Addition Of Ether Research Articles

Negligible Substituent Effect as Key to Synthetic Versatility: a Computational‐Experimental Study of Vinyl Ethers Addition to Nitrile Oxides

AbstractA tangible substituent effect may be perceived as a good feature in developing an organic reaction. This work demonstrates that, on the contrary, a zero‐slope Hammet plot should be sought. The synthesis of isoxazoles by consecutive cycloaddition of nitrile oxides to vinyl ethers and alcohols elimination was studied computationally and experimentally. We performed a Hammett studyin silicoto demonstrate a negligible substituent effect (i. e., broad substrate scope) in the addition of benzyl vinyl ether to nitrile oxides. The modeling was performed at the ωB97X‐V/def2‐TZVP//PBE0‐D4/def2‐TZVP+SMD(benzene) level of theory within the RIJCOSX approximation. The experimental evaluation validated the computational model. A versatile methodology for synthesizing substituted isoxazolines and isoxazoles was proposed as the main result. We present this work as a successful example of how quantum chemical modeling can re‐boost the classic Hammett approach to the optimization and design of organic synthetic methodologies. We anticipate further Hammett studiesin silico, considering the current trend for data‐driven chemical research.

Nickel-Catalyzed Enantioselective C(sp 3 )–H Arylation of Ketones with Aryl Ethers via Selective C Ar –O Cleavage to Construct All-Carbon Quaternary Stereocenters

Nickel-Catalyzed Enantioselective C(sp ³ )–H Arylation of Ketones with Aryl Ethers via Selective C _Ar –O Cleavage to Construct All-Carbon Quaternary Stereocenters

Modelling of laminar diffusion flames with biodiesel blends and soot formation

Modelling of soot formation and oxidation of biodiesel fuels is a challenge, due to the complexity of the chemical reactions and soot formation pathways. In this paper, the discretised population balance approach and a PAH-HACA based detailed soot model have been coupled with an in-house CFD code to simulate a laminar diffusion flame with blends of different components of oxygenated biodiesel fuel, and employed to predict combustion performance and soot formation. The simulation aims to reproduce a target experiment which investigated the effects of dibutyl ether (DBE) addition to the biodiesel surrogate (methyl decanoate, MD) by increasing the mole fraction of DBE from 0 to 40%. A combined and reduced MD–DBE–PAH mechanism developed from three sub-mechanism branches has been employed in the simulation. The simulation results show that temperature rises as the DBE percentage increases to 40%. The swallow-tail shape of the soot occurrence zone and the quantity of soot production are correctly predicted. Regarding the effect of soot suppression, the model has basically captured the reducing tendency of soot formation in the measurements as the DBE addition increases from 0% to 40%. Concentrations of PAHs and C3 species contributing to the formation of aromatic rings are slightly reduced due to the addition of DBE, which is a leading cause of soot suppression. However, on the whole, the numerical solution featured much smaller differences than those observed in the experiment among laminar flames with different MD/DBE ratios, because the combined MD–DBE–PAH mechanism only present a slight difference of concentrations of soot precursor species.

Performance and Emission Characteristics of Diesel Engine Using Ether Additives: A Review

Pressure on alternative fuels and strict environmental regulations are driving a strategic shift in the efficient use of renewable biofuels. One of the promising biofuel candidates recently interested by scholars is a biological or organic additive that is added into diesel or biodiesel fuel to improve engine performance and reduce pollutant emissions. With efforts to improve efficiency and combustion quality in cylinders, combustion characteristics, flame structure and emission formation mechanism in compression ignition (CI) engines using blended fuel with organic additives have been studied on the effect of additive properties on the combustion behaviour. In this review, the physicochemical properties of typical organic additives such as ethers compounds and their effects on engine performance and emission characteristics have been discussed and evaluated based on conclusions of recent relevant literature. The results of the analysis revealed the prospect of using ether additives to improve combustion in cylinders and reduce pollutant emissions from CI engines. Obviously, the presence of higher oxygen content, lower viscosity and density, and higher cetane number resulted in a positive change in the combustion dynamics as well as a chain of mechanisms for the formation of pollutant precursors in the cylinder. Therefore, ether additives have a significant contribution to the sustainable energy strategy of the transportation sector in the next period when internal combustion engines still dominate in the competition for energy system choices equipped on vehicles.

