Oxidation Of Primary Alcohols Research Articles

Au/Pt Bimetallic Nanowires with Stepped Pt Sites for Enhanced C-C Cleavage in C2+ Alcohol Electro-oxidation Reactions.

Efficient C-C bond cleavage and oxidation of alcohols to CO2 is the key to developing highly efficient alcohol fuel cells for renewable energy applications. In this work, we report the synthesis of core/shell Au/Pt nanowires (NWs) with stepped Pt clusters deposited along the ultrathin (2.3 nm) stepped Au NWs as an active catalyst to effectively oxidize alcohols to CO2. The catalytic oxidation reaction is dependent on the Au/Pt ratios, and the Au1.0/Pt0.2 NWs have the largest percentage (∼75%) of stepped Au/Pt sites and show the highest activity for ethanol electro-oxidation, reaching an unprecedented 196.9 A/mgPt (32.5 A/mgPt+Au). This NW catalyst is also active in catalyzing the oxidation of other primary alcohols, such as methanol, n-propanol, and ethylene glycol. In situ X-ray absorption spectroscopy and infrared spectroscopy are used to characterize the catalyst structure and to identify key reaction intermediates, providing concrete evidence that the synergy between the low-coordinated Pt sites and the stepped Au NWs is essential to catalyze the alcohol oxidation reaction, which is further supported by DFT calculations that the C-C bond cleavage is indeed enhanced on the undercoordinated Pt-Au surface. Our study provides important evidence that a core/shell structure with stepped core/shell sites is essential to enhance electrochemical oxidation of alcohols and will also be central to understanding electro-oxidation reactions and to the future development of highly efficient direct alcohol fuel cells for renewable energy applications.

Development of sustainable green catalysts for oxidation of alcohols via decorated palladium nanoparticles on magnetic carbon nanotube/MOF

Using a straightforward method, this study fabricated an eco-friendly low-cost magnetic nanocomposite consisting of magnetic carbon nanotube/MOF as a stabilizer. Pd nanoparticles (Pd NPs) were then decorated on the designed magnetic carbon nanotube/MOF microspheres, and the resulting magnetic carbon nanotube/MOF/Pd NPs nanocomposite were employed as heterogeneous catalysts in Aerobic oxidation of primary and secondary alcohols. The attractiveness of this work is in the selective oxidation of several types of active and inactive alcohol substrates. The most important feature of this catalyst is its successful recovery and simple separation repeatedly without reducing its activity and selectivity. The active surface area of this Nanocatalyst is very large due to its structural properties, and as a result, it provides more available catalytic sites, which increases its activity. The identification techniques used to investigate the structural properties of this Nanocatalyst confirm its successful synthesis and appropriate palladium loading into the catalyst sites. The oxidation of alcohols was determined by Gas Chromatography (GC). The 100% selectivity, excellent turnover number (TON), high yield, almost complete and fast conversion of alcohol to the desired aldehydes and ketones without more oxidation, and easy and no-trouble isolation of product and catalyst are outstanding features of this catalytic system. The use of picolinaldehyde lead to the high loading of Pd NPs, reducing the catalyst content needed for the reaction. Regarding the high catalyst loading, using a small amount of catalyst is recommended for proceeding with the reaction efficiently.

Front Cover: Poly(glycerol‐co‐glyceric acid) Functionalized Nanodiamonds by Nitroxyl Radical‐Catalyzed Oxidation of Primary Alcohols in Poly(glycerol) as Scaffolds for Further Conjugation (ChemNanoMat 9/2023)

Front Cover: Poly(glycerol‐<i>co</i>‐glyceric acid) Functionalized Nanodiamonds by Nitroxyl Radical‐Catalyzed Oxidation of Primary Alcohols in Poly(glycerol) as Scaffolds for Further Conjugation (ChemNanoMat 9/2023)

Fungal lyophilisates as catalysts for organic synthesis: Preparative oxidations with the white-rot fungus Bjerkandera adusta

A clean and selective “on-water-on-air” oxidation of primary alcohols to the corresponding aldehydes with mycelium lyophilisates of the non-toxic white-rot fungus Bjerkandera adusta was developed. The biocatalytic protocol is simple and the catalyst is readily accessible as a powder, which could be stored at least for 7 months without changes of activity. The catalytic activity of the fungus is associated with the presence of aryl-alcohol oxidase, that was isolated from the lyophilisate and characterised. Remarkably, a dichotomy in the fungal reactivity was observed, as the corresponding growing cultures catalyse the reverse process, selectively reducing aldehydes to the corresponding alcohols. Enzymatic oxidations by B. adusta are an excellent non-toxic alternative to metal-mediated oxidations in the lab with potential in food, beverage, cosmetic, and pharmaceutical industries, as it tolerates many functional groups.

