Sustainable Catalytic Amination of Diols: From Cycloamination to Monoamination

<i>N</i>-Alkyl amines are extensively applied in the synthesis of functional materials, pharmaceuticals, and pesticides. The reaction of diols with amines is attractive and has been investigated for more than 30 years by using iridium, ruthenium, and other catalysts. However, the main products with diols as starting materials, especially for C₄–C₆ diols, are N-heterocyclic compounds because cyclization reaction is favorable in thermodynamics. Here, for the first time, a simple and non-noble catalyst CuNiAlO_<i>x</i> prepared by a coprecipitation method was developed for the reaction of C₄–C₆ diols with amines to give monoamination products. This method offers an efficient and environmentally friendly method for the selective monoamination of diols

Hydroxyl Group-Regulated Active Nano-Pd/C Catalyst Generation via in Situ Reduction of Pd(NH₃)_<i>x</i>Cl_<i>y</i>/C for <i>N</i>‑Formylation of Amines with CO₂/H₂

The reductive <i>N</i>-formylation of amines using CO₂ and hydrogen is a promising means of incorporating CO₂ into value-added chemicals. To date, there has been a lack of heterogeneous catalyst systems that are sufficiently active and selective for <i>N</i>-formylation of primary amines with CO₂ and H₂. For the first time, we report that a highly active palladium nanoparticle supported on an hydroxyl group-functionalized carbon material has been designed for the <i>N</i>-formylation of aliphatic primary amines with CO₂ and H₂. XPS, XRD, FT-Raman, and TEM characterizations revealed the adsorbing of Pd­(NH₃)_<i>x</i>Cl<i>_y</i> onto the carbon support during catalyst preparation, followed by in situ reduction to generate active nano-Pd particles. The catalytic activity of the Pd/C catalysts can be tuned efficiently by the hydroxyl group, which can modulate the hydrophilic/hydrophobic properties of the carbon surface, and promote the adsorption of CO₂ and the amines near the Pd sites. The results described here may promote the design of an active catalyst for CO₂ recycling and <i>N</i>-formyl amine synthesis

Cu₂O-promoted degradation of sulfamethoxazole by <i>α</i>-Fe₂O₃-catalyzed peroxymonosulfate under circumneutral conditions: synergistic effect, Cu/Fe ratios, and mechanisms

<p>To promote the application of iron oxides in sulfate radical-based advanced oxidation processes, a convenient approach using Cu₂O as a catalyst additive was proposed. Composite catalysts based on <i>α</i>-Fe₂O₃ (CTX%Cu₂O, <i>X</i> = 1, 2.5, 5, and 10) were prepared for peroxymonosulfate (PMS) activation, and sulfamethoxazole was used as a model pollutant to probe the catalytic reactivity. The results show that a synergistic catalytic effect exists between Cu₂O and <i>α</i>-Fe₂O₃, which was explained by the promoted reduction of Fe(III) by Cu(I). Iron K-edge X-ray absorption spectroscopy investigations indicated that the promoted reduction probably occurred with PMS acting as a ligand that bridges the redox centers of Cu(I) and Fe(III). The weight ratio between Cu₂O and <i>α</i>-Fe₂O₃ influenced the degradation of sulfamethoxazole, and the optimal ratio depended on the dosage of PMS and catalysts. With 40 mg L^–1 PMS and 0.6 g L^–1 catalyst, a pseudo-first-order constant of ∼0.019 min^–1 was achieved for CT2.5%Cu₂O, whereas only 0.004 min^–1 was realized for <i>α</i>-Fe₂O₃. Nearly complete degradation of the sulfamethoxazole was achieved within 180 min under the conditions of 40 mg L^–1 PMS, 0.4 g L^–1 CT2.5%Cu₂O, and pH 6.8. In contrast, less than 20% degradation was realized with <i>α</i>-Fe₂O₃ under similar conditions. The CT2.5%Cu₂O catalyst had the best stoichiometric efficiency of PMS (0.317), which was 4.5 and 5.8 times higher than those of Cu₂O (0.070) and <i>α</i>-Fe₂O₃ (0.054), respectively. On the basis of the products identified, the cleavage of the S–N bond was proposed as a major pathway for the degradation of sulfamethoxazole.</p

Novel route for the synthesis of 8-oxa-3-azabicyclo[3.2.1]octane: One-pot aminocyclization of 2,5-tetrahydrofurandimethanol catalyzed by Pt/NiCuAlOx

2,5-Tetrahydrofurandimethanol (THFDM) was selectively transformed into 8-oxa-3-azabicyclo[3.2.1] octane (OABCO), a valuable building block for the synthesis of bioactive molecules, via one-pot aminocyclization with ammonia catalyzed by Pt/NiCuAlOx. Under optimized conditions (200 °C, 6–16 h, 0.5 MPa hydrogen, 0.4 MPa ammonia), the OABCO yield reached 58% with 100% THFDM conversion

Highly Selective N‑Monomethylanilines Synthesis From Nitroarene and Formaldehyde via Kinetically Excluding of the Thermodynamically Favorable N,N-Dimethylation Reaction

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

Reductive Amination of Furanic Aldehydes in Aqueous Solution over Versatile NiyAlOx Catalysts

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