Anilines are one
of the important chemical feedstocks and are utilized
for the preparation of a variety of pharmaceuticals, agrochemicals,
pigments, and dyes. In this context, the catalytic reduction of nitro
functionality is an industrially vital process for the synthesis of
aniline derivatives. Herein, we report an efficient nanosized bimetallic
Pd–Au/TiO
2
nanomaterial which is proved to be quite
efficient for rapid catalytic hydrogen transfer reduction of nitroarenes
into corresponding amines. Significantly, the reduction process is
successful under solvent-free and mild green atmospheric conditions.
Bimetallic Pd–Au nanoparticles served as the active center,
and TiO
2
played as a support in hydrogen transfer from
the source hydrazine monohydrate. Typical results highlighted that
the reactions were very rapid and the products were obtained in good
to excellent yields. Significantly, the process was successful in
the presence of a very low amount catalyst (0.1 mol %). Furthermore,
the reaction showed good chemoselectivity and compatiblity with double
or triple bond, aldehyde, ketone, and ester functionalities on the
aromatic ring. Typical results indicated the true heterogeneous nature
of the Pd–Au/TiO
2
nanocatalyst, where the catalyst
retained the activity, without loss of its activity.
Hybrid heterogeneous catalyst, palladium(0) on copper ferrite nanowires has been synthesized and characterized. Significantly, this catalyst for the first time employed in the Jeffrey Heck reaction between iodo-arenes and allylic alcohols.
Palladium oxide (PdO) supported carbon nanomaterials were designed and tested for Heck olefination of aryl halides. Various carbonaceous materials, such as single walled carbon nanotubes (SWCNT), multiwalled carbon nanotubes (MWCNT), carbon nanofiber (CNF), graphene oxide (GO) and reduced graphene oxide (RGO) were screened as support for PdO nanoparticles. The structural and phase formation of PdO on carbon materials was confirmed by X-ray diffraction, whereas, surface area and porous nature of the carbon materials was confirmed by N 2 adsorption studies. The morphology of the materials was studied by electron microscopy. Among these catalysts, PdO/GO catalyst showed the best catalytic activity (turnover number 410 and frequency 205 h -1 ) for the Heck olefination and the catalyst was reused successfully up to 3 cycles, which confirms the true heterogeneous nature.
We report a nanocatalyst CoOx/TiO2 with different loadings of CoOx by a solid state synthesis method for the green hydrogenation of nitroarenes under visible light irradiation. Notably, we observed very good selectivity, conversion and functional group tolerance with high yields.
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