Ether Formation Research Articles

Exploring the Adsorption and Reactions of Methyl Radicals on M(111) Surfaces (M = Cu, Ag, Au): A DFT Study.

It was reported that adsorbed methyl radicals produce ethane with Ag0- and Au0-nanoparticles in aqueous media, whereas on Cu0-powders, the product is methanol. The source of these differences was explored computationally, using the DFT method. The results indicate that up to six radicals can be adsorbed on Ag(111) and Au(111), (top site), while only four can be adsorbed on Cu(111) (fcc site), each surface containing eight atoms. The diffusion of the radicals on the surface is very easy on silver and copper, as this is achieved with a very low barrier (0.06 eV and 0.15 eV for Ag(111) and Cu(111), respectively), while on Au(111), the barrier is higher, 0.51 eV. The formation of ethane via a reaction of two adsorbed radicals is thermodynamically plausible for all studied coverage ratios on the three surfaces, but kinetically, it is plausible at room temperature only on Au(111) and Ag(111) at full coverage. Ethane can also be produced on Au(111) and Ag(111) by a collision of a solvated radical and an adsorbed radical. This is a barrierless process. On Cu(111), the yield of such a process is CH4(aq), and an adsorbed CH2 which reacts further with a non-adsorbed water molecule to produce adsorbed CH3OH.

TBAT-Catalyzed Dioxasilinane Formation from Beta-Hydroxy Ketones.

Beta-hydroxy ketones can be reduced using a sequence of ruthenium-catalyzed silyl etherification followed by tetrabutylammonium fluoride (TBAF) promoted intramolecular hydrosilylation. Switching from TBAF to tetrabutylammonium difluorotriphenylsilicate (TBAT), even without first forming the silyl ether, gave cyclic dioxasilinane products. These somewhat sensitive compounds could be isolated pure by column chromatography using florisil as the stationary phase. Alternatively, the dioxasilinane were regioselectively opened with methyl lithium, affording the corresponding differentiated 1,3-diol with selective protection of the secondary alcohol as its diphenylmethylsilyl (DPMS) ether. A mechanism is proposed involving TBAT-catalyzed silyl ether formation followed by TBAT-promoted intramolecular carbonyl hydrosilylation. This mechanism is supported by the observed diastereoselectivity of the reaction, which was consistent with other carbonyl hydrosilylations thought to proceed intramolecularly.

Flame‐Retardant Rigid Polyurethane Foam Composites Based on Piperazine Pyrophosphate/Steel Slag: A New Strategy for Utilizing Metallurgical Solid Waste

ABSTRACTIn this work, piperazine pyrophosphate (PAPP) and metallurgical solid steel slag (SS) are used to fabricate flame‐retardant rigid polyurethane foam (RPUF) composites through a one‐step all‐water foaming technology. The thermal stability, combustion properties, and flame retardancy of the PAPP/SS composite were investigated by thermogravimetric (TG) analysis, cone calorimetry, limiting oxygen index testing (LOI), and UL‐94 vertical burn testing. RPUF‐3 showed a char residue of 28.6 wt% at 750°C compared with 24.9 wt% of the pure sample, indicating better thermal stability of the FRPRUF composites. RPUF‐3 possessed an LOI of 21.5 vol% and achieved a V‐0 level in the UL‐94 test. Cone calorimetry displayed the peak heat release rate and fire growth rate index of RPUF‐3 were decreased by 12.66% and 41.6%, respectively, compared with those of pure RPUF. PAPP/SS incorporation led to the formation of compact char layer structures during combustion. Pyrophosphoric acid, generated from the decomposition of PAPP, promotes the formation of esters, ethers, and alcohols, whereas metal oxides in SS enhance the compactness of the char layer. This enhanced structural integrity obstructs mass and heat transmission in the combustion zone, effectively improving condensed‐phase flame retardancy. This approach offers a novel strategy for the fabrication of high‐performance RPUF composites and the high‐value utilization of SS.

