Aerobic Oxidation Of Alcohols Research Articles

Musa acuminata free tepal (MAFT) crop- mediated synthesis of copper oxide nanocatalyst (MAFT-CuO nanocatalyst): Investigation of aerobic oxidation and dye decolourization via eco-friendly approach

Crop development is used to address environmental problems in the industry. Environmental pollutants, particularly humble or toxic chemicals and dyes, are contaminants in industrial wastewater. Recently, green technology has become important for controlling the chemical risks associated with environmental issues. This study focused on valuable crop materials to form green catalysts that can be used to control chemical toxicity in industrial wastewater. In this study, Musa acuminata-free tepal (MAFT) crops and musa were used to mediate the formation of copper nanocatalyst for environmental pollution. The synthesised nanocatalyst was analysed by XPS, XRD, TEM, SEM, FT-IR, GC-EI-MS, and TGA-DSC. The production of Cu–O in the 512 cm−1 peak range was verified by FT-IR analysis. The XRD peaks associated with the cubic crystalline structures of copper (110) and (200) were used to confirm the Musa acuminata-free tepal CuO nanocatalyst. The SEM images of the Cu and CuO nanocatalyst in the Musa acuminata free tepal showed that the particles were almost spherical. The size of the synthesised Musa acuminata free tepal CuO nanocatalyst core-shell nanostructures was identified using HR-TEM. GC-MS investigations also verified the aerobic oxidation of the main alcohol to aldehyde, with a retention time of 30.34. The MAFT was 80 % of CBB G250 dye decolourised at 24 h, and the MAFT-CuO nanocatalyst was decolourised the CBB G250 dye at 80 % in 20 min and aerobic oxidation at the same time (dual application). Furthermore, our nanocatalyst could be effectively recycled without significant loss of catalytic activity, and the use of safe, environmentally benign MAFT-Cu and CuO nanocatalyst is considered a green chemistry approach that helps avoid wastewater treatment. MAFT-Cu and CuO nanocatalyst were successfully synthesised using Musa acuminata free tepal extract assisted by reflux sample preparation system instruments as a new, green, eco-friendly, and fast process for nanocatalyst synthesis. In the past, there have been no reported applications of MAFT-Cu and CuO nanocatalyst for decolourisation and aerobic oxidation. Nevertheless, we were able to accomplish these procedures with the help of CuO and MAFT-Cu nanocatalyst. Therefore, the most effective naturally occurring environmental catalysts for aerobic oxidation processes are MAFT-CuO nanocatalyst. They are non-toxic and environmentally benign, exhibit strong aerobic oxidation catalytic performance, and have long-lasting benefits for water quality. Additionally, they are more recoverable and biodegradable.

Molecular Photocatalysts Based on Quinolinium-Grafted Polyoxometalates for Efficient One-Step Aerobic Oxidation of Benzyl Alcohols to Benzoic Acids

Molecular Photocatalysts Based on Quinolinium-Grafted Polyoxometalates for Efficient One-Step Aerobic Oxidation of Benzyl Alcohols to Benzoic Acids

Engineering MPC-Assisted Heterojunctional Photo-Oxidation Tailored by Interfacial Design of a P-Modulated C3N4 Heterojunction for Improved Aerobic Alcohol Oxidation.

The creation of two-dimensional van der Waals (VDW) heterostructures is a sophisticated approach to enhancing photocatalytic efficiency. However, challenges in electron transfer at the interfaces often arise in these heterostructures due to the varied structures and energy barriers of the components involved. This study presents a novel method for constructing a VDW heterostructure by inserting a phosphate group between copper phthalocyanine (CuPc) and boron-doped, nitrogen-deficient graphitic carbon nitride (BCN), referred to as Cu/PO4-BCN. This phosphate group serves as a charge mediator, enabling effective charge transfer within the heterostructure, thus facilitating electron flow from BCN to CuPc upon activation. As a result, the photogenerated electrons are effectively utilized by the catalytic Cu2+ core in CuPc, achieving a conversion efficiency of 96% for benzyl alcohol (BA) and a selectivity of 98.8% for benzyl aldehyde (BAD) in the presence of oxygen as the sole oxidant and under illumination. Notably, the production rate of BAD is almost 8 times higher than that observed with BCN alone and remains stable over five cycles. The introduction of interfacial mediators to enhance electron transfer represents a pioneering and efficient strategy in the design of photocatalysts, enabling the proficient transformation of BA into valuable derivatives.

