Continuous-flow synthesis of carboxylic acids from alcohols platinum and silicon dioxide-catalyzed hydrogen peroxide oxidation.

A continuous-flow method for the direct oxidation of alcohols to carboxylic acids is reported, employing hydrogen peroxide (HO) and a platinum (Pt) catalyst within a flow reactor system. This approach allows for precise control over the contact time between the reactants and the catalyst, enabling optimization of reaction conditions. By analyzing the yields of both aldehydes and carboxylic acids as a function of weight hourly space velocity (WHSV), selective synthesis of carboxylic acids was achieved without the formation of corresponding aldehydes.

Photoinduced B-H Arylation of N-Heterocyclic Carbene Boranes with Sulfonyl(hetero)arenes.

Arylborane complexes ligated by N-heterocyclic carbenes (NHCs) can be synthesized by photoirradiation of a mixture of NHC-boranes and sulfonyl(hetero)arenes. The reaction occurs under mild and convenient conditions without any photocatalyst, which are realized by a radical chain mechanism involving NHC-boryl radicals and sulfonyl radicals. This reaction offered the opportunity to reveal the photophysical property of a 2-borylnaphtho[1,2-]thiazole derivative.

Chiroptical Response of Carbon Nanocages Enhanced by Achiral Guests.

Opening up [60]fullerene makes itself inherently chiral without loss of congenital π-conjugation. An immoderately large aperture on [60]fullerene, however, renders the molecule less rigid and therefore it would reduce dissymmetry factors. Herein, we examined supramolecular technique in geometrical reinforcement of chiral open-[60]fullerenes by encasing achiral guests such as Ar, CO, and CHCN.

DNA Duplex Containing Ag-Mediated Cytosine-Cytosine Base Pairs as a Catalyst Precursor for the 4-Nitrophenol Reduction with NaBH.

Catalytic applications of DNA duplexes containing Ag-mediated cytosine-cytosine base pairs (C-Ag-C) have not been well investigated. In this study, we demonstrate a novel approach for forming highly active DNA-capped Ag nanoparticle (DNA-AgNP) catalysts for the reduction of 4-nitrophenol (4-NP) using sodium borohydride (NaBH). This approach is based on the generation of DNA-AgNPs from DNA duplexes containing C-Ag-C (DNA duplex-Ag).

One-Step Esterification of Phosphoric, Phosphonic and Phosphinic Acids with Organosilicates: Phosphorus Chemical Recycling of Sewage Waste.

Global concerns regarding the depletion and strategic importance of phosphorus resources have increased demand for the recovery and recycling. However, waste-derived phosphorus compounds, primarily as chemically inert phosphoric acid or its salts, present a challenge to their direct conversion into high-value chemicals. We aimed to develop an innovative technology that utilizes the large quantities of sewage waste, bypasses the use of white phosphorus, and enables esterification of phosphoric acid to produce widely applicable phosphate triesters.

Catalytic Concerted SAr Reactions of Fluoroarenes by an Organic Superbase.

We herein propose that the catalytic concerted SAr reaction is a powerful method to prepare functionalized aromatic scaffolds. Classic stepwise SAr reactions involving addition/elimination processes require the use of electron-deficient aromatic halides to stabilize Meisenheimer intermediates, despite their widespread use in medicinal chemistry research. Recent efforts have been made to develop concerted SAr reactions involving a single transition state, allowing the use of electron-rich substrates based on the use of stoichiometric amounts of strong bases or reactive nucleophiles.

Streamlined Synthesis of Ellagitannins: Site-Selective Functionalization of the Glucose Core and Stereodivergent Construction of the Hexahydroxydiphenoic Groups.

Ellagitannins are a class of plant polyphenols with a structural diversity of around 1000. Because those with attractive biological activities have been reported, synthetic studies have been performed. The purpose of this perspective is to provide an outlook toward future developments on ellagitannin chemistry and medicinal applications by overviewing synthetic studies.

Retraction: Enhancement of the photocatalytic activity of rhenium(I) complexes by encapsulation in light-harvesting soft nanotubes.

Retraction of 'Enhancement of the photocatalytic activity of rhenium(I) complexes by encapsulation in light-harvesting soft nanotubes' by Naohiro Kameta , , 2017, , 10116-10119, https://doi.org/10.1039/C7CC05337A.

