Oxidation Of Alcohols Research Articles

Electrochemical and Non-Electrochemical Pathways in the Electrocatalytic Oxidation of Monosaccharides and Related Sugar Alcohols into Valuable Products.

In this contribution, we review the electrochemical upgrading of saccharides (e.g., glucose) and sugar alcohols (e.g., glycerol) on metal and metal-oxide electrodes by drawing conclusions on common trends and differences between these two important classes of biobased compounds. For this purpose, we critically review the literature on the electrocatalytic oxidation of saccharides and sugar alcohols, seeking trends in the effect of reaction conditions and electrocatalyst design on the selectivity for the oxidation of specific functional groups toward value-added compounds. Importantly, we highlight and discuss the competition between electrochemical and non-electrochemical pathways. This is a crucial and yet often neglected aspect that should be taken into account and optimized for achieving the efficient electrocatalytic conversion of monosaccharides and related sugar alcohols into valuable products, which is a target of growing interest in the context of the electrification of the chemical industry combined with the utilization of renewable feedstock.

Methanol, ethylene glycol, and glycerol photoelectrochemical oxidation reactions on BiVO4: Zr,Mo/Pt thin films: A comparative study

The green H2 production plays a key role in the energy transition, however it still needs improvements to be applied in a large scale. The water oxidation reaction, as an anodic process to provide both protons and electrons for H2 production, possesses kinetic limitations. Therefore, the use of an alternative process like the oxidation of biomass-derivative species is extremely desired to replace water oxidation during H2 production. In this work, we provide a comparative study of different small organic molecules (methanol, ethylene glycol (EG), and glycerol) as alternatives to water oxidation at pristine BiVO4, Mo-Zr dopped BiVO4, and Pt co-catalyst BiVO4 photoanodes in neutral media. While the band energy diagram and surface morphology are similar for the distinct materials, the presence of Zr-Mo increases the charge carriers density. The presence of Pt acts as co-catalyst for the organic molecules. Regardless of the material employed, the activity order for each organic molecule reaction was: jwater< jmethanol < jEG < jglycerol affeered by both linear potential sweep and chronoamperometry at 1.23 V vs RHE. The presence of both Zr-Mo and Pt increases the photoactivity for the alcohol's oxidation, however the presence of Pt is more advantageous for glycerol oxidation than for other species, maintaining 80 % of activity after 24 h electrolysis. The reactivity of alcohols can be tentatively explained by the greater stability of radicals formed from larger molecules.

Ex Situ Electro‐Organic Synthesis – A Method for Unrestricted Reaction Control and New Options for Paired Electrolysis

AbstractClassic in situ electro‐organic synthesis with substrates in an electrolyzer must compromise process conditions to balance electro‐ and thermochemical steps at both electrodes. This often restricts efficiency and product selectivity, since requirements may deviate for electrochemical (catalyst activation) and chemical (organic synthesis) steps, as well as for paired anode‐ and cathode reactions. Breaking this barrier, we report ex situ electro‐organic synthesis as a versatile method that enables unique product selectivity and unusual product pairs. We exemplify the concept for pairing H2 evolution (HER) with anodic alcohol oxidation. The two‐step method accomplishes this by separating cathode reactions from organic substrate oxidation, and anodic electrocatalyst activation from chemical conversion of organic substrates in time and space. First, the electro‐oxidation of Ni(OH)2 anodes to NiOOH is paired with H2 production by alkaline water electrolysis. Then, “charged” NiOOH electrodes are removed from the electrolyzer and used in external vessels to oxidize model substrate benzyl alcohol under regeneration of Ni(OH)2. Free choice of reaction media outside the electrolyzer allows to selectively obtain benzoic acid (in water) or benzaldehyde (in n‐hexane), whereas classic in situ electrosynthesis only produces the acid together with H2. Perspectively, the method enables electrosynthesis of previously inaccessible products paired to H2 generation.

