
ClSO3H
O
O
Si OH
Si OH
dry CH2Cl2
O
O
Si OH
Si
O
O
O
Si
O
O
OH
Si
Si
O
O
OH
Si
O
Si
O
OH
Si
Si
Diatomite-SO3H
Diatomite
Scheme 1. Preparation of diatomite-SO3H.
The functional groups attached to diatomite are quantitatively
determined by back acid–base titration ( SO3H) in diatomite-SO3H
0.2 mmol H+ sites per 0.02 g of diatomite-SO3H (values calculated
by the weight of diatomite-SO3H) at 25 ◦C. Also, the pH of resulted
diatomite-SO3H (10%, w/v) was determined using pH meter. At first
0.5 g diatomite-SO3H was dispersed in 5 ml H2O by ultrasonic bath
for 60 min then measured and approximately about 0.48.
14-(4-Hydroxyphenyl)14H-dibenzo[a,j]xanthenes (3k): Pink
solid, m.p. = 137–138 ◦C, (m.p. = 138–140 ◦C) [38]; IR (KBr)/ꢀ
(cm−1): 3405, 1592, 1511, 1402, 1250, 1242, 815; 1H NMR (CDCl3,
400 MHz)/ı ppm:4.97 (br s, 1H, OH), 6.43(s, 1H, CH), 6.55–8.36 (m,
16H, Ar); 13C NMR/(CDCl3, 100 MHz)/ı ppm: 37.41, 115.70, 118.00,
118.40, 123.10, 124.62, 127.23, 129.11, 129.20, 129.78, 131.53,
131.81, 137.90, 149.11, 154.24.
The XRF of Bardscan diatomite and diatomite-SO3H were pro-
vided and the results are indicated below: The parent material,
had the following chemical composition (in mass%): SiO2 (66.39),
Al2O3 (11.30), Fe2O3 (4.30), CaO (3.42), MgO (1.62), BaO (3.06), SO3
(3.02), K2O (1.11), Na2O (0.905), TiO2 (0.431), P2O5 (0.230), SrO
(0.222), MnO (0.085), Cl (0.03), ZrO2 (0.025), Cr2O3 (0.018), CuO
(0.017), Rb2O (0.005) and diatomite-SO3H had the following chem-
ical composition (in mass%): SiO2 (51.54), SO3 (11.90), Al2O3 (8.77),
BaO (3.88), Fe2O3 (3.59), CaO (2.94), MgO (1.14), K2O (0.982), Na2O
(0.849), TiO2 (0.371), SrO (0.194), Cl (0.120), P2O5 (0.086), MnO
(0.074), Cr2O3 (0.024), ZrO2 (0.019), CuO (0.018), and Rb2O (0.005).
Scanning electron micrographs were recorded to understand
morphological changes occurring on the catalyst. The SEM image
of diatomite-SO3H before and after ClSO3H treatment is shown in
Fig. 1. The morphology, as observed by SEM images, shows signifi-
cant difference between diatomite and diatomite-SO3H. Diatomite
had lamellar aggregates of irregular plate-like shapes which are
very smooth with fluffy appearance. After sulfonation of the
diatomite, the aggregates were foliated with rougher surfaces. On
the other hand, it is observed that some impurities have been
deposited on the diatomite particles.
14-(3-Methoxy)14H-dibenzo[a,j]xanthenes (3l): Pale pink
solid, m.p. = 173–174 ◦C, (m.p. = 174–176 ◦C) [36]; IR (KBr)/ꢀ
(cm−1): 3067, 3014, 2934, 1582, 1454, 1431, 1401, 1247, 1050,
964, 806, 743; 1H NMR (CDCl3, 400 MHz)/ı ppm:3.63 (s, 3H, OCH3),
6.45 (s, 1H, CH), 6.51 (dd, 2H, J = 7.5 Hz, ArH), 7.02–7.46 (m, 6H,
ArH), 7.55 (t, 2H, J = 7.5 Hz, ArH), 7.78 (t, 4H, J = 7.5 Hz, ArH), 8.39
(d, 2H, J = 7.5 Hz, ArH) ppm.