Oxygen vacancy engineering via doping Sr at the La-site of LaMnO3 to promote the ability for aerobic oxidation of benzyl alcohol

Aerobic selective oxidation is a prospective route to synthesize fine chemicals and their intermediates in modern industries, yet the development of an efficient catalyst remains a challenge, due to the limitations in O2 adsorption and activation. Herein, we report a promising La1-xSrxMnO3 (LSMO-x) perovskite oxide for aerobic oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) via oxygen vacancy engineering. Through the substitution of Sr at the La-site of LaMnO3, the quantity of oxygen vacancies, which are active site of molecular oxygen, is greatly increased, thereby improving the efficiency for oxygen activation and the reaction activity. The optimal catalyst, LSMO-0.15, shows BzOH conversion of 97.0 % and BzH selectivity of 93.4 %, at 50 °C, for 3 h. The importance of oxygen vacancy for the reaction is verified by DFT calculations, by comparing the adsorption energies of reactants on LaMnO3 containing with and without oxygen vacancy. A reaction mechanism is also proposed, in which the adsorption and activation of O2 occurs on the oxygen vacancy, and that of BzOH occurs on the Mn4+ ions. The activated O2 and BzOH then react with each other to release H2O and yield BzH.

Aerobic oxidation of aliphatic alcohol in cotton surface using epigallocatechin-3-gallate-iron (II, III) oxide (EGCG-Fe3O4) nanocatalyst from green tea extract

ABSTRACT This study involved the synthesis of epigallocatechin-3-gallate-Iron (II, III) oxide (EGCG- Fe3O4) nanocatalysts by reacting Fe2O3 with EGCG extracted from green tea (Camellia sinensis) aqueous extract. This environmentally friendly method was used as an alternative to traditional synthesis routes. The EGCG- Fe3O4 nanocatalysts were characterised using various techniques, including fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), BET Surface area analysis, analysis and vibrating sample magnetometer (VSM). The results showed that the Fe3O4 nanocatalyst absorption peak at 363 nm indicated the formation of the Fe3O4 nanocatalyst, while the EGCG absorption peak shifted slightly to 274 nm, indicating the formation of the EGCG nanocatalyst. The conversion of final product aliphatic aldehyde from aliphatic alcohol in cotton surface via a solvent free aerobic oxidation using EGCG-Fe3O4 nanocatalyst. The final product of aliphatic aldehyde was confirmed by 1H and 13C NMR. The molecular weight of the product was determined by mass spectral characterisation (EI-MS), which showed a molecular ion m/z of 72.06 (M+, 100%), which was confirmed by the molecular weight of isobutyraldehyde conforming to the molecular mass using EI-MS mass spectral analysis. This method has been used for aerobic oxidation of aliphatic alcohols in the textile and pharmaceutical industries and offers several advantages, including the use of environmentally friendly reaction conditions, reduced catalyst concentrations, high product yields, affordability, absence of solvents, and recovery and reuse of the EGCG-Fe3O4 nanocatalyst.

Low-temperature aerobic oxidation of alcohols to aldehydes over La1-xKxMnO3 nanofiber tubes: Issues on O2 adsorption and activation

Aerobic oxidation of alcohols to aldehydes is a green and prospective route to synthesize fine chemicals, but the high activation barrier and low solubility in organic solvents of O2 make this technology a challenge. Herein, we report an electrospinning synthesis of K doped LaMnO3 perovskite (La1-xKxMnO3), with nanofiber tube (NFT) structure, for efficient liquid-phase aerobic oxidation of alcohols to aldehydes at low temperature. The NFT structure improves the capacity of material to capture O2, the generated oxygen vacancy, caused by K doping, increases the sites to adsorb O2, and the evolved (110) lattice plane promotes the ability to activate O2. The optimized La0.95K0.05MnO3 shows above 93 % conversion and selectivity, even is conducted at 50 °C, for 3 h, which is the lowest temperature reported for aerobic oxidation of alcohols using noble metal-free catalysts. Simulated calculations suggest that the O-O bond can be automatically ruptured if O2 is adsorbed on the (110) lattice plane of the material.

Visible Light-Mediated Selective Aerobic Oxidation of Alcohols Catalyzed by Disulfide in Batch and Flow.

