Mild and Selective Hydrogenation of Nitro Compounds using Palladium Nanoparticles Supported on Amino-Functionalized Mesocellular Foam

Preparation of magnetic biochar functionalized by polyvinyl imidazole and palladium nanoparticles for the catalysis of nitroarenes hydrogenation and Sonogashira reaction

Catalysts are essential materials in biotechnology, medicine, industry, and chemistry. On the other hand, recycling and using waste materials is important in economic efficiency and green chemistry. Thus, biochar was prepared from the stem and roots of the Spear Thistle to recover waste. After magnetizing the biochar, its surface was modified with polyvinyl imidazole. Finally, this modified biochar was decorated with Pd nanoparticles and used as a selective and recyclable nanocatalyst in the hydrogenation of nitroarenes and the Sonogashira reaction. The structure of this organic-inorganic nanocatalyst has been characterized by FESEM-EDS, XRD, FT-IR, TEM, and VSM techniques. In the hydrogenation reaction with the amount of 30 mg of nanocatalyst, the temperature of 50 °C in the water solvent, the reaction efficiency reached 99% for 30 min. In addition, under optimal conditions for the Sonogashira reaction: 1.0 mmol iodobenzene, 1.2 mmol phenylacetylene, 20 mg MBC-PVIm/Pd, 2 mmol K2CO3 in H2O at 50 C for 15 min, the reaction efficiency reached 95%. The recyclability of magnetic nanocatalysts was investigated and recognized this nanocatalyst can be used several times without notable loss of its activity.

High Turnover Pd/C Catalyst for Nitro Group Reductions in Water. One-Pot Sequences and Syntheses of Pharmaceutical Intermediates

Commercially available Pd/C can be used as a catalyst for nitro group reductions with only 0.4 mol % Pd loading. The reaction can be performed using either silane as a transfer hydrogenating agent or simply a hydrogen balloon (∼1 atm pressure). With this technology, a series of nitro compounds was reduced to the desired amines in high chemical yields. Both the catalyst and surfactant were recycled several times without loss of reactivity.

Three-Dimensional Network Pd-Ni/γ-Al2O3 Catalysts for Highly Active Catalytic Hydrogenation of Nitrobenzene to Aniline under Mild Conditions

In view of the current situation of high cost and low catalytic efficiency of the commercial Pd-based catalysts, adding transition metals (Ni, Co, etc.) to form the Pd-M bimetallic catalyst not only reduces the consumption of Pd but also greatly improves the catalytic activity and stability, which has attracted increasing attention. In this work, the three-dimensional network Pd-Ni bimetallic catalysts were prepared successfully by a liquid-phase in situ reduction method with the hydroxylated γ-Al₂O₃ as the support. Through investigating the effects of the precursor salt amount, reducing agent concentration, stabilizer concentration, and reducing stirring time on the synthesis of the Pd-Ni nanocatalyst, the three-dimensional network Pd-Ni bimetallic nanostructures with four different atomic ratios were prepared under an optimal condition. The obtained wire-like Pd-Ni catalysts have a uniform diameter size of about 5 nm and length up to several microns. After closely combining with the hydroxylated γ-Al₂O₃, the supported Pd-Ni/γ-Al₂O₃ catalysts exhibit nearly 100% conversion rate and selectivity for the hydrogenation of nitrobenzene to aniline at low temperature and normal pressure. The stability testing of the supported Pd-Ni/γ-Al₂O₃ catalysts shows that the conversion rate still remained above 99% after 10 cycles. There is no doubt that the supported catalysts show significant catalytic efficiency and recyclability, which provides important theoretical basis and technical support for the preparation of low-cost, highly efficient catalysts for the hydrogenation of nitrobenzene to aniline.

Highly Diastereoselective Palladium-Catalyzed Oxidative Cascade Carbonylative Carbocyclization of Enallenols

A palladium-catalyzed oxidative cascade carbonylative carbocyclization of enallenols was developed. Under mild reaction conditions, a range of cis-fused [5,5] bicyclic γ-lactones and γ-lactams with a 1,3-diene motif were obtained in good yields with high diastereoselectivity. The obtained lactone/lactam products are viable substrates for a stereoselective Diels-Alder reaction with N-phenylmaleimide, providing polycyclic compounds with increased molecular complexity.