Effects of delayed addition of polycarboxylate ether on one-part alkali-activated fly ash/slag pastes: Adsorption, reaction kinetics, and rheology

The admixture addition method is one of the vital factors influencing the fresh performance of ordinary Portland cement (OPC) through directly affecting the adsorption, hydration, and rheology. However, such an issue is less researched in the one-part alkali-activated materials (AAMs), which have great potentials in the industry due to their simple operation, similar to OPC. This study reports and discusses the effects of delayed polycarboxylate ether (PCE) addition at different contents on adsorption, reaction kinetics, and rheology of one-part AAMs. It is found that the delayed PCE addition had minimized the competitive adsorption phenomenon and reduced the consumption rate of PCE surfactants, which in turn facilitates easier adsorption of silicate species onto the GGBS grains. This had decreased the retardation effect of PCE, slightly improved the compressive strength, and lowered the viscosity and yield stress of the one-part AAMs. The mechanisms that govern such observations are further discussed.

Two Environmentally Friendly Alkyl-o-Glucoside-Based Formulations for Hole Cleaning during Heavy and Extra-Heavy Oilfield Drilling

Summary The formulation of antiaccretion additives for cleaning the hole in long-range directional or tangential wells in heavy and extraheavy oil reservoirs is considered a technological challenge due to the unconsolidated characteristics of the formations (such as gravel, sand, pea, etc.) as well as the physicochemical properties of the heavy crude oil. In this work, we propose a hole cleaning formulation that can solubilize the asphaltenes present in Mexican heavy crude oil and that is also efficient in eliminating the accretion due to heavy oil fractions. Alkyl-o-glucoside (APG) whose alkyl group has 12 carbons was used as the biosurfactant. The addition of the cosurfactant ethylene glycol butyl ether (EGBE) to the aqueous solution of APG reduced its surface tension. The aqueous APG solutions were able to solubilize the asphaltenes inside the micelles. The addition of EGBE increased the stability of the aspahltenes/APG/water emulsion. The APG/EGBE/Limonene antiaccretion additive proposed in this work for the mobilization of the trapped nonaqueous phase liquid showed a higher cleaning efficiency factor (CEF) than conventional diluents. Higher cleaning efficiency was obtained when the test temperature was increased.

Effects of air-side dimethyl ether premixing on combustion characteristics of nonpremixed biodiesel/air counterflow flames

Counterflow flame modeling was conducted to investigate the effects of air-side dimethyl ether premixing on the combustion of biodiesel/air non-premixed flames, using the detailed kinetic mechanisms of bio-diesel and dimethyl ether. Methyl decanoate was adopted as the bio-diesel surrogate component. Comparative analyses focused on heat release, methyl decanoate oxidation, and the soot precursor, i.e. benzene production in the flames. The complex triple-flame structures were observed in the flames with air-side addition of dimethyl ether. Due to the interactions in the hybrid reaction zones, the flames with air-side premixing had higher peak temperatures, broadened flame thickness, and greater production of the integrated OH radical, consequently resulting in more robust flame power. The reactions related to self-pyrolysis and H-abstraction are the top main routes for methyl decanoate oxidation. The thermal effect induced by the higher flame temperature enhanced the radial leakage of MD and other intermediates and lowered the benzene production rate. The non-premixed reaction zone was the most active region for benzene production. The air-side premixing could exert its chemical effect on benzene formation within this zone by changing propargyl and phenyl chemistry.

THE INFLUENCE OF DIFFERENT PHENYL MOIETY SUBSTITUTIONS OF SILDENAFIL DERIVATIVES ON THEIR POTENTIAL INTERACTION TOWARD PHOSPHODIESTERASE TYPE-5

Sildenafil has FDA approval as the first agent for erectile dysfunction oral therapy. It works by inhibiting the phosphodiesterase type 5 enzyme and preventing the breakdown of cyclic guanosine monophosphate. Therefore, this study aims to modify the structure of sildenafil to obtain a safer derivative with better phosphodiesterase type-5 inhibition activity. An interaction assessment using molecular docking and dynamic simulation (in silico) was carried out to evaluate the interaction affinity of the derivatives with the phenyl moiety, which has different substituents for PDE5. The results showed that the removal of 4-methylpiperazine-sulfonyl and methoxy from the moiety as well as the addition of propyl ether in the para position led to significant changes in pharmacokinetic properties and affinity toward PDE5. This substituent enables two hydrogen interactions between the Gln817 amino acid residue and the pyrazolopyrimidine ring with a binding energy of -115.65 kJ/mol. Through the reduction of competitive interference for H-bonding with water, these interactions indicate the presence of a higher affinity protein-ligand association. Furthermore, the root-mean-square deviation profile of this sildenafil derivative-PDE5 complex was significantly lower compared to the other five ligand-enzyme complexes, and this indicates a stable conformation.

