Transit Met Chem
(Scheme 2), oxidative coupling of thiols (Scheme 3) and
synthesis of 5-substituted tetrazoles (Scheme 4). In order to
optimize the reaction conditions, initially we took the
oxidation of sulfide as a model reaction, and the effects of
solvent, amount of catalyst and H2O2 were studied. As
shown in Table 1, Fe3O4-AMPD-Cu (0.005 g) plus H2O2
(0.5 mL) without any added solvent were the optimal
reaction conditions for the oxidation of methyl phenyl
sulfide.
for the oxidation of sulfides in the presence of our catalyst
with previously reported catalysts from the literature
(Table 8). Noticeably, the present catalyst showed shorter
reaction times and better yields than the other catalysts.
More importantly, in comparison with other catalysts, ease
of operation, cheap and commercially available materials
and stability are several advantages of the present system.
Conclusion
Using the optimized reaction conditions, a range of
sulfoxides with different functional groups were prepared
from of the corresponding sulfides, with the results shown
in Table 2.
In conclusion, we have prepared a novel and magnetically
recoverable nanocatalyst as a highly active and stable cat-
alyst for the synthesis of 5-substituted tetrazoles and for
oxidation reactions. This nanocatalyst is prepared from
commercially available, ecologically benign, cheap and
chemically inert reagents, and shows good reaction times,
easy separation from reaction media by an external magnet,
operational simplicity, practicability and high efficiency.
The products were obtained as oils [26], except for
products 2a (M.p. 63–65 °C [26]) and 2c (M.p.
136–138 °C [27]).
In order to evaluate Fe3O4-AMPD-Cu as a heteroge-
neous catalyst for the oxidative coupling of thiols, we
chose mercaptosuccinic acid as a model substrate in the
presence of various solvents and with different amounts of
Fe3O4-AMPD-Cu and hydrogen peroxide.
Acknowledgements The authors are deeply grateful to University of
Kurdistan (Grant No. 1000 dollars) and University of Ilam for
financial support of this research project.
As shown in Table 3, Fe3O4-AMPD-Cu (0.005 g) plus
H2O2 (30% aqueous, 0.4 mL) in ethanol at room temper-
ature were the optimal reaction conditions for the oxidative
coupling of mercaptosuccinic acid.
References
With these optimized conditions in hand, we next
investigated a range of thiols with different functional
groups. As evident from Table 4, all the examined thiols
afforded the corresponding products in short times with
good to excellent yields.
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