Nanoscale Fe2O3-based catalysts for selective hydrogenation of nitroarenes to anilines

High catalytic activity of mesoporous Co–N/C catalysts for aerobic oxidative synthesis of nitriles

We report the synthesis and assessment of novel mesoporous cobalt-coordinated nitrogen-doped carbon catalysts (meso-Co–N/C) for highly efficient synthesis of nitriles.

Reactivity and mechanism investigation of selective hydrogenation of 2,3,5-trimethylbenzoquinone on in situ generated metallic cobalt

We successfully developed Co-based catalysts for efficient and selective hydrogenation of TMBQ. Metallic Co was proved to be responsible for TMBQ hydrogenation. The hydrogenation process was also investigated by DFT calculation.

A MOF-derived Co–CoO@N-doped porous carbon for efficient tandem catalysis: dehydrogenation of ammonia borane and hydrogenation of nitro compounds

A metal–organic framework-derived Co–CoO@N-doped porous carbon exhibits excellent catalytic activity, chemoselectivity and magnetic recyclability for the tandem dehydrogenation of NH₃BH₃ and hydrogenation of nitro compounds.

Nitrogen-doped porous carbon materials: promising catalysts or catalyst supports for heterogeneous hydrogenation and oxidation

Developing novel and efficient catalysts is a critical step in common heterogeneous hydrogenation and oxidation reactions.

Efficient conversion of biomass-derived furfuryl alcohol to levulinate esters over commercial α-Fe2O3

An efficient process for the production of levulinate esters from biomass-derived furfuryl alcohol in liquid alcohol over commercial α-Fe₂O₃ was firstly investigated.

Synthesis of nitriles from amines using nanoscale Co3O4-based catalysts via sustainable aerobic oxidation

The selective oxidation of amines for the benign synthesis of nitriles under mild conditions is described.

Recyclable Earth-Abundant Metal Nanoparticle Catalysts for Selective Transfer Hydrogenation of Levulinic Acid to Produce γ-Valerolactone

Nanoparticles (NPs) derived from earth-abundant metal(0) carbonyls catalyze conversion of bio-derived levulinic acid into γ-valerolactone in up to 93% isolated yield. This sustainable and green route uses non-precious metal catalysts and can be performed in aqueous or ethanol solution without using hydrogen gas as the hydrogen source. Generation of metal NPs using microwave irradiation greatly enhances the rate of the conversion, enables the use of ethanol as both solvent and hydrogen source without forming the undesired ethyl levulinate, and affords recyclable polymer-stabilized NPs.

Immobilized ruthenium metal-containing ionic liquid-catalyzed dehydrogenation of dimethylamine borane complex for the reduction of olefins and nitroarenes

An efficient immobilized ruthenium metal containing ionic liquid (ImmRu-IL) catalyst has been developed for the transfer hydrogenation of olefins and nitroarenes. This methodology uses eco-friendly dimethylamine borane as a reducing agent.

Mesoporous carbon derived from vitamin B12: a high-performance bifunctional catalyst for imine formation

Mesoporous carbon derived from natural vitamin B₁₂ is applied for the first time in organic synthesis and exhibits exceptionally high dual activity for imine formation via the cross-coupling of alcohols with amines and the self-coupling of primary amines.

Pyrite nanoparticles: an Earth-abundant mineral catalyst for activation of molecular hydrogen and hydrogenation of nitroaromatics

Pyrite (FeS₂) nanoparticles, a kind of Earth-abundant mineral, can efficiently activate molecular hydrogen under mild conditions.

Fe2O3/NGr@C- and Co–Co3O4/NGr@C-catalysed hydrogenation of nitroarenes under mild conditions

An improved hydrogenation of nitroarenes using nano-structured iron- and cobalt-based catalysts is presented.

A highly active non-precious metal catalyst based on Fe–N–C@CNTs for nitroarene reduction

An efficient Fe–N–C@CNTs for the hydrogenation of nitroarenes was prepared. ε-Fe₃N is the active site and nitrogen/carbon atoms serve as bridges to transport the dissociated hydrogen atoms via spillover effect.

