Reductive N‑Alkylation of Nitro Compounds to <i>N</i>‑Alkyl and <i>N</i>,<i>N</i>‑Dialkyl Amines with Glycerol as the Hydrogen Source

As the sustainable and promising hydrogen source, here, glycerol was directly used as the hydrogen source for the reductive amination of alcohol using nitrobenzene as the starting material. The amination of alcohols, especially aliphatic alcohols with different structures, was realized, and mono- or disubstituted amines were synthesized with excellent yields. The reaction mechanism was also explored

Water as Co-Hydrogen Donor in Reductive Aminations

Reductive amination generates an important reaction in fine chemical synthesis. The employment of water as the hydrogen donor for reductive amination might solve the long-time hydrogen supply problem. Here, we present our new results on reductive <i>N-</i>methylation reactions of amine with paraformaldehyde with water as the co-hydrogen donor catalyzed by a simple supported nanogold catalyst, i.e., Au/Al₂O₃. <i>N-</i>Methyl amines or <i>N</i>,<i>N</i>-dimethyl amines can be selectively synthesized with excellent yields. Isotope tracing reactions confirmed the transformation of hydrogen from water in the final product. In addition, this method can be applied in the <i>N</i>-methylation reactions of bioactive molecules with excellent performance. This concept may supply a potential methodology for sustainable reductive amination

Palladium-Catalyzed Synthesis of Alkylated Amines from Aryl Ethers or Phenols

Synthesis of alkylated amines is an important and attractive task in organic chemistry. Herein, we demonstrate a general protocol to produce alkylated amines via the catalytic coupling of amines with aromatic ethers or phenols. This transformation is performed in the presence of a heterogeneous palladium catalyst, and the key to its success is the use of a Lewis acid (LA) co-catalyst. This method shows broad substrate scope and a variety of phenols, including lignin-derived fragments, can be converted to the desired products smoothly. Preliminary mechanistic investigations reveal that this straightforward domino transformation occurs via a hydrogenolysis/reduction/condensation/reduction process

Reductive Amination of Aldehydes and Amines with an Efficient Pd/NiO Catalyst

<div><p></p><p>By applying a simple Pd/NiO catalyst, the reductive amination of amines and aldehydes can progress efficiently under mild reaction conditions, and 24 substituted amines with different structures were synthesized with up to 98% isolated yields.</p> </div

Construction of Highly Active and Selective Molecular Imprinting Catalyst for Hydrogenation

Surface molecular imprinting (MI) is one of the most efficient techniques to improve selectivity in a catalytic reaction. Heretofore, a prerequisite to fabricating selective catalysts by MI strategies is to sacrifice the number of surface-active sites, leading to a remarkable decrease of activity. Thus, it is highly desirable to design molecular imprinting catalysts (MICs) in which both the catalytic activity and selectivity are significantly enhanced. Herein, a series of MICs are prepared by sequentially adsorbing imprinting molecules (nitro compounds, N) and imprinting ligand (1,10-phenanthroline, L) over the copper surface of Cu/Al2O3. The resulting Cu/Al2O3-N-L MICs not only offer promoted catalytic selectivity but also enhance catalytic activity for nitro compounds hydrogenation by an creating imprinting cavity derived from the presorption of N and forming new active Cu-N sites at the interface of the copper sites and L. Characterizations by means of various experimental investigations and DFT calculations disclose that the molecular imprinting effect (promoted activity and selectivity) originates from the formation of new active Cu-N sites and precise imprinting cavities, endowing promoted catalytic selectivity and activity on the hydrogenation of nitro compounds

Active Pd Catalyst for the Selective Synthesis of Methylated Amines with Methanol

Selective N-methylation of amines with methanol is an important reaction in the synthesis of high-value-added fine chemicals, including dyes, surfactants, pharmaceuticals, agrochemicals, and materials. However, N-methylated amines possess higher reactivities and are prone to further transform into N,N-dimethylated amines. Therefore, it is still a challenge to controllably regulate the selectivity of N-methylation using heterogeneous catalysts without the use of base. Herein, we developed a series of Pd/Zn­(Al)O catalysts with abundant basic sites, and the selectivity of N-methylation was controlled by a heterogeneous Pd/Zn­(Al)O catalyst with a Zn/Al ratio of 10 and a Pd loading of 0.4 wt % in the pressure of H2. The experimental results showed that the appropriate basic properties of the catalyst were beneficial to form the desired N-methylated amine. The low loading of Pd in the catalyst was highly dispersed on the support, providing sufficient active sites. These were attributed to the Zn vacancies formed by Al-doped Zn, which were beneficial to form the highly active and stable Pd sites. Furthermore, a series of amines and nitrobenzenes with different functional groups were well tolerated for the selective synthesis of N-methylated amines in the absence of base

Catalytic Activity Enhancement on Alcohol Dehydrogenation via Directing Reaction Pathways from Single- to Double-Atom Catalysis

To further improve the intrinsic reactivity of single-atom catalysts (SACs), the controllable modification of a single site by coordinating with a second neighboring metal atom, developing double-atom catalysts (DACs), affords new opportunities. Here we report a catalyst that features two bonded Fe–Co double atoms, which is well represented by an FeCoN6(OH) ensemble with 100% metal dispersion, that work together to switch the reaction mechanism in alcohol dehydrogenation under oxidant-free conditions. Compared with Fe-SAC and Co-SAC, FeCo-DAC displays higher activity performance, yielding the desired products in up to 98% yields. Moreover, a broad diversity of benzyl alcohols and aliphatic alcohols convert into the corresponding dehydrogenated products with excellent yields and high selectivity. The kinetic reaction results show that lower activation energy is obtained by FeCo-DAC than that by Fe-SAC and Co-SAC. Moreover, computational studies demonstrate that the reaction path by DACs is different from that by SACs, providing a rationale for the observed enhancements

Correction to “Synthesis and Characterization of Iron–Nitrogen-Doped Graphene/Core–Shell Catalysts: Efficient Oxidative Dehydrogenation of <i>N</i>‑Heterocycles”

Correction to “Synthesis and Characterization of Iron–Nitrogen-Doped Graphene/Core–Shell Catalysts: Efficient Oxidative Dehydrogenation of <i>N</i>‑Heterocycles