Enhancing thermal stability and viscosity of cellulose ether using propylene carbonate as a transesterification agent for oilfield applications

This study presents the utilisation of Propylene Carbonate (PC), along with an alkali-based solution, to modify the Hydroxyethyl Methyl Cellulose (HEMC) polymer to mitigate the thermal degradation of cellulose ether. The experimental results from FTIR and XRD analysis confirmed the addition of a new function group to the HEMC backbone and the formation of a new organic carbonate-based cellulose ether. Shear viscosity experiments were conducted at concentrations of 0.50-wt.% to 2-wt.% at ambient and elevated temperatures ranging from 80°C-110°C using a rheometer. All polymeric solutions exhibited shear-thinning behaviour, and the viscosity of polymeric solutions was enhanced by increasing the concentration of modified HEMC solutions. The modified HEMC solutions exhibited higher viscosity at 1000 s-1 shear rate at 110ºC compared to the native HEMC solutions, confirming the enhanced thermal stability of the PC-based modified HEMC solution. Alkali-based modified HEMC solution exhibited low shear viscosity at ambient temperature. The alkali-based polymeric solution’s viscosity was increased by 48% at a high shear rate at 110ºC. In conclusion, 0.50-wt.% and 01-wt.% concentration of alkali-based PC-modified HEMC solution proved efficient in maintaining viscosity under ambient conditions, increasing solubility and exhibiting improved thermal stability at geothermal conditions for oil field applications.

Origin of 13C NMR chemical shifts elucidated based on molecular orbital theory: paramagnetic contributions from orbital-to-orbital transitions for the pre-α, α, β, α-X, β-X and ipso-X effects, along with effects from characteristic bonds and groups.

13C NMR chemical shifts (δ(C)) were analysed via MO theory, together with the origin, using σ d(C), σ p(C) and σ t(C), where C4- was selected as the standard for the analysis since σ p(C: C4-) = 0 ppm. An excellent relationship was observed between σ d(C) and the charges on C for (C4+, C2+, C0, C2- and C4-) and (C4-, CH2 2-, CH3 - and CH4). However, such a relationship was not observed for the carbon species other than those above. The occupied-to-unoccupied orbital (ψ i →ψ a ) transitions were mainly employed for the analysis. The origin was explained by the pre-α, α, β, α-X, β-X and ipso-X effects. The pre-α effect of an approximately 20 ppm downfield shift is theoretically predicted, and the observed α and β effects of approximately 10-15 ppm downfield shifts are well reproduced by the calculations, as are the variations in the α-X, β-X and ipso-X effects. Large downfield shifts caused by the formation of ethene (∼120 ppm), ethyne (∼60 ppm) and benzene (∼126 ppm) from ethane and carbonyl (∼146 ppm) and carboxyl (∼110 ppm) groups from CH3OH are also reproduced well by the calculations. The analysis and illustration of σ p(C) through the ψ i →ψ a transitions enables us to visualize the effects and to understand the δ(C) values for the C atoms in the specific positions of the species. The occupied-to-occupied orbital (ψ i →ψ j ) transitions are also examined. The theoretical investigations reproduce the observed results of δ(C). The origin for δ(C) and the mechanism are visualized, which allows us to image the process in principle. The role of C in the specific position of a compound in question can be more easily understood, which will aid in the development of highly functional compounds based on NMR.

Low-temperature catalytic oxidation of ethanol over doped nickel phosphates.

This work is focused on the synthesis and performance of Ni3(PO4)2-based catalysts doped with Cu, Co, Mn, Ce, Zr, and Mg for the complete oxidation of ethanol, aiming at reducing emissions from ethanol-blended gasoline. Nickel phosphate was prepared via the co-precipitation method, followed by impregnation with the specified dopants. The catalysts were thoroughly characterized by XRD, N2-physisorption, XRF, FTIR and Raman spectroscopy, FESEM, NH3-TPD, CO2-TPD, and H2-TPR to explain their performance. All catalysts achieved complete ethanol conversion (100%) at a temperature below 320°C. The performance of the catalysts was strongly influenced by the dopant type of which Co, Ce, Mn, and Mg showed high CO2 selectivity (selectivity > 90% at 95% ethanol conversion temperature (T95)). The mechanism of oxidation is affected by the acido-basicity of the catalysts and the redox properties leading to a reaction through ethylene formation over the acid catalysts and acetaldehyde over the basic catalysts. The redox properties of the doped catalysts play a crucial role in enhancing the catalytic activity and selectivity toward CO₂, as the redox-active dopants facilitate the activation of oxygen species, which are essential for the complete oxidation of ethanol. In particular, Co and Ce demonstrated superior redox characteristics, facilitating the conversion of intermediate species and leading to higher CO2 selectivity while minimizing undesirable by-products.

