Amide Solvents Research Articles

Degradation of stable thermosetting epoxy resins mediated by bases in amide solvents

Degradation of stable thermosetting epoxy resins mediated by bases in amide solvents

Amide solvents for extraction and separation of 1-hexene from n-heptane: Effect of the amount of methyl groups

In this work, the influence mechanism of methyl group in the structure of amide solvent on the extraction and separation of alkene (1-hexene or 1-octene) from n-heptane has been studied by a combination of liquid–liquid equilibrium (LLE) experiments and quantum chemical calculations. For LLE experiments, as the number of methyl groups in the extractant structure increases, its selectivity for alkene (1-hexene or 1-octene) gradually decreases, and the distribution coefficients of alkene (1-hexene or 1-octene) and n-heptane gradually increase. In the interaction between 1-hexene and extractant, the amount and intensity of C-H⋯O interactions, as well as the presence or absence of N/C-H⋯π interactions and their intensities, are all affected by the amount (0,1,2,3) of methyl group introduced into the amide solvent. The existence of the C-H⋯O and N-H⋯π interactions were verified by the infrared spectroscopy. With increasing methyl group amounts in the extractant structure, the dispersion interaction strengthens, while the contribution percentage of electrostatic interaction and ΔEelst/ΔE declines, leading to the increase of distribution coefficient and decrease of selectivity for alkene (1-hexene or 1-octene) respectively.

Enzymatic Knoevenagel condensation in dual‐functionalized water‐mimicking ionic liquids and tertiary amide solvents

AbstractBACKGROUNDKnoevenagel condensation is an important tool for building carbon–carbon (CC) bonds, especially when catalyzed by enzymes to enable a potentially high chemo‐, regio‐ and/or stereoselectivity. Although many Knoevenagel condensation reactions are carried out in aqueous solutions, insoluble hydrophobic substrates often lead to poor catalytic efficiencies. The use of water‐miscible organic solvents improves the substrate solubilization, but usually induces activity suppression or inactivation of enzymes. There is a great need to develop alternative solvents for both substrate dissolution and enzyme compatibility in CC bond formation reactions.RESULTSOur group previously developed dual‐functionalized water‐mimicking ionic liquids (ILs) for the activation and stabilization of hydrolases (e.g. lipase and protease). In the present study, we evaluated the Knoevenagel condensation of 4‐chlorobenzaldehyde with acetylacetone, and found that porcine pancreas lipase in water‐mimicking ILs carrying ammonium, imidazolium and benzimidazolium cations enabled higher reaction rates (up to 3.22 μmol min−1 g−1 lipase) and better yields than tert‐butanol, glymes and [BMIM][Tf2N]. Interestingly, tertiary amide solvents such as N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethylformamide (DMF) and N,N‐dimethylacetamide (DMAc) led to 8.2‐ to 11.1‐fold increases in the initial rate (up to 35.66 μmol min−1 g−1 lipase) when compared with dual‐functionalized ILs, which is likely due to some synergistic effect of these tertiary amides with the lipase.CONCLUSIONDual‐functionalized ILs based on ammonium, imidazolium and benzimidazolium cations improved Knoevenagel condensation reaction rates and yields when compared with tert‐butanol and glymes. Tertiary amides (NMP, DMF and DMAc) significantly increased the reaction rate. © 2024 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Solvatomorphic phase transitions and tunable luminescence emission in lanthanide metal-organic frameworks.

Four new metal-organic frameworks with the formulae [Sm2(phen)2(NO3)2(chdc)2]·2solv, where solv = N,N-dimethylformamide (DMF; 1), N,N-dimethylacetamide (DMA; 2), N,N-diethylformamide (DEF; 3), N-formylpiperidine (NFP; 4), phen = 1,10-phenanthroline and chdc2- = trans-1,4-cyclohexanedicarboxylate were synthesized and structurally characterized. These compounds are based on similar binuclear samarium(III)-carboxylate blocks, bound by flexible chdc linkers into layered sql-type coordination networks. The amide solvents drive different intralayer block orientations between 1 and 2-4 and different layer-to-layer packings in all the described compounds. A pronounced dependence of the emission color upon the excitation wavelength variation was determined for 1-4, while the relative impacts of Sm3+ and phen emission on overall luminescence were found to depend strongly on these packings, and their reasonable correlation to the distances between the closest π-π-stacked phen moieties in the structures was revealed. Phase transitions between compounds 1-4 were studied by means of powder X-ray diffraction. Additionally, bimetallic near-white luminophores were obtained for phases 3 and 4 by doping their synthetic systems with a minor (∼5%) Tb3+ additive. In general, this study shows a possibility of tuning the luminescence properties of porous metal-organic frameworks by minor structural differences induced by solvent-driven dynamics with no apparent quenching or other direct impact on the optical properties of the included solvent.