Қоспалы отынның негізгі қасиеттері (дизель отыны + диметил эфирі) және диметил эфирі қоспасының дизельдік қозғалтқыш жұмысының көрсеткіштеріне әсерін теориялық бағалау

In the work, there was carried out a physical and chemical analysis of alternative fuels, from which there was selected dimethyl alcohol. A number of theoretical calculations were carried out to evaluate the main properties of the mixed fuel and the effect of the addition of dimethyl ether on the performance of the diesel engine. For a more complete assessment of the effect of mixed fuel on engine performance, there were used regression modeling methods. The regression coefficients were calculated on a PC using the MATLAB application software package. Theoretical calculations and mathematical modeling have shown that the addition of 30% dimethyl ether to diesel fuel is the most effective part of the mixture to reduce the environmental performance of diesel engines.

From mixed group 13 cations [M(AlCp*)3]+ (M = Ga/In/Tl) to an Al4 + cluster.

AlCp*-complexes with transition metals have shown to be highly reactive and enable C-H or Si-H bond activation. Yet, complexes of AlCp* with low-valent main-group metals are scarce. Here, we report the syntheses of [M(AlCp*)3][Al(ORF)4] (RF = C(CF3)3) with M = Ga, In, Tl, which include the first covalent Al-In and Al-Tl bonds. For M = Ga, AlCp*-coordination induced the formation of the dication [Ga2(AlCp*)6]2+ in the solid state, which exhibits a solvent and temperature dependent monomer-dimer equilibrium in solution. By contrast, the In and Tl complexes are monomeric and prone to reduction to the metal by the electron-rich AlCp*-moieties. The QTAIM analysis suggests that the metal centres are already highly reduced in the complexes, while the positive charge is distributed onto the AlCp* units. Addition of Me3TACN (1,4,7-trimethyl-1,4,7-triazacyclononane) to the Ga- and Tl-complex salts resulted in an isomerization to the novel low-valent Al4 + cation [(Me3TACN)Al(AlCp*)3][Al(ORF)4]. Intermittently formed tetrahedral GaAl3 + clusters could be structurally characterized. From a detailed mechanistic study of this isomerization, the very high yield and clean preparation of [(Me3TACN)Al(AlCp*)3][Al(ORF)4] was devised from [M(Me3TACN)][Al(ORF)4] (M = Ga, Tl) and [(AlCp*)4].

Role of crown ether in the perovskite precursor for doctor-bladed perovskite solar cells: investigation by liquid-phase scanning electron microscopy

Addition of crown ether to the perovskite precursor effectively reduced the size of perovskite-based micelles and retarded the perovskite growth rate in the doctor-bladed perovsktie film.

Evaluation of Waste Plastic Pyrolysis Oil Performance with Diethyl Ether Additive on Insulated Piston Diesel Engine

Considering the amount of waste plastics has risen significantly, energy may be extracted from it. Not only is it possible to dispose of waste plastics by converting them to fuel, but it is also possible to extract energy from them. Our research is motivated by the prospect of using waste plastics as a source of energy through waste plastic pyrolysis oil (WPPO). The innovation of this research is that it will assess the efficiency of plastic pyrolysis oil derived from Low-Density Polyethylene (LDPE) on a Thermal Barrier Coated (TBC) piston engine. The incremental ratio of WPPO to pure diesel with the addition of diethyl ether (DEE) was determined and its output and exhaust emission standards were evaluated using a direct injection single cylinder low heat rejection diesel engine. The results for the WPPO blends were promising as with TBCW20DEE10 demonstrating a 5 to 15% increase in carbon monoxide under different load conditions. TBCW20DEE10 confirmed a greater reduction of hydrocarbons varying from 5 to 12 %. At half load condition, TBCW20DEE10 emits approximately 3.5 % less unit of smoke.

Trade-Off Study on Economy and Environmental Aspects of a Dual-Fuel Diesel Engine Using Diesel Additive and Producer Gas

