Chemoselective reduction of a nitro group through transfer hydrogenation catalysed by Ru0-nanoparticles stabilized on modified Montmorillonite clay

Abstract

Ru 0 -nanoparticles of approximately 5 nm size were generated by incipient impregnation of RuCl 3 into the nanopores of the acid activated Montmorillonite clay followed by polyol reduction. Acid activation of the clay increases the surface area by generating nanopores (0-10 nm), which act as a host and stabilize nanoparticles in the pores. The generated Ru 0 -nanoparticles exhibit inter-planar lattice fringe spacing of 0.21 nm of the face centered cubic lattice of Ru 0 crystals, and show efficient catalytic activity in the chemoselective transfer hydrogenation reduction of substituted nitrobenzenes to corresponding anilines with high yield of conversion (56-97%) and selectivity (91-100%) depending upon the nature of the substituents. The reactions were carried out in the presence of isopropanol, which served as the solvent as well as the reductant. The catalysts were found to be active for several catalytic runs.

In situ stabilization of Pd0-nanoparticles into the nanopores of modified Montmorillonite: Efficient heterogeneous catalysts for Heck and Sonogashira coupling reactions

“…The differential volumes versus pore diameter plot (Fig. 2) indicated relatively narrow pore size distributions and these nano range pores can be advantageously utilized for the in situ synthesis of various metal nanoparticles as reported by us recently [8][9][10]12,13].…”

“…The Montmorillonite clay is collected from the natural deposition of western part of India, processed and activated with mineral acid under controlled conditions to generate a matrix having high surface area and contain micro-and mesopores with diameter in the range 0-10 nm on the surface. These nano range pores act as 'host' for in situ generation of Pd 0 -nanoparticles and also restrict the growth of the particles up to desired range [8][9][10]12,13]. The Pd 0 -nanoparticles act as efficient heterogeneous catalysts for Heck and Sonogashira reactions under mild reaction condition.…”

“…In addition, due to stringent and growing environmental regulations, there has also been increasing interest to employ 'green' procedure for synthesis of nanoparticles. Recently, our group have reported [8,9] very efficient Cu 0 -and Ru 0 -nanocatalysts stabilized on nanopores of modified Montmorillonite clay for synthesizing important organic molecules by following adequate 'greener' procedure.…”

“…The nano-catalyst contains highly reactive surfaces and their catalyzed reactions are likely to provide the advantages of high atom efficiency, simplified isolation of products and easy recovery and recyclability of the catalysts . The overall performance of nanomaterials is dependent on the size, shape and textural parameters of the particles as well as the supporting materials on which these nanoparticles are stabilized [7][8][9][10][11][12][13][14][15][16]. Different types of materials have been employed to support nanoparticles including mesoporous materials, activated carbon, polymers, dendrimers, organic ligands, metal oxides [14,[22][23][24][25][26][27].…”

“…The development of novel metal and metal oxide nanomaterials as catalyst precursors for organic synthesis is a challenge for researchers [7][8][9][10][11][12][13][14][15][16]. The nano-catalyst contains highly reactive surfaces and their catalyzed reactions are likely to provide the advantages of high atom efficiency, simplified isolation of products and easy recovery and recyclability of the catalysts .…”