Rapid Formation of Acetaldehyde and Its Influence on Ozone Formation in a Petrochemical Industrialized Region

Rapid Formation of Acetaldehyde and Its Influence on Ozone Formation in a Petrochemical Industrialized Region

Geminal-Cu Catalysts Drive Efficient C-C Coupling to Boost Ethylene Production via Electrochemical CO2 Reduction

Single-atom catalysts have emerged as promising materials for CO2RR. This study explores geminal copper catalysts for the CO2RR into ethylene. The adjacent Cu-Cu sites facilitate ethylene formation by allowing thermodynamically...

Electromagnetic milling promoted mechanochemical copper-catalyzed C–O coupling reaction for diaryl ether formation

We developed a novel solid-state electromagnetic milling facilitated Ullmann C–O bond synthesis method. This method uses less new copper catalyst and ligand combination, and can complete the reaction in a shorter time with less abrasive aid.

How Do Variants of Residues in the First Coordination Sphere, Second Coordination Sphere, and Remote Areas Influence the Catalytic Mechanism of Non-Heme Fe(II)/2-Oxoglutarate Dependent Ethylene-Forming Enzyme?

The ethylene-forming enzyme (EFE) is a Fe(II)/2-oxoglutarate (2OG) and l-arginine (l-Arg)-dependent oxygenase that primarily decomposes 2OG into ethylene while also catalyzing l-Arg hydroxylation. While the hydroxylation mechanism in EFE is similar to other Fe(II)/2OG-dependent oxygenases, the formation of ethylene is unique. Various redesign strategies have aimed to increase ethylene production in EFE, but success has been limited, highlighting the need for alternate approaches. It is crucial to incorporate an accurate and comprehensive description of the integrative and multidimensional effects of the protein environment to enhance the redesign strategy in metalloenzymes, particularly in EFE. This involves understanding the role of the second coordination sphere (SCS) and long-range (LR) interacting residues, correlated motions, electronic structure, intrinsic electric field (IntEF), as well as the stabilization of transition states and reaction intermediates. In this study, we employ a molecular dynamics-based quantum mechanics/molecular mechanics approach to examine the integrative effects of the protein environment on reactions catalyzed by EFE variants from the first coordination sphere (FCS, D191E), SCS (A198V and R171A) and LR (E215A). The study uncovers how substitutions at different positions in EFE similarly impact the ethylene-forming reaction while posing distinct effects on the hydroxylation reaction. Results predict the effect of the variants in controlling the 2OG coordination mode in the Fe(II) center. Specifically, the study suggests that D191E uniquely prefers transitioning from an off-line to an in-line 2OG coordination mode before dioxygen binding. However, studies on the 2OG flip in the presence of off-line approaching dioxygen and dioxygen binding in the D191E variant indicate that the 2OG flip might not be feasible in the 5C Fe(II) state. Calculations show the possibility of a hydrogen atom transfer (HAT)-assisted oxygen flip in EFE and its variants (other than D191E). MD simulations elucidate the characteristic dynamic change in the α7 region in the D191E variant that might contribute to its increased hydroxylation reaction. Results indicate the possibility of forming an in-line ferryl from the IM2 (Fe(III)-partial bond intermediate) in the D191E variant. This alternative pathway from IM2 may also exist in WT EFE and other variants, which are yet to be explored. The study also delineates the impact of substitutions on the electronic structure and IntEF. Overall, the calculations support the idea that understanding the integrative and multidimensional effects of the protein environment on the reactions catalyzed by EFE variants provides the basics for improved enzyme redesign protocols of EFE to increase ethylene production. The results of this study will also contribute to the development of alternate redesign strategies for other metalloenzymes.