14-(4-Methoxy)14H-dibenzo[a,j]xanthenes (3 m): pink solid,
m.p. = 204–205 ◦C, (m.p. = 202–203 ◦C) [39], IR (KBr)/ꢀ (cm−1):
3062, 1594, 1510, 1458, 1398, 1248, 960, 814, 744; 1H NMR (CDCl3,
400 MHz)/ı ppm: 6.45 (s, 1H, CH), 6.67–6.69 (d, 2H, J = 8.4, Ar),
7.40–7.44 (m, 4H, Ar), 7.47–7.49 (d, 2H, J = 8.8, Ar), 7.56–7.60 (t,
2H, J = 7.2, Ar), 7.78–7.80 (d, 2H, J = 8.8, Ar), 7.82–8.84 (d, 2H, J = 8.0,
Ar), 8.38–8.40 (d, 2H, J = 8.4, Ar); 13C NMR/(CDCl3, 100)/ı ppm:
37.14, 55.06, 113.87, 117.55, 118.04, 122.73, 123.60, 124.25, 126.40,
126.79, 128.77, 128.84, 129.20, 131.11, 131.45, 137.42, 148.68,
157.86; UV (CH2Cl2)/ꢁmax (nm): 246, 230.
14-(4-Methyl)14H-dibenzo[a,j]xanthenes (3n): pale yellow
solid, m.p. = 228–230 ◦C, (m.p. = 227–228 ◦C) [36], IR (KBr)/ꢀ
(cm−1): 3069, 1623, 1591, 1531, 1458, 1399, 1244, 961, 810, 741;
1H NMR (CDCl3, 400 MHz)/ı ppm: 6.46 (s, 1H, CH), 6.95–6.97 (d,
2H, J = 8.0, Ar), 7.39–7.43 (m, 4H, Ar), 7.47–7.50 (d, 2H, J = 9.2, Ar),
7.56–7.60 (t, 2H, J = 9.2, Ar), 7.78–7.80 (d, 2H, J = 8.8, Ar), 7.82–8.84
(d, 2H, J = 8.0, Ar), 8.39–8.41 (d, 2H, J = 8.8, Ar); 13C NMR/(CDCl3,
100)/ı ppm: 20.91, 37.64, 117.46, 118.02, 122.72, 124.22, 126.77,
128.11, 128.77, 128.79, 129.19, 131.08, 131.46, 135.91, 142.14,
148.68; UV (CH2Cl2)/ꢁmax (nm): 247, 232.
The surface area (BET), pore volume and pore size of diatomite
and diatomite-SO3H were provided. The corresponding results are
shown in Table 1.
The pore size distribution, as calculated by the BJH method from
the desorption branch of the nitrogen isotherm, reveals that the
prepared samples contain pore size between 2 and 120 nm (Fig. 2).
Table 1
Surface area, pore volume and pore size of diatomite and diatomite-SO3H.
3. Results and discussion
Name
Surface areaa
(m2/g)
Total pore
Volume
(cm3/g)
Pore size
(nm)b
3.1. Characterization of diatomite-SO3H
Diatomite
Diatomite-SO3H
73.36
74.03
0.141
0.158
6.87
7.6
Diatomite is a type of widespread natural nanoporous material
which provides a suitable support. A new heterogeneous catalyst
has been prepared from the reaction of diatomite and chlorosul-
fonic acid (Scheme 1).
a
The BET (Brunauer–Emmet–Teller) surface area.
b
The average pore diameter was obtained by using the BJH (Barrett, Joyner and
Halenda) model.

H. Naeimi, Z.S. Nazifi / Applied Catalysis A: General 477 (2014) 132–140
135
Fig. 3. Nitrogen adsorption–desorption isotherms of diatomite and diatomite-
SO3H.
loss that was attributable to the loss of adsorbed solvent or trapped
water from the catalyst. A weight loss of approximately 10% weight
occurred between 150 and 500 ◦C that was likely a consequence of
the loss of SO3H groups.
The characterization of diatomite-SO3H was performed by
Fourier transform spectroscopy (FT-IR). As shown in Fig. 5, the
high symmetry presented on diatomite, very weak infrared sig-
nals, due to the weak difference of charge state and very small
induced electric dipole. After functionalization of diatomite, new
bands are clearly seen. The presence of the sulfonic acid group is
also demonstrated by the bands at 1071, 1175 and 579 cm−1, which
correspond to the symmetric, asymmetric SO2 and C S stretching
modes, respectively (Fig. 5).
