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Comprehensive Summary: Herein, we present a method for the homogeneous hydrogenation of nitroarenes to produce anilines using low catalyst loading (1 mo%) of copper N‐heterocyclic carbene complexes as the catalyst and ammonia borane as the source of hydrogen. A wide range of nitroarenes, featuring diverse functional groups, were selectively transformed into their corresponding primary aromatic amines with high yields. This process can be readily scaled up and exhibits compatibility with various sensitive functional groups, including halogen, trifluoromethyl, aminomethyl, alkenyl, cyano, ester, amide, and hydroxyl. Notably, this catalytic methodology finds application in the synthesis of essential drug compounds. Mechanistic investigations suggest that the in‐situ‐generated Cu‐H species may serve as active intermediates, with reduction pathways involving species such as azobenzene, 1,2‐diphenylhydrazine, nitrosobenzene, and N‐phenylhydroxylamine. [ABSTRACT FROM AUTHOR]

Arylamines, serving as crucial building blocks in natural products and finding applications in multifunctional materials, are synthesized on a large scale via an electrophilic nitration/reduction sequence. However, the current methods for aromatic C–H amination have not yet attained the same level of versatility as electrophilic nitration. Here we show an extensively investigated transition metal-free and regioselective strategy for the amination of nitrobenzenes, enabling the synthesis of 4-nitro-N-arylamines through C(sp2)-H/N-H cross-coupling between electron-deficient nitroarenes and amines. Mechanistic studies have elucidated that the crucial aspects of these reactions encompass the generation of nitrogen radicals and recombination of nitrobenzene complex radicals. The C(sp2)-N bond formation is demonstrated to be highly effective for primary and secondary arylamines as well as aliphatic amines under mild conditions, exhibiting exceptional tolerance towards diverse functional groups in both nitroarenes and amines (>100 examples with yields up to 96%). Notably, this C(sp2)-H/N-H cross-coupling exhibits exclusive para-selectivity. Direct radical C–H amination strategies have exhibited innovation, but challenges remain with C–H amination of electron-poor nitroarenes due to the essence of the electron-deficient nitrogen radical. Herein, the authors report a transition metal-free dehydrogenative C(sp2)-H/N-H cross-coupling between electron-poor nitroarenes and amines. [ABSTRACT FROM AUTHOR]

The active sites of CuO@rGO composite nanomaterials are resolved by the synthetic modes that enhance carrier mobility. In this study, a legitimate composite nanomaterial of cupric oxide with reduced graphene oxide (CuO@rGO) has been synthesised by in-situ chemical reduction of a mixture of graphene oxide and CuO nanoparticles. The graphene oxide nanosheet and CuO nanoparticle respectively have been prepared by the modified Hummers method and sol–gel method (using healthy and environment-friendly D-dextrose as a reducing agent). The average size 24.5 nm (FESEM), hydrodynamic size 412.8 nm (DLS) and 001 index FCC pattern (XRD) prove the well-defined CuO nanoparticles. FT-IR spectra (presence of C=C, C–O–C and R–O bond), FESEM morphology and EDX blueprint (maximum Cu2+ ions) are strongly establishing the formation of the nanocomposite. TEM morphology also exhibits the well incorporation of CuO nanoparticles (size ≈ 22 nm and d ≈ 0.25 nm) with rGO nanosheets. In reduction (pale-yellow nitroarenes changed to colourless), the catalytic efficiency (%) of an active surface of CuO@rGO is 76.5, 78.4, 75.2 and 65.4 for nitrobenzene (20 min, λmax = 235 nm), p-nitroaniline (10 min, λmax = 306 nm), o-nitroaniline (15 min, λmax = 284–294 nm), and 2,4-DNPH (30 min, λmax = 300 nm) respectively up to five cycles in the presence of aqueous NaBH4 (reductive agent). The reductions are kinetically favourable and follow pseudo first-order kinetics with rate constant (min−1) are 6.72 × 10−2, 4.75 × 10−2, 2.75 × 10−2, and 6.23 × 10−3 for nitrobenzene, p-nitroaniline o-nitroaniline and 2,4-DNPH, respectively. The nanocomposite is mesoporous and shows type-IV adsorption isotherm (BET). [ABSTRACT FROM AUTHOR]

In this study, a TiO2-P25 photocatalyst was chemically complexed with a triethanolamine (TEOA) molecule using visible light irradiation and its photocatalytic activity was evaluated in the photoreduction of a wide range of nitroaromatic compounds. The chemically adsorbed TiO2-TEOA complexes were characterized by Fourier-transform infrared spectroscopy, thermogravimetric analysis, UV–vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, N2 adsorption/desorption isotherm analysis and dynamic light scattering (DLS) analysis. The TEOA-functionalized TiO2-P25 surface complex shows enhanced photocatalytic activity under visible light irradiation (λ = 400 nm) when compared to pure TiO2-P25. This enhancement results from the charge transfer (CT) complex formation between TiO2 and TEOA, as well as electron transfer via a ligand-to-metal charge transfer (LMCT) mechanism. Interestingly, in the presence of a nitro compound (NC), the chemically absorbed TiO2-TEOA forms a TiO2-TEOA-NC triad complex system. The three components spontaneously self-assemble into a heterosupramolecular system that performs electron transfer as a single function. As a result, after absorbing visible light, the triad system demonstrates unique photocatalytic performance as compared to both TiO2-TEOA and TEOA-nitro complexes. The increased charge separation in the triad system was demonstrated by photocurrent and electrochemical impedance spectroscopy (EIS) under visible light irradiation. Electrochemical techniques, including photocurrent, impedance, light absorption and emission spectroscopies, demonstrated that increasing the current and charge separation within the triad system effectively inhibits the recombination of electron-hole pairs. The results of the study indicate that the conversion of nitroarenes to their corresponding amines can take place rapidly and on a large scale, yielding excellent results even under atmospheric pressure and air. It is noteworthy that this is the first study in this area, which highlights the potential of reducing nitroarenes into their corresponding amines with a high efficiency of up to 5 mmol using a photocatalytic procedure. The chemoselectivity of this system was excellent, even in the presence of other reducible groups in the nitro compound. Additionally, a one-pot reductive conversion of nitroarenes to amides was carried out with high efficiency using triethyl orthoformate, acetic anhydride, and benzoic anhydride. [ABSTRACT FROM AUTHOR]