Ultrasonic treatment-assisted reductive deposition of Cu and Pd nanoparticles on ultrathin 2D Bi2S3 nanosheets for selective electrochemical reduction of CO2 into C2 compounds.

In this work, we have ultrasonically deposited Cu and Pd nanoparticles on Bi2S3 nanoparticles, prepared using an ultrasonication assisted hydrothermal method. We implemented intense ultrasonic waves bearing frequency of 20kHz and power of 750W at the acoustic wavelength of 100mm to reduce Cu and Pd nanoparticles on the Bi2S3 surface. The XRD confirmed the formation of highly crystalline Bi2S3 nanoparticles with a pure orthorhombic phase and the deposition of copper (Cuo) and palladium (Pdo) nanoparticles was indicated by the strengthening and broadening of the peaks. XPS also confirmed the formation of Cuo and Pdo nanoparticles on Bi2S3. The Transmission Electron Microscopy (TEM) also exhibited the deposition of Cu and Pd nanoparticles on the Bi2S3 nanosheets which was further confirmed using high resolution TEM analysis. The electrochemical CO2 reduction by Cu-Pd/Bi2S3 electrocatalyst using Cu foam as the conducting support led to the formation of acetaldehyde and ethylene as the major products. The rate of formation of ethylene was found to be 488.5 μ mol g-1h-1 at an applied potential of -0.6V (vs. RHE), with the best Faradaic efficiency of 57.09% at -0.4V (vs. RHE). Among the liquid phase products, acetaldehyde was the major product showing the maximum Faradaic efficiency of 6.473% at -0.2V (vs. RHE), with a total formation rate of 64.27 μ mol g-1h-1. The results revealed that the Cu-Pd/Bi2S3 electrocatalyst was more selective to C2 products while the pure Bi2S3 nanoparticles majorly produced C1 compounds.

Comparative Selectivity of CO and CO2 Reduction Using Cu Electrocatalysts in Zero-Gap MEA Cells

The electrochemical reduction of CO2 to C2 products is believed to proceed via the formation of adsorbed CO as an intermediate. Although ethylene is frequently reported as the main product when using Cu electrocatalysts, recent studies have demonstrated that directly feeding CO can result in the selective formation of acetate. In this study, we investigate the electrochemical reduction of CO2 and CO using Cu electrocatalysts prepared by a one-pot synthesis method employing hydrazine as a reducing agent and polyvinylpyrrolidone (PVP) as a capping agent in a Membrane Electrode Assembly (MEA) cell configuration. We investigated the electrochemical reduction of CO2 and CO using Cu electrocatalysts prepared by a one-pot synthesis method in a Membrane Electrode Assembly (MEA) cell configuration. While CO2 reduction primarily yields ethylene (36.99%), followed by hydrogen, CO, and ethanol, feeding CO directly under the same potential increases the total C2 product yield from 52% to 83%, with acetate becoming the dominant product at 63%. Employing a phosphate buffer to maintain an alkaline pH of 8 further enhances acetate selectivity, reaching 90% with KOH. We propose a mechanism involving a common acetyl intermediate for ethylene formation from CO2 and a ketene intermediate for CO reduction to acetate. Our results highlight the significant impact of feed, electrolyte composition, and pH on product distribution, with direct CO reduction favoring C2 products and alkaline pH promoting acetate selectivity. These findings offer insights for optimizing the electrochemical reduction of CO2 and CO. Figure 1

Advancing the C[formula omitted] low-temperature oxidation chemistry through species measurements in a rapid compression machine, Part A: 1-Butene