XRD measurement was used to identify the crystalline structure
of the products. As can be shown, the XRD patterns of diatomite
and diatomite-SO3H samples are plotted in Fig. 6 can match well
with the characteristic peaks, which indicate that the structure
of diatomite can be remained after the surface modification with
chlorosulfonic acid. The XRD patterns of the particles show char-
acteristic peaks at (2ꢂ = 20.0768, 22.17, 23.00, 23.82, 26.11, 26.80,
27.94, 29.01, 31.77, 33.03, 39.67, 41.07, 43.17, 49.38, 55.14, 60.43,
62.21, 65.86, 68.02, 68.02, 73.11, 75.56). The average crystallite size
was calculated equal to 40.3 nm using Debye–Scherrer equation,
D = kꢁ/ˇ cos ꢂ where k is a constant (generally considered as 0.94),
Fig. 1. SEM images of (a) diatomite (b) diatomite-SO3H.
As shown in Fig. 3, the nitrogen adsorption/desorption isotherm
of diatomite and diatomite-SO3H was characterized as a type II
isotherm with an H3 hysteresis loop, according to the IUPAC clas-
sification [40,41]. The hysteresis is associated with the filling and
emptying of the mesopores by capillary condensation. Sulfonation
of diatomite did not evidently change the shape of the isotherms
of the samples (Fig. 3).
A thermo gravimetric analysis (TGA) was used to study the ther-
mal stability of the acid catalyst (Fig. 4). The TGA curve was divided
into several regions corresponding to different mass lose ranges.
The first region, which occurred below 150 ◦C, displayed a mass
˚
ꢁ is the wavelength of Cu K␣ (1.54 A), ˇ is the corrected diffraction
line full-width at half-maximum (FWHM), and ꢂ is Bragg’s angle
[35].
Fig. 2. Pore size distributions of diatomite and diatomite-SO3H.
Fig. 4. TGA curves of (a) diatomite and (b) diatomite-SO3H.

136
H. Naeimi, Z.S. Nazifi / Applied Catalysis A: General 477 (2014) 132–140
Fig. 5. FT-IR spectra of (a) diatomite and (b) diatomite-SO3H.
3.2. Application of diatomite-SO3H as heterogeneous catalyst in
the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes
the general experimental procedure. The corresponding products
are summarized in Table 3. The yields of most xanthene products
are higher than 90%. Thus, benzaldehydes bearing 4-substituents
(entries 3 and 8) slightly afford the better product yields. This slight
difference is also seen in 2-substituted benzaldehydes (entries 2, 4,
5 and 6). In this study, 14-aryl-14-H-dibenzo[a,j]xanthenes as prod-
ucts in a new method were prepared using the model reaction of
␤-naphthole and various aromatic aldehyhes in the presence of cat-
alytic amount of diatomite-SO3H (0.05 g) at 90 ◦C under solvent free
conditions. After the separation of the product, the catalyst as a by-
product is removable by washing with CH2Cl2, and easily recycled
to catalyze the preparation of 14-aryl-14-H-dibenzo[a,j]xanthenes
with excellent yields.
Initially, in order to optimization of the reaction con-
ditions, we are considered the reaction of ␤-naphthol and
4-chlorobezaldehyde in a 2:1 ratio as a model substrate in the
presence of various catalytic amounts of diatomite-SO3H under sol-
vent free conditions at 90 ◦C as a heterogeneous catalyst (Table 2).
The obtained results from the reaction to determine the optimum
amount of catalyst are presented in Table 2. In this reaction, the
best results were obtained using 0.05 g of catalyst (as can be seen
from Table 2, entry 6). While a higher amount of catalyst did not
affect on desired product yield (Table 2, entry 7).