A scalable and operationally simple on water seleno‐mediated reduction of nitroarenes to the respective aryl amines with NaBH4 is described. The reaction proceeds under transition metal‐free conditions and is promoted by the formation of Na2Se, which is the effective reducing agent involved in the mechanism. This mechanistic information enabled the development of a mild NaBH4‐free protocol for the selective reduction of nitro derivatives bearing labile moieties, including nitrocarbonyl compounds. The selenium‐containing aqueous phase can be successfully reused up to four reduction cycles, thus further improving the efficiency of the protocol disclosed. [ABSTRACT FROM AUTHOR]

Selenium-promoted oxidations enable a broad range of valuable oxidative functional group interconversions. Anilines are oxidized with hydrogen peroxide in water in the presence of selenium catalysts. The selenium catalyst determines the nature of the oxidation product; whereas nitroarenes are obtained employing diphenyl diselenide or benzeneseleninic acid, azoxyarenes are formed using selenium dioxide or sodium seleninate. The reaction mechanism relies on the reactivity of Se(IV) active oxidants, while Se(VI) species have been demonstrated not to be involved in. [ABSTRACT FROM AUTHOR]

Chemical explosive detection through a feasible, straightforward, and efficient technique is essential for human safety. A Schiff base 2,2′-(azinodimethylidyne)-bis-benzoic acid (2) was synthesized, characterized, and cyclized to form 2-(1,3-dihydro-1-oxoisobenzofuran-3-yl)phthalazin-1(2H)-one (1) upon treatment with various transition and lanthanide metal ions, especially with Cd(II). Further, the cyclized product 1 could act as a nanomolar sensitive fluorescent 'turn-off' probe for 2-nitrophenol (o-NP, 86%) and picric acid (PA, 81%), wherein, the selectivity of 1 was higher for PA over o-NP. The fluorescence quenching of 1 in the presence of PA and o-NP may be attributed to the energy-transfer mechanism. The binding constants for o-NP and PA were in the order of 104 M−1, while the Stern–Volmer constants (Ksv) were estimated to be in the order 105. The limits of detection (LoDs) for 1 toward o-NP and PA were determined to be 4.52 ppb and 6.81 ppb, respectively, while the limits of quantification (LoQs) were determined to be 15.06 ppb and 22.69 ppb, respectively in DMF/H2O. Probe 1 showed excellent selectivity toward o-NP and PA over a wide range of analytes, including cations, nitroaromatics, phenols, and aromatic amines. The present findings demonstrated that Cd(II) induced the rapid production of 1, which could serve as an ultrasensitive probe for o-NP and PA and was highly selective for PA with no interference of ions, nitro-explosives, phenols, or aromatic amines. The nitro-explosives o-NP and PA could also be determined in real Ganga river water samples using 1, which strongly suggest its possibility for practical applications. [ABSTRACT FROM AUTHOR]

The reduction of nitroarenes to arylamines is a synthetically important transformation both in the laboratory and in industry. Herein, Palladium (Pd) nanoparticles were synthesized via incorporation with mesoporous fumed silica material by doping technique. Water was used as a solvent and the as-synthetized material was reduced by using NaBH4 to ensure the total transformation of PdO into Pd nanoparticles. The synthesized sample was characterized by using inductively coupled plasma (ICP) elemental analysis, X-ray powder diffraction (XRD), N2 sorption measurement, scanning electron microscope (SEM), energy-dispersive spectroscopy (EDX), and transmission electron microscopy (TEM). Data showed that the Pd nanoparticles were successfully synthesized and supported on the mesoporous silica with an average size in the ranges of 10–20 nm, with an irregular shape. The purity of the synthesized sample was confirmed by EDX analysis which exhibits the presence of Si, O, and Pd. The catalytic activity of the prepared sample was evaluated in the heterogeneous reduction of nitroarenes to aromatic amines. Reduction reaction was monitored by Shimadzu GC-17A gas chromatography (GC, Japan) equipped with flam ionization detector and RTX-5 column, 30 m × 0.25 mm, 1-μm film thickness. Helium was used as carrier gas at flow rate 0.6 mL/min. Interestingly, the green hydrogenation of nitroarenes to primary amine compounds was achieved in an aqueous solution with high efficiency and in a short time; moreover, the reusability of heterogeneous Pd-SiO2 was performed for four repeated cycles with more than 88% of efficiency at the fourth run. Finally, the heterogeneity of catalysis with high reliability and eco-friendly processes is a super new trend of nitroarenes reduction in the industry and economic scales. [ABSTRACT FROM AUTHOR]

Catalytic hydrogenation of nitroarenes is an efficient and commonly used route for preparing aromatic amines. The cost-effective metallic Ni catalyst prefers to be used for its superior hydrogenation activity, but they generally are not stable enough and usually show poor reusability. In this work, carbon nanotube encapsulating metallic Ni catalysts were prepared by simple ball milling and calcining the mixture of poss-octaphenyl and nickel (II) acetate tetrahydrate. The as-prepared metallic nickel encapsulated catalyst Ni@CNT-800 exhibited excellent stability in the hydrogenation reaction, no any activity decrease was observed after ten runs whether at high conversion or low conversion. [ABSTRACT FROM AUTHOR]

An account of our development of reactions to construct N -heterocycles by triggering cyclization–migration tandem reactions from aryl azides, nitroarenes, and aryl amines is described. The reactivity patterns of metal N -aryl nitrenes, nitrosoarenes, N -aryl nitrogen radical anions, and N -aryl nitrenoids are compared. 1 Introduction 2 Unlocking the Reactivity Embedded in Aryl Azides 3 Exploiting the Reactivity of Nitrosoarenes Generated from Nitroarenes 4 Radical Anion N -Aryl Nitrogen Reactive Intermediates from Nitroarenes 5 Oxidation of Aryl Amines to Access Electrophilic N -Aryl Nitrenoids 6 Conclusion [ABSTRACT FROM AUTHOR]

The development of high‐efficiency and low‐cost heterogeneous catalysts with superior selectivity for the reduction of nitro compounds is desirable. Herein, we prepared Co‐based nitrogen‐doped meso‐microporous carbon (Co/N−C) derived from polyvinylpyrrolidone (PVP)‐coated zeolitic imidazolate framework (ZIF)‐67 as a heterogeneous catalyst for the synthesis of aromatic amines via in‐situ restricted pyrolysis. The structure, morphology, and catalytic activity of Co/N−C were investigated, and the results indicated that Co/N−C‐800 has the combined advantage of the excellent catalytic activity of cobalt nanoparticles and the high mass transfer rate of the N‐doped meso‐microporous carbon framework, achieving superior catalytic ability for the selective hydrogenation of 20 representative nitroaromatic compounds. Co/N−C‐800 was recyclable by simple separation due to the strong magnetism of the Co nanoparticles and exhibited excellent reusability, with 100 % yield of aniline even after six cycles. The catalytic reduction may be attributed to the dissociation of hydrazine to H+/H− via the action of Co/N−C. [ABSTRACT FROM AUTHOR]

