M.K. Alavijeh, M.M. Amini, B. Notash et al.
Journal of Molecular Structure 1232 (2021) 130045
̅
terized. H BTC-SO acted as a structure-directing building block in
167.4 (C = O), 140.9, 134.0, 132.7, 130.0 (Ar). IR bands (KBr) ῡ
3
3
−1
the synthesized potassium CP. The catalytic activities of the H BTC-
(cm ) 523, 630, 651, 700, 758, 845, 907, 1019, 1081, 1188, 1245,
1306, 1414, 1608, 1726, 3032, 3083, 3288, 3510, and 3595.
3
SO .H O, as a novel, simple organocatalyst, and the rarely explored
3
3
potassium CPs were studied in the CO2 cycloaddition reaction.
For the preparation of (H3BTC-SO3).H3Oꢀ2H2O (BTC = 1,3,5-
benzenetricarboxylate) (2), 250 mg of 1 was dissolved in 20 mL
of deionized water and pass through a column (20 × 1 cm) con-
taining Dowex-50W-X8, a strongly acidic cation-exchange resin.
The column was eluted by deionized water, and the resulted so-
lution was collected and allowed to crystalize by slow evaporation
of water at room temperature. The titled compound was charac-
terized by FTIR, 1H-, and 13C NMR spectroscopies, and the struc-
ture of 2 was determined by single-crystal X-ray diffraction. Anal.
2. Experimental
2
.1. Materials and instrumentation
All chemicals and solvents were commercially available and
used without purification. Infrared spectra were recorded on a
Bomem MB-Series FTIR spectrometer. 1H and 13C NMR data were
Calcd. (Found) for C9H12O12S: C 31.40 (31.22); H 3.51 (3.65). 1
H
collected on a Bruker AVANCE 300 MHz spectrometer utilizing D O
2
NMR (300 MHz, D2O) δ (ppm): 8.10 (s, 2H, 2 (Ar−H)). 13C NMR
as solvent and tetramethylsilane as an internal standard. A STOE
diffractometer equipped with Cu Kα radiation (λ = 0.15418 nm)
was used to record powder X-ray diffraction (XRD) patterns. Ther-
mogravimetric analysis (TGA) was performed using a Bahr STA-503
(75.43 MHz, D2O): 171.3, 167.4 (C = O), 141.0, 133.8, 132.3, 130.1
−1
(Ar). IR bands (KBr) ῡ (cm ): 518, 625, 661, 701, 758, 860, 912,
1020, 1076, 1194, 1245, 1322, 1409, 1614, 1731, 3030, 3077, and
3430.
−1
instrument at a heating rate of 10 °C min under airflow. The CHN
elemental analysis was accomplished using a Perkin-Elmer 2400
CHN analyzer.
2
.1.1. X-ray crystallography
2.3. Cycloaddition reaction of CO2 with epoxide and catalyst
regeneration
The X-ray diffraction measurements were made on a STOE
IPDS-II diffractometer with graphite-monochromated Mo-Kα radi-
ation. Single-crystals of 1 and 2 were mounted on glass fiber and
used for data collection. Cell constants and an orientation matrix
for data collection were obtained by the least-square refinement
of 7248, 7588 reflections for 1 and 2, respectively. Both data were
collected at room temperature to a maximum 2θ value of 58.32
and 58.34° for 1 and 2, respectively. Diffraction data were collected
in a series of ω scans in 1° oscillation and integrated using the
Stoe X-AREA [47] software package. Numerical absorption correc-
tion was applied using X-RED [48] and X-SHAPE [49] software. The
data were corrected for Lorentz and polarizing effects. The struc-
tures were solved by direct methods [50] and subsequent differ-
ence Fourier maps and then refined on F2 by a full-matrix least-
squares procedure using anisotropic displacement parameters [51].