After optimization of the reaction conditions, the reaction of
␤-naphthol with several aldehydes was carried out according to
To show the merit of the present work in comparison with
reported results in the literature, we compared the results of
ditomite-SO3H catalyst with reported catalysts in the synthesis
of 14-aryl-14-H-dibenzo[a,j]xanthenes from the reaction of ␤-
naphthol and various aromatic aldehydes (Table 4). As can be seen
in this table, the present catalyst was found to be the most efficient
catalyst among all of the tested catalysts in this reaction. Though
each of the above mentioned methods has demonstrated its own
merits, several of these methods suffer from one or more draw-
backs such as; long reaction times (Table 4, entries 2–11), use of
hazardous catalyst, harsh reaction conditions, excess of catalysts
and low yields (Table 4, entries 6, 8, and 11). While, the reaction
in the presence of ditomite-SO3H was indicated a lot of significant
such as; low reaction times, excellent product yields, simplicity of
the reaction, naturally safe, economical, eco-friendly and recyclable
biomimetic catalyst. These advantages can be related to the highly
activity due to its nanoporosity and high surface area.
For reusability of the catalyst, after the separation of solid prod-
ucts (3f) with CH2Cl2 completely, diatomite-SO3H catalyst was
recycled for several times without any decrease in catalytic activity,
the yields ranged from 97% to 92% (Fig. 7).
The structure of products were confirmed by spectroscopic
and physical data such as; IR, 1H NMR, 13C NMR and UV–vis.
The infrared spectra of the 14-(4-chlorophenyl)14H-dibenzo
[a,j]xanthene exhibit a band at 1243 cm−1 assigned to ꢀ (C O). In
the 1H NMR spectra the signal around ı = 7.10–8.34 ppm is assigned
to the protons of the aromatic rings ꢀ (CH CH), the signal of the
aliphatic rings ꢀ (CH) is showed at 6.48 ppm and the 13C NMR
Fig. 6. XRD patterns of (a) diatomite and (b) diatomite-SO3H.

H. Naeimi, Z.S. Nazifi / Applied Catalysis A: General 477 (2014) 132–140
137
Table 2
The synthesis of 14-(4-chlorophenyl)14H-dibenzo[a,j] xanthenes under different amounts of catalyst.
Entry
Diatomite-SO3H (g)
Time (min)
Yielda (%)
1
2
3
4
5
6
7
–
180
30
30
30
30
7
0
20
50
75
95
95
95
0.02
0.03
0.04
0.05
0.05
0.06
30
a
Isolated yields.
spectrum the signal around ı = 117.50–148.51 ppm is assigned to
the carbons of the aromatic rings (CH CH) and the signal of the
aliphatic rings ꢀ (CH) is shown at 39.87 ppm.
3.3. The proposed reaction mechanism
The formation of 14-aryl-14-H-dibenzo[a,j]xanthenes from ␤-
naphthol and aromatic aldehyde in the presence of ditomite-SO3H
as catalyst can be explained by a tentative mechanism is presented
in Scheme 2. One molecule of ␤-naphthol was firstly condensed
with an activated aromatic aldehyde (I) to provide intermediate
(II), which can be regarded as a fast Knoevenagel addition. Then
the active methylene of the second molecule of ␤-naphthol reacted
with intermediate (II) via conjugate Michael addition to produce
the intermediate (III), which undergoes intramolecular cyclodehy-
dration to give the 14-aryl-14-H-dibenzo[a,j]xanthenes (V).
Fig. 7. Reusability of diatomite-SO3H.
Scheme 2. Proposed reaction mechanism.

138
H. Naeimi, Z.S. Nazifi / Applied Catalysis A: General 477 (2014) 132–140
Table 3
Synthesis of 14-aryl-14-H-dibenzo[a,j]xanthenes in the presence of diatomite-SO3H under solvent free conditions at 90 ◦C.
Entry
Aldehyde
Product
Time (min)
Yielda
TONb
46.5
TOFc (h−1
)
M.p. (◦C)
183–184
M.p. (◦C)
182–183
1
10
93
279.1
2
12
88
44.0
220.0
212–213
214–215
3
7
95
47.5
407.2
289–290
287–288
4
10
91
45.5
273.1
229–230
227–228
5
8
92
46.0
345.1
251–253
250–253
6
8
90
45.0
337.6
213–214
214–215
7
3
96
48.0
960.0
212–213
210–211

H. Naeimi, Z.S. Nazifi / Applied Catalysis A: General 477 (2014) 132–140
139
Table 3 (Continued)
Entry Aldehyde
Product
Time (min)
Yielda
TONb
48.5
TOFc (h−1
)
M.p. (◦C)
308–309
M.p. (◦C)
310–311
8
2
97
1455.2
9
10
11
3
20
15
96
92
82
48.0
46.0
41.0
960.0
138.0
164.0
232–234
240–241
138–140
232–234
242–243
139–140
12
5
89
44.5
534.0
197–199
198
13
10
85
42.5
318.8
172–173
174–176
14
17
85
42.5
150.0
228–230
227–228

140
H. Naeimi, Z.S. Nazifi / Applied Catalysis A: General 477 (2014) 132–140
Table 3 (Continued)
Entry
Aldehyde
Product
Time (min)
Yielda
TONb
42.0
TOFc (h−1
)
M.p. (◦C)
203–205
M.p. (◦C)
202–203
15
13
84
193.9
a
Isolated yields.