Transition metal single atom catalysts (SACs) with M1-Nx coordination configuration have shown outstanding activity and selectivity for hydrogenation of nitroarenes. Modulating the atomic coordination structure has emerged as a promising strategy to further improve the catalytic performance. Herein, we report an atomic Co1/NPC catalyst with unsymmetrical single Co1-N3P1 sites that displays unprecedentedly high activity and chemoselectivity for hydrogenation of functionalized nitroarenes. Compared to the most popular Co1-N4 coordination, the electron density of Co atom in Co1-N3P1 is increased, which is more favorable for H2 dissociation as verified by kinetic isotope effect and density functional theory calculation results. In nitrobenzene hydrogenation reaction, the as-synthesized Co1-N3P1 SAC exhibits a turnover frequency of 6560 h−1, which is 60-fold higher than that of Co1-N4 SAC and one order of magnitude higher than the state-of-the-art M1-Nx-C SACs in literatures. Furthermore, Co1-N3P1 SAC shows superior selectivity (>99%) toward many substituted nitroarenes with co-existence of other sensitive reducible groups. This work is an excellent example of relationship between catalytic performance and the coordination environment of SACs, and offers a potential practical catalyst for aromatic amine synthesis by hydrogenation of nitroarenes. Modulating the atomic coordination structure has emerged as a promising strategy to further improve catalytic performance. Here, the authors report an atomic Co1/NPC catalyst with unsymmetrical single Co1N3P1 sites that displays high activity and chemoselectivity for hydrogenation of functionalized nitroarenes. [ABSTRACT FROM AUTHOR]

The relevance of aryl amines as raw materials for a variety of applications has prompted substantial research into developing highly efficient protocols for hazardous nitroarenes reduction. To that end, a new sustainable and heterogeneous palladium nanocatalyst was fabricated by immobilization of PdNPs on the new magntic support composed of carboxymethyl-imidazolium ionic liquid-grafted chitosan Schiff base and magnetic graphene oxide (CMICSB-MGO) nanocomposites. The spectral, thermal, and microscopic analyses results revealed the successful formation of the magnetic support and nanocatalyst. The activity of the new nanocatalyst (CMICSB-MGO-Pd) in the catalytic reduction of hazardous nitroarenes to convert them into valuable aminoarenes was studied. The findings demonstrated that the new nanocatalyst has excellent catalytic activity, superior recoverability, as well as outstanding reusability under very mild reaction conditions. Moreover, this nanocatalyst can be recycled up to 8 catalytic runs, without significant loss in its efficacy or Pd leaching. Thus, the new magnetic support and nanocatalyst are more eco-friendly and sustainable choices for large-scale use and could pave the way for developing other metal-based catalysts for versatile applications in the future. [ABSTRACT FROM AUTHOR]

The efficient reduction of nitro compounds to their corresponding amino compounds has been a challenging task. In this study, we developed a method for the rapid reduction of aromatic nitro compounds to aromatic amines. The method uses B 2 pin 2 as the reducing agent and NaOH as the base, and the reaction can be completed in 15 min at 50 °C. A range of nitro compounds containing a variety of sensitive functional groups, such as halogen, thioether, cyano, vinyl, and heteroaryl were chemoselectively reduced to the corresponding anilines in good yields. [Display omitted] • Developed a metal-free method for the rapid reduction of aromatic nitro compounds. • The reaction can be completed at 50 °C in 15 min. • Nitroarenes with sensitive groups can converted into the corresponding anilines. [ABSTRACT FROM AUTHOR]

The method for the homogeneous hydrogenation of nitroarenes to produce aromatic amines using low catalyst loading (1 mo%) of air‐stable copper N‐heterocyclic carbene complexes as the catalyst and ammonia borane as the source of hydrogen is reported. More details are discussed in the article by Han et al. on page 1721—1726. [ABSTRACT FROM AUTHOR]

Binary ruthenium‐phosphorus nanoparticles (NPs) with different Ru/P ratio were prepared in mild conditions using white phosphorus (P4) as phosphorus source. Accurate study of both their morphology and structure at the atomic level by TEM and HAADF‐STEM, respectively, showed that Ru2P and RuP have a narrow size distribution (ca. 3.3 nm) and are lacking an ordered ruthenium phosphide lattice. 31P Solid State NMR highlighted the existence of three different phosphorus species consistently with the lack of a metal phosphide lattice and finally XPS revealed that the true nature of these nanoparticles can be better described as a ruthenium‐phosphorus alloy. As a benchmark test, the selective hydrogenation of nitroarenes to primary aromatic amines was studied and evidenced how the P‐alloying imparts a surface modification resulting in a higher catalytic activity and excellent chemoselectivity of Ru2P in comparison to Ru(0) and RuP. [ABSTRACT FROM AUTHOR]

It is of great urgency to eliminate nitroaromatic compounds (NACs) in wastewater due to their high residue and toxicity. Photocatalysis reduction is considered to be an efficient technology for converting NACs to their corresponding aromatic amines. In this work, a visible-light-driven hybrid photocatalyst was synthesized by covalently doping Fe phthalocyanine (FePc) into graphitic carbon nitride skeleton. Compared to the pristine gCN, the optimized gCN-FePc-1 photocatalyst showed enhanced absorption in visible light region, which promoted photogenerated charge transfer and separation. Using p-nitrophenol (p-NP) as the model pollutant, the CN-FePc-1 effectively reduced it to p-aminophenol (p-AP), with the photocatalytic reaction rate being 18 and 3 times higher, respectively, than those of the pristine gCN and the mechanically mixed photocatalyst of gCN/FePc. Moreover, excellent photocatalytic universality for other NACs, high stability, and good reusability also were confirmed. Based on the band structure of the gCN-FePc-1 photocatalyst, a plausible mechanism was proposed to illustrate the photocatalytic reduction process of p-NP to p-AP. This study demonstrates that the covalent modification of FePc into gCN skeleton is an effective strategy to modulate the electronic structure, and the hybrid gCN-FePc is a potential visible-light-driven photocatalyst that potentially can be used for eliminating NAC contamination in wastewater. [ABSTRACT FROM AUTHOR]