Abstract Experiments are performed on a diesel engine working in a single-fuel mode using fossil diesel (FD) as well as 5% and 10% (v/v) di-ethyl ether (DEE) additives with FD as fuels as well as in dual-fuel mode using the aforementioned fuels as pilot fuels along with producer gas (PG) as a primary fuel. This study aims to draw comparative analyses of engine combustion, performance, and emission characteristics using the aforementioned fuel combinations to establish the most suitable fuel strategy for a diesel engine. The study revealed greater control over nitric oxide (NO) and smoke opacity in dual-fuel mode compared to single-fuel mode operations. The addition of DEE with FD produced lower hydrocarbon (HC) and carbon monoxide (CO) emissions and comparable NO emissions along with reduced smoke opacity compared to FD in both modes of operation. Furthermore, in a dual-fuel mode operation, the diesel percentage energy substitution (PES) reduced with an increase in the DEE content in the blends. The trade-off study involving engine performance and emissions with respect to the cost of operation revealed that the fuel strategy used in dual-fuel mode operation delivered better engine performance along with reduced NO emission and smoke opacity at lower operational cost compared to all the considered fuel strategy in single-fuel mode operation. Especially, FD + 5% DEE + PG and FD + 10% DEE + PG fuel strategies were found to be the most suitable dual-fuel mode combinations in a diesel engine in terms of their superior engine performance and lower emissions along with better economy.

Analysis Of The Use Of Diethyl Ether Additives In Biodiesel (B20) On Diesel Engine Exhaust Gas Emissions

Although biodiesel is an alternative fuel that has promising potential for use in diesel engines. However, currently, biodiesel used in the market is still the dominant content of diesel from fossil fuels and biodiesel is used as additional material. The purpose of this research is to reduce the number of exhaust emissions produced by biodiesel (B20). This research was conducted using an experimental method, several samples were tested from biodiesel fuel (B20), then biodiesel was added with diethyl ether (DEE) with a ratio of 1%, 2%, 3%, 4% and 5% in each litre. Testing of several samples was carried out to measure the level of exhaust gas emission (opacity) produced by each sample using the Opacity Smokemeter. The results of the research from the addition of diethyl ether (DEE) to biodiesel (B20) were able to reduce the level of opacity. The lowest opacity level was found in the diethyl ether (DEE) mixture of 5%, namely 42.37%. Where the value of the difference or decrease in smoke thickness or opacity when compared to biodiesel (B20) is 2.88% for B20 + 1% DEE, 4.26% for B20 + 2% DEE, 7.70% for B20 + 3% DEE, 10,50% for B20 + 4% DEE and 12.76% for B20 + 5% DEE.

Alkaline aerobic oxidation of native softwood lignin in the presence of Na+-cyclic polyether complexes

Alkaline aerobic oxidation is a promising way to convert lignin to low molecular weight phenols, especially 4-hydroxybenzaldehydes. Our previous studies reported that oxidation of softwood lignin samples with a bulky cation, Bu4N+, facilitates selective production of vanillin (4-hydroxy-3-methoxybenzaldehyde). This study presents vanillin production from native softwood lignin in Japanese cedar (Cryptomeria japonica) in NaOH aq. in the presence of cyclic polyethers, with our expectation that Na+-polyether complexes exhibit effects similar to those of Bu4N+. Oxidation of wood flour (10 mg) in 4.0 M NaOH aq. (2.0 mL) at 120 °C under air gave vanillin with 6.2 wt% lignin-based yield, which was raised to 15.2 wt% by the addition of 15-crown-5 (1,4,7,10,13-pentaoxacyclopentadecane). On the other hand, such effect was not observed with the addition of tetraethylene glycol dimethyl ether, a non-cyclic analog of 15-crown-5. Mechanistic study with a lignin model compound revealed that stabilization of a vanillin precursor by the complex cation was a reason for the increased vanillin yield exhibited by the crown ether. This is similar to the influence of Bu4N+ reported previously, suggesting effective control of aerobic oxidation by large size cationic species.

Closer Look at Inverse Electron Demand Diels–Alder and Nucleophilic Addition Reactions on s-Tetrazines Using Enhanced Sampling Methods

Inverse electron demand [4+2] Diels–Alder (iEDDA) reactions as well as unprecedented nucleophilic (azaphilic) additions of R-substituted silyl-enol ethers (where R is Phenyl, Methyl, and Hydrogen) to 1,2,4,5-tetrazine (s-tetrazine) catalyzed by hbox {BF}_{3} have recently been discovered (Simon et al. in Org Lett 23(7):2426–2430, 2021), where static calculations were employed for calculation of activation energies. In order to have a more realistic dynamic description of these reactions in explicit solution at ambient conditions, in this work we use a semiempirical tight-binding method combined with enhanced sampling techniques to calculate free energy surfaces (FESs) of the iEDDA and azaphilic addition reactions. Relevant products of not only s-tetrazine but also its derivatives such as hbox {BF}_{3}-mediated s-tetrazine adducts are investigated. We reconstruct the FESs of the iEDDA and azaphilic addition reactions using metadynamics and blue moon ensemble, and compare the ability of different collective variables (CVs) including bond distances, Social PeRmutation INvarianT (SPRINT) coordinates, and path-CV to describe the reaction pathway. We find that when a bulky Phenyl is used as a substituent at the dienophile the azaphilic addition is preferred over the iEDDA reaction. In addition, we also investigate the effect of hbox {BF}_{3} in the diene and steric hindrance in the dienophile on the competition between the iEDDA and azaphilic addition reactions, providing chemical insight for reaction design.