Synthesis of Black Phosphorene Quantum Dots from Red Phosphorus.

Black phosphorene quantum dots (BPQDs) are most commonly derived from high-cost black phosphorus, while previous syntheses from the low-cost red phosphorus (Pred ) allotrope are highly oxidised. Herein, we present an intrinsically scalable method to produce high quality BPQDs, by first ball-milling Pred to create nanocrystalline Pblack and subsequent reductive etching using lithium electride solvated in liquid ammonia. The resultant ~25 nm BPQDs are crystalline with low oxygen content, and spontaneously soluble as individualized monolayers in tertiary amide solvents, as directly imaged by liquid-phase transmission electron microscopy. This new method presents a scalable route to producing quantities of high quality BPQDs for academic and industrial applications.

Production of Magnetic Arsenic-Phosphorus Alloy Nanoribbons with Small Band Gaps and High Hole Conductivities.

Quasi-1D nanoribbons provide a unique route to diversifying the properties of their parent 2D nanomaterial, introducing lateral quantum confinement and an abundance of edge sites. Here, a new family of nanomaterials is opened with the creation of arsenic-phosphorus alloy nanoribbons (AsPNRs). By ionically etching the layered crystal black arsenic-phosphorus using lithium electride followed by dissolution in amidic solvents, solutions of AsPNRs are formed. The ribbons are typically few-layered, several micrometers long with widths tens of nanometers across, and both highly flexible and crystalline. The AsPNRs are highly electrically conducting above 130 K due to their small band gap (ca. 0.035 eV), paramagnetic in nature, and have high hole mobilities, as measured with the first generation of AsP devices, directly highlighting their properties and utility in electronic devices such as near-infrared detectors, quantum computing, and charge carrier layers in solar cells.

Dissolution Modulation of Formamidinium‐Based Perovskite for Regulated Crystallinity in Printable Mesoscopic Solar Cells

The photovoltaic, luminescence, and detector fields have witnessed the robust application prospects of solution‐processed halide perovskites. Deep insights into solution can pave the way toward the precise crystallization control of halide perovskites for giving full play to the advantages of those materials. Herein, the dissolution behavior of formamidinium lead iodide (FAPbI3) together with lead iodide in amide solvents with regulated coordination ability at increasing temperature and under different molar ratio between formamidinium iodide (FAI) and PbI2 is studied. The solvent coordination ability, temperature, and FAI/PbI2 molar ratio demonstrate equivalent influence on the dissolution, and increasing those factors tends to increase the solubility first and decrease it then for Pb compounds. It is proposed that there are interchangeable Pb solute forms including solvent‐containing lead complexes and solvated lead halide fragments in solution and the interconversion of both solutes driven by the above factors brings the solubility change. The modulated dissolution affects the crystallization behaviors of FAPbI3 when preparing single crystals, nanocrystal dispersions, and thin films, and allows for regulated crystallinity in printable mesoscopic solar cells which demonstrate a power conversion efficiency of 18.40%.

Analysis of the kinetics of soluble polyimide formation by the thermal imidization of polyamic acids in amide solvents with allowance for the side reaction of anhydride group hydrolysis

Analysis of the kinetics of soluble polyimide formation by the thermal imidization of polyamic acids in amide solvents with allowance for the side reaction of anhydride group hydrolysis

Multitunable LCST and UCST Behaviors of Y-Junction-Bearing Polyacrylamides

Rational design of thermoresponsive polymers allows facile control over LCST/UCST and nano-object shapes. Despite tremendous progress, it remains a challenge to monitor chain conformations as the solvent isotope affects types of phase transitions. This study aims at addressing the challenge by construction of thermoresponsive Y-junction-bearing polyacrylamides with nontraditional intrinsic luminescence. With an increasing carbon number of substituents connecting with ester groups (x = 1, 2, 3, 4, 6, 8, 10, and 12), copolymers transform from hydrophilic (x = 1) to LCST (x = 2) and dual LCST/UCST (x ≥ 3) in H2O, while no UCST is available in D2O due to more stable amide–solvent hydrogen bonding and strengthened intra-/intermolecular interactions. Meanwhile, copolymer aqueous solutions can exhibit substituent/pH-dependent evolution orders of single, dual, and triple phase transitions, and asymmetric V-shaped evolution of LCST/UCST values with increasing pH is usually observed. Although 1H NMR analysis can only reveal the solvation status of subunits in the LCST region, fluorescence analysis allows to elucidate intra-/intermolecular hydrogen bonding interactions in LCST/UCST regions. Thermoinduced self-assembly in water renders sphere-to-nanocapsule-to-lamella-to-nanocapsule transitions. These important findings provide us with considerable insight into hydrogen bonding-related UCST formation by rational macromolecular design. Our study may open new avenues for regulating phase transitions and exploring solvent isotope effects.