Alkene chemistry plays a crucial role in the autoignition and oxidation of larger hydrocarbons. Unlike its other isomers, 1-butene is characterized by a two-stage ignition process. Various previous studies of 1-butene oxidation have used experimental techniques, including the measurement of ignition delay times in rapid compression machines (RCM) and in shock tubes, the determination of flame velocities, and the measurement of species concentrations in flames and in jet-stirred reactors (JSR). JSR studies provide an important insight into intermediate species formation at low temperatures but are constrained to low pressures and/or highly diluted conditions. To bridge the gap between JSR and engine-relevant conditions, this study presents species concentration measurements during the oxidation of 1-butene at 733 K and 30 bar under stoichiometric ’air-like’ conditions in an RCM, complemented by IDT measurements in the temperature range of 680–910 K. We designed an innovative 2-valve sampling setup to reduce quantitative uncertainties and the time required for species measurements. Our results indicate that existing 1-butene models fail to accurately predict the IDTs and the formation of the key oxidation intermediates. In response, potential optimizations for an improved kinetic model based on NUIGMech1.3 are discussed. Rate parameters for predominantly fuel consumption pathways, along with other reactions and thermochemical properties in the Waddington mechanism, have been altered within expected uncertainty limits to reflect the experimentally observed IDTs and species concentrations of this study and other validation data from the literature. However, the refined model does not predict the formation of 2-ethenyloxirane and ethene, indicating a gap in our understanding of the chemistry of these components. Overall, this study demonstrates the importance of measuring intermediates under the same conditions as IDTs to accurately address deficiencies in current kinetic mechanisms, and represents the first phase of a comprehensive investigation advancing the understanding of C4 oxidation chemistry.Novelty and significance statementThe novelty of this research lies in the design of an innovative sampling system for RCM species measurements, lowering the time for experimental execution and the uncertainties of the measurements. This enabled first-time species measurements during the oxidation of butene isomers in an RCM at high pressure and low level of dilution, contributing to the refinement of the 1-butene sub-mechanism within the NUIGMech1.3 framework. This research contributes to the understanding of the oxidation of alkenes, an important class of intermediates in gasoline and biofuel combustion. It emphasizes the need to measure intermediate species at the same conditions as ignition delay times, which are essential for understanding oxidation pathways under engine-relevant conditions. This research is part of a broader investigation of C4 oxidation chemistry, along with our companion work on n-butane. The resulting kinetic model is capable of reproducing most of the available n-butane and 1-butene validation targets.

Analysis of Poly(ethylene glycol) from the conservation of 17th century shipwreck Vasa and associated wooden objects

Vasa, a Swedish warship that sunk in 1628 and was excavated in 1961, and associated wooden objects underwent a preservation process using various low molecular weights (600, 1500, and 4000 Mn) of poly(ethylene glycol) (PEG) to gradually displace the water within the wooden structure, preventing the collapse of the waterlogged wood upon drying. However, after six decades of aging after application, to what extent are these polymers degraded? To investigate this, a Soxhlet apparatus was used to extract PEG from wooden samples of Vasa, and lyophilization was used to dry aqueous PEG solutions, these samples being the runoff accumulated during the application of different molecular weights of PEG to Vasa and other associated wooden objects. These samples underwent analysis via matrix-assisted laser desorption/ionization – time-of-flight mass spectrometry (MALDI-TOF MS), gel permeation chromatography (GPC), and 1H and 13C nuclear magnetic resonance (NMR) spectroscopy.The primary discovery was that the PEG within Vasa exhibited minimal degradation, with the dominant identified species, as determined by MALDI-TOF MS and NMR spectroscopy, being HO-PEG-OH. However, small quantities of HO-PEG-OH had undergone degradation, resulting in the formation of PEG chains with distinct end groups, notably a range of carbonyl-based compounds, including aldehydes, carboxylic acids, and esters, as observed through MALDI-TOF MS, 1H, and 13C NMR spectroscopy. These mass spectrometry product peaks could be confirmed by the expected mass difference through various end-group functionalizations, such as oxidations, esterifications, or ether formations. In addition to the carbonyl-based degradation products, some PEG chains had completely cleaved into two separate lower molecular weight HO-PEG-OH polymers, each approximately half of their original molecular weight, as revealed by GPC analysis.

Conversion of Sugars to Lactic Acid using Homogeneous Niobium-Substituted Polyoxometalate Catalysts.