The Anionic Pathway in the Nickel-Catalysed Cross-Coupling of Aryl Ethers.

The Ni‐catalysed cross‐coupling of aryl ethers is a powerful method to forge new C−C and C−heteroatom bonds. However, the inert C(sp2)−O bond means that a canonical mechanism that relies on the oxidative addition of the aryl ether to a Ni0 centre is thermodynamically and kinetically unfavourable, which suggests that alternative mechanisms may be involved. Here, we provide spectroscopic and structural insights into the anionic pathway, which relies on the formation of electron‐rich hetero‐bimetallic nickelates by adding organometallic nucleophiles to a Ni0 centre. Assessing the rich co‐complexation chemistry between Ni(COD)2 and PhLi has led to the structures and solution‐state chemistry of a diverse family of catalytically competent lithium nickelates being unveiled. In addition, we demonstrate dramatic solvent and donor effects, which suggest that the cooperative activation of the aryl ether substrate by Ni0‐ate complexes plays a key role in the catalytic cycle.

The Anionic Pathway in the Nickel‐Catalysed Cross‐Coupling of Aryl Ethers

AbstractThe Ni‐catalysed cross‐coupling of aryl ethers is a powerful method to forge new C−C and C−heteroatom bonds. However, the inert C(sp2)−O bond means that a canonical mechanism that relies on the oxidative addition of the aryl ether to a Ni0 centre is thermodynamically and kinetically unfavourable, which suggests that alternative mechanisms may be involved. Here, we provide spectroscopic and structural insights into the anionic pathway, which relies on the formation of electron‐rich hetero‐bimetallic nickelates by adding organometallic nucleophiles to a Ni0 centre. Assessing the rich co‐complexation chemistry between Ni(COD)2 and PhLi has led to the structures and solution‐state chemistry of a diverse family of catalytically competent lithium nickelates being unveiled. In addition, we demonstrate dramatic solvent and donor effects, which suggest that the cooperative activation of the aryl ether substrate by Ni0‐ate complexes plays a key role in the catalytic cycle.

Improved saccharification of pretreated lignocellulose by Clostridium thermocellum with the addition of surfactant, low loading of cellulose

Saccharification of lignocellulose is prerequisite for the biorefinery. Clostridium thermocellum is a promising candidate for the hydrolysis of lignocellulose. A study on the saccharification by Clostridium thermocellum combined with surfactant and cellulase addition was investigated. The reducing sugars content increased with increasing substrate loading in the fermentation of C. thermocllum with isooctyl alcohol polyoxyethylene ether (IAPE) addition. Based on IAPE addition, the glucose content of two-step saccharification was higher than that of the batch saccharification. Besides, the addition of IAPE and Triton X-100 had the same effect on saccharification. The saccharification performance was related to the substrate, especially the lignin content. For the fed-batch hydrolysis of 20 % (w/v) rice straw pretreated by hydrogen peroxide-acetic acid (HPAC), 66.9 g/L glucose and 19.5 g/L xylose were obtained by using C. thermocellum DSM 1313 and 1 FPU/g substrate cellulase with 0.1 % (w/v) IAPE addition, and the glucose and xylose yield reached 63.2 % and 37.4 % respectively.

INFLUENCE OF DIBENZYL ETHER (DBE) ADDITION ON THE STRUCTURE OF CHROMIUM CARBIDE COATING OBTAINED BY THE MOCVD METHOD FROM COL “BARKHOS”

Investigations of the effect of the addition of dibenzyl ether (DBE) to the chromium organic liquid (COL) “Barkhos” on the structure and performance properties of chromium carbide coatings obtained by chemical deposition of their gas phase have been carried out. It is shown that the use of the DBE additive expands the temperature range for the formation of chromium carbide coatings with a horizontally layered structure, which are more resistant to corrosion and erosion wear. In this case, there is an increase in the adhesive strength and cavitation resistance of the coatings. The use of the DBE additive reduces the through porosity of the coatings. Coatings obtained with DBE additives have an abnormally high resistance to electrochemical dissolution in comparison with other materials used for work in corrosive environments.