The green synthesis of (hetero)aromatic amines is highly expected but challenging. Here, we demonstrate a promising protocol for the room-temperature reductive C–N coupling of nitroarenes mediated by direct light without any catalyst, avoiding harsh reaction conditions of all involving reported homogeneous and heterogeneous thermal catalyses. In addition, the promotive photothermal synergistically catalytic reductive C–N coupling of nitroarenes was further proven by combining 365 nm of UV light with heterogeneous plasmonic MoO3 nanosheets. The catalytic tests reveal that the light-mediated reaction process closely correlates with the applied light wavelength. Impressively, exfoliated MoO3 affords better photoresponsive efficiency, promotive photoelectron transfer, and plasmonic photothermal conversion effect, thus improving the thermal reactivity by photothermal synergy in contrast to bulky MoO3. More importantly, we further reveal the coupling efficiency of the reaction with a greener ethanol solution compared to that using an optimal toluene solvent by light combined with MoO3 nanosheets. The light-mediated reductive coupling reaction mechanism and superiority were further validated by DFT calculations and control experiments. The present protocol demonstrates broad substrate scopes, high functional-group tolerance, excellent chemoselectivity, and great practical applicability. [ABSTRACT FROM AUTHOR]

Aromatic tertiary amines are one of the most important classes of organic compounds in organic chemistry and drug discovery. It is difficult to efficiently construct tertiary amines from primary amines via classical nucleophilic substitution due to consecutive overalkylation. In this paper, we have developed a radical tandem C-N coupling strategy to efficiently construct aromatic tertiary amines from commercially available carboxylic acids and nitroarenes. A variety of aromatic tertiary amines can be furnished in good yields (up to 98%) with excellent functional group compatibility under mild reaction conditions. The use of two different carboxylic acids also allows for the concise synthesis of nonsymmetric aromatic tertiary amines in satisfactory yields. Mechanistic studies suggest the intermediacy of the arylamine–(TPP)Fe(III) species and might provide a possible evidence for an SH2 (bimolecular homolytic substitution) pathway in the critical C-N bond formation step. Aromatic tertiary amines are versatile building blocks in organic synthesis. In this article, the authors report on an iron-catalysed reaction for the decarboxylative C-N coupling from carboxylic acids and nitroarenes, leading to non-symmetric tertiary aromatic amines. [ABSTRACT FROM AUTHOR]

Water-soluble organic nitrogen (WSON) is ubiquitous in fine particulate matter (PM 2.5) and poses health and environmental risks. However, there is limited knowledge regarding its comprehensive speciation and source-specific contributions. Here, we conducted chemical characterization and source apportionment of WSON in 65 PM 2.5 samples collected in Hong Kong during a 1-yr period. Using various mass-spectrometry-based techniques, we quantified 22 nitrogen-containing organic compounds (NOCs), including 17 nitroaromatics (NACs), four amines, and urea. The most abundant amine and NACs were dimethylamine and 4-nitrocatechol, respectively. Two secondary (i.e., secondary formation and secondary nitrate) and five primary sources (i.e., sea salt, fugitive dust, marine vessels, vehicle exhaust, and biomass burning) of WSON and these three categories of NOCs were identified. Throughout the year, secondary sources dominated WSON formation (69.0%), while primary emissions had significant contributions to NACs (77.1%), amines (75.9%), and urea (83.7%). Fugitive dust was the leading source of amines and urea, while biomass burning was the main source of NACs. Our multi-linear regression analysis revealed the significant role of sulfate, NO 3 , nitrate, liquid water content, and particle pH on WSON formation, highlighting the importance of nighttime NO 3 processing and heterogeneous and aqueous-phase formation of NOCs in the Hong Kong atmosphere. [Display omitted] • Aerosol phase WSON is mainly secondarily formed (69.0%) in Hong Kong. • Heterogeneous and aqueous-phase reactions and nighttime NO 3 oxidation are major formation pathways of WSON. • Sulfate and NO 3 played key roles in WSON formation. • Nitroaromatic compounds were predominantly from biomass-burning. • Amines and urea were primarily from dust and crustal origin. [ABSTRACT FROM AUTHOR]

Nitro compounds are an important class of organic molecules with broad application in organic synthesis, medicinal chemistry, and materials science. Among the variety of methodologies available for their synthesis, the direct oxidation of primary amines represents an attractive alternative route. Efforts towards the development of oxidative procedures for the synthesis of nitro derivatives have spanned over the past decades, leading to a wide variety of protocols for the selective oxidative conversion of amines to nitro derivatives. Methods for the synthesis of nitroarenes via oxidation of aryl amines, with particular emphasis on recent advances in the field, are summarised in this review. [ABSTRACT FROM AUTHOR]

This paper reports the synthesis and characterization of SBA-15/melamine–formaldehyde nanocomposite impregnated with Pd(0) nanoparticles, SBA-15@Pr-NH2/MF-Pd(0). The catalytic ability of the prepared material was shown in the reduction in aromatic nitro compounds in the presence of hydrazine hydrate as a hydrogen source. The reaction parameters, including the amount of hydrazine, solvent, and catalyst dosage, were optimized. It was observed that SBA-15@Pr-NH2/MF-Pd(0) acts as a highly active, operationally simple, and safe catalyst under optimal reaction conditions. The reactions proceed in EtOH within a short reaction time, and excellent yields/TOFs were obtained for a wide range of aromatic nitro compounds. It was shown that the prepared catalyst is stable and could be reused in consecutive runs after separation. [ABSTRACT FROM AUTHOR]

Regio‐ and enantioselective hydroarylamination, hydroalkylamination and hydroamidation of styrenes have been developed by NiH catalysis with a simple bioxazoline ligand under mild conditions. A wide range of enantioenriched benzylic arylamines, alkylamines and amides can be easily accessed by nitroarenes, hydroxylamines and dioxazolones, respectively as amination reagents. The chiral induction in these reactions is proposed to proceed through an enantiodifferentiating syn‐hydronickellation step. [ABSTRACT FROM AUTHOR]

Developing and/or modifying fundamental chemical reactions using chemical industry-favorite heterogeneous recoverable catalytic systems in the water solvent is very important. In this paper, we developed convenient, green, and efficient approaches for the chemoselective reduction of nitroarenes, N-acetylation of arylamines, and one-pot reductive acetylation of nitroarenes in the presence of the recoverable heterogeneous carbon-supported palladium (Pd/C) catalytic system in water. The utilize of the simple, effective, and recoverable catalyst and also using of water as an entirely green solvent along with relatively short reaction times and good-to-excellent yields of the desired products are some of the noticeable features of the presented synthetic protocols. [ABSTRACT FROM AUTHOR]