The catalytic conversion of biomass into high-value chemicals is an increasing field of research. This study uniquely investigates the use of various Keggin-type heteropoly salts (HPS) for the chemical conversion of sugars into lactic acid under mild conditions of 160 °C and 20 bar N2. In the first phase, Nb- and V-substituted HPSs were employed to synthesize lactic acid from dihydroxyacetone, an intermediate in the conversion of sugars to lactic acid. Results indicated that increasing the Nb content within the Keggin structure enhances the yield of lactic acid while reducing the formation of the byproduct acetaldehyde. A correlation was established between the redox activity of the HPS and the catalytic performance. The most active catalyst, Na5[PNb2Mo10O40], (NaNb2) achieved a lactic acid yield of 20.9 % after 1 h of reaction. In the second phase of the study, NaNb2 was applied for the conversion of different sugars including glucose, fructose, mannose, sucrose, xylose, and cellobiose. It was demonstrated that the catalyst remains active for complex hexoses, achieving lactic acid yields of up to 12 %. Post-mortem analysis using infrared (IR) and Raman spectroscopy, nuclear magnetic resonance (NMR), and inductively coupled plasma optical emission spectrometry (ICP-OES) confirmed the stability of NaNb2.

Significant Biogenic Source of Oxygenated Volatile Organic Compounds and the Impacts on Photochemistry at a Regional Background Site in South China.

Oxygenated volatile organic compounds (OVOCs) significantly modulate atmospheric chemistry, but the sources and air quality impacts of OVOCs in aged urban outflows remain to be elucidated. At a background site in South China, the ozone formation potential of six nonformaldehyde OVOCs studied was equivalent to that of 3.56 ppbv of formaldehyde, more than half of which was contributed by acetaldehyde. Source apportionment incorporating photochemical age revealed that considerable fractions (52.7%-62.6%) of the OVOCs were of biogenic origin, except for ethanol, which was primarily derived from anthropogenic emissions. The oxidation of cis-/trans-2-butene explained 71.1% of the in situ acetaldehyde formation. In contrast, α/β-pinenes and isoprene contributed 73.8% and 28.4% to acetone and methylglyoxal formation, respectively. An average of 12.4% of net in situ ozone (O3) production rate was attributed to the OVOCs studied, where the biogenic fractions accounted for 59%. The changes in the O3 production rate and hydroxyl radical (OH) concentration caused by OVOCs were mainly affected by ozone formation sensitivity. The effects of primary acetaldehyde and acetaldehyde-led O3 on secondary acetaldehyde formation were weak at this background site; however, they cannot be ignored in polluted areas. This study provides a scientific basis for mitigating O3 pollution driven by biogenic emissions and OVOCs.

Distribution of volatile composition from co-pyrolysis of NMH coal and dealkaline lignin

Experimental studies on co-pyrolysis of coal and lignin are carried out on a fixed-bed reactor to investigate composition and transformation of the co-pyrolysis products. The results show that co-pyrolysis reduces yield of char and promotes yield of gas, the maximum pyrolysis gas yield increases by 33.1%. Co-pyrolysis has a significant promotion effect on generation of CH4 and CO. The interaction between the pyrolyzed volatile fractions of coal and lignin shows the most pronounced interaction at a coal to lignin mixing ratio of 1:1, and the pyrolysis tar yield shows a positive synergistic effect. Guaiacols are converted to monophenols and bisphenols during the co-pyrolysis process. Content of monophenols and bisphenols increase by 2.9% and 9.8%, respectively, while content of guaiacols decreases by 5.1% compared with the theoretically calculated values. The breakage of carbonyl and carboxyl groups, and the interaction with volatile components are enhanced, which inhibits formation of ethers, aldehydes and acids, and promotes generation of phenols, release of oxygenated gases and stabilization of pyrolysis tar. The introduction of lignin into coal pyrolysis also significantly promotes the upgrading of tar in which light components is nearly 90%.