Selective aerobic oxidation of alcohols in batch and flow can be realized under light irradiation, utilizing disulfide as the photocatalyst, and a variety of primary and secondary alcohols were converted to the corresponding aldehydes or ketones in up to 99% yield and high selectivity. The reaction efficiency could be increased even further by combining a continuous-flow strategy. Detailed mechanistic studies have also been achieved to determine the role of oxygen and disulfides in this oxidation.

Aerobic benzyl alcohol oxidation by copper(I)(2,2′-bipyridine)-based catalysts

“In situ” prepared cationic Cu(I) complexes bearing 2,2’-bipyridine ligands and trifluoromethylsulfonate (triflate) have been used to catalyze the aerobic oxidation of benzyl alcohol to benzaldehyde in acetonitrile in the presence of (2,2,6,6-tetramethylpiperidin-1-yl) oxyl (TEMPO). A combination of catalytic reactions, operando1H NMR spectroscopic studies and the analysis of the molecular structure of the Cu(I) precatalysts in acetonitrile by means of DFT calculations shed light on the notable influence of counter-anion ligand interactions on the observed catalytic activity.

An In‐Situ‐Formed Copper‐Based Perfluorinated Catalytic System for the Aerobic Oxidation of Alcohols

AbstractHerein, we report a new catalytic protocol for the aerobic oxidation of alcohols. The catalytic system is formed in situ, in a straightforward and user‐friendly manner, combining a widely available copper source (Cu2O) with one imidazolium salt precursor bearing perfluorinated moieties. Our protocol uses TEMPO, as additive, and the reaction takes place at the interface of a biphasic solvent system, consisting of anisole and 1‐bromoperfluorooctane. The as‐prepared carbonyl compounds remain in the organic solvent, while the catalytic system remains in the fluorous phase. In this manner, the isolation and purification of the desired products are quite facile. Our protocol uses low catalytic loadings and is more efficient with primary alcohols, affording the desired products in good to excellent yields. The fluorous phase containing the catalytic system can be efficiently recovered and reused for at least six times, without a significant decrease in its catalytic efficiency.

Insight into the promotional effect of Ce doped in (FeCoNiCrMn)3O4 high entropy oxides for solvent-free aerobic oxidation of benzyl alcohol

It is desired but challenging to develop a non-noble metal catalyst for the selective oxidation of benzyl alcohol with O2 under solvent-free conditions. Herein, a series of Ce-doped high entropy oxides (Ce/HEOs) were prepared via co-precipitation and subsequent thermal treatment method. It was found that, the doping of Ce could remarkably promote the catalytic activity for selective oxidation of benzyl alcohol to benzaldehyde. The improved activity was ascribed to the good distribution of active Ce species, the increased oxygen vacancies, and the synergistic effect between CeO2 and high entropy oxides (HEOs). In addition, the surface oxygen of Ce/HEOs towards Ce displayed stronger reducibility compared to that of bare CeO2, endowing it stronger deprotonation ability towards benzyl alcohol during the reaction. The prepared catalyst exhibited satisfactory reusability and stability owing to the entropy-stabilized effect of HEOs and the interaction between CeO2 and HEOs, and negligible loss in catalytic activity was observed after seven runs. Besides, DFT calculations disclosed that, with the doping of Ce, the Ce/HEOs catalyst possessed stronger adsorption ability towards benzyl alcohol, and lower free energy was required for the rate-determining step during the whole oxidative reaction. This work gave some insights into the promotional effect of Ce doped into high entropy oxides for the solvent-free catalytic oxidation of benzyl alcohol.

Catalytic aerobic oxidation of lignin-based vanillyl alcohol over LaFeO3 perovskite towards vanillin production: Relationships between the activity and acid-base property as well as oxygen vacancy