High-Current Capable and Non-Flammable Protic Organic Electrolyte for Rechargeable Zn Batteries.

Rechargeable Zinc batteries (RZBs) are considered a potent competitor for next-generation electrochemical devices, due to their multiple advantages. Nevertheless, traditional aqueous electrolytes may cause serious hazards to long-term battery cycling through fast capacity fading and poor Coulombic efficiency (CE), which happens due to complex reaction kinetics in aqueous systems. Herein, we proposed the novel adoption of the protic amide solvent, N-methyl formamide (NMF) as a Zinc battery electrolyte, which possesses a high dielectric constant and high flash point to promote fast kinetics and battery safety simultaneously. Dendrite-free and granular Zn deposition in Zn-NMF electrolyte assures ultra-long lifespan of 2000 h at 2.0 mA cm-2/2.0 mAh cm-2, high CE of 99.57 %, wide electrochemical window (~3.43 V vs. Zn2+/Zn), and outstanding durability up to 10.0 mAh cm-2. This work sheds light on the efficient performance of the protic non-aqueous electrolyte, which will open new opportunities to promote safe and energy-dense RZBs.

High‐Current Capable and Non‐Flammable Protic Organic Electrolyte for Rechargeable Zn Batteries

AbstractWiederaufladbare Zinkbatterien (RZBs) gelten aufgrund ihrer zahlreichen Vorteile als potente Konkurrenten für elektrochemische Geräte der nächsten Generation. Dennoch können herkömmliche wässrige Elektrolyte aufgrund der komplexen Reaktionskinetik in wässrigen Systemen durch schnellen Kapazitätsabfall und schlechte Coulomb′sche Effizienz (CE) ernsthafte Gefahren für den langfristigen Batteriebetrieb verursachen. Wir haben hier die neuartige Verwendung des protischen Amid‐Lösungsmittels N‐Methylformamid (NMF) als Zinkbatterie‐Elektrolyt vorgeschlagen, dass eine hohe Dielektrizitätskonstante und einen hohen Flammpunkt besitzt, um gleichzeitig eine schnelle Kinetik und Batteriesicherheit zu fördern. Die dendritenfreie und körnige Zn‐Abscheidung im Zn‐NMF‐Elektrolyten gewährleistet eine ultralange Lebensdauer von 2000 Stunden bei 2.0 mA cm−2/2.0 mAh cm−2, ein hohes CE von 99.57 %, ein breites elektrochemisches Fenster (≈3.43 V vs. Zn2+/Zn) und eine hervorragende Haltbarkeit bis zu 10.0 mAh cm−2. Diese Arbeit wirft ein Licht auf die effiziente Leistung des protischen nichtwässrigen Elektrolyten, der neue Möglichkeiten zur Förderung sicherer und energiedichter RZBs eröffnen wird.

Amide and Urea Based Solvents for Li–O2 Batteries. Part II: Evaluation of Decomposition Pathways Using Density Functional Theory

Potential decomposition mechanisms are investigated using density functional theory (DFT) for a set of amide and urea solvents. Reaction energies and barriers are reported for proton and hydrogen abstraction, and preferred abstraction sites are identified. The N–H bond of secondary amides and the α-hydrogen atoms are more susceptible to proton abstraction than other sites in the solvent molecules. Additionally, hydrogen abstraction is more favorable at the N-alkyl substituents as well as α-hydrogen atoms that result in the formation of secondary and tertiary radicals. All proton abstraction energies are sensitive to the presence of a coordinating Li+, but the hydrogen abstraction energies do not depend on the presence of a Li+. The stabilization due to the presence of Li+ is most pronounced for sites near the carbonyl group where the Li+ interacts with the lone pair of electrons formed by proton abstraction and the carbonyl O atom. The initial steps of a Baeyer–Villiger oxidation type mechanism are also examined. Barriers for these initial steps are significantly lower if HO2– is the oxidant compared to LiO2–. A comparison to our previously reported experimental results indicates that no single reaction could be identified as the rate-limiting step that would predict the performance of this set of solvents in Li–O2 batteries.