b
c
Turnover number represents the average number of substrate molecules converted into the product per molecule of catalyst.
Turnover number per hour (TOF).
Table 4
The synthesis of 14-(4-nitrophenyl)14H-dibenzo[a,j]xanthene using different catalysts.
Entry
Catalyst
Time
Yielda (%)
Temperature (◦C)
Reference
1
2
3
4
5
6
7
8
9
Diatomite-SO3H
Cellulose sulfuric acid
PFPAT
SBA-15-SO3H
SiO2-Pr-SO3H
TCCA
H2SO4/SiO2
Dowex-50 W
Yb(OTf)3
H5PW10V2O40
Iodine
2 min
120 min
180 min
24 h
40 min
50 min
60 min
2 h
97
90
96
91
98
74
97
84
91
92
85
90
110
r.t.
–
[29]
[30]
[31]
[32]
[33]
[34]
[22]
[42]
[13]
[43]
85
125
110
125
100
110
100
90
3 h
1 h
2.5 h
10
11
a
Isolated yields.
4. Conclusions
[14] R.M. Ion, D. Frackowiak, A. Planner, K. Wiktorowicz, Acta Biochim. Pol. 45 (1998)
833–845.
[15] A. Banerjee, A.K. Mukherjee, Stain Technol. 56 (1981) 83–85.
[16] M. Ahmad, T.A. King, D. Ko, B.H. Cha, J. Lee, J. Phys. D: Appl. Phys. 35 (2002)
1473–1476.
[17] C.G. Knight, T. Stephens, Biochem. J. 258 (1989) 683–689.
[18] A.R. Khosropour, M.M. Khodaei, H. Moghannian, Synlett (2005) 955–958.
[19] B. Das, B. Ravikanth, R. Ramu, K. Laxminarayana, B. Vittal Rao, J. Mol. Catal. A:
Chem. 255 (2006) 74–77.
In summary, a heterogeneous diatomite-SO3H was prepared
and characterized by XRF, BET, SEM, TGA, XRD and IR spectroscopy.
In this research, we have been described the synthesis of 14-aryl-
14-H-dibenzo[a,j]xanthenes via condensation of ␤-naphthol with
different kinds of aromatic aldehydes. The application of diatomite-
SO3H as a highly efficient, inexpensive, easy work-up, and reusable
natural catalyst makes the present procedure eco-friendly and
economically acceptable. In addition, low-cost, solvent free, non-
toxicity, high yields of the desired products and short reaction times
is supporting the method toward the green chemistry.
[20] L. Nagarapu, S. Kantevari, V.C. Mahankhali, Catal. Commun.
1173–1177.
8 (2007)
[21] A. Saini, S. Kumar, J.S. Sandhu, Synlett (2006) 1928–1932.
[22] S. Ko, C.F. Yao, Tetrahedron Lett. 47 (2006) 8827–8829.
[23] Y.Y. Myint, M.A. Pasha, Synth. Commun. 34 (2004) 4477–4482.
[24] S.B. Patil, R.P. Bhat, S.D. Samant, Synth. Commun. 36 (2006) 2163–2168.
[25] L. De Luca, G. Giacomelli, A. Porcheddu, J. Org. Chem. 67 (2002) 6272–6274.
[26] A. Porcheddu, G. Giacomelli, M. Salaris, J. Org. Chem. 70 (2005) 2163–2361.
[27] H.R. Shaterian, M. Ghashang, A. Hassankhani, Dyes Pigment 76 (2008)
564–568.