Stable and Versatile Pd Precursors for the Preparation of Robust Pd Catalysts Under Continuous-Flow.

To achieve global sustainability, the chemical and engineering communities require the development of versatile precursors that can be used to synthesize robust catalysts. To meet this demand, we developed a new Pd precursor for highly efficiently incorporating fine Pd-metal into supports. An atmospherically stable Pd precursor (Pd-80) was prepared by thermally promoting the aerobic oxidation of tetrakis(triphenylphosphine)palladium.

Facile Depolymerization of Thermally Stable Polyetherethersulfone and Polyetheretherketone Using Hydroquinone and Bases.

Super engineering plastics such as polyetheretherketone (PEEK) and polyetherethersulfone (PEES) exhibit thermal stability, chemical resistance, and mechanical strength. Such characteristics are attributed to their robust chemical structures composed of stable aryl ethers. These features make chemical recycling difficult.

A DFT Mechanistic Study on the Aza-Aldol Reaction of Boron Aza-Enolates: Relative Stability of Six-Membered Transition State and Its Relevance to the Coordination Mode of the Leaving Group.

The mechanism of the aza-aldol reaction between boron aza-enolate and benzaldehyde is investigated by using density functional theory calculations. The result shows that the - isomer is preferentially formed, consistent with experimental observations. The six-membered ring transition state (TS) with the boat form leads to the isomer, while the more unstable chair TS does to the isomer.

Exploring Catalytic Intermediates in Pd-Catalyzed Aerobic Oxidative Amination of 1,3-Dienes: Multiple Metal Interactions of the Palladium Nanoclusters.

Metal nanoclusters (NCs) have unique properties because of their small size, which makes them useful as catalysts in reactions like cross-coupling. Pd-catalyzed oxidative amination, which involves dehydrogenative C-N bond formation, uses Pd complexes as the active species. It is known that the catalytic conditions involve the formation of Pd(0) species from Pd NCs, but the precise role of Pd NCs in the transformations has not been established.

Organophotocatalytic access to -glycosides: multicomponent coupling reactions using glycosyl bromides.

Photochemical multi-component coupling reactions initiated by the activation of glycosyl bromides in the presence of 1,4-bis(diphenylamino)benzene (BDB) as an organic photocatalyst were developed. -glycosides accompanied by olefin (di)functionalization were obtained. This method allows us to access various -glycosides with alkene, carbonyl, alcohol, ether, and amide functionalities.

Trigonal-Bipyramidal Pt(0) and Pd(0) Anions.

Anionic Pt(0) and Pd(0) complexes with unprecedented trigonal-bipyramidal geometry have been prepared and thoroughly characterized by experimental and computational means. Coordination of a σ-acceptor borane moiety supported by three phosphine buttresses enhances the electrophilicity of M(0) and triggers the binding of soft anions (X = Br, I, CN).

Characterization of changes in the electronic structure of platinum sub-nanoclusters supported on graphene induced by oxygen adsorption.

As the sizes of noble metal catalysts, such as platinum, have been successfully minimized, fundamental insights into the electronic properties of metal sub-nanoclusters are increasingly sought for optimizing their catalytic performance. However, it is difficult to rationalize the catalytic activities of metal sub-nanoclusters owing to their more complex electronic structure compared with those of small molecules and bulky solids. In this study, the adsorption of molecular oxygen on a Pt sub-nanocluster supported on a graphene layer was analyzed using density functional theory.

Complete sequence randomness of lactate-based copolymers (LAHBs) with varied lactate monomer fractions employing a series of propionyl-CoA transferases.

Previously, we biosynthesized an evolved version of a bio-based polylactide (PLA) on microbial platforms using our engineered lactate-polymerizing enzyme (LPE). This lactate (LA)-based copolyester, LAHB, has advantages over PLA, including improved flexibility and biodegradability, and its properties can be regulated through the LA fraction. To expand the LA-incorporation capacity and improve polymer properties, in the state of in vivo LAHB production, propionyl-CoA transferases (PCTs) that exhibited enhanced production of LA-CoA than the conventional PCTs were selected.

A rare olive compound oleacein functions as a TrkB agonist and mitigates neuroinflammation both in vitro and in vivo.

