A Green Reduction of Aromatic Nitro Compounds to Aromatic Amines Over a Novel Ni/SiO2 Catalyst Passivated with a Gas Mixture

Selective Reduction of Nitro Compounds by Organosilanes Catalyzed by a Zirconium Metal-Organic Framework Supported Salicylaldimine-Cobalt(II) Complex

Reducing nitro compounds to amines is a fundamental reaction in producing valuable chemicals in industry. Herein, the synthesis and characterization of a zirconium metal-organic framework-supported salicylaldimine-cobalt(II) chloride (salim-UiO-CoCl) and its application in catalytic reduction of nitro compounds are reported. Salim-UiO-Co displayed excellent catalytic activity in chemoselective reduction of aromatic and aliphatic nitro compounds to the corresponding amines in the presence of phenylsilane as a reducing agent under mild reaction conditions. Salim-UiO-Co catalyzed nitro reduction had a broad substrate scope with excellent tolerance to diverse functional groups, including easily reducible ones such as aldehyde, keto, nitrile, and alkene. Salim-UiO-Co MOF catalyst could be recycled and reused at least 14 times without noticeable losing activity and selectivity. Density functional theory (DFT) studies along with spectroscopic analysis were employed to get into a comprehensive investigation of the reaction mechanism. This work underscores the significance of MOF-supported single-site base-metal catalysts for the sustainable and cost-effective synthesis of chemical feedstocks and fine chemicals.

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.

Reduction of Nitro Compounds Using 3d-Non-Noble Metal Catalysts

The reduction of nitro compounds to the corresponding amines is one of the most utilized catalytic processes in the fine and bulk chemical industry. The latest development of catalysts with cheap metals like Fe, Co, Ni, and Cu has led to their tremendous achievements over the last years prompting their greater application as "standard" catalysts. In this review, we will comprehensively discuss the use of homogeneous and heterogeneous catalysts based on non-noble 3d-metals for the reduction of nitro compounds using various reductants. The different systems will be revised considering both the catalytic performances and synthetic aspects highlighting also their advantages and disadvantages.

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.

Aqueous extract from seeds of Silybum marianum L. as a green material for preparation of the Cu/Fe3O4 nanoparticles: A magnetically recoverable and reusable catalyst for the reduction of nitroarenes

In this paper, we report the green synthesis of the Cu/Fe3O4 nanoparticles using Silybum marianum L. seeds extract and their application as magnetically separable nanocatalyst for the reduction of nitroarenes. Our method is clean, nontoxic and environment friendly. The synthesized nanocatalyst is characterized by XRD, TEM, EDS and UV-visible techniques. UV-visible spectroscopy is used to monitor the kinetics of the Cu/Fe3O4 nanoparticles formation. The results from Fourier transform infrared spectroscopy showed that the C=O and C-O groups in the plant seeds extract played a critical role in capping the nanoparticles. The expected reaction mechanism in the formation of nanoparticles is also reported. The catalyst is recoverable by magnetic decantation and could be reused several times without significant loss in catalytic activity.

Highly effective Ru/CMK-3 catalyst for selective reduction of nitrobenzene derivatives with H2O as solvent at near ambient temperature

Ru nanoparticles entrapped in ordered mesoporous carbon exhibit superior efficiency in the reduction of nitroarenes in water with hydrazine monohydrate.

Generation of Cu nanoparticles on novel designed Fe3O4@SiO2/EP.EN.EG as reusable nanocatalyst for the reduction of nitro compounds

Reusable magnetic Cu nanocatalyst was designed and characterized. An efficient and mild method for the reduction of aromatic nitro compounds.

Magnetic NiO nanoparticles confined within open ends MWCNTs: a novel and highly active catalyst for hydrogenation and synthesis of imines

The novel catalyst is highly active for hydrogenation and synthesis of imines.

Facile one-pot tandem reductive amination of aldehydes from nitroarenes over a hierarchical ZSM-5 zeolite containing palladium nanoparticles

Palladium nanoparticles embedded in hierarchical zeolite act as an acid–metal bifunctional catalyst for efficient reductive amination of aldehyde from nitroarenes.

Synthesis under mild conditions and high catalytic property of bimetal Ni–Cu/SiO2 hollow spheres

Bimetal Ni–Cu/SiO₂ hollow spheres which have been first synthesized and have higher catalytic properties than Ni/silica and commercial Raney Ni with the conversion of nitrobenzene reaching 95% within 1 h.

Advancement in methodologies for reduction of nitroarenes

Recent advancement in reduction methods of nitroarenes are reviewed. The different methods are classified based on the source of hydrogen utilized during reduction and the mechanism involved in the reduction process.

Magnetically recoverable Ni/C catalysts with hierarchical structure and high-stability for selective hydrogenation of nitroarenes

A magnetic Ni/C catalyst with hierarchical structure has been synthesized and exhibits a high stability for selective hydrogenation of nitroarenes.

Preparation and characterization of Ni/mZSM-5 zeolite with a hierarchical pore structure by using KIT-6 as silica template: an efficient bi-functional catalyst for the reduction of nitro aromatic compounds

Ni/mZSM-5 hierarchical zeolite and the acidic form of it were prepared as novel bi-functional catalysts which showed excellent activity for reduction of nitro aromatic compounds in aqueous medium at room temperature.

A covalently anchored 2,4,6-triallyloxy-1,3,5-triazine Pd(ii) complex over a modified surface of SBA-15: catalytic application in hydrogenation reaction

Highly efficient and reusable SBA-15–TAT–Pd(ii) has been synthesized by anchoring a 2,4,6-triallyloxy-1,3,5-triazine (TAT) complex over the organo-functionalized surface of SBA-15.

Aromatic organic contaminant removal from an aqueous environment by p(4-VP)-based materials

p(4-vinylpyridine) (p(4-VP)) hydrogels were prepared in bulk (macro, 5 × 6 mm) and in nanosizes (370 nm) dimensions. The prepared hydrogels were used to remove organic aromatic contaminates such as 4-nitrophenol (4-NP), 2-nitrophenol (2-NP), phenol (Ph) and nitrobenzene (NB) from an aqueous environment. Important parameters affecting the absorption phenomena, such as the initial concentration of the organic species and the absorbent, absorption rate, absorption capacity, pH and the temperature of the medium, were evaluated for both hydrogel sizes. The absorption capacity of bulk and microgels were found to be 4-NP>2-NP>Ph>NB. Furthermore, p(4-VP) microgels were embedded in poly(acrylamide) (p(AAm)) bulk hydrogel as a microgel-hydrogel interpenetrating polymer network and proved to be very practical in overcoming the difficulty of using the microgels in real applications. Moreover, it was demonstrated that separately prepared magnetic ferrite particles inserted inside p(4-VP) microgels during synthesis allowed for trouble-free removal of p(4-VP)-magnetic composite microgels from the aqueous environment by an externally applied magnetic field upon completion of their task.

Phosphane-free green protocol for selective nitro reduction with an iron-based catalyst

Iron phthalocyanine with iron sulfate has been successfully applied for high chemo- and regioselective reduction of aromatic nitro compounds to give the corresponding amines in a green solvent system without using any toxic ligand. The catalytic systems were also compatible with a large range of other reducible functional groups, such as keto, acid, amide, ester, halogen, lactone, nitrile, N-benzyl, O-benzyl, hydroxy, and heterocycles. In the present study, dinitro compounds have been regioselectively reduced to the corresponding amines with high yield. In most of the cases the conversion and selectivity was greater than 99% as determined by GC-MS analysis.