TEMPO‐Catalyzed Continuous‐Flow Aerobic Oxidations of Alcohols on Silica

Abstract2,2,6,6′‐Tetramethylpiperidine‐N‐oxyl (TEMPO) is a highly efficient oxidation catalyst, valued for its environmentally benign nature, particularly in comparison to transition‐metal catalysts. Despite their merits, TEMPO‐based catalysts are not notably cost‐effective. Immobilization of TEMPO onto supports offers a promising strategy to overcome this limitation. In this work, we present the synthesis and application of immobilized TEMPO catalysts 2–5, prepared via a straightforward condensation reaction, for the aerobic oxidation of alcohols. These catalysts demonstrate remarkable activity for alcohol oxidations under continuous‐flow conditions, employing nitric acid as the co‐catalyst. Notably, catalyst 2 immobilized by COOH silica gel exhibits outstanding performance for the oxidation of benzyl alcohol by oxygen gas, achieving a turnover frequency (TOF) of 15 h−1 and a turnover number (TON) exceeding 300. Catalyst 2 further demonstrates broad substrate scope, effectively oxidizing primary, secondary, and benzylic alcohols. Post‐reaction analysis of spent catalyst 2 reveals that deactivation primarily stems from nitrosation of the N−O bond. Interestingly, the amide moiety remains intact despite the harsh acidic reaction conditions.

Generation of Triplet States by Host‐Stabilized Through‐Space Conjugation for the Construction of Efficient Supramolecular Photocatalysts

AbstractPromoting the generation of triplet states is essential for developing efficient photocatalytic systems. This research presents a novel approach of host‐stabilized through‐space conjugation via the combination of covalent and non‐covalent methods. The designed building block, 4,4′‐(1,4(1,4)‐dibenzene cyclohexaphane‐1,4‐diyl)bis(1‐phenylpyridinium) chloride, features inherently stable through‐space conjugation. When this block forms a 1 : 1 host–guest complex with cucurbit[8]uril, the through‐space conjugation is further stabilized within the confined cavity. Both the generation and lifetime of triplet state are significantly increased, resulting from the host‐stabilized through‐space conjugation. Additionally, the ultrahigh binding constant of 6.58×1014 M−1 ensures the persistence of host‐stabilization effect. As a result, the host–guest complex acts as a highly efficient catalyst in the photocatalytic oxidation of thioether and aromatic alcohol. In the photodegradation of lignin, a complex natural product, the host–guest complex also exhibits high efficiency, demonstrating its robustness. This line of research is anticipated to enrich the toolbox of supramolecular photochemistry and provide a strategy for fabricating efficient supramolecular photocatalysts.

Assessment of Quality of Life of Caregivers of Patient with Alcoholic Liberty Disease

Alcoholic liver disease (ALD) is a progressive condition resulting from chronic and excessive alcohol consumption, leading to liver cell damage. Although the liver is the primary site for alcohol oxidation, a small amount is also metabolized in the stomach. Ethanol metabolism primarily produces acetaldehyde, a toxic byproduct responsible for symptoms such as facial flushing, headaches, nausea, and increased heart rate, all of which contribute to the development of ALD. The risk of developing ALD varies among individuals, but it generally increases with alcohol intake beyond certain thresholds: more than two standard drinks per day for men and more than one standard drink per day for women. Alcoholic liver disease (ALD) can progress to fibrosis and cirrhosis, potentially leading to liver infection. The prevalence of ALD fluctuates over time and varies by region due to factors such as alcohol consumption patterns, healthcare accessibility, and public health initiatives. ALD poses a significant global health challenge, highlighting the need for increased awareness about the dangers of excessive alcohol consumption and the promotion of responsible drinking practices. Medical guidance and support are essential in educating individuals about the risks of overconsumption. According to the latest surveillance report from the National Institute on Alcohol Abuse and Alcoholism, liver cirrhosis ranked as the 12th leading cause of death in the United States in 2007, with 29,925 deaths, nearly 48% of which were alcohol-related.

Sugar alcohol degradation in Archaea: uptake and degradation of mannitol and sorbitol in Haloarcula hispanica

The halophilic archaeon Haloarcula hispanica utilizes the sugar alcohols mannitol and sorbitol as carbon and energy sources. Genes, enzymes, and transcriptional regulators involved in uptake and degradation of these sugar alcohols were identified by growth experiments with deletion mutants and enzyme characterization. It is shown that both mannitol and sorbitol are taken up via a single ABC transporter of the CUT1 transporter family. Then, mannitol and sorbitol are oxidized to fructose by two distinct dehydrogenases. Fructose is further phosphorylated to fructose-1-phosphate by a haloarchaeal ketohexokinase, providing the first evidence for a physiological function of ketohexokinase in prokaryotes. Finally, fructose-1-phosphate is phosphorylated via fructose-1-phosphate kinase to fructose-1,6-bisphosphate, which is cleaved to triosephosphates by a Class I fructose-1,6-bisphosphate aldolase. Two distinct transcriptional regulators, acting as activators, have been identified: an IclR-like regulator involved in activating genes for sugar alcohol uptake and oxidation to fructose, and a GfcR-like regulator that likely activates genes involved in the degradation of fructose to pyruvate. This is the first comprehensive analysis of a sugar alcohol degradation pathway in Archaea.