Poly(glycerol‐co‐glyceric acid) Functionalized Nanodiamonds by Nitroxyl Radical‐Catalyzed Oxidation of Primary Alcohols in Poly(glycerol) as Scaffolds for Further Conjugation

AbstractPoly(glycerol) (PG) functionalization is versatile to make various nanoparticles dispersible in aqueous media. In addition, the abundant hydroxy groups in PG give scaffolds for further modification to introduce suitable functional groups. For example, carboxylic group (−COOH) has been introduced through the reaction of hydroxy (−OH) group in PG with succinic anhydride. However, ester linkage in the succinate moiety in the PG layer is subjected to hydrolysis. In this work, we develop an alternative way for a novel −COOH containing PG functionalized detonation nanodiamonds (DND‐PG‐COOH) via oxidation of primary −OH group of PG chain by nitroxyl radical catalysts well‐known as TEMPO or its analogues. The content of −COOH is found to be precisely controlled by the amount of oxidant.

Oxidation of Primary Alcohols and Aldehydes to Carboxylic Acids with 1-Hydroxycyclohexyl Phenyl Ketone.

The oxidation of primary alcohols to the corresponding carboxylic acids is one of the fundamental and useful reactions in organic synthesis. In this paper, we report our comprehensive results toward the oxidation of primary alcohols and aldehydes to acids via hydride transfer reactions mediated by 1-hydroxycyclohexyl phenyl ketone. Under the strong basic conditions of sodium tert-butoxide, the room temperature oxidations tolerate a range of functional groups, including vulnerable tert-butanesulfinamides, amines, sulfides, olefins, and heterocycles, and provide good to excellent yields. Most importantly, our oxidation procedure can be applied to chemoselective oxidation of primary alcohols and aldehydes to carboxylic acids in the presence of secondary alcohols.

Kinetic Studies of the Oxidation of Primary Acyclic and Secondary Cyclic Perfumery alcohols using N- Bromosuccinimide in Alkaline Medium

Kinetic Studies of the Oxidation of Primary Acyclic and Secondary Cyclic Perfumery alcohols using N- Bromosuccinimide in Alkaline Medium

Investigation of Fenebrutinib Metabolism and Bioactivation Using MS3 Methodology in Ion Trap LC/MS.

Fenebrutinib is an orally available Bruton tyrosine kinase inhibitor. It is currently in multiple phase III clinical trials for the management of B-cell tumors and autoimmune disorders. Elementary in-silico studies were first performed to predict susceptible sites of metabolism and structural alerts for toxicities by StarDrop WhichP450™ module and DEREK software; respectively. Fenebrutinib metabolites and adducts were characterized in-vitro in rat liver microsomes (RLM) using MS3 method in Ion Trap LC-MS/MS. Formation of reactive and unstable intermediates was explored using potassium cyanide (KCN), glutathione (GSH) and methoxylamine as trapping nucleophiles to capture the transient and unstable iminium, 6-iminopyridin-3(6H)-one and aldehyde intermediates, respectively, to generate a stable adducts that can be investigated and analyzed using mass spectrometry. Ten phase I metabolites, four cyanide adducts, five GSH adducts and six methoxylamine adducts of fenebrutinib were identified. The proposed metabolic reactions involved in formation of these metabolites are hydroxylation, oxidation of primary alcohol to aldehyde, n-oxidation, and n-dealkylation. The mechanism of reactive intermediate formation of fenebrutinib can provide a justification of the cause of its adverse effects. Formation of iminium, iminoquinone and aldehyde intermediates of fenebrutinib was characterized. N-dealkylation followed by hydroxylation of the piperazine ring is proposed to cause the bioactivation to iminium intermediates captured by cyanide. Oxidation of the hydroxymethyl group on the pyridine moiety is proposed to cause the generation of reactive aldehyde intermediates captures by methoxylamine. N-dealkylation and hydroxylation of the pyridine ring is proposed to cause formation of iminoquinone reactive intermediates captured by glutathione. FBB and several phase I metabolites are bioactivated to fifteen reactive intermediates which might be the cause of adverse effects. In the future, drug discovery experiments utilizing this information could be performed, permitting the synthesis of new drugs with better safety profile. Overall, in silico software and in vitro metabolic incubation experiments were able to characterize the FBB metabolites and reactive intermediates using the multistep fragmentation capability of ion trap mass spectrometry.