Intermetallic Ni2Si/SiCN as a highly efficient catalyst for the one-pot tandem synthesis of imines and secondary amines

For the one-pot reductive amination of benzaldehyde with nitrobenzene, intermetallic Ni₂Si/SiCN from the decomposition of a nickel-modified polysilazane precursor exhibited high activity (>99%) and high selectivity (92% to aromatic amine).

Copper oxide-graphene oxide nanocomposite: efficient catalyst for hydrogenation of nitroaromatics in water

A low-cost nanocomposite catalyst containing copper oxide (CuO) nanoparticles (NPs) on graphene oxide (GO) was fabricated by a facile hydrothermal self-assembly process. The segregated CuO NPs and GO exhibited negligible catalytic activities for the reduction of nitroaromatics. However, their hybrid composite accomplished facile reduction with high conversions for several substituted nitroaromatics in aqueous NaBH4 solution; synergetic coupling effect of CuO NPs with GO in the nanocomposite catalyst provided excellent catalytic activity. The nanocomposite catalyst could be separated from the reaction mixture and recycled consecutively.

Highly efficient aqueous phase reduction of nitroarenes catalyzed by phosphine-decorated polymer immobilized ionic liquid stabilized PdNPs

Phosphino-decorated polymer immobilised ionic liquid-stabilised PdNPs are highly efficient catalysts for the aqueous phase hydrogenation and transfer hydrogenation of aromatic nitro compounds in batch and continuous flow.

Cobalt nanoparticles supported on N-doped mesoporous carbon as a highly efficient catalyst for the synthesis of aromatic amines

Inexpensive and reusable transition metal heterogeneous catalysts exhibiting excellent catalytic performance represent an attractive alternative to noble metal and homogeneous catalysts. In this work, we fabricated a novel nanocatalyst comprised of Co nanoparticles (NPs) supported on a N-doped mesoporous carbon (Co/mCN-900) by simple one-pot pyrolysis of a homogeneous mixture of melamine, polyacrylonitrile, and Co(NO₃)₂·6H₂O under a N₂ atmosphere at 900°C. The as-obtained Co/mCN-900 catalyst displayed a fluffy mesoporous structure with highly dispersed and accessible Co NPs acting as catalytic active sites. The Co/mCN-900 catalyst was effective in hydrogenating nitroarenes at milder conditions (i.e., 1MPa H₂ and 120°C) as compared to previously reported Co- and Ni-based catalysts. The Co/mCN-900 catalyst also catalyzed the reductive N-alkylation of nitroarenes with carbonyl compounds to form the corresponding aromatic secondary amines under very mild reaction conditions. In addition, the Co/mCN-900 catalyst showed good reusability since its morphology and activity were maintained after several reaction cycles. Therefore, this work provides a facile and promising method for fabricating non-precious transition metal-based catalysts with excellent performance and great potential for sustainable chemistry applications.

Facile fabrication of γ-Fe2O3-nanoparticle modified N-doped porous carbon materials for the efficient hydrogenation of nitroaromatic compounds

Novel γ-Fe₂O₃-nanoparticle modified N-doped porous carbon materials were facilely prepared and used for efficient catalytic hydrogenation of nitroaromatic compounds.

Efficient and chemoselective hydrogenation of nitroarenes by γ-Fe2O3 modified hollow mesoporous carbon microspheres

A novel γ-Fe₂O₃ NP-modified hollow mesoporous carbon microsphere nanocatalyst was prepared and used as a magnetically recyclable catalyst for the catalytic hydrogenation of nitroarenes with high conversion as well as 100% selectivity for aniline.

Palladium modified magnetic mesoporous carbon derived from metal–organic frameworks as a highly efficient and recyclable catalyst for hydrogenation of nitroarenes

Magnetic mesoporous carbon (Fe–MC) derived from MOFs as catalyst support to fabricate Pd nanoparticles based catalyst Fe@Pd–MC for hydrogenation of nitroarenes.