A new heterogeneous catalyst was obtained by growing graphene quantum dots on chitosan and subsequent immobilization of Pd nanoparticles. The catalyst after characterization was used in the reduction of nitroarenes to the corresponding amines by NaBH4 as a weak reducing agent of nitro compounds. The catalyst exhibited excellent catalytic activity and selectivity under mild reaction conditions in water as a green solvent during 1 h. Additionally, the catalyst can be reused for five consecutive runs without any significant decrease in its activity and selectivity. [ABSTRACT FROM AUTHOR]

Palladium nanoparticles with unique catalytic activity and high stability are synthesized. These nanoparticles exhibit excellent catalytic reduction activity for nitroaromatics in green solvents in the presence of H2 at ambient pressure and temperature. The prominent advantages of this nanotechnology include low consumption of catalyst, excellent chemoselectivity, high reusability of the catalyst, and environmentally green solvents. [ABSTRACT FROM AUTHOR]

[Display omitted] • The electronic structure of Pt is modulated by CePO 4 due to the metal-support interaction. • The CePO 4 support has strong adsorption capacity of substrate. • The support plays a role as new active sites under hydrogen spillover. • CePO 4 /Pt catalyst exhibits a high TOF value up to 1476 h−1 in hydrogenation of nitroarenes. Supported catalysts are widely used in selective hydrogenation of nitroarenes, in which the choice of support has an important effect on the catalytic reaction rate and the selectivity of products. Herein, CePO 4 as support to stabilize Pt nanoparticles for selective hydrogenation of nitroarenes is presented. The catalyst achieves a remarkable selectivity of aromatic amine production (>95 %) with a high turnover frequency (1476 h−1). Mechanistic studies reveals that the electronic structure of Pt is modulated by CePO 4. In comparison to conventional CeO 2 /Pt catalyst, the Pt sites on CePO 4 are negatively charged. Such configuration allows facile dissociation of H 2 on Pt sites. Meanwhile, the potential-determining step (the formation of Ph-HNOH from Ph-HNO) on CePO 4 /Pt (0.73 eV) is a significantly lower than CeO 2 /Pt (1.15 eV), thereby favoring the pathway for aromatic amine production on Pt sites. Moreover, the CePO 4 support has strong adsorption capacity of substrate, which plays a role as new active sites when adsorbed substrates are activated by active hydrogen species via hydrogen spillover. This work provides a new perspective into the development of selective nitroarenes conversion through the artful design of supported catalysts. [ABSTRACT FROM AUTHOR]

Aromatic amines are important intermediates in organic synthesis. In this work, an innovative method of synthesizing aromatic amines was designed, which simplified the reduction of nitro groups by using the complexation of borane with neighboring lone pair. The versatility and effectiveness of this technology make it a superior alternative to traditional methods, which is emphasized by the successful application in 12 different examples. [Display omitted] [ABSTRACT FROM AUTHOR]

• The method designs and prepares a new MoSe 2 nanocatalytic material that can accomplish the catalytic performance within the reaction system for three times recycling. • The reaction system has good reaction adaptability to nitroaromatics substituted with various functional groups and can be carried out at room temperature without high temperature and pressure. • The highest conversion rate of nitroaromatics is >99 %, and the highest selectivity of the corresponding aromatic amine can reach 74 %. A mild and green nitro-reduction method was developed using PEG200(4)@C@MoSe 2 @MWCNT driven by UV light. The photocatalytic performance of MoSe 2 was enhanced by MWCNTs and polyethylene glycol, and the catalyst was characterized by SEM, TEM, XRD, and TGA. Eleven reduction applications had been accomplished, in which the conversion of 3-nitrobenzonitrile reached up to >99% and the selectivity of 3-aminobenzonitrile reached up to 74%. Although the selectivity of the target products was low, it provided a new approach for the photocatalytic reduction of nitroaromatics and also brought new insights into the photocatalytic application of MoSe 2. [Display omitted] [ABSTRACT FROM AUTHOR]

Throughout the present research, cellulose nanocrystals (CNCs) have been modified with 3‐aminopropyltriethoxysilane (APTES) and also they have been exploited as the support for palladium nanoparticles (Pd NPs) using palladium complex. Moreover, Fourier Transform Infrared Spectroscopy(FT‐IR), Powder X‐ray Diffraction(PXRD), Field Emission Scanning Electron Microscopy(FE‐SEM), Energy Dispersive X‐ray Spectroscopy(EDS), Transmission Electron Microscopy(TEM), Inductively Coupled Plasma Optical Emission Spectroscopy(ICP‐OES) and Thermal gravimetric Analysis(TGA) were employed to characterize the Pd@CNC‐APTES nanocatalyst. The catalytic activity of the nanocatalyst has been investigated in the reduction of p‐Nitrophenol(p‐NP) and the other nitroaromatic compounds to the corresponding amine. Furthermore, the catalyst could be recycled four times without the considerable loss of Pd content and with a high level of p‐NP conversion. Using experimental results, thermodynamic parameters were calculated by Arrhenius and Eyring equations. The findings revealed the significant catalytic activity of Pd@CNC‐APTES nanocatalyst for the reduction of p‐NP and its derivatives by sodium borohydride(NaBH4) at room temperature. [ABSTRACT FROM AUTHOR]

Candida parapsilosis ATCC 7330 supported gold nanoparticles (CpGNP), prepared by a simple and green method can selectively reduce nitroarenes and substituted nitroarenes with different functional groups like halides (–F, –Cl, –Br), olefins, esters and nitriles using sodium borohydride. The product aryl amines which are useful for the preparation of pharmaceuticals, polymers and agrochemicals were obtained in good yields (up to >95%) using CpGNP catalyst under mild conditions. The catalyst showed high recyclability (≥10 cycles) and is a robust free flowing powder, stored and used after eight months without any loss in catalytic activity. [ABSTRACT FROM AUTHOR]

The development of Pt nanocatalysts for the selective hydrogenation of nitroaromatic compounds to the corresponding amines is of great significance to solve the drawbacks associated with a low reserve of Pt. Herein, we develop a protocol for the preparation of a Pt/titanium carbide-based MXene heterostructure for the selective reduction of nitroaromatic compounds. In the heterostructure, well-defined and nano-sized metallic Pt crystallites are uniformly decorated on Ti3C2Tx nanosheets using a mild reducing agent of ammonia borane without additional stabilizing agents. The selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN) was employed as a model reaction to investigate the catalytic performance of the as-synthesized heterostructure, denoted as Pt/Ti3C2Tx-D-AB. Notably, this catalyst can catalyze the complete conversion of p-CNB to p-CAN with 99.5% selectivity, superior to that of Pt/Ti3C2Tx-D-SB synthesized with sodium borohydride. The high performance of the present catalytic system can be ascribed to the well-dispersed Pt nanoparticles, the abundant surface electron-efficient Pt(0), and the synergistic catalysis between Pt/Ti3C2Tx-D-AB and water. This catalyst also shows generality toward the selective hydrogenation of a series of nitroaromatic compounds to the corresponding amines with high efficiency. The present study provides a strategy to synthesize efficient catalysts for catalytic applications. [ABSTRACT FROM AUTHOR]