КІНЕТИКА ВЗАЄМОДІЇ КАЛІЙСУПЕРОКСИДУ З 18-КРАУН-6

The dissolution processes of KO2 in the presence of 18-crown-6 in dimethylsulfoxide (DMSO) were studied, and the properties of the complexes formed were compared with the properties of complexes with KCl, KBr, KI, and KOH (in the general case, KX). Using the electrical conductivity measurement method, the change in the electrical conductivity of the КО2 -18-crown-6 - solvent, КOH - 18-crown-6 - solvent and KBr - 18-crown-6 - solvent systems during the formation of the corresponding ions during the interaction of the crown ether with КХ was studied in solid form. Complex formation in the systems KO2-18-crown-6-solvent, KOH-18-crown-6-solvent and KBr-18-crown-6-solvent in dimethyl sulfoxide was studied. It is shown that the dependences of the specific electrical conductivity of the solution on time during the interaction of KO2, KOH and KBr c 18-crown-6 in DMSO are typical kinetic curves with asymptotes. The limiting stage is the interaction of the dissolved reagent with the surface of the solid substance. Possible kinetic mechanisms of the process were analyzed. It is shown that the change in electrical conductivity over time under these conditions is described by an exponential equation. The coefficients of this equation are determined for different systems. It is proved that the value of the parameter that characterizes the content of ions at t®¥ depends on the concentration of each of the reactants and is determined by the concentration of the one of them that is present in the mixture in the smallest amount. The resulting kinetic equations make it possible to estimate the time required to reach equilibrium. It is shown that the time to reach the asymptotic values ​​depends on the nature of the anion. The dependence of the electrical conductivity of solutions of salts and KOH in the presence of 18-crown-6 in the equilibrium state on the concentration of the components was established. It has been proved that the kinetics of the formation of the crown ether - salt complex dissociated into ions is described by an exponential equation, the parameters of which depend on the concentration of the component taken in shortage and the nature of the anion. The dependence of electrical conductivity on the composition of binary mixtures KBr - KO2, KCl - KO2, KI - KO2 was established for the first time. The resulting kinetic equations make it possible to estimate the time required to reach equilibrium. It is shown that the equilibrium solutions retain their properties for 150 hours and can be further used to study reactions involving active oxygen.

Electrochemical Formation of C2+ Products Steered by Bridge-Bonded *CO Confined by *OH Domains.

During the electrochemical CO2 reduction reaction (eCO2RR) on copper catalysts, linear-bonded CO (*COL) is commonly regarded as the key intermediate for the CO-CO coupling step, which leads to the formation of multicarbon products. In this work, we unveil the significant role of bridge-bonded *CO (*COB) as an active species. By combining in situ Raman spectroscopy, gas and liquid chromatography, and density functional theory (DFT) simulations, we show that adsorbed *OH domains displace *COL to *COB. The electroreduction of a 12CO+13CO2 cofeed demonstrates that *COB distinctly favors the production of acetate and 1-propanol, while *COL favors ethylene and ethanol formation. This work enhances our understanding of the mechanistic intricacies of eCO(2)RR and suggests new directions for designing operational conditions by modifying the competitive adsorption of surface species, thereby steering the reaction toward specific multicarbon products.

Ether and ester formation from peroxy radical recombination: a qualitative reaction channel analysis

Abstract. The least volatile organic compounds participating in atmospheric new-particle formation are very likely accretion products from self- and cross-reactions of peroxy radicals (RO2). It has long been assumed that the only possible accretion product channel in this reaction is that forming a peroxide (RO2+RO2→ROOR+O2), but it has recently been discovered that a rapid alkoxy radical (RO) decomposition may precede the accretion step of the mechanism, forming slightly fragmented but more stable ether (ROR) or ester (RC′(O)OR) accretion products. In this work, the atmospheric implications of this new reaction channel have been explored further by using a modified version of the Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) software to generate a large amount of representative RO2 + RO2 reactive pairs formed from the oxidation of typical primary hydrocarbons and by applying structure–activity relationships (SARs) to predict the potential accretion products. These data are analysed in terms of the formation of low-volatility products, and new discoveries are presented on what types of RO2 are especially efficient (and which are surprisingly inefficient) at forming accretion products. These findings are discussed in terms of the atmospheric relevance of these new RO2 + RO2 reaction channels. As the generation of these data rests on several simplifications and assumptions, many open questions worthy of later studies are also raised.