N. Azgomi, M. Mokhtary / Journal of Molecular Catalysis A: Chemical 398 (2015) 58–64
59
Scheme 1. One-pot synthesis of 1,3-thiazolidin-4-ones catalyzed by MNPs@SiO2-IL.1.
Table 1
anilines and thioglycolic acid in solvent-free condition to provide
a series of 1,3-thiazolidin-4-one. The method provides rapid and
easy access to thiazolidinone compounds in high to excellent yields
a
Synthesis of 4a by MNPs@SiO2-IL in different solvents.
Entry
Solvent
Yield (%)b
(
Scheme 1).
1
2
3
4
5
6
7
8
9
EtOH
H2O
CH3CN
THF
CH2Cl2
EtOAc
DMF
58
48
62
50
42
77
53
22
2
. Experimental
PhMe
solvent-free
High-purity chemical reagents were purchased from the Merck
c
94
Chemical Company. Melting points were determined using an
Electrothermal Mk3 apparatus and are uncorrected. NMR spectra
were recorded in DMSO-d6 on a Bruker Advance DRX-400 MHz
instrument spectrometer using TMS as internal standard. FT-IR
spectra were obtained with potassium bromide pellets in the range
a
Reaction conditions: benzaldehyde (1 mmol), anilines (1 mmol), thioglycolic
acid (1 mmol) and NMPs@SiO2-IL (0.0007 g) at reflux temperature of solvents after
1
h.
b
Isolated yields.
Reaction performed at 70 C.
c
◦
−1
4
00–4000 cm with a Perkin-Elmer 780 spectrometer. Nanostruc-
tures were characterized using a D8-ADVACE (XRD) diffractometer
Cu-K␣, radiation, l = 0.154056 nm), at a scanning speed of 20 min–1
2
1
.3. Synthesis of
-methyl-3-(3-trimethoxysilylpropyl)-1H-imidazol-3-ium
chloride (IL)
(
from 108 to 1008 (2u). Transmission electron microscopy (TEM)
measurements were carried out on a Philips CM10 analyzer operat-
ing at 100 kV. Thermal gravimetric analysis (TGA) was recorded on
a Shimadzu-50 system at a heating rate of 10 C/min. The magnetic
measurement was carried out in a vibrating sample magnetometer
1
-Methylimidazole (13.6 mL, 0.17 mol) and (3-chlor-opropyl)
◦
◦
trimethoxysilane (31 mL, 0.17 mol) were refluxed at 80 C for three
days in the absence of any catalyst and solvent under Ar atmo-
sphere. The unreacted materials were washed with diethyl ether
(
Model 7300 VSM system, Lake Shore Cryotronic, Inc., Westerville,
OH, USA) at room temperature.
(
3× 8 mL). The diethyl ether was removed under reduced pressure
at room temperature, followed by heating under high vacuum, to
yield a yellowish viscous liquid. Isolated yield was 98%.
2
.1. General procedure for the preparation of Fe O4 nanoparticles
3
2.4. General procedure for the preparation of
Fe O @SiO -3-chloropropyltriethoxysilane nanoparticles
(MNPs@SiO -IL)
2
3
4
2
Typically, 0.01 mol FeCl ·4H O and 0.03 mol FeCl ·6H O were
2
2
3
2
dissolved into 200 mL distilled water. Thereafter, under rapid
mechanical stirring, NaOH was added to the solution and the pH
value was controlled in the range 12 ≤ pH ≤ 13. Then, different
2
mmol of Fe O4@SiO2 MNPs and 20 mL THF were mixed
3
together in a beaker, and then 20 mmol of NaH was dispersed
in to the mixture by ultrasonication. 22 mmol 1-methyl-3-
amounts of hydrazine hydrate (N H ·H O, 80% concentration) was
2
4
2
added to the above suspension. The reaction was continued for
about 24 h at room temperature. During this period, the pH value
was adjusted by NaOH and kept in the range 12 ≤ pH ≤ 13. The black
(3-trimethoxysilylpropyl)-1H-imidazol-3-ium chloride was added
drop-wise at room temperature and stirred for another 16 h at
◦
6
0 C. The resultant products were collected and washed with
Fe O MNPs were then rinsed several times with distilled water and
3
4
ethanol and deionized water in sequence, and then dried under
◦
dried at 60 C under vacuum.
◦
vacuum at 60 C for 2 h for further use.
2.5. General synthesis of 1,3-thiazolidin-4-ones
2
.2. General procedure for the preparation of Fe O @SiO
A mixture of aromatic aldehyde (1 mmol), anilines (1 mmol),
3
4
2
nanoparticles
thioglycolic acid (1 mmol) and MNPs@SiO -IL (0.0007 g) was stirred
at 70 C for the appropriate time, as shown in Table 1. Comple-
2
◦
0
.02 mol of Fe O MNPs were dispersed in a mixture of 80 mL of
tion of the reaction was indicated by TLC monitoring. The reaction
mixture was cooled to ambient temperature, and the crude solid
residue was recrystallized from n-hexan/ethyl acetate to afford
pure crystals of the proper 1,3-thiazolidin-4-ones in 86–95% yields.
The products were characterized by FT-IR, NMR and physical
constants.
3
4
ethanol, 20 mL of deioned water and 2.0 mL of 28 wt% concentrated
ammonia aqueous solution, followed by the addition of 0.20 g of
tetraethyl orthosilicate (TEOS). After vigorous stirring for 24 h, the
final suspension was repeatedly washed, filtered for several times
◦
and dried at 60 C in the air.