R. Fazaeli et al. / Journal of Molecular Catalysis A: Chemical 374–375 (2013) 46–52
47
2.4. Selected spectroscopic data
O
S
2
EtOH
Dibutyl sulfoxide (2a): Mp 34–35 ◦C. 1H NMR (400 MHz, CDCl3,
␦): 0.97 (t, 6H, J = 7.4 Hz), 1.41–1.57 (m, 4H), 1.72–1.79 (m, 4H),
2.60–2.73 (m, 4H). 13C NMR (100 MHz, CDCl3, ␦): 13.64, 22.05,
24.56, 52.13.
Cat: 3mol%
Cat: V@MIL(101)
H2O2 (8 mol %), r.t.
S
Methyl phenyl sulfoxide (2b): Mp 30–31 ◦C. IR (max, KBr,
cm−1): 530, 690, 751, 957, 1037, 1431, 1647, 2922, 3004; 1H NMR
(400 MHz, CDCl3, ␦): 2.73 (s, 3H), 7.49–7.57 (m, 3H), 7.61–7.67 (m,
2H). 13C NMR (100 MHz, CDCl3, ␦): 43.95, 123.47, 129.33, 131.00,
145.72.
1
CH3CN
Cat: 4mol%
O
O
S
3
Scheme 1. Oxidation of sulfides (1) to sulfoxides (2) and sulfunes (3) in the presence
of V@MIL(101) as catalyst at room temperature.
Diphenyl sulfoxide (2c): Mp 72–73 ◦C. 1H NMR (400 MHz, CDCl3,
␦): 7.42–7.49 (m, 6H), 7.63–7.66 (m, 4H). 13C NMR (100 MHz, CDCl3,
␦): 124.77, 129.30, 131.03, 145.61.
were monitored by thin layer chromatography. The X-ray pow-
dered diffraction patterns were performed on a Bruker-D8 advance
Benzyl 4-bromobenzyl sulfoxide (2d): Mp 139–140 ◦C. IR (
,
max
KBr, cm−1): 1028; 1H NMR (500 MHz, CDCl3, ␦): 3.78(d, 1H,
J = 13.1 Hz), 3.89(d, 1H, J = 13.09 Hz), 3.95 (s, 2H), 7.2 (d, 2H,
J = 8.3 Hz), 7.32–7.33 (m, 2H), 7.40–7.44 (m, 3H), 7.54(d, 2H,
J = 8.3 Hz).
with automatic control. The patterns were run with mo◦nochro-
−1
˚
matic Cu K␣ (1.5406 A) radiation with a scan rate of 2 min
.
The BET specific surface areas and pore volumes of the catalysts
were determined by the adsorption/desorption of nitrogen at liquid
nitrogen temperature with a Micromeritics Bel sorp mini II instru-
ment. The pore sizes of the catalysts were obtained from the peak
positions of the distribution curves determined from the adsorption
branches of the isotherms.
4-Nitrobenzyl phenyl sulfoxide (2e): Mp 161–163 ◦C. IR (
,
max
KBr, cm−1): 1026, 1345, 1515; 1H NMR (200 MHz, CDCl3, ␦): 4.04
(d, 1H, J = 12.0 Hz), 4.24 (d, 1H, J = 12.0 Hz), 7.13 (d, 1H, J = 6.5 Hz),
7.40–7.51 (m, 5H), 8.12 (d, 2H, J = 6.5 Hz).
Methyl 2-(phenylsulfinyl)acetate (2j): Isolated as yellow oil. IR
(max, KBr, cm−1): 487, 691, 749, 1045, 1444, 1736, 2927; 1H NMR
(400 MHz, CDCl3, ␦): 3.72 (s, 3H), 3.68(d, 1H, J = 13.6 Hz), 3.86 (d,
1H, J = 13.6 Hz), 7.52–7.59 (m, 3H); 7.66–7.73 (m, 2H).
Dibutyl sulfone (3a): Mp 46–47 ◦C. 1H NMR (400 MHz, CDCl3,
␦): 0.97 (t, 6H, J = 7.4 Hz), 1.44–1.53 (m, 4H), 1.78–1.86 (m, 4H),
2.93–2.97 (m, 4H). 13C NMR (100 MHz, CDCl3, ␦): 13.53, 21.78,
23.93, 52.46.
2.1. Preparation of MIL-101(Cr)
The synthesis of the MIL-101(Cr) catalysts was adapted from the
literature [12]. For the synthesis of Cr-MIL(101) a mixture of 1.63 g
of chromium (III) nitrate, Cr(NO3)3·9H2O (97%), 0.7 g of terephthalic
acid, C6H4-1,4-(CO2H)2 (97%), 0.20 g of hydrofluoric acid, HF (40%),
and 20 g of distilled water, H2O, was added in a Teflon container
inside an autoclave. Then the autoclave was heated for 8 h at 493 K
in an oven under static conditions. Once the synthesis was com-
pleted, the solid product was doubly filtered off using two glass
filters with a pore size between 40 and 100 m to remove the free
terephthalic acid. Then a solvothermal treatment was sequentially
performed using ethanol (95% EtOH with 5% H2O) at 353 K for 24 h.