Developing high-performance acid-base catalysis over perovskite for alcohol aerobic oxidation has received increasing attention, but the fundamental understanding of its surface acid-base property and performance relationship remains largely unknown. Accordingly, a series of LaFeO3 perovskites were fabricated via modified Pechini approach with the addition of different chelating agents to modulate their respective acid-base amount and oxygen vacancy concentration, which subsequently were employed in the aerobic oxidation of vanillyl alcohol (a lignin model), to generate vanillin for elucidating the relationships between the catalytic activity of LaFeO3 perovskite and its acid-base property as well as oxygen vacancy. The results demonstrated that existence of non-linear relationships between the vanillin yield and the acid-base amount as well as oxygen vacancy concentration of LaFeO3 catalyst. Moreover, neither acid-base sites nor oxygen vacancies were the solely factors affecting the activity of LaFeO3 perovskite towards vanillyl alcohol oxidation for vanillin production. Mechanism studies proclaimed that the reactive oxygen species derived from the adsorption of molecule oxygen on oxygen vacancies generated by anion defects combing with Lewis acid sites (Fe3+/Fe2+) to yield FeOx active pairs, which jointly dominated the pathway for vanillyl alcohol oxidation to produce vanillin. Overall, this work offers guidance for designing effective perovskite-based catalysts for lignin conversion to produce value-added chemicals by selectively modulating its acid-base property and oxygen vacancy.

Palladium-based pseudohomogeneous catalyst for highly selective aerobic oxidation of benzylic alcohols to aldehydes

This study presents a novel class of pseudohomogeneous catalysts (PHC) based on carbon quantum dots functionalized with terpyridine ligands (CQDs-Tpy) to immobilize and stabilize palladium nanoparticles (Pd NPs). Extensive characterization techniques clearly confirmed the successful stabilization of Pd NPs on CQDs-Tpy. The effectiveness of the catalyst was demonstrated in the selective aerobic oxidation of primary and secondary of benzylic alcohols to aldehydes in the absence of additives and phase transfer catalyst (PTC). Remarkably, the reactions predominantly yielded aldehydes without further oxidation to carboxylic acids. By employing low catalyst loadings (0.13 mol%), high conversions (up to 89%) and excellent selectivity (> 99%) of the aldehyde derivatives were achieved. Moreover, the CQDs-Tpy/Pd NPs catalyst displayed suitable catalytic activity and recyclability, offering potential economic advantages. This promising approach opens up new opportunities in the field of catalysis for designing subnanometric metal-based PHCs.

Retraction: Aqueous aerobic oxidation of alkyl arenes and alcohols catalyzed by copper(II) phthalocyanine supported on three-dimensional nitrogen-doped graphene at room temperature.

Retraction of 'Aqueous aerobic oxidation of alkyl arenes and alcohols catalyzed by copper(II) phthalocyanine supported on three-dimensional nitrogen-doped graphene at room temperature' by Mojtaba Mahyari et al., Chem. Commun., 2014, 50, 7855-7857, https://doi.org/10.1039/C4CC01406E.

Synthesis of a sustainable and robust heterogeneous TEMPO catalyst utilizing activated carbon for aerobic alcohol oxidation

Ozone-induced surface-carbonylation and reductive amination to construct stable TEMPO grafting on activated carbon with prominent durability and prolonged lifetime.

Catalytic Activity of Nonaggregating Cu Nanoparticles Supported in Pores of Zeolite for Aerobic Oxidation of Benzyl Alcohol.

Cu nanoparticles (NPs) as catalysts have the good advantage of being more abundant than noble metal NPs. In this study, we synthesized nonaggregating Cu NPs supported in Y-type zeolite by the photoreduction method. In this method, Cu ions in pores of zeolite can be slowly reduced with a small amount of reductant at room temperature. The high-resolution transmission electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction patterns, and UV-Vis spectra supported that nonaggregating Cu NPs existed in the pores of zeolite. Catalytic activities of Cu NP-zeolite were investigated for the aerobic oxidation of benzyl alcohol. Our Cu NP-zeolite had a large turnover frequency of 17 h-1. The yield of benzaldehyde increased in proportion to the amount of Cu loading at ≤0.5 wt %, indicating that Cu NPs in pores of zeolite work as catalysts for selective aerobic oxidation of benzyl alcohol. The high catalytic activity was brought by nonaggregating Cu NPs in pores of zeolite. The catalytic reaction for other aromatic alcohols with electron-donating groups proceeded, whereas it did not proceed for the aromatic alcohols with electron-withdrawing groups or aliphatic alcohols, indicating that the interaction between zeolite and the benzene ring also contributed to the reaction. This study would be expected to contribute to the development of Cu NP catalysts.