An efficient hydrogenation catalyst in sulfuric acid for the conversion of nitrobenzene to p-aminophenol: N-doped carbon with encapsulated molybdenum carbide

The transfer of catalytic function from molybdenum carbide to N-doped carbon for catalytic hydrogenation of nitrobenzene to p-aminophenol.

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.

A metal–organic framework-templated synthesis of γ-Fe2O3 nanoparticles encapsulated in porous carbon for efficient and chemoselective hydrogenation of nitro compounds

The pyrolysis of metal–organic framework affords γ-Fe₂O₃ nanoparticles well dispersed inside porous carbon, exhibiting excellent catalytic activity, chemoselectivity and recyclability in the hydrogenation of diverse nitro compounds under mild conditions.

Nitrogen-doped carbon supported iron oxide as efficient catalysts for chemoselective hydrogenation of nitroarenes

Chemoselective hydrogenation has been widely used in the production of fine chemicals, and developing heterogeneous catalysts with high activity and chemoselectivity is always a challenging topic.

Assembly of Primary (Hetero)Arylamines via CuI/Oxalic Diamide-Catalyzed Coupling of Aryl Chlorides and Ammonia

A general and practical catalytic system for aryl amination of aryl chlorides with aqueous or gaseous ammonia has been developed, with CuI as the catalyst and bisaryl oxalic diamides as the ligands. The reaction proceeds at 105-120 °C to provide a diverse set of primary (hetero)aryl amines in high yields with various functional groups.

A Rhodium Nanoparticle-Lewis Acidic Ionic Liquid Catalyst for the Chemoselective Reduction of Heteroarenes

We describe a catalytic system composed of rhodium nanoparticles immobilized in a Lewis acidic ionic liquid. The combined system catalyzes the hydrogenation of quinolines, pyridines, benzofurans, and furan to access the corresponding heterocycles, important molecules present in fine chemicals, agrochemicals, and pharmaceuticals. The catalyst is highly selective, acting only on the heteroaromatic ring, and not interfering with other reducible functional groups.

Fabrication of Ruthenium Nanoparticles in Porous Organic Polymers: Towards Advanced Heterogeneous Catalytic Nanoreactors

A novel strategy has been adopted for the construction of a copolymer of benzene-benzylamine-1 (BBA-1), which is a porous organic polymer (POP) with a high BET surface area, through Friedel-Crafts alkylation of benzylamine and benzene by using formaldehyde dimethyl acetal as a cross-linker and anhydrous FeCl3 as a promoter. Ruthenium nanoparticles (Ru NPs) were successfully distributed in the interior cavities of polymers through NaBH4, ethylene glycol, and hydrothermal reduction routes, which delivered Ru-A, Ru-B, and Ru-C materials, respectively, and avoided aggregation of metal NPs. Homogeneous dispersion, the nanoconfinement effect of the polymer, and the oxidation state of Ru NPs were verified by employing TEM, energy-dispersive X-ray spectroscopy mapping, cross polarization magic-angle spinning (13)C NMR spectroscopy, and X-ray photoelectron spectroscopy analytical tools. These three new Ru-based POP materials exhibited excellent catalytic performance in the hydrogenation of nitroarenes at RT (with a reaction time of only ≈ 30 min), with high conversion, selectivity, stability, and recyclability for several catalytic cycles, compared with other traditional materials, such as Ru@C, Ru@SiO2, and Ru@TiO2, but no clear agglomeration or loss of catalytic activity was observed. The high catalytic performance of the ruthenium-based POP materials is due to the synergetic effect of nanoconfinement and electron donation offered by the 3D POP network. DFT calculations showed that hydrogenation of nitrobenzene over the Ru (0001) catalyst surface through a direct reaction pathway is more favorable than that through an indirect reaction pathway.

