Organic Transformation Processes Research Articles

Crafting in situ boron and selenium-doped carbon nitride nanosheets for turbocharged benzaldehyde to benzyl alcohol under solar spectrum

This research focuses on the fabrication and application of in situ boron and selenium-doped carbon nitride nanosheets as effective photocatalysts using sun spectrum irradiation to convert turbocharged benzaldehyde to benzyl alcohol. To optimize the doping method for enhanced activity, the effect of changing dopant concentrations on catalytic efficiency was thoroughly investigated. Furthermore, a through analysis of the reactive species involved in the conversion process helped to clarify the photocatalytic process. Based on charge transfer and low recombination, the results indicate that boron and selenium dopants work synergistically to improve catalytic efficiency. This research helps to improve the development of new photocatalytic materials for the sustainable and ecologically friendly transformation of organic molecules under solar spectrum irradiation. The regeneration of NADH using B,Se-CN photocatalyst demonstrates very good efficiency. It also demonstrated the high conversion efficiency of benzaldehyde to benzyl alcohol. This study emphasizes the possible use of B,Se-CN composite in the area of photoinduced conversion-based organic transformation. The knowledge gathered from this research opens up new avenues for the development and enhancement of effective photocatalysts that might be used in a range of solar-powered organic transformation processes.

Copper oxides supported sulfur-doped porous carbon material as a remarkable catalyst for reduction of aromatic nitro compounds

Synthesis and manufacturing of metal–organic framework derived carbon/metal oxide nanomaterials with an advisable porous structure and composition are essential as catalysts in various organic transformation processes for the preparation of environmentally friendly catalysts. In this work, we report a scalable synthesis of sulfur-doped porous carbon-containing copper oxide nanoparticles (marked CuxO@CS-400) via direct pyrolysis of a mixture of metal–organic framework precursor called HKUST-1 and diphenyl disulfide for aromatic nitro compounds reduction. X-ray diffraction, surface area analysis (BET), X-ray energy diffraction (EDX) spectroscopy, thermal gravimetric analysis, elemental mapping, infrared spectroscopy (FT-IR), transmission electron microscope, and scanning electron microscope (FE-SEM) analysis were accomplished to acknowledge and investigate the effect of S and CuxO as active sites in heterogeneous catalyst to perform the reduction-nitro aromatic compounds reaction in the presence of CuxO@CS-400 as an effective heterogeneous catalyst. The studies showed that doping sulfur in the resulting carbon/metal oxide substrate increased the catalytic activity compared to the material without sulfur doping.

A Facile Approach of Fabricating Bifunctional Catalysts for Redox Applications by Uniformly Immobilized Metallic Nanoparticles on NiCr LDH

This study discloses the development of NiCr LDH, Ag@NiCr LDH, and Pd@NiCr LDH bifunction catalysts using a hydrothermal coprecipitation method followed by sol immobilization of metallic nanoparticles. The structures and morphologies of the synthesized nanocomposites were analyzed using FTIR, XRD, XPS, BET, FESEM-EDX, and HRTEM. The catalytic effectiveness of the samples was evaluated by tracking the progression of NaBH4-mediated nitrobenzene (NB) reduction to aniline and CO oxidation using UV-visible spectrophotometry and an infrared gas analyzer, respectively. Pd@NiCr LDH displayed much higher performance for both reactions than the bare NiCr LDH. The catalyst Pd@NiCr LDH showed robust catalytic activity in both the oxidation of carbon monoxide (T50% (136.1 °C) and T100% (200.2 °C)) and NaBH4-mediated nitrobenzene reduction (98.7% conversion and 0.365 min-1 rate constant). The results disclose that the Ni2+@ Cr3+/Cr6+ @Pd° ion pairs inside the LDH act as a charge transfer center and hence significantly enhance the catalytic performance. As a result, this research offers the novel NiCr LDH catalyst as a bifunctional catalyst for air depollution control and the organic transformation process.

UV light-driven late-stage skeletal reorganization to diverse limonoid frameworks: A proof of concept for photobiosynthesis.

Late-stage skeletal reorganization (LSSR) is a type of fascinating organic transformation processes in natural product total synthesis. However, few facile and effective LSSR methodologies have hitherto been developed. Here, LSSR of limonoid natural products via photochemical cascades is first reported. Starting from xyloelves A and B, nine distinct limonoid products with five unprecedented scaffolds are generated. The photocascade pathways of these natural products and mechanistic rationale via intramolecular triplet energy transfer are revealed by quantum mechanical calculations. Most notably, ultraviolet light-driven transannular and stereoselective C→C 1,4-acyl migration is first found as a photochemical approach, particularly for LSSR of natural products. This approach holds promise for designing LSSR strategies to access bioactive cage-like molecules. Besides that, our findings provide a clear proof of concept for natural product photobiosynthesis. Xyloelf A, substantially ameliorating concanavalin A-induced liver injury in mice, could be used as a unique molecular template for hepatoprotective drug discovery.

