Abstract
Surface engineering is a promising strategy to improve the catalytic activities of heterogeneous catalysts. Nevertheless, few studies have been devoted to investigate the catalytic behavior ...differences of the multiple metal active sites triggered by the surface imperfections on catalysis. Herein, oxygen vacancies induced Fe
2
O
3
catalyst are demonstrated with different Fe sites around one oxygen vacancy and exhibited significant catalytic performance for the carbonylation of various aryl halides and amines/alcohols with CO. The developed catalytic system displays excellent activity, selectivity, and reusability for the synthesis of carbonylated chemicals, including drugs and chiral molecules, via aminocarbonylation and alkoxycarbonylation. Combined characterizations disclose the formation of oxygen vacancies. Control experiments and density functional theory calculations demonstrate the selective combination of the three Fe sites is vital to improve the catalytic performance by catalyzing the elemental steps of PhI activation, CO insertion and C-N/C-O coupling respectively, endowing combinatorial sites catalyst for multistep reactions.
The selective N-monomethylation of amines is an important topic in fine chemical synthesis. Herein, for the first time, we described a selective N-monomethylation reaction of amines with ...paraformaldehyde and H2 in the presence of a CuAlOx catalyst. A variety of amines, including primary aromatic amines, benzylamine and cyclohexylamine, as well as secondary amines, have been shown to be compatible with this reaction.
Abstract
Bridging homogeneous and heterogeneous catalysis is a long-term pursuit in the field of catalysis. Herein, we report our results in integration of nano- and molecular catalysis via catalytic ...synthesis of nitrogen doped carbon layers on AlOx supported nano-Cu which can finely tune the catalytic performance of the supported copper catalyst. This synthetic catalytic material, which can be generated in situ by the reaction of CuAlOx and 1,10-Phen in the presence of hydrogen, could be used for controllable synthesis of N,N-dimethylformamide (DMF) from dimethylamine and CO
2
/H
2
via blocking reaction pathways of further catalytic hydrogenation of DMF to N(CH
3
)
3
. Detailed characterizations and DFT calculations reveal that the presence of N-doped layered carbon on the surface of the nano-Cu particles results in higher activation energy barriers during the conversion of DMF to N(CH
3
)
3
. Our primary results could promote merging of homogeneous catalysis and heterogeneous catalysis and CO
2
recycling.
Generally, a homogeneous catalyst exhibits good activity and defined active sites but it is difficult to recycle. Meanwhile, a heterogeneous catalyst can easily be reused but its active site is ...difficult to reveal. It is interesting to bridge the gap between homogeneous and heterogeneous catalysis via controllable construction of a heterogeneous catalyst containing defined active sites. Here, we report that a molecularly defined, single-active site heterogeneous catalyst has been designed and prepared via the oxidative polymerization of maleimide derivatives. These polymaleimide derivatives can be active catalysts for the selective oxidation of heterocyclic compounds to quinoline and indole via the recycling of -C=O and -C-OH groups, which was confirmed by tracing the reaction with GC-MS using maleimide as the catalyst and by FT-IR analysis with polymaleimide as the catalyst. These results might promote the development of heterogeneous catalysts with molecularly defined single active sites exhibiting a comparable activity to homogeneous catalysts.
The synthesis of N-monomethylamine remains a challenging topic because the N,N-dimethylation reaction is thermodynamically favorable. In this work, the kinetically controlled N-monomethylamine ...synthesis from nitroarene and paraformaldehyde/H2 is reported to have superhigh N-monomethylamine selectivity in the presence of a Pd/TiO2 catalyst. The superior selectivity should be attributed to the preferential adsorption of the primary amine over N-monomethylamine on the Pd/TiO2 surface, as elucidated by NH3/Me2NH-TPD, while the excellent catalytic activity could be associated with the good H2 activation ability and high amine adsorbing capacity of the catalyst, as elucidated by NH3-TPD and H2-TPR tests. Good results were obtained with a variety of nitroarenes containing methyl, methoxyl, hydroxyl, fluoride, trifluoromethyl, ester, and amide substituents as starting materials, and the potential synthetic utility of this protocol in pharmaceutical is illustrated by N-monomethylation of drug molecules, such as clinidipine, nimesulide, procaine, and methyl aminosalicylate.
Nitrogen-doped carbon materials with enhanced CO2 adsorption were prepared by the salt and base co-activation method. First, resorcinol-formaldehyde resin was synthesized with a certain salt as an ...additive and used as a precursor. Next, the resulting precursor was mixed with KOH and subsequently carbonized under ammonia flow to finally obtain the nitrogen-doped carbon materials. A series of samples, with and without the addition of different salts, were prepared, characterized by XRD (X-ray powder diffraction), elemental analysis, BET (N2-adsorption-desorption analysis), XPS (X-ray photoelectron spectroscopy) and SEM (Scanning electron microscopy) and tested for CO2 adsorption. The results showed that the salt and base co-activation method has a remarkable enhancing effect on the CO2 capture capacity. The combination of KCl and KOH was proved to be the best combination, and 167.15 mg CO2 could be adsorbed with 1 g nitrogen-doped carbon at 30 °C under 1 atm pressure. The materials characterizations revealed that the introduction of the base and salt could greatly increase the content of doped nitrogen, the surface area and the amount of formed micropore, which led to enhanced CO2 absorption of the carbon materials.
Catalytic hydrosilylation represents a straightforward and atom-efficient methodology for the creation of C–Si bonds. In general, the application of homogeneous platinum complexes prevails in ...industry and academia. Herein, we describe the first heterogeneous single atom catalysts (SACs), which are conveniently prepared by decorating alumina nanorods with platinum atoms. The resulting stable material efficiently catalyzes hydrosilylation of industrially relevant olefins with high TON (≈105). A variety of substrates is selectively hydrosilylated including compounds with sensitive reducible and other functional groups (N, B, F, Cl). The single atom based catalyst shows significantly higher activity compared to related Pt nanoparticles.
Prochiral aminoketones are key intermediates for the synthesis of optically active amino alcohols, and glycerol is one of the main biomass‐based alcohols available in industry. In this work, glycerol ...was catalytically activated and purposefully converted with amines to generate highly valuable prochiral aminoketones, as well as N‐formamides and N‐methyl amines, over CuNiAlOx catalyst. The catalyst structure can be anticipated as nano‐Ni species on or in CuAlOx via the formation of nano‐ Cu−Ni alloy particles. This concept may present a novel and valuable methodology for glycerol utilization.
Amines to an end: The catalytic transformation of glycerol into value‐added molecules is an important field in sustainable chemistry. In this work, glycerol was activated and reacted directionally with primary and secondary amines to generate highly valuable prochiral aminoketones, N‐formamide, and N‐methyl amine with excellent yields over a simple CuNiAlOx catalyst.
N
-Alkyl amides have wide applications in the biological, pharmaceutical and organic chemical industry. Accordingly, their synthesis has attracted great attention. Among different methods, the
N
...-alkylation of amides with alcohols constitutes an attractive process for their synthesis because alcohol is readily available, and water is generated as the sole byproduct. Although considerable progress has been made in the area of the direct coupling of amides with alcohols in the past few decades, the review on this aspect is almost vacant. This review summarizes the recent development of
N
-alkylation of amides with alcohols according to the classification of catalysts.
The present review summarizes the recent development of
N
-alkylation of amides with alcohols according to the classification of catalysts.
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