The reduction of nitroarenes to the corresponding aromatic amines is one of the most popular reactions in organic synthesis with significant application in pharmaceutical and manufacture industry. In the last decades, many efforts have been devoted to the design highly effective, chemoselective, low‐cost and eco‐friendly protocols. In this sense, the reduction of nitroarenes via transfer hydrogenation using formic acid as hydrogen source has gained great relevance with tremendous advance over the last year as an attractive and competitive strategy to classical protocols. The efforts have mainly been focused on the discovery of efficient catalyst based on advanced mesoporous support material loaded with transition metals or metallic nanoparticles, the optimization conditions for non‐supported catalyst as well as convenient energy source to achieve an efficient and selective catalytic transfer hydrogenation (CTH) at room temperature. In the present review, several examples of reduction of nitroarenes using formic acid are shown as well as a comprehensive discussion about the role of catalyst, energy source and mechanism of reaction in the transfer hydrogenation process. [ABSTRACT FROM AUTHOR]

The transition metal free reduction of aromatic/heteroaromatic nitro compounds to amines has been improved employing phenyl(2‐quinolyl)methanol (PQM) as organocatalyst in the presence of NaBH4 or NaCNBH3 as stoichiometric reducing agent. The procedure is chemoselective for NO2 group reduction with high tolerance of many functionalities. The reaction pathway strongly depends on the substituents present on the nitroarene ring. However, a careful choice of the reaction conditions allows to address the reduction process towards the corresponding anilines (isolated in 17–91 % yields). The use of substoichiometric amounts of PQM allows more sustainable processes: reaction products are easily isolated and PQM can be directly recovered at the end of the reaction and recycled. [ABSTRACT FROM AUTHOR]

Silver nanoparticles loaded into shell of poly (styrene‐N‐isopropylmethacrylamide‐co‐acrylic acid) core shell [P (SNA‐CS)] gel particles were synthesized and analyzed by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), ultraviolet–visible spectroscopy (UV–vis) and dynamic light scattering (DLS). Catalytic activity of Ag@P (SNA‐CS) particles was investigated by reducing p‐nitroaniline (p‐NA) into p‐aminoaniline (p‐AA) in the presence of sodium borohydride (NaBH4) reductant. Molecules of the substrate adsorbed on the surface of silver nanoparticles interact with borohydride ions (BH4−) to form p‐AA. Other nitroarenes like o‐nitroaniline (o‐NA), p‐nitrophenol (p‐NP) o‐nitrophenol (o‐NP), 2,4‐dinitrophenol(2,4‐DNP) were also reduced into their corresponding aryl amines using Ag@P (SNA‐CS) composite microgels as catalyst. Reported catalyst efficiently reduced the nitro aromatic compounds individually as well as simultaneously at ambient temperature. Effect of different reaction conditions (catalyst dose, concentration of NaBH4 and concentration of p‐NA) on reaction completion time, value of apparent rate constant (kapp) and reduction efficiency of the catalyst for reduction of p‐NA was also demonstrated. Ag@P (SNA‐CS) catalyst was found to be able to retain activity up to four cycles. [ABSTRACT FROM AUTHOR]

A Heterogeneous catalyst developed for selective reduction of nitroarenes to the analogous anilines using formic acid as hydrogen source. This catalytic procedure offers a simplistic path to prepare aromatic amines in good to excellent yields. Especially, even anilines functionalized with other potentially reducible moieties are obtained with high selectivity. Herein, we report convenient and stable bimetallic AgPd nanocatalyst supported on metal organic framework coated with polyaniline. Hydrogenation of nitroarenes gave analogues anilines with excellent yields at 90 °C in 6 h with no use of additives. Catalyst maintained stable performance in five repeated cycles. [ABSTRACT FROM AUTHOR]

• Palladium doped zeolites synthesised for catalysis. • Pd nanoparticles of controllable size incorporated into the zeolite pore system. • Pd@MWW and Pd@BEA zeolites shape-selectively catalyzes hydrogenation. • Active and highly selective catalyst for hydrogenation of nitroarenes. Hydrogenation of nitroarenes is a catalytic reaction of high interest owing to the importance of the resulting aromatic amines in the chemical industry. Up to date, various metal@zeolite catalysts have been reported for this transformation. Herein, Pd@Beta and Pd@MWW catalysts were synthesized by ion exchange with Pd(NH 3) 4 (NO 3) 2 and characterized by XRD, nitrogen sorption, ICP-OES, electron microscopy and FTIR(CO). Structural and textural analysis proved no significant changes of the zeolites after the Pd precursor was introduced. STEM images proved the uniform distribution of metal species in zeolite crystals. Average size of Pd NPs is 2.6 nm and 1.7 nm for Beta and MWW zeolites, respectively. The resulting Pd@Beta catalyst exhibited higher catalytic activity compared to Pd@MWW in the hydrogenation of nitroarenes. The electronic/steric effects of substrates and products were also investigated for both catalysts. Nitroarenes with electron-donating groups exhibit higher initial reaction rates than nitroarenes containing electron-withdrawing groups. The nitroarenes bearing functionalized groups in the ortho -position are harder to hydrogenate than corresponding meta - and para - isomers because of the steric hindrance effect. [ABSTRACT FROM AUTHOR]

The catalysts 1 wt% palladium supported on carbon nanoglobules (CNGs) were shown to be highly active in the liquid-phase hydrogenation of various nitroarenes and provided nearly 100% selectivity to aromatic amines at complete conversion under mild conditions (323 K, 0.5 MPa, 1 h). The catalytic activity (in terms of turnover frequency and substrate conversion) and selectivity depend on the kind of CNGs support, catalyst preparation method and the reaction conditions (solvent nature). The Pd/CNGs catalyst can be repeatedly used while maintaining the same catalytic performance. The excellent performances of Pd/CNGs catalysts can be due to the globular morphology of the supports as well as the absence of micropores and pronounced surface defects. [ABSTRACT FROM AUTHOR]