The resulting solid was soaked in 1 M of ammonium fluoride, NH4F,
solution at 343 K for 24 h and was immediately filtered and washed
with hot water. The solid was finally dried overnight and stored at
433 K under air atmosphere.
Methyl phenyl sulfone (3b): Mp 89–90 ◦C. 1H NMR (400 MHz,
CDCl3, ␦): 3.06 (s, 3H), 7.56–7.60 (m, 2H), 7.65–7.69 (m, 1H),
7.95–7.97 (m, 2H). 13C NMR (100 MHz, CDCl3, ␦): 44.67, 127.32,
129.34, 133.67, 140.58.
Diphenyl sulfone (3c): Mp 128–129 ◦C. 1H NMR (400 MHz,
CDCl3, ␦): 7.48–7.59 (m, 6H), 7.94–7.97 (m, 4H). 13C NMR (100 MHz,
CDCl3, ␦): 127.65, 129.26, 133.15, 141.61.
Benzyl 4-bromobenzyl sulfone (3d): Mp 176–178 ◦C. IR (
,
max
KBr, cm−1): 1116, 1299; 1H NMR (400 MHz, CDCl3, ␦): 4.02 (s, 2H),
4.14 (s, 2H), 7.17–7.60 (m, 9H).
4-Nitrobenzyl phenyl sulfone (3e): Mp 204–205 ◦C. IR (
,
max
KBr, cm−1): 1140, 1302, 1341, 1519; 1H NMR (400 MHz, CDCl3, ␦):
4.44 (s, 2H), 7.10 (d, 2H, J = 6.5 Hz), 7.40–7.70 (m, 5H), 8.18 (d, 2H,
J = 6.5 Hz).
2.2. Preparation of V@MIL(101)
2-Hydroxyethyl phenyl sulfone (3k): 1H NMR (400 MHz, CDCl3,
␦): 2.04 (br, 1H), 3.35 (t, 2H, J. 5.2 Hz), 4.01 (t, 2H, J.5.2 Hz), 7.60
(t, 2H, J.7.6 Hz), 7.68–7.72 (m, 1H), 7.95 (d, 2H, J.7.6 Hz). 13C NMR
(100 MHz, CDCl3, ␦): 56.33, 58.24, 127.95, 129.47, 134.07, 138.94.
V@MIL(101) catalysts were prepared by an alcoholic impregna-
tion method. A methanol solution of NH4VO3 to achieve a final V
content of 1.4–5.6 wt% of V atoms was contacted with the MIL car-
rier at 60 ◦C, and the methanol was rotaevaporated until complete
dryness. Then the catalysts were dried overnight in air at 120 ◦C,
followed by calcination at 600 ◦C for 4 h in air.
2.3. Synthesis of sulfoxides and sulfones
3.1. Physico-chemical characterization
To a stirred suspension of the selected sulphide (10 mmol) and
the heterogeneous catalyst 4.2% V@MIL(101) (0.1 g, ∼2.5 mol%) in
methanol (10 ml), H2O2 (8 mmol) was added in one portion. The
slurry was stirred at room temperature for 20 min. The catalyst was
filtered off and washed with methanol (10 ml). Ethyl acetate (10 ml)
was added and resulting solution was dried with anhydrous sodium
sulphate and evaporated in vacuo to afford the crude product which
was purified by column chromatography on silica gel (10% EtOAc in
hexane) to afford the pure sulfoxide. Similar method was utilized
to produce sulfones. In this case 4 mol% of V@MIL(101) in CH3CN
were utilized.
Fig. 1 presents the FTIR spectra in the skeletal region of
4000–400 cm−1 for the V-loaded MIL materials As shown in the
spectrum of the parent MIL (Fig. 1a), sharp peaks with high intensity
in the range of 1400–1600 cm−1 indicate the stretching vibra-
tions of C C bound to aromatic ring. This notion is strengthened
by C H weak peak at 3070 cm−1. Strong bands in the region of
1800–1300 cm−1 correspond to ꢀas(COO), ꢀs(COO), and ꢀ(C C)
vibrations, implying the presence of dicarboxylate linker in the
MIL framework. Rather weak and narrow bands at 1017 and
749 cm−1 can be attributed to ı(C H) and ꢁ (C H) vibrations of
aromatic rings, respectively. Weak bands in the spectral region