Acknowledgement
[28] B. Rajitha, B. Sunil Kumar, Y. Thirupathi Reddy, P. Narsimha Reddy, N. Sreeni-
vasulu, Tetrahedron Lett. 46 (2005) 8691–8693.
The authors are grateful to University of Kashan for supporting
this work by Grant No. 159148/30.
[29] J. Venu Madhava, Y. Thirupathi Reddy, P. Narsimha Reddy, M. Nikhil Reddy, S.
Kuarma, P.A. Crooksb, B. Rajitha, J. Mol. Catal. A: Chem. 304 (2009) 85–87.
[30] S. Khaksar, N. Behzadi, Chinese J. Catal. 33 (2012) 982–985.
[31] M.A. Naik, D. Sachdev, A. Dubey, Catal. Commun. 11 (2010) 1148–1153.
[32] G. Mohammadi Ziarani, A.R. Badiei, M. Azizi, Sci. Iran. C 18 (2011) 453–457.
[33] B. Maleki, M. Gholizadeh, Z. Sepehr, Bull. Korean Chem. Soc. 32 (5) (2011)
1697–1702.
References
[1] F.Y. Wang, H.F. Zhang, Chinese J. Geochem. 14 (1995) 140–152.
[2] P. Yuana, D.Q. Wua, H.P. Hea, Z.Y. Linb, Appl. Surf. Sci. 227 (2004) 30–39.
[3] B. Bahramian, F. Doulati Ardejanib, V. Mirkhanic, K. Badiid, Appl. Catal. A: Gen.
345 (2008) 97–103.
[34] G.B. Dharma Rao, M.P. Kaushik, A.K. Halve, Tetrahedron Lett. 53 (2012)
2741–2744.
[35] R. Massart, IEEE Trans. Magn. 17 (1981) 1247–1248.
[36] R. Kumar, G.C. Nandi, R.K. Verma, M.S. Singh, Tetrahedron Lett. 51 (2010)
442–445.
[37] H. Naeimi, Z.S. Nazifi, J. Chinese Chem. Soc. 60 (2013) 1113–1117.
[38] S. Puri1, B. Kaur, A. Parmar, H. Kumar, Heterocyclic Lett. 1 (2011) 269–274.
[39] R. Fareghi-Alamdari, M. Golestanzadeh, F. Agend, N. Zekri, C. R. Chim. 16 (2013)
878–887.
[40] F. Meshkani, M. Rezaei, Powder Technol. 199 (2010) 144–148.
[41] G. Leofanti, M. Padovanb, G. Tozzolac, B. Venturelli, Catal. Today 41 (1998)
207–219.
[42] W. Su, D. Yang, C. Jin, B. Zhang, Tetrahedron Lett. 49 (2008) 3391–3394.
[43] G.H. Mahdavinia, S. Rostamizadeh, A.M. Amani, Z. Emdadi, Ultrason. Sonochem.
16 (2009) 7–10.
[4] J.F. Lemonas, Am. Ceram. Soc. Bull. 6 (1997) 92–95.
[5] O. San, R. Goren, C. Ozgur, Int. J. Miner. Process. 93 (2009) 6–10.
[6] S. Aytas, S. Akyil, M.A.A. Aslani, U. Aytekin, J. Radioanal. Nucl. Chem. 240 (1999)
973–996.
[7] P.B. Michell, K. Atkinson, Miner. Eng. 4 (1991) 1091–1113.
[8] P. Yuana, D.Q. Wua, H.P. Hea, Z.Y. Lin, Appl. Surf. Sci. 227 (2004) 30–39.
[9] H. Hadjar, B. Hamdi, M. Jaber, J. Brendlé, Z. Kessaissia, H. Balard, J.B. Donnet,
Microporous Mesoporous Mater. 107 (2008) 219–226.
[10] X. Li, C. Bian, W. Chen, J. He, Appl. Surf. Sci. 207 (2003) 378–383.
[11] A.N. Dadhania, V.K. Patel, D.K. Raval, C. R. Chim. 15 (2012) 378–383.
[12] J.P. Poupelin, G. Saint-Ruf, O. Foussard-Blanpin, G. Narcisse, G. Uchida-Ernouf,
R. Lacroix, Eur. J. Med. Chem. 13 (1978) 67–71.
[13] R. Tayebee, S. Tizabi, Chinese J. Catal. 33 (2012) 962–969.