Porous Aromatic Framework Covalently Embedded with N‐Hydroxyphthalimide as Metal‐free Heterogeneous Catalyst for Highly Efficient and Selective Aerobic Oxidation

AbstractIdeal catalysts with all‐around advantages including high efficiency and selectivity, environment‐benign and good recyclability, etc. have been long‐sought yet challenging. Herein, the stable porous aromatic framework covalently embedded with N‐Hydroxyphthalimide (NHPI) organocatalytic site was constructed to establish an ideal catalytic system. The synthesized PAF‐NHPI catalyst was demonstrated to be metal‐free, highly efficient, selective, recyclable and heterogeneous for the aerobic oxidation of various alcohols, aldehydes, olefins, and hydrosilanes (totally 66 examples). As a proof‐of‐concept, the continuous PAF‐NHPI packed bed reactor achieved persistent conversion of 1‐phenylethanol to acetophenone up to 95 % yield. This work provides the inspiration for developing ideal catalysts in practical production of fine chemicals.

Copper on charcoal: TEMPO free Cu0 nanoparticles catalyzed aerobic oxidation of alcohols

A highly efficient and Tempo-free catalytic aerobic alcohol oxidation method has been developed using charcoal-supported Cu0 nanoparticles（Cu-A） in conjunction with pyridine. Various alcohols, bearing different functional groups, can be readily oxidized to their corresponding ketones and aldehydes under mild conditions.

Organic-inorganic hybridized Mo/Pd-based complexes as efficient catalysts for selective aerobic oxidation of benzyl alcohols

Organic-inorganic hybrid crystalline compounds have demonstrated outstanding potential utilization in a wide range of catalytic applications. Herein, three organic–inorganic hybrids Mo/Pd-based complexes Mo2O4(CF3COO)2(DMSO)4 (compound 1), Pd(C6H5CH2)2NCS2)2 (compound 2) and Pd[(CH3)2CHCH2NCS2]2 (compound 3) have been controllably synthesized and fully characterized. Remarkably, benefiting from coordinated solvent molecules, the dinuclear oxomolybdates 1 exhibits the efficient homogeneous catalytic activities for the selective aerobic oxidation of benzyl alcohols under ambient pressure (yields up to 90%). Moreover, compound 1 can be reused three cycles in the reactions without significant loss of activity and the possible catalytic mechanisms also be proposed.

Innovative development of hybrid nanocatalyst (ATH-ZnONPs) through green methods for achieving visible light-induced photocatalytic aerobic oxidation of benzyl alcohols into corresponding aldehydes and ketones

In recent research, there has been a surging interest in green methods for manufacturing metal oxide photocatalysts and enabling organic transformations in gentle conditions. This study achieved a groundbreaking development, introducing zinc oxide nanoparticles sensitized with anthocyanin dye (ATH-ZnONPs) for the very first time. The reducing agents in pomegranate leaves were utilized to synthesize ZnONPs from zinc salt. Simultaneously, anthocyanin dye was extracted from pomegranate flowers and linked with the ZnONPs. The FT-IR functional group analysis provided evidence of the successful conjugation of ZnONPs and ATH dye. SEM, EDX, and Elemental Mapping analysis unveiled the spherical morphology and nanocrystalline structure of ATH-ZnONPs, with particle sizes falling within the range of 50–70 nm. XRD analysis verified the hexagonal structural configuration of ZnONPs within the hybrid nanocomposite, with calculated lattice parameters of a = 3.261 Å and c = 5.207 Å. UV–Vis and DRS spectroscopy demonstrated that the composite efficiently harnesses visible light irradiation, exhibiting an energy bandgap of 2.22 eV. The assessment of ZnONPs through BET analysis unveiled a pore volume of 0.053 cm3/g, an SSA of 14.223 m2/g, and an average pore size of 4.18 nm, underscoring the mesoporous characteristics of ZnONPs. Importantly, the photocatalytic performance of the synthesized ATH-ZnONPs was thoroughly examined under blue LED light exposure. This investigation encompassed the evaluation of catalyst dosage, the impact of the light source, stability, regeneration, and the potential for reuse in the aerobic oxidation of benzyl alcohols, resulting in their corresponding aldehydes and ketones. 1HNMR and 13CNMR were used to characterize the products. The results of these studies highlight the versatile potential of this composite for a wide range of photocatalytic applications.

Flowerlike Nanosheet-Based High-Entropy Oxides as Catalysts for Aerobic Oxidation of Benzyl Alcohol

Flowerlike Nanosheet-Based High-Entropy Oxides as Catalysts for Aerobic Oxidation of Benzyl Alcohol