The Swiss Army Knife of Electrodes: Pillar[6]arene-Modified Electrodes for Molecular Electrocatalysis Over a Wide pH Range.

Molecularly-modified electrode materials that maintain stability over a broad pH range are rare. Typically, each electrochemical transformation necessitates a specifically tuned system to achieve strong binding and high activity of the catalyst. Here, we report the functionalisation of mesoporous indium tin oxide (mITO) electrodes with the macrocyclic host molecule pillar[6]arene (PA[6]). These electrodes are stable within the pH range of 2.4-10.8 and can be equipped with electrochemically active ruthenium complexes through host-guest interactions to perform various oxidation reactions. Benzyl alcohol oxidation serves as a model reaction in acidic media, while ammonia oxidation is conducted to assess the systems performance under basic conditions. PA[6]-modified electrodes demonstrate catalytic activity for both reactions when complexed to different guest molecules and can be reused by reabsorption of the catalyst after its degradation. Furthermore, the system can be employed to perform subsequent reactions in electrolyte with varying pH, enabling the same electrode to be utilised in multiple different electrocatalytic reactions.

The Swiss Army Knife of Electrodes: Pillar[6]arene‐Modified Electrodes for Molecular Electrocatalysis Over a Wide pH Range

AbstractMolecularly‐modified electrode materials that maintain stability over a broad pH range are rare. Typically, each electrochemical transformation necessitates a specifically tuned system to achieve strong binding and high activity of the catalyst. Here, we report the functionalisation of mesoporous indium tin oxide (mITO) electrodes with the macrocyclic host molecule pillar[6]arene (PA[6]). These electrodes are stable within the pH range of 2.4–10.8 and can be equipped with electrochemically active ruthenium complexes through host–guest interactions to perform various oxidation reactions. Benzyl alcohol oxidation serves as a model reaction in acidic media, while ammonia oxidation is conducted to assess the systems performance under basic conditions. PA[6]‐modified electrodes demonstrate catalytic activity for both reactions when complexed to different guest molecules and can be reused by reabsorption of the catalyst after its degradation. Furthermore, the system can be employed to perform subsequent reactions in electrolyte with varying pH, enabling the same electrode to be utilised in multiple different electrocatalytic reactions.

Trace Ru Incorporation Boosted Co2P Nanorods for Superior Water Electrolysis and Substrate-Paired Electrolysis Toward Value-Added Chemicals in Alkaline Medium.

Electro-valorization of biomass-derived chemicals has ensured sustainable production of value-added products, an effective approach for reducing carbon footprint, through renewable energy. Electrochemical oxidation and reduction reactions in aqueous media using H2O as a potential source for active hydrogenated and oxygenated species fulfill the purpose. In this study, Ru─Co2P nanorods are explored as a bifunctional electrocatalyst toward valorization of Organics at basic media. The in-situ electrogenerated Co3+ and Co4+ species act as active oxidants toward product selectivity. An overpotential of 68mV is found for hydrogen evolution reaction (1m NaOH) with Ru─Co2P. Further, used as cathode, Ru─Co2P effectively reduces furfuraldehyde to furfuryl alcohol and p-nitrophenol to p-aminophenol. Ru doping enables ease of formation of active species both for reduction and oxidation, faster charge transfer between catalyst to absorbates. Density Functional Theory calculation establishes Ru incorporation in Co2P surface results in enhanced adsorption of substrates. Ru doping modulates the electronic structure of Co2P which changes the density of states resulting in faster water dissociation and water splitting. To reach 10mAcm-2 current density only 1.6V is required for water electrolysis, whereas 1.4V is enough for substrate-paired electrolysis with simultaneous oxidation of benzyl alcohol and reduction of p-nitro phenol.