Dual role of chlorogenic acid as an influential precursor in synthesizing nano‐sized Cu(II) complexes and investigating its catalytic role in the oxidation of alcohols and its antibacterial activity

Chlorogenic acid (3-O-caffeoyl-D-quinic acid) (CGA) is a compound found in a large kind of food, including fruits, vegetables, olive oil, spices, and coffee. CGA has the ability to bind with several metal ions to increase its biological activity. In the last ten years, CGA has attracted considerable attention due to its biological activity like anticancer, antioxidant, and antibacterial. In this present study, we used CGA and Cu(II) for the synthesis of the metal complexes. As a ligand for the synthesis of novel nanoscale Cu(II) complex, the CGA has been used. Then the product was characterized by FT-IR spectroscopy, FESEM, XRD, and EDAX. FESEM image for nanoscale copper(II) complex showed nanoparticles with an average diameter of 40 nm. XRD of synthesized nanoscale copper(II) complex gives characteristic peaks at 2θ°: 33.12, 36.37, 38.77, 48.83, 53.52, 58.82, 63.47, 66.34, and 68.91. Significantly, our product showed remarkable catalytic activity toward the oxidation of primary and secondary alcohols. The antibacterial activity of the final product was assessed against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) bacteria using an inhibition zone test. The synthesized nanoscale Cu(II) complex exhibited strong antibacterial activity against both of these bacteria.

PtCu Nanoparticle Catalyst for Electrocatalytic Glycerol Oxidation: How Does the PtCu Affect to Glycerol Oxidation Reaction Performance by Changing pH Conditions?

In this work, we show that finding and controlling optimum pH environments with Pt-based alloy catalysts can create high catalytic performances for electrocatalytic glycerol oxidation reaction (EGOR). Compared to a Pt/C catalyst, the PtCu/C alloy catalyst has higher reaction rate and turnover frequency (TOF) values by increasing the pH. Specifically, the reaction rate and TOF of the PtCu/C catalyst at pH 13 were 2.93 and 6.65 times higher than those of Pt/C, respectively. The PtCu/C catalyst also showed lower onset potential value and higher mass and specific activities than the Pt/C by increasing the pH. This indicates that the Cu in the PtCu alloy improves the catalytic activity for the EGOR in an OH− group-rich environment. In the case of the PtCu/C catalyst at a high pH condition, the selectivities of tartronic acid and oxalic acid tended to increase as the selectivity of lactic acid decreased. This result means that the PtCu alloy follows primary alcohol oxidation pathways, which are more favorable in an OH− group-rich environment than with only Pt. This study proposes that it is critical to optimize and control the reaction conditions for developing efficient EGOR catalysts.

Coordination cage with structural “defects” and open metal sites catalyzes selective oxidation of primary alcohols

Coordination cage with structural “defects” and open metal sites catalyzes selective oxidation of primary alcohols

Sustainable Solvent-Free Selective Oxidation of Benzyl Alcohol Using Ru(0) Supported on Alumina

The selective oxidation of primary alcohols into their corresponding carbonyl compounds is challenging because of the easy over oxidization to acids and esters. The traditional reaction requires large amounts of solvent and oxidant, causing serious environmental issues. Recently, several efforts have been made to transform the reaction into a more sustainable process. Here, we investigated the solvent-free oxidation of benzyl alcohol using air as a green oxidant in the presence of ruthenium supported on alumina and zirconia, thereby meeting atom economy and environmental requirements. The materials were extensively characterized and, in addition to their activity, selectivity, and reusability, the environmental sustainability of the process was assessed according to green chemistry metrics. XRD, TEM, and XPS analyses suggest that the formation of metallic Ru on the support plays a key role in the catalytic activity. Ru supported on alumina, after a reduction treatment, achieves good activity (62% conversion) and a complete selectivity in a very sustainable process (without a solvent and with air as oxidant), as indicated by the very low E-factor value. The formulation is very stable and maintains high activity after recycling.