Aromatic amino compounds are important and universally used chemical intermediates in a wide range of industrial fields. Thus, their production with high efficiency and selectivity under ambient conditions is expected and demanded in modern industry. Herein, a series of superfine CoNi alloy nanoparticles embedded in Al2O3 nanosheet (CoxNi1−x/Al2O3, where x represents the content of Co in the precursor) catalysts was fabricated from CoNiAl-LDH and used to catalyze the tandem dehydrogenation of ammonia borane (AB) and hydrogenation of nitroaromatics to the corresponding amines. Systematic experiments indicate that the composition, size, morphology and catalytic performance of the CoxNi1−x/Al2O3 catalysts can be easily controlled by changing the content of Ni in the CoNiAl-LDH precursor. Particularly, Co0.67Ni0.33/Al2O3 exhibited the best tandem catalytic performance among the six samples. This as-prepared catalyst not only showed a moderate turn-over-frequency value (TOF: 34.5 molH2 molCo0.67Ni0.33−1 min−1 at 298 K without base or additives) and relatively low activation energy (32.4 kJ mol−1) for the dehydrogenation of AB, but also superior catalytic activity (conversion yield reaching up to 100%) and selectivity (>99%) for the tandem reductive transformation of in excess of sixteen types of nitroaromatics to aromatic amines. Density functional theory (DFT) calculations suggest that the construction of the CoNi alloy optimized the electronic structure with respect to the pure component, promoting its activity for AB hydrolysis and nitroaromatics hydrogenation. Finally, the catalyst could be easily recycled using a magnet due to the magnetic properties of the Co0.67Ni0.33 alloy. [ABSTRACT FROM AUTHOR]

A green procedure is described for supporting Pd nanoparticles on hydroxyapatite (HAP), which serves as a highly-stable heterogeneous catalyst displaying excellent activity for the aqueous expeditious reduction of nitroaromatics to the corresponding amines with sodium borohydride, and oxidation of primary and secondary alcohols by hydrogen peroxide with high yields and selectivities. The structural features of the prepared catalyst are confirmed by latest techniques including field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The reusability of the heterogeneous catalyst was affirmed in the aqueous reduction of nitrobenzene and oxidation of cycloheptanol for six consecutive runs without significant loss of catalytic activity. [ABSTRACT FROM AUTHOR]

• Hydrogenation of aromatic nitro compounds. • Half sandwich Ruthenium(II) complex catalyzed hydrogenation. • Reduction of nitro compounds catalyzed by transition metal complexes. • Ruthenium mediated reduction of organic nitro compounds to amino compounds. We present herein the synthesis and characterization of two ruthenium(II) half-sandwich complexes (1·PF 6 and 2·PF 6) featuring phosphine-free ligands N-(pyridin-2-yl)quinolin-2-amine (L-1) and N-(4-methylpyridin-2-yl)quinolin-2-amine (L-1). The molecular structures of both complexes were determined by single-crystal X-ray diffraction. These complexes functioned as excellent phosphine-free catalytic systems for the synthesis of aryl amines from corresponding nitroarenes by employing sodium borohydride under mild conditions in ethanol. Intermediacy of [Ru–H] has been established by spectroscopic studies. The reduction showed good chemo selectivity in presence of −COOH and –NHCOMe functionality. [Display omitted] [ABSTRACT FROM AUTHOR]

• Low-coordinated Pt was fabricated via dealloying of Ni-Pt alloy. • High m -DNB to m -PDA hydrogenation activity due to the effect of low coordination. • Effectively synthesize various aromatic amines at ambient temperature and pressure. Catalytic hydrogenation of aromatic nitro-compounds to corresponding aromatic amines is an environmental-friendly transformation for the production of dyes and pigments in industrial. Herein, an efficient low-coordinated Pt derived from Ni-Pt alloy archored on silica has been fabricated via dealloying process. Transmission electron microscopy (TEM) analysis confirmed an equivalent metal particle size to the reference dense Pt. Additionally, the characterizations revealed that the generation of unsaturated coordination in the resultant material leads to enhanced active surface area, increased fraction of low-coordinated and electron-enriched Pt. The as-prepared low-coordinated Pt catalyst was applied for liquid-phase m-dinitrobenzene (m-DNB) hydrogenation. Under the reaction conditions of ambient temperature, atmospheric pressure and m-DNB/Pt molar ratio of 140, both the m-DNB conversion and the selectivity to m-phenylenediamine (m-PDA) reached 99% within 2 h, superior to those observed over the reference dense Pt and the reported Pt-based catalysts. The enhanced catalytic properties were attributed to the promotional effect of unsaturated coordinated structure, which provided more Pt active sites with low coordination number and high electron density. This study demonstrates the importance of unsaturated coordination in metallic catalysts and establishes a powerful protocol for the design of an effective metal catalyst for the hydrogenation of a range of nitroaromatic compounds. [ABSTRACT FROM AUTHOR]

• Ag nanoparticles were synthesized and stabilized in acrylamide based polymer microgels. • The hybrid system was used as catalysts for reduction of a variety of nitroarenes. • The catalytic system was found to be highly stable and efficient. • Catalyst can be easily recovered and re-used many times without any significant loss of activity. Poly(N-isopropylacrylamide-co-acrylamide) (PNA-BIS-2) microgels were synthesized by free radical precipitation polymerization in aqueous medium. Spherical Ag nanoparticles with diameter of 10–20 nm were fabricated inside the PNA-BIS-2 microgels by in-situ reduction of silver nitrate using sodium borohydride as reducing agent. The Ag nanoparticles- loaded hybrid microgels were characterized by Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Energy dispersive X-ray (EDX), Scanning transmission electron microscopy (STEM), Ultraviolet visible spectroscopy (UV Visible), Thermogravimetric analysis (TGA) and X-ray diffraction (XRD). Ag contents in the hybrid system were determined by inductively coupled plasma - optical emission spectrometry (ICP-OES). Various nitroarenes were successfully converted into their respective aromatic amines with good to excellent yields (ranging from 75% to 97%) under mild reaction conditions. The catalyst has ability to successfully convert substituted nitroarenes into desired products keeping many functionalities intact. The catalyst can be stored for long time without any sign of aggregation and can be used multiple times without any significant loss in its catalytic activity. [ABSTRACT FROM AUTHOR]