Advancements in Primary Alcohol Oxidation Leading to Carboxylic Acids: A Detailed Review

This review article explores the direct oxidation of primary alcohols into carboxylic acids, highlighting its importance in organic synthesis for producing valuable chemicals in a sustainable and efficient manner. Carboxylic acids are widely employed in a wide range of applications, encompassing food preservatives, insecticides, dye intermediates, coatings, plasticizers, spices, flavors, scents, and a variety of industries such as polymers, solvents, and medications. This review article covers recent advancements in catalytic systems, including catalysts based on transition metals, organocatalysts, nanocatalysts, and electrochemical methods. It examines the impact of reaction conditions such as solvents, temperature, and substrate scope on these processes. The review also delves into mechanistic insights and recent developments in tandem and cascade reactions, aiming to provide a comprehensive understanding of current strategies and future research directions in this field.

Regulating Chlorine and Hydrogen Atom Transfer for Selective Photoelectrochemical C─C Coupling by Cu-coordination Effect at Semiconductor/Electrolyte Interfaces.

Semiconductor-based photoelectrochemical (PEC) organic transformations usually show radical characteristics, in which the reaction selectivity is often difficult to precisely control due to the nonselectivity of radicals. Accordingly, several simple organic reactions (e.g., oxidations of alcohols, aldehydes, and other small molecules) have been widely studied, while more complicated processes like C─C coupling remain challenging. Herein, a synergistic heterogeneous/homogeneous PEC strategy is developed to achieve a controllable radical-induced C─C coupling reaction mediated by the copper-coordination effect at the semiconductor/electrolyte interfaces, which additionally exerts a significant impact on the product regioselectivity. Through experimental studies and theoretical simulations, this study reveals that the copper-chloride complex effectively regulates the formation of chloride radicals, a typical hydrogen atom transfer agent, on semiconductor surfaces and stabilizes the heterogeneous interfaces by suppressing the radical-induced surface passivation. Taking the Minisci reaction (the coupling between 2-phenylquinoline and cyclohexane) as a model, the yield of the target C─C coupling product reaches up to 90% on TiO2 photoanodes with a selectivity of 95% and long-term stability over 100h. Moreover, such a strategy exhibits a broad scope and can be used for the functionalization of various heteroaromatic hydrocarbons.

Novel Inorganic-Organic Dual-Photosensitizing Dinuclear-Metal Self-Assembly System for Efficient Artificial Photosynthesis without Sacrificial Electron Donors.

Owing to the unique synergistic effect, dinuclear-metal-molecule-catalysts (DMCs) show excellent performance in catalytic fields. However, for overall photocatalytic CO2 reaction (CO2RR), it is still a challenge to construct well-matched photosensitizer (PS) components for DMCs-based photocatalysts. Inorganic-quantum-dot PS possesses capacities of multiple exciton generation and catalyzing water oxidation but is incompatible with DMCs. In contrast, organic PS can be covalently linked with DMCs but inescapable of using sacrificial electron donors. For overall photocatalytic CO2RR, organic-inorganic dual-photosensitizing system might be a promising candidate. Herein, we employed covalent-linking and electrostatic-driven approaches to construct the self-assembly of pyrene-sensitized Co2L DMCs (Py-Co2L) and perovskite (PVK) quantum dots, i.e., PVK@[Py-Co2L]. Using H2O as an electron donor, PVK@[Py-Co2L] realized 105.24 μmol·g-1·h-1 CO yield in photocatalytic CO2RR, much higher than PVK (15.44 μmol·g-1·h-1) and PVK@Co2L (32.30 μmol·g-1·h-1), ascribing to the efficient photogenerated charge separation and transfer. The experimental results and theoretical investigations demonstrated that the pyrene linked on Co2L boosted the electron delivery from PVK to DMCs. Besides, this strategy could also be extended to the photocatalytic H2 evolution coupled with alcohol oxidation. As a proof-of-concept, our work lightens the integration of DMCs, organic and inorganic PS components, promoting the development of photocatalysis without sacrificial electron donors.