Elucidation of Active Sites and Mechanistic Pathways of a Heteropolyacid/Cu-Metal–Organic Framework Catalyst for Selective Oxidation of 5-Hydroxymethylfurfural via Ex Situ X-ray Absorption Spectroscopy and In Situ Attenuated Total Reflection-Infrared Studies

Chemoselective oxidation of 5-hydroxymethylfurfural (HMF) over non-noble metals to produce a bioplastic monomer, 2,5-furandicarboxylic acid (FDCA), under alkaline-free conditions is challenging and worthy of investigation. HMF oxidation into FDCA involves the concurrent oxidation of primary alcohol and an aldehyde functional group into carboxylic groups, which therefore demand a bifunctional catalyst containing dual active sites and chemoselective oxidation of HMF. The present work demonstrated the formation of new selective active sites in a composite porous material (Cu-BTC_PMA) that consists of Cu-BTC (metal–organic framework (MOF)) and polyoxometalate (POM). The porous framework provides (Cu-BTC_PMA) the desired chemoselectivity, while a selective Cu metal center in Cu-BTC (MOF) and Cu–O–Mo sites functions as active sites for the concurrent oxidation of HMF into FDCA. This catalyst exhibited a HMF conversion of 89% and an FDCA selectivity of 92.3% under base-free and mild reaction conditions. In detail, X-ray absorption spectroscopy analysis demonstrated the chemical bond tuning, as well as electronic structural modulations of MOF and POM at the molecular level, which directs the formation of new synergistic interfacial active sites and charge transfer states. This phenomenon causes the generation of the unique redox environment of copper and the multiple oxidation states along with the oxygen vacancy in the Cu-BTC_PMA catalyst, which most likely behaves as active sites for base-free oxidation. A kinetics study of this reaction was followed using in situ attenuated total reflection-infrared spectroscopy, demonstrating the stabilization of the specific intermediates that lead to the formation of FDCA. Moreover, we made comparative density functional theory and quantum theory of atoms in molecules investigations on the surface interaction between the reactant (HMF) and two catalyst models of Cu-BTC and Cu-BTC_PMA to interpret quantitatively the higher catalytic activity of the Cu-BTC_PMA catalyst. The kinetics study also evaluates the rate-determining step and activation energy for the multistep oxidation reactions.

Visible Light-Induced Oxidation of Alcohols by a Luminescent Osmium(VI) Nitrido Complex: Evidence for the Generation of PhIO+ as a Highly Active Oxidant in the Presence of PhIO

Although alcohols are readily oxidized by a variety of oxidants, their oxidation by metal nitrido complexes is yet to be studied. We report herein visible-light-induced oxidation of primary and secondary alcohols to carbonyl compounds by a strongly luminescent osmium(VI) nitrido complex (OsN). The proposed mechanism involves initial rate-limiting hydrogen-atom transfer (HAT) from the α-carbon of the alcohol to OsN*. Attempts to develop catalytic oxidation of alcohols by OsN* using PhIO as the terminal oxidant resulted in the formation of novel osmium(IV) iminato complexes in which the nitrido ligand is bonded to a δ-carbon of the alcohol. Experimental and theoretical studies suggest that OsN* is reductively quenched by PhIO to generate PhIO+, which is a highly active oxidant that readily undergoes α- and δ-C-H activation of alcohols.

