Synthesis of methyl piperazinyl-quinolinyl α-aminophosphonates derivatives under microwave irradiation with Pd–SrTiO3 catalyst and their antibacterial and antioxidant activities

The Application of Microwaves, Ultrasounds, and Their Combination in the Synthesis of Nitrogen-Containing Bicyclic Heterocycles

The use of alternative energy sources, such as microwaves (MW) or ultrasounds (US), and their mutual cross-combination have been widely described in the literature in the development of new synthetic methodologies in organic and medicinal chemistry. In this review, our attention is focused on representative examples, reported in the literature in the year range 2013-2023 of selected N-containing bicyclic heterocycles, with the aim to highlight the advantages of microwave- and ultrasound-assisted organic synthesis.

Rationally tailored redox ability of Sn/γ-Al2O3 with Ag for enhancing the selective catalytic reduction of NO x with propene

The development of excellent selective catalytic reduction (SCR) catalysts with hydrocarbons for lean-burn diesel engines is of great significance, and a range of novel catalysts loaded with Sn and Ag were studied in this work. It was found that the synergistic effects of Sn and Ag enabled the 1Sn5Ag/γ-Al₂O₃ (1 wt% Sn and 5wt% Ag) to exhibit superior C₃H₆-SCR performance. The de-NO _x efficiency was maintained above 80% between 336 and 448 °C. The characterization results showed that the presence of AgCl crystallites in the 1Sn5Ag/γ-Al₂O₃ catalyst helped its redox ability maintain an appropriate level, which suppressed the over-oxidation of C₃H₆. Besides, the number of surface adsorbed oxygen (O_α) and hydroxyl groups (O_γ) were enriched, and their reactivity was greatly enhanced due to the coexistence of Ag and Sn. The ratio of Ag⁰/Ag⁺ was increased to 3.68 due to the electron transfer effects, much higher than that of Ag/γ-Al₂O₃ (2.15). Lewis acid sites dominated the C₃H₆-SCR reaction over the 1Sn5Ag/γ-Al₂O₃ catalyst. The synergistic effects of Sn and Ag facilitated the formation of intermediates such as acetates, enolic species, and nitrates, and inhibited the deep oxidation of C₃H₆ into CO₂, and the C₃H₆-SCR mechanism was carefully proposed.

Effective reduction of nitric oxide over a core-shell Cu-SAPO-34@Fe-MOR zeolite catalyst

In this study, a core-shell catalyst of Cu-SAPO-34@Fe-MOR was successfully prepared through a silica-sol adhesion method, and its performance for selective catalytic reduction of nitric oxide by NH₃ (NH₃-SCR) was evaluated in detail. The Fe-MOR coating has not only increased the high-temperature activity and broadened the reaction temperature window of Cu-SAPO-34 to a large extent, but also increased the hydrothermal stability of Cu-SAPO-34 markedly. It is demonstrated that a strong synergistic interaction effect exists between Cu²⁺ and Fe³⁺ ions and promotes the redox cycle and oxidation-reduction ability of copper ions, which greatly accelerates the catalytic performance of the core-shell Cu-SAPO-34@Fe-MOR catalyst. Abundant isolated Cu²⁺ ions and Fe³⁺ ions on the ion exchange sites performing NO _x reduction at low and high temperature region lead to the broad reaction temperature window of Cu-SAPO-34@Fe-MOR. In addition, more weakly adsorbed NO _x species formed and the increased number of Lewis acid sites may also contribute to the higher catalytic performance of Cu-SAPO-34@Fe-MOR. On the other hand, the better hydrothermal ageing stability of Cu-SAPO-34@Fe-MOR is related to its lighter structural collapse, fewer acidic sites lost, more active components (Cu²⁺ and Fe³⁺) maintained, and more monodentate nitrate species formed in the core-shell catalyst after hydrothermal ageing. Last, the mechanism study has found that both Langmuir-Hinshelwood ("L-H") and Eley-Rideal ("E-R") mechanisms play an essential role in the catalytic process of Cu-SAPO-34@Fe-MOR, and constitute another reason for its higher activity compared with that of Cu-SAPO-34 (only "L-H" mechanism).

Chemistry of 2-(Piperazin-1-yl) Quinoline-3-Carbaldehydes

Abstract:

This review described the preparation of 2- chloroquinoline-3-carbaldehyde derivatives 18 through Vilsmeier-Haack formylation of N-arylacetamides and the use of them as a key intermediate for the preparation of 2-(piperazin-1-yl) quinoline-3-carbaldehydes. The synthesis of the 2- (piperazin-1-yl) quinolines derivatives was explained through the following chemical reactions: acylation, sulfonylation, Claisen-Schmidt condensation, 1, 3-dipolar cycloaddition, one-pot multicomponent reactions (MCRs), reductive amination, Grignard reaction and Kabachnik-Field’s reaction.

Synthesis and Properties of SrTiO3 Ceramic Doped with Sm2O3

The aim of this work was to study the effect of samarium oxide doping on a SrTiO₃ perovskite ceramic. After analyzing the data obtained on the morphological features of the synthesized structures, it was found that an increase in the dopant concentration led not only to a change in the morphological features, but also in the density of the ferroelectrics. Using the X-ray diffraction method, it was found that doping with Sm₂O₃ led to the formation of a multiphase system of two cubic phases of SrTiO₃ and Sm₂O₃. At the same time, an increase in the concentration of Sm₂O₃ dopant led to a change in the crystallinity degree, as well as deformation of the structure. Evaluation of the efficiency of use of synthesized ferroelectrics as catalysts for purification of aqueous media from manganese showed that an increase in the concentration of Sm₂O₃ dopant led to an increase in purification efficiency by 50–70%.

Diethyl [(4-{(9H-carbazol-9-yl)methyl}-1H-1,2,3-triazol-1-yl)(benzamido)methyl]phosphonate

The title compound, diethyl [(4-{(9H-carbazol-9-yl)methyl}-1H-1,2,3-triazol-1-yl)(benzamido)methyl]phosphonate, was synthesized with excellent yield and high regioselectivity through 1,3-dipolar cycloaddition reaction between the α-azido diethyl amino methylphosphonate and the heterocyclic alkyne, 9-(prop-2-yn-1-yl)-9H-carbazole. The cyclization reaction by “click chemistry” was carried out in a water/ethanol solvent mixture (50/50), in the presence of copper sulfate pentahydrate and catalytic sodium ascorbate. The characterization of the structure of the resulting 1,4-regioisomer was performed by 1D and 2D-NMR experiments, infrared spectroscopy, and elemental analysis.