Unraveling the roles of atomically-dispersed Au in boosting photocatalytic CO2 reduction and aryl alcohol oxidation

Atomically-dispersed metal-based materials represent an emerging class of photocatalysts attributed to their high catalytic activity, abundant surface active sites, and efficient charge separation. Nevertheless, the roles of different forms of atomically-dispersed metals (i.e., single-atoms and atomic clusters) in photocatalytic reactions remain ambiguous. Herein, we developed an ethylenediamine (EDA)-assisted reduction method to controllably synthesize atomically dispersed Au in the forms of Au single atoms (AuSA), Au clusters (AuC), and a mixed-phase of AuSA and AuC (AuSA+C) on CdS. In addition, we elucidate the synergistic effect of AuSA and AuC in enhancing the photocatalytic performance of CdS substrates for simultaneous CO2 reduction and aryl alcohol oxidation. Specifically, AuSA can effectively lower the energy barrier for the CO2→*COOH conversion, while AuC can enhance the adsorption of alcohols and reduce the energy barrier for dehydrogenation. As a result, the AuSA and AuC co-loaded CdS show impressive overall photocatalytic CO2 conversion performance, achieving remarkable CO and BAD production rates of 4.43 and 4.71 mmol g−1 h−1, with the selectivities of 93% and 99%, respectively. More importantly, the solar-to-chemical conversion efficiency of AuSA+C/CdS reaches 0.57%, which is over fivefold higher than the typical solar-to-biomass conversion efficiency found in nature (ca. 0.1%). This study comprehensively describes the roles of different forms of atomically-dispersed metals and their synergistic effects in photocatalytic reactions, which is anticipated to pave a new avenue in energy and environmental applications.

Fabrication of CdIn2S4/ZnS S-scheme heterojunction via in-situ phase transformation for boosting photocatalytic conversion of organic compounds

Developing efficient photocatalysts is one of green and low cost tactic for addressing the environmental deterioration and energy crisis. Therefore, it remains a fantastic and important strategy to design an efficient junction between different semiconductors for harvesting solar light, boosting the redox capability. Herein, the fabrication of ZnS in situ decorated CdIn2S4 (referred to as CIS-Zx) were prepared by converting ZnS particles on Cd2In4S surface by a facile cation exchange method during solvothermal synthesis. According to a series of PEC measurements and DFT calculations, the bending of band edge as well as the establishing of built-in electric field in the interface of CIS/ZnS heterojunction were concluded, causing the formation of in-situ S-scheme heterojunctions in CdIn2S4/ZnS. The in-situ S-scheme heterojunctions can effectively ameliorate the migration behaviors of photo-generated charges. Compared with pure CdInS4, ZnS and physically mixed CdIn2S4/ZnS, the CIS-Zxin-situ S-scheme heterojunction exhibits efficient photocatalytic activity and stability in the selective reduction of aromatic nitro compounds and oxidation of aromatic alcohols, it is hoped that this work will open up a new avenue for innovative applications of in-situ S-scheme heterojunctions.

The Adaptative Modulation of the Phosphinito–Phosphinous Acid Ligand: Computational Illustration Through Palladium-Catalyzed Alcohol Oxidation

The phosphinito–phosphinous acid ligand (PAP) is a singular bidentate-like self-assembled ligand exhibiting dissymmetric but interchangeable electronic properties. This unusual structure has been used for the generation of active palladium hydride through alcohol oxidation. In this paper, we report the first theoretical highlight of the adaptative modulation ability of this ligand within a direct H-abstraction path for Pd and Pt catalyzed alcohol oxidation. A reaction forces study revealed rearrangements in the ligand self-assembling system triggered by a simple proton shift to promote the metal hydride generation via concerted six-center mechanism. We unveil here the peculiar behavior of the phosphinito–phosphinous acid ligand in this catalysis.

Perspectives on Photocatalytic Paper‐Based Batteries Fueled by Alcohol

AbstractAmid growing energy demands, innovative solutions are essential to power a variety of devices. Paper‐based microfluidic fuel cells (PμFCs), powered by eco‐friendly alcohols derived from biomass, present a promising option. While lightweight and disposable, they mainly rely on costly noble‐metal catalysts for high efficiency. In this context, the concept of photo paper batteries (pPBs), utilizing affordable sunlight‐activated semiconductors to drive alcohol oxidation on paper, opens the possibility to disposable and affordable energy solutions. Our review highlights recent progress in PμFCs fueled by alcohols like methanol, ethanol, ethylene glycol, and glycerol. We explore semiconductor advancements driving anodic reactions and envision the potential of pPBs. To achieve practical pPBs, refining semiconductors, electrode design, and microfluidic engineering are pivotal. This short review highlights the transformative potential of pPBs and beckons researchers to partake in shaping this new field.