A procedure for the synthesis of N‐methyl‐arylamines directly from nitroarenes using methanol as green methylating agent was developed. The key to success is the use of a specific catalyst system consisting of palladium acetate and the ligand 1‐[2,6‐bis(isopropyl)phenyl]‐2‐[tert‐butyl(2‐pyridinyl)phosphino]‐1H‐Imidazole (L1). The generality of this protocol is demonstrated in the synthesis of more than 20 N‐methyl‐arylamines under comparably mild conditions. Combining this novel methodology with subsequent coupling processes using the same catalyst allows for efficient diversification of aromatic nitro compounds to a broad variety of amines including drug molecules. Take "Me" on: The first Pd‐catalyzed N‐methylation of nitroarenes with methanol is reported. The generality of the developed protocol is demonstrated in the synthesis of more than 20 N‐methyl‐arylamines under comparably mild conditions. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • N -Methylation of aliphatic amines and anilines by methanol under N 2. • N -Monomethylation of aliphatic amines under H 2. • One-pot synthesis of methyl anilines from nitroarenes and methanol under H 2. • Relationship between TOFs and adsorption energy of H on metal surface. Abstract We report herein the selective N -methylation of amines and nitroarenes with methanol under basic conditions using carbon-supported Pt nanoparticles (Pt/C) as a heterogeneous catalyst. This method is widely applicable to four types of N -methylation reactions: (1) N,N -dimethylation of aliphatic amines under N 2 , (2) N -monomethylation of aliphatic amines under 40 bar H 2 , (3) N -monomethylation of aromatic amines under N 2 , and (4) tandem synthesis of N -methyl anilines from nitroarenes and methanol under 2 bar H 2. All these reactions under the same catalytic system showed high yields of the corresponding methylamines for a wide range of substrates, high turnover number (TON), and good catalyst reusability. Mechanistic studies suggested that the reaction proceeded via a borrowing hydrogen methodology. Kinetic results combined with density functional theory (DFT) calculations revealed that the high performance of Pt/C was ascribed to the moderate metal–hydrogen bond strength of Pt. [ABSTRACT FROM AUTHOR]

Abstract: Ni2B@Cu2O and Ni2B@CuCl2 are introduced as simple and efficient earth-abundant transition-metal-based nanocomposites for the green one-pot reductive acetylation of aromatic nitro compounds and direct N-acetylation of arylamines using a solvent-free mechanochemical grinding technique. The designed Ni2B-based nanocomposites were characterized by Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) spectroscopy. Notable advantages of these methods include broad substrate scope, use of a solvent-free mechanochemical grinding technique, implementation of earth-abundant transition-metal-based nanocomposites as simple and practical catalysts, and short reaction time and high yield at ambient condition. The mentioned methods can also be successfully applied for the synthesis of a broad range of other amides (especially substituted acetamides) using green chemistry protocols. Also, the recoverability and reusability of the mentioned new nanocomposites were investigated.Graphical abstract: [ABSTRACT FROM AUTHOR]

• Easily synthesis of [C 4 (DABCO) 2 ].NiCl 4 as a new lewis acid catalyst. • FT-IR, EDX, FESEM, XRD, TGA, DRS and ICP-OES were used to characterize the catalyst. • [C 4 (DABCO) 2 ].NiCl 4 displayed excellent performance in the reduction of different nitroarens, N -acetylation of arylamines, and one-pot reductive acetylation of nitroarenes. • Reusability of the catalyst. The present paper describes convenient, green, and efficient approaches for the chemoselective reduction of nitroarenes, N -acetylation of arylamines, and one-pot reductive acetylation of nitroarenes in the presence of a new nickel ion-containing DABCO based ionic liquid, formulated as [C 4 (DABCO) 2 ].NiCl 4. The prepared catalyst was examined using FT-IR, FESEM, XRD, EDS, ICP-OES, TGA, DRS and TEM analyses. The reported protocols are accompanied with several advantages including the introduction of a novel nontoxic ionic liquid catalyst, green reaction conditions, chemoselectivity, short reaction times and high yields of the products. Significantly, the used Lewis acidic catalyst could be successfully recycled for at least six times without the considerable lose in its catalytic efficiency. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The reaction of cyclohexanones with amines proceeded under an ethylene atmosphere in the presence of a catalytic amount of palladium/carbon to afford a variety of arylamines in good to high yields. The present reaction was carried out under completely non‐aerobic conditions, and which is in contrast with the previously reported aerobic system. has wide applicability affording a variety of aromatic amines, and co‐product of the reaction is only gaseous ethane. Thus, this method is environmentally friendly. This protocol was applied intramolecularly to provide a novel method for the construction of quinoline and isoquinoline compounds. [ABSTRACT FROM AUTHOR]

In this paper, we report a simple synthesis of four new nickel boride-based nanocomposites, namely Ni2B@ZrCl4, Ni2B@Cu2O, Ni2B@CuCl2 and Ni2B@FeCl3, from commercially available and cheap starting materials. All of the new Ni2B-based nanocomposites were well characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Further, the catalytic applications of these new nanocomposites were successfully evaluated in the wet-solvent-free reduction of aromatic nitro compounds to arylamines with sodium borohydride (NaBH4) at room temperature by a mechanochemical grinding technique. All the introduced catalytic systems provide excellent yields of arylamines in very short reaction times for a wide range of substrates. Also, recoverability and reusability of the new nanocomposites were investigated. We report a simple synthesis of four new Ni2B-based nanocomposites, namely Ni2B@ZrCl4, Ni2B@Cu2O, Ni2B@CuCl2, and Ni2B@FeCl3, which were characterized by FT-IR, XRD, SEM, and EDX. The catalytic applications of these nanocomposites were successfully evaluated in the wet-solvent-free reduction of nitroarenes to arylamines with NaBH4 at room temperature by a mechanochemical grinding technique. [ABSTRACT FROM AUTHOR]

Metallic Co–MoO 3 catalysts supported on ordered mesoporous SBA-15 were first prepared through in situ reaction of SBA-15-supported Co–Mo oxides with 1,10-phenanthroline. The resulting Co–MoO 3 /NC@SBA-15 catalysts with N-doped carbon (NC) exhibited high catalytic activity and chemoselectivity for selective reduction of various functionalized nitroarenes to the corresponding arylamines in ethanol with hydrazine hydrate at near room temperature (30 °C). For reduction of all tested substrates (28 examples), the catalyst could afford a conversion of >99% and arylamine selectivity of >99%. The excellent catalytic performance of the Co–MoO 3 /NC@SBA-15 was attributed to the Co–N χ (C)–Mo active sites generated through the interaction between the surface Co–N χ (C) and MoO 3 species, promoting the dissociation of hydrazine molecule into the active H* species for the reduction of nitro groups. After the seventh cycle for reduction of 4-methoxylnitrobenzene, the 2%Co–MoO 3 /NC@SBA-15 showed little change in catalytic performance, textural properties, size and dispersion of metal species and valence states of elements, indicating high stability and recyclability. [ABSTRACT FROM AUTHOR]