A manganese catalyst for highly reactive yet chemoselective intramolecular C(sp(3))-H amination

C-H bond oxidation reactions underscore the existing paradigm wherein high reactivity and high selectivity are inversely correlated. The development of catalysts capable of oxidizing strong aliphatic C(sp(3))-H bonds while displaying chemoselectivity (that is, tolerance of more oxidizable functionality) remains an unsolved problem. Here, we describe a catalyst, manganese tert-butylphthalocyanine [Mn((t)BuPc)], that is an outlier to the reactivity-selectivity paradigm. It is unique in its capacity to functionalize all types of C(sp(3))-H bond intramolecularly, while displaying excellent chemoselectivity in the presence of π functionality. Mechanistic studies indicate that [Mn((t)BuPc)] transfers bound nitrenes to C(sp(3))-H bonds via a pathway that lies between concerted C-H insertion, observed with reactive noble metals such as rhodium, and stepwise radical C-H abstraction/rebound, as observed with chemoselective base metals such as iron. Rather than achieving a blending of effects, [Mn((t)BuPc)] aminates even 1° aliphatic and propargylic C-H bonds, demonstrating reactivity and selectivity unusual for previously known catalysts.

Selective Catalytic Hydrogenation of Heteroarenes with N-Graphene-Modified Cobalt Nanoparticles (Co3O4-Co/NGr@α-Al2O3)

Cobalt oxide/cobalt-based nanoparticles featuring a core-shell structure and nitrogen-doped graphene layers on alumina are obtained by pyrolysis of Co(OAc)2/phenanthroline. The resulting core-shell material (Co3O4-Co/NGr@α-Al2O3) was successfully applied in the catalytic hydrogenation of a variety of N-heteroarenes including quinolines, acridines, benzo[h], and 1,5-naphthyridine as well as unprotected indoles. The peculiar structure of the novel heterogeneous catalyst enables activation of molecular hydrogen at comparably low temperature. Both high activity and selectivity were achieved in these hydrogenation processes, to give important building blocks for bioactive compounds as well as the pharmaceutical industry.

Designing versatile heterogeneous catalysts based on Ag and Au nanoparticles decorated on chitosan functionalized graphene oxide

Herein we report the covalent grafting of chitosan on graphene oxide (GO) followed by a simple approach for anchoring silver (AgNPs) and gold (AuNPs) nanoparticles onto a chitosan grafted graphene oxide surface by a NaBH4 reduction method. Catalytic activity of prepared heterogeneous GO grafted chitosan stabilized silver and gold nanocatalysts (GO-Chit-Ag/AuNPs) was explored for the reduction of aromatic nitroarenes and degradation of hazardous azo dyes in the presence of NaBH4. Both catalysts were found to exhibit excellent catalytic activity towards the reduction of aromatic nitroarenes and azo dyes degradation. Furthermore, the nanocatalysts were found to be selective towards the reduction of nitro groups in halonitroarenes without any dehalogenation under mild conditions.

Facile Protocol for Catalytic Frustrated Lewis Pair Hydrogenation and Reductive Deoxygenation of Ketones and Aldehydes

A series of ketones and aldehydes are reduced in toluene under H2 in the presence of 5 mol % B(C6F5)3 and either cyclodextrin or molecular sieves affording a facile metal-free protocol for reduction to alcohols. Similar treatment of aryl ketones resulted in metal-free deoxygenation yielding aromatic hydrocarbons.

Hydrogenation using iron oxide-based nanocatalysts for the synthesis of amines

In this protocol, we describe the preparation of nanoscale iron oxide-based materials and their use in the catalysis of different hydrogenation reactions. Pyrolysis of a Fe(OAc)2-phenanthroline complex on carbon at 800 °C under argon atmosphere results in the formation of nanoscale Fe2O3 particles surrounded by nitrogen-doped graphene layers. By applying these catalysts, the hydrogenation of structurally diverse and functionalized nitroarenes to anilines proceeds with excellent selectivity. Furthermore, we have shown that one-pot reductive amination of carbonyl compounds with nitroarenes is also possible in the presence of these iron oxide catalysts. We report herein the synthesis of more than 40 amines, which are important feedstocks and key intermediates for pharmaceuticals, agrochemicals and polymers. The detailed preparation of the catalysts and the procedures for the hydrogenation processes are presented. The overall time required for the catalyst preparation and for the hydrogenation reactions are 35 h and 20-35 h, respectively.