Atomic factors are from the International Tables for X-ray Crystal-
lography [52]. All refinements were performed using the X-STEP32
crystallographic software package [53]. In compound 2, all hydro-
gens attached to oxygens were found in a difference Fourier maps
and refined isotropically. Other hydrogen atoms were positioned
In a typical procedure, 4 mmol styrene oxide, 5 mol% TBAB
(tetrabutylammonium bromide) and 5 mol% catalyst were loaded
into a vial, which was filled with 1 atm of CO2. The reaction mix-
ture was stirred at 110 °C for 10 h, and after cooling, some chlo-
roform was added to the reaction vessel, and the catalyst was re-
moved by centrifugation. Purification of the crude product was per-
formed by column chromatography using ethyl acetate/n-hexane
(1:3, v:v) as an eluent to obtain the pure product. mp 49–51 °C
(lit. 50–51 °C) [54,55]. 1H NMR (300 MHz, CDCl3) δ (ppm): 4.40 (t,
1H, (–CH2)), 4.84 (t, 1H, (–CH2)), 5.70 (t, 1H, (–CH)), 7.37–7.49 (m,
5H, Ph). After each catalytic cycle, the catalyst was separated by
centrifugation from the reaction mixture, washed with chloroform,
and dried at 80 °C for the next catalytic run.
3. Results and discussion
˚
geometrically and refined as riding atoms with C—H = 0.93 A,
3.1. Synthesis of the compounds
Uiso(H) = 1.2Ueq(C). Crystal data and refinement for compounds
1
and 2 are summarized in Table S1, and selected bond length and
Bifunctional-substituted isomers of tricarboxylate monosul-
fate aromatic compounds have rarely been explored. Three
different structures of monosulfono-benzene-tricarboxylic acid
have been found in literature, as shown in Scheme 1. Metal
salts of 5-sulfono-benzene-1,3,5-tricarboxylic acid (5-sulfonyl-1,2,4-
benzenetricarboxylic acid or 1,2,4C-5S) are commercially available.
They have been used to synthesize different CPs and MOFs [56,57],
while the structures of the other two have been found in two
patents with no further information [58]. In this study 2-sulfono-
angles are given in Table S2 and Table S3 in the ESI†.
2
.2. Synthesis of [K(H BTC-SO )(H O) ]n (1) and
3
3
2
2
(
C H O S).H Oꢀ2H O ((H BTC-SO ).H Oꢀ2H O) (2)
9 5 9 3 2 3 3 3 2
For the synthesize of 1, 5 mL of mesitylene was poured into a
round bottom flask, then 4 mL of the oleum was added, and the
mixture was stirred for 5 min. The resulting white precipitate was
filtered and dried at ambient temperature. Subsequently, the sul-
fonated mesitylene (10.42 g, 0.056 mol) was dissolved in 250 mL
of deionized water in a 500 mL round bottom flask. The flask was
placed in the ice bath, and then KMnO4 (41.18 g, 0.26 mol) was
added stepwise in 3 h. Then, the reaction mixture was refluxed
benzene-1,3,5-tricarboxylic acid (1,3,5–2S or H BTC-SO .H O), were
3
3
3
successfully synthesized in two-step, as shown in Scheme 2. Sul-
fonation of mesitylene has been performed in the first step. It
should be mentioned that the synthesis of sulfonated mesitylene
has previously been reported by other methods [59,60], in the
presence of different catalysts at a higher temperature and longer
time with a lower yield. Sulfonated mesitylene in this work was
prepared in much higher yield using oleum at ambient tempera-
ture only in 5 min. In the next step, the methyl groups were suc-
cessfully oxidized, and after work up a potassium CP and the first
for 48 h and then filtered to remove the residual MnO . After the
2
addition of HCl to the filtrate, the solution allowed to crystallize
by slow evaporation. The resulting colorless crystals were collected
and characterized by FTIR, 1H-, and 13C NMR spectroscopies and
CHN analysis. The structure of the complex was determined by
single-crystal X-ray diffraction. Anal. Calcd. (Found) for C H KO11 S:
coordination polymer of the H BTC-SO3 has been formed. The pure
9
9
3
C 29.67 (29.09); H 2.49 (2.38). 1H NMR (300 MHz, D O) δ (ppm):
crystalline ligand (H BTC-SO ).H Oꢀ2H O (2) was obtained by the
ion-exchange technique.
2
3
3
3
2
13
8
.08 (s, 2H, 2 (Ar−H)). C NMR (75.43 MHz, D O): δ (ppm): 171.5,
2
2