Structural Construction of Au–Pd Nanocomposite for Alkali-Free Oxidation of Benzyl Alcohol

A bimetallic Au-Pd system is an alternative candidate to catalyze primary alcohol oxidation and is of crucial importance for the sustainable chemical industry. However, understanding the bimetallic system in terms of the nanostructure is still challenging. Herein, we adopt the in situ colloid immobilization to obtain a series of bimetallic AuxPdy/CNT samples supported by carbon nanotubes (CNTs). Elaborate characterizations confirmed the bimetallic structure of AuPd alloy particles with randomly dispersed Pd2+ on the surface, forming the AuPd@PdO structure on CNTs. Unlike the monometallic samples, bimetallic ones, particularly Au1Pd1/CNT, efficiently transformed benzyl alcohol in an alkali-free mild condition. The DFT simulation confirmed the electron-rich gold atoms as a steric and electronic regulator to confine the electron-deficient Pd atoms in alloy particles. The interacted metal sites in the alloy system activated the alcohol with optimized adsorption configuration. Surface Pd2+ transported active oxygen to capture the abstracted H on alcohol. The collaboration between metal sites facilitated the transformation of benzyl alcohol to benzaldehyde with the selectivity of 91.8% by a fast TOF of 1274 h-1 at only 80 °C.

MXene Aerogel Derived Ultra-Active Vanadia Catalyst for Selective Conversion of Sustainable Alcohols to Base Chemicals.

Selective oxidation reactions are an important class of the current chemical industry and will be highly important for future sustainable chemical production. Especially, the selective oxidation of primary alcohols is expected to be of high future interest, as alcohols can be obtained on technical scales from biomass fermentation. The oxidation of primary alcohols produces aldehydes, which are important intermediates. While selective methanol oxidation is industrially established, the commercial catalyst suffers from deactivation. Ethanol selective oxidation is not commercialized but would give access to sustainable acetaldehyde production when using renewable ethanol. In this work, it is shown that employing 2D MXenes as building blocks allows one to design a nanostructured oxide catalyst composed of mixed valence vanadium oxides, which outperforms on both reactions known materials by nearly an order of magnitude in activity, while showing high selectivity and stability. The study shows that the synthesis route employing 2D materials is key to obtain these attractive catalysts. V4C3Tx MXene structured as an aerogel precursor needs to be employed and mildly oxidized in an alcohol and oxygen atmosphere to result in the aspired nanostructured catalyst composed of mixed valence VO2, V6O13, and V3O7. Very likely, the bulk stable reduced valence state of the material together coupled with the nanorod arrangement allows for unprecedented oxygen mobility as well as active sites and results in an ultra-active catalyst.

Amino-cobalt(II)phthalocyanine supported on silica chloride as an efficient and reusable heterogeneous photocatalyst for oxidation of alcohols

The selective photocatalytic oxidation of alcohols is considered as a valuable process in order to produce aldehydes and ketones. In the present study, novel heterogeneous and recoverable cobalt (II) phthalocyanine (CoPc) was designed and synthesized through a covalent binding between an amino-cobalt (II) phthalocyanine on the surface of silica, and named as TACoPc/Si-Cl. This catalyst was fully characterized using IR, X-ray diffraction patterns (XRD), Scanning electron microscope (SEM), Transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), element analysis (CHN), and ultraviolet–visible spectroscopy (UV/Vis). Various reaction parameters such as catalyst amount, temperature, time, solvent and amount of oxidant were investigated in the oxidation of primary and secondary alcohols to the corresponding carbonyl compounds. The desired products were obtained with acceptable efficiency and selectivity of over 98%, under visible light irradiation conditions. The supported catalyst exhibited a higher reactivity than the unsupported and after the reaction comes off easily and reusable. The recovered catalyst was reused six times. The obtained results show that the stability, efficiency and selectivity of described catalyst have not changed much compared to the fresh catalyst.