Efficient and selective photocatalytic oxidation of benzylic alcohols with built-in electric field CsPbBr3/SiO2 nanocomposites through Fe3+ gradient doping

Lead halide perovskite nanocrystals (PNCs) have emerged as promising materials for photocatalysis due to their exceptional optoelectronic properties, yet achieving efficient charge separation and selective oxidation reactions remains a significant challenge. In this study, we report the synthesis of Fe3+-doped CsPbBr3/SiO2 nanocomposites (Fe-PNCs/SNPs) with gradient energy levels, designed to enhance photocatalytic performance. Our results demonstrate that Fe3+ doping introduces mid-gap states, promotes photoinduced charge separation, and generates reactive oxygen species (ROS) such as O2− and OH radicals under sunlight-simulating light irradiation from a 300 W Xe arc lamp. The Fe20-PNCs/SNPs catalyst achieved over 99 % conversion of benzyl alcohol to benzaldehyde with high selectivity and stability in the ethanol under ambient conditions. Additionally, the catalyst exhibited excellent recyclability and broad substrate tolerance. These findings highlight the innovative design of gradient energy levels in perovskite nanocomposites, offering a new strategy for enhancing photocatalytic efficiency in selective organic transformations.

Unleashing the synergistic potential of 2D-2D nanosheet based S-scheme heterojunction: Cooperative boosting of CO2 reduction to solar fuel and biomass valorization.

Harnessing inexhaustible solar energy for CO2 valorization is substantial step toward achieving carbon-neutral energy cycle. However, CO2 conversion often exhibits slow kinetics, necessitating the utilization of sacrificial agents making the process economically unfeasible. In the ongoing quest for sustainable and economically feasible CO2 valorization, herein the photoreduction of CO2 to CO coupled with biomass-based alcohol oxidation to fine chemicals is reported via Bi2WO6/g-C3N4 (BWO/g-CN) 2D-2D nanosheet based S-scheme heterojunction. Importantly, BWO/g-CN-60 exhibits highest photocatalytic activity with CO production rate of 6.87 mmol g-1 h-1, accompanied by >98% selectivity and selective oxidation of veratryl alcohol to veratraldehyde, with notable yield of 42% in 6 h under simulated solar light. The apparent quantum yield (AQY) of 14.3% is achieved for CO production at the wavelength of 420 nm. Additionally, the formed heterostructure results in enhanced charge separation and accelerated charge transfer kinetics as validated by PL, EIS, and photocurrent studies. EPR, 13CO2 labeling, DFT studies, and various controlled experiments provided deeper insight into the mechanism of underlying photo-redox process. Thus, the current study presents a sustainable paradigm for CO2 mitigation by converting it into solar fuel, while synergistically producing the fine chemicals through effectively harnessing the full potential of charge carriers.

Aerobic Oxidation of Vanillyl Alcohol to Vanillin Over CeO2‐Co3O4 Catalyst

AbstractA promising CeO2‐Co3O4 (9 : 1 mole ratio based on oxides) non‐noble metal based mixed oxide catalyst was explored for selective oxidation of vanillyl alcohol with molecular oxygen to produce vanillin under atmosphere pressure. In particular, to enhance its efficiency, this catalyst was prepared by adopting different preparation methods namely, template assisted, coprecipitation with and without surfactant, wet‐impregnation, and solution combustion. The prepared catalysts were characterized by XRD, Raman, BET surface area, ICP‐OES, FE‐SEM, HR‐TEM, H2‐TPR, and XPS. Among various catalysts investigated, the template assisted synthesized catalyst exhibited superior activity (100 % conversion and selectivity) and high stability. The better activity of this catalyst was found to be due to reduced crystallite size, high specific surface area (92 m2/g), more surface oxygen, and improved redox behaviour as confirmed from XRD, BET surface area, XPS, and H2‐TPR analysis, respectively. The stability of the catalyst was tested by reusability test and was observed that there is not much decrease in the catalytic activity up to five cycles. Further, the catalytic activity was optimized by varying the reaction parameters such as time, solvent, temperature, and catalyst weight.