Fe3O4-carbon spheres core–shell supported palladium nanoparticles: A robust and recyclable catalyst for suzuki coupling reaction

Suzuki-Miyaura (S-M) is regarded the most powerful way for synthesis biaryls, triaryls, or incorporating of substituted aryl moieties in organic preparation by the cross-coupling of aryl boronic acid with aryl halides using the Pd catalyst. This work reports the combining of the hydrothermal and microwave-assisted protocol to convert the glucose to magnetic carbon spheres (Fe3O4-CSPs) decorated with Pd nanoparticles (NPs) as the catalyst for Suzuki-Miyaura cross-coupling reactions. The physicochemical properties in the produced composite were examined using FESEM, HRTEM, nitrogen isotherms, Raman spectroscopy, FTIR, XPS, and XRD. The as-fabricated composite Pd/Fe3O4-CSPs is mostly spherical with a core–shell structure and possesses a great surface area of 253.2 m2·g−1. Its catalytic performance demonstrates that the composite has excellent stability and high tolerance Suzuki-Miyaura cross-coupling reactions in 30 min at 80 °C. Both activated and deactivated aryl halides provided excellent yield. The as-fabricated catalyst was recycled for up to four catalytic cycles without a substantial decline in performance. Moreover, this research offers a facile roadmap for synthesizing Pd/Fe3O4-CSPs composites and promoting the practical implementation of Pd/Fe3O4-CSPs catalysts for organic transformation processes.

Coinage Metal-Catalyzed Asymmetric Reactions of ortho-Alkynylaryl and Heteroaryl Aldehydes and Ketones.

Coinage metals have become the metal of choice due to their excellent catalytic activity in organic transformation processes. Combining various chiral ligands and coinage metals became a productive area of research and access to heterocyclic derivatives according to an efficient and sustainable manner. This review was devoted to the various recently developed coinage metal-catalyzed domino processes of ortho-alkynylaryl and heteroaryl aldehydes and ketones leading to functionalized heterocycles. Various gold chiral complexes were presented, and methods of preparations of chromenes along with indoles were covered. Ag-chiral complexes are also prone to interesting activities such as cyclization followed by reduction and functionalization with enolizable ketones or (diazomethyl)phosphonate. Asymmetric Cu-catalyzed domino cyclization and asymmetric transfer hydrogenation reactions efficiently led to functionalized chromenes. Some remarkable examples involving copper associated with ruthenium in the context of a cyclization and asymmetric hydrogenation process were also presented.

Graphene–TiO2 nanocomposite photocatalysts for selective organic synthesis in water under simulated solar light irradiation

Heterogeneous photocatalysis offers a promising route to realize green oxidation processes in organic synthesis because such selective organic transformation processes can be enabled under solar light irradiation with ambient conditions. In this research, graphene–TiO2 nanocomposites have been utilized for aerobic selective oxidation of benzylic alcohols to corresponding aldehydes and acids in water under simulated solar light irradiation. The photocatalytic performance and related properties of solvent exfoliated graphene–TiO2 (SEG–TiO2) and reduced graphene oxide–TiO2 (RGO–TiO2) have been comparatively studied. It has been found that decreasing the defect density of graphene, by using SEG instead of graphene oxide (GO) as the precursor of RGO, can enhance the photoactivity of graphene–TiO2 nanocomposites due to the improved electron conductivity of SEG as compared to that of RGO. It is hoped that this work would stimulate further interest in utilizing graphene–semiconductor nanocomposite photocatalysts in the field of green-chemistry-oriented photocatalytic selective organic transformation.

High temperature reactions of water with heavy oil and bitumen: Insights into aquathermolysis chemistry during steam-assisted recovery

To better understand the hot water-mediated organic transformation process (aquathermolysis) that occurs during the steam-assisted recovery of heavy oils and bitumen we have performed a series of experiments that subject a heavy oil to progressively higher temperatures and pressures in the presence of liquid water. As temperature and pressure increases, from ambient conditions to 300°C and 1250 psig (8.6MPa), a floating oil (flotate) is generated and is composed of mostly aliphatic hydrocarbons that appear to be generated at the expense of polars and asphaltenes. Analyses of hopane maturity parameters for the flotate indicate lower temperatures than the starting material suggesting the liberation of hopanes and, therefore, other hydrocarbons, from asphaltenes. Infrared spectra confirm changes in overall organic constitution as the relative abundance of hydrocarbons to oxygen-containing functional groups increases in the flotate. At the highest temperatures and pressures (325°C, 1750 psig (13.8MPa)) the flotate is at a maximum relative amount, the untransformed heavy oil is at a minimum and significant amounts of methane are generated indicating the onset of cracking. Steam-assisted recovery of heavy oil, therefore, leads to changes in the chemical constitution of a number of chemical fractions generating a lighter oil and gases that must be taken into account when planning field operations for production.

ChemInform Abstract: Development of Ceria‐Supported Ruthenium Catalysts for Green Organic Transformation Processes

AbstractReview: 82 refs.

Development of Novel Heterogeneous Catalyst Using Inorganic Ion Exchanger and Their Applications for Green Organic Transformation Process

高機能固体触媒の開発には，ターゲットとする反応に応じて触媒活性点近傍の構造や電子的状態を原子レベルで精密に制御する必要がある。我々は，Layered Hydroxy Double Salt の一種である Ni-Zn 複塩基性塩（NiZn), Ni1-xZn2x(CH3COO−)2x(OH)2·nH2O, のユニークな特性に注目し，触媒担体あるいはそれ自体を触媒とする斬新な触媒設計を行ってきた。本稿では，不安定なアニオン性遷移金属水酸化物錯体をアニオン交換によって NiZn 層間内へ安定担持する触媒設計や，反応場となる NiZn 層間スペースを精密制御する触媒設計，NiZn の構造中の孤立カチオンを Lewis 酸点として利用する触媒設計についてその概要を述べる。開発した触媒は，酸素分子を酸化剤とするアルコール類の酸化反応やホウ素化合物とエノン類の高効率 1,4-付加反応，水溶媒中での Knoevenagel 縮合反応や CO2 のエポキシドへの化学的固定化反応など，環境調和型物質変換反応へ応用した結果についても紹介する。