An efficient electrocatalytic system composed of nickel oxide and nitroxyl radical for the oxidation of bio-platform molecules to dicarboxylic acids

Selective oxidation of biomass and its derivatives to dicarboxylic acids represents a promising route for biomass valorization. However, the co-presence of multiple functional groups in biomass molecules makes the selective oxidation of particular functional a challenging task. Here, we demonstrate an efficient electrocatalytic system consisting of nickel oxide (NiO) and a nitroxyl radical, i.e., 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) or 4-acetamido-TEMPO (ACT), for the selective oxidation of key bio-platform molecules including glucose, xylose and 5-hydroxymethylfurfural (HMF) into corresponding dicarboxylic acids, i.e., glucaric acid, xylaric acid, and 2,5-furandicarboxylic acid (FDCA). NiO is clarified as the active catalyst for the oxidation of aldehyde in bio-platform molecules to carboxylic acid, while TEMPO or ACT is responsible for the oxidation of primary alcohol to aldehyde. The combination of NiO and TEMPO or ACT significantly accelerated the tandem oxidation of aldehyde and hydroxyl groups in glucose, xylose and HMF, thus achieving excellent yields (83%–99%) of dicarboxylic acids. Moreover, the combination catalyst enables the selective oxidation of glucose and xylose with high concentrations (e.g., 20 wt%), which offers a promising strategy for biomass valorization.

Candida parapsilosis carbonyl reductase as a tool for preliminary screening of inhibitors for alcohol dehydrogenase induced skin sensitization

Human alcohol dehydrogenases, specifically ADH1 oxidize primary alcohols to aldehydes in the skin. These aldehydes act as haptens, leading to sensitization. Inhibition of these ADH enzymes may help in combating skin allergies. In the present study, the recombinantly purified stereospecific enzyme from Candida parapsilosis ATCC 7330, Candida parapsilosis Carbonyl Reductase (CpCR) has 23.31 % sequence similarity with human alcohol dehydrogenase ADH1B1. These two enzymes have perfectly overlapping cofactor and zinc binding domains. CpCR was found to oxidize primary alcohols to their corresponding aldehydes. Oxidation of primary alcohols by CpCR was further optimized with cinnamyl alcohol as the model substrate that initially showed a conversion of 56 % ± 0.25, and upon optimization increased to 98.2 % ± 0.23. An increase of 20–50 % in the conversion rate has been observed for various primary alcohols under the optimized reaction conditions. A simple and efficient model was designed for the screening of compounds that inhibit CpCR with the possibility of mitigating the action of skin allergens by inhibiting ADH1. p-Nitrophenylglyoxal (PNG) was found to be a good inhibitor for CpCR which showed inhibitory activity at very low concentration (IC50,100 mM ± 1.27) as compared to the standard inhibitor 4-methyl pyrazole (4MP) (IC50, 400 mM ± 2.05).

Chemoselective derivatisation and ultrahigh resolution mass spectrometry for the determination of hydroxyl functional groups within complex bio-oils.

Bio-oils are a renewable alternative resource for the production of fine chemicals and fuels. Bio-oils are characterised by a high content of oxygenated compounds with a diverse array of different chemical functionalities. Here, we performed a chemical reaction to transform the hydroxyl group of the various components in a bio-oil prior to characterisation with ultrahigh resolution mass spectrometry (UHRMS). The derivatisations were first evaluated using twenty lignin-representative standards with different structural features. Our results indicate a highly chemoselective transformation of the hydroxyl group despite the presence of other functional groups. Mono- and di-acetate products were observed in acetone-acetic anhydride (acetone-Ac2O) mixtures for non-sterically hindered phenols, catechols and benzene diols. Dimethyl sulfoxide-Ac2O (DMSO-Ac2O) reactions favoured the oxidation of primary and secondary alcohols and the formation of methylthiomethyl (MTM) products of phenols. The derivatisations were then performed in a complex bio-oil sample to gain insights into the hydroxyl group profile of the bio-oil. Our results indicate that the bio-oil before derivatisation is composed of 4500 elemental compositions containing 1-12 oxygen atoms. After the derivatisation in DMSO-Ac2O mixtures, the total number of compositions increased approximately five-fold. The reaction was indicative of the variety of hydroxyl group profiles within the sample in particular the presence of phenols that were ortho and para substituted, non-hindered phenols (about 34%), aromatic alcohols (including benzylic and other non-phenolic alcohols) (25%), and aliphatic alcohols (6.3%) could be inferred. Phenolic compositions are known as coke precursors in catalytic pyrolysis and upgrading processes. Thus, the combination of chemoselective derivatisations in conjunction with UHRMS can be a valuable resource to outline the hydroxyl group profile in elemental chemical compositions in complex mixtures.