Background: Neuroinflammation is widely acknowledged as a characteristic feature of almost all neurological disorders and specifically in depression- and anxiety-like disorders. In recent years, there has been significant attention on natural compounds with potent anti-inflammatory effects due to their potential in mitigating neuroinflammation and neuroplasticity.

Methods: In the present study, we aimed to evaluate the neuroprotective effects of oleacein (OC), a rare secoiridoid derivative found in extra virgin olive oil.

Depolymerization of Polyester Fibers with Dimethyl Carbonate-Aided Methanolysis.

Polyester fibers, comprising mostly poly(ethylene terephthalate) with high crystalline content, represent the most commonly produced plastic for ubiquitous textiles, and approximately 60 million tons are manufactured annually worldwide. Considering the social issues of mismanaged waste produced from used textile products, there is an urgent demand for sustainable waste polyester fiber recycling methods. We developed a low-temperature, rapid, and efficient depolymerization method for recycling polyester fibers.

Quantification of microbial community assembly processes during degradation on diverse plastispheres based on physicochemical characters and phylogenetic bin-based null model analysis.

To understand the differences in degradation processes depending on the chemical properties of polymers, it is necessary to both quantify the microbiome composition and evaluate the process of microbial turnover (i.e., community assembly processes) in a variety of polymer materials.

Probing the Surface of Oxide Nanoparticles Using DNP-Enhanced High-Resolution NMR of Quadrupolar Nuclei.

The surfaces of nanomaterials with applications in optoelectronics and catalysis control their physicochemical properties. NMR spectroscopy, enhanced by dynamic nuclear polarization (DNP), is a powerful approach to probe the local environment of spin-1/2 nuclei near surfaces. However, this technique often lacks robustness and resolution for half-integer quadrupolar nuclei, which represent more than 66% of the NMR-active isotopes.

Mitigating the Poisoning Effect of Formate during CO Hydrogenation to Methanol over Co-Containing Dual-Atom Oxide Catalysts.

During the hydrogenation of CO to methanol over mixed-oxide catalysts, the strong adsorption of CO and formate poses a barrier for H dissociation, limiting methanol selectivity and productivity. Here we show that by using Co-containing dual-atom oxide catalysts, the poisoning effect can be countered by separating the site for H dissociation and the adsorption of intermediates. We synthesized a Co- and In-doped ZrO catalyst (Co-In-ZrO) containing atomically dispersed Co and In species.

Modification of poly(lactate) via polymer blending with microbially produced poly[(R)-lactate-co-(R)-3-hydroxybutyrate] copolymers.

This study investigated the effect of polymer blending of microbially produced poly[(R)-lactate-co-(R)-3-hydroxybutyrate] copolymers (LAHB) with poly(lactate) (PLA) on their mechanical, thermal, and biodegradable properties. Blending of high lactate (LA) content and high molecular weight LAHB significantly improved the tensile elongation of PLA up to more than 250 % at optimal LAHB composition of 20-30 wt%. Temperature-modulated differential scanning calorimetry and dynamic mechanical analysis revealed that PLA and LAHB were immiscible but interacted with each other, as indicated by the mutual plasticization effect.

A comparative transcriptomics analysis reveals ethylene glycol derivatives of squalene ameliorate excessive lipogenesis and inflammatory response in 3T3-L1 preadipocytes.

Squalene (SQ) is a natural compound with anti-inflammatory, anti-cancer, and anti-oxidant effects, but due to its low solubility, its biological properties have been greatly underestimated. This study aims to explore the differences in gene expression patterns of four newly synthesized amphipathic ethylene glycol (EG) derivatives of SQ by whole-genome transcriptomics analysis using DNA microarray to examine the mRNA expression profile of adipocytes differentiated from 3T3-L1 cells treated with SQ and its EG derivatives. Enrichment analyses of the transcriptional data showed that compared with SQ, its EG derivatives exerted different, in most cases desirable, biological responses.

Enhancing continuous-flow reactions compression-molding of solid catalysts and dilutants in packed-bed systems.

In this study, we present an improved packed-bed system designed for continuous-flow reactions using platinum (Pt)-black powder and silica gel (SiO). The Pt-leaching from the reaction column is suppressed compression-molding of the Pt and SiO. Scanning electron microscopy results and particle-size distribution analysis demonstrate that crushed and downsized SiO is effective in suppressing outflow.