The role of terminal coordinated amides in a series of Ca-tatb frameworks: pore size regulation and fluorescence sensing tunability

Amide solvents were used as terminal coordinated molecules to tune the pore sizes of Ca-MOFs, achieving the pore size controllable fluorescence sensing performance towards trinitrophenol (TNP).

Does Urea Preferentially Interact with Amide Moieties or Nonpolar Sidechains? A Question Answered Through a Judicious Selection of Model Systems.

The transfer model suggests that urea unfolds proteins mainly by increasing the solubility of the amide backbone, probably through urea-induced increase in hydrogen bonding. Other studies suggest that urea addition increases the magnitude of solvent-solute van der Waals interactions, which increases the solubility of nonpolar sidechains. More recent analyses hypothesize that urea has a similar effect in increasing the solubility of backbone and sidechain groups. In this work, we compare the effects of urea addition on the solvation of amides and alkyl groups. At first, we study the effects of urea addition upon solvent hydrogen bonding acidity and basicity through the perturbation in the fluorescence spectrum of probes 1-AN and 1-DMAN. Our results demonstrate that the solvent's hydrogen bonding properties are minimally affected by urea addition. Subsequently, we show that urea addition does not perturb the intra-molecular hydrogen bonding in salicylic acid significantly. Finally, we investigate how urea preferentially interacts with amide and alkyl groups moieties in water by comparing the effects of urea addition upon the solubility of acetaminophen and 4-tertbutylphenol. We show that urea affects amide and t-butyl solubility (lowers the transfer free energy of both amide (backbone) and alkyl (sidechain) groups) in a similar fashion. In other words, preferential interaction of urea with both moieties contributes to protein denaturation.

Combined H-N Cross-Polarization and Carbonyl Detection NMR Spectroscopy Allow to Record High-Resolution, High-Sensitivity Spectra of Alpha-Synuclein in Bacterial Cells.

Studies of intrinsically disordered proteins (IDPs) under physiological conditions by conventional NMR methods based on proton detection are severely limited by fast proton amide solvent exchange. Carbon detection has been proposed as a solution to the exchange problem but is hampered by low sensitivity. Here, we present a protocol combining proton-nitrogen cross-polarization and carbonyl detection to record high-resolution and high-sensitivity NMR spectra of IDPs under physiological conditions. The protocol describes a step-by-step method to register high-quality N-CO correlation spectrum of alpha-synuclein in E.coli bacterial cells at 37°C.

Zinc-Free, Scalable Reductive Cross-Electrophile Coupling Driven by Electrochemistry in an Undivided Cell.

Nickel-catalyzed reductive cross-electrophile coupling reactions are becoming increasingly important in organic synthesis, but application at scale is limited by three interconnected challenges: a reliance on amide solvents (complicated workup, regulated), the generation of stoichiometric Zn salts (complicated isolation, waste disposal issue), and mixing/activation challenges of zinc powder. We show here an electrochemical approach that addresses these three issues: the reaction works in acetonitrile with diisopropylethylamine as the terminal reductant in a simple undivided cell (graphite(+)/nickel foam(-)). The reaction utilizes a combination of two ligands, 4,4'-di-tert-butyl-2,2'-bipyridine and 4,4',4''-tri-tert-butyl-2,2':6',2''-terpyridine. Studies show that, alone, the bipyridine nickel catalyst predominantly forms protodehalogenated aryl and aryl dimer, whereas the terpyridine nickel catalyst predominantly forms bialkyl and product. By combining these two unselective catalysts, a tunable, general system results because excess radical formed by the terpyridine catalyst can be converted to product by the bipyridine catalyst. As the aryl bromide becomes more electron rich, the optimal ratio shifts to have more of the bipyridine nickel catalyst. Lastly, examination of a variety of flow-cell configurations establishes that batch recirculation can achieve higher productivity (mmol product/time/electrode area) than single-pass, that high flow rates are essential to maximizing current, and that two flow cells in parallel can nearly halve the reaction time. The resulting reaction is demonstrated on gram scale and should be scalable to kilogram scale.

SYNTHESIS AND OPTICAL CHARACTERIZATION OF PEROVSKITE LAYER FOR SOLAR CELL APPLICATION

Solvent engineering offers fine control over the photovoltaic efficiency, film morphology, and crystallization quality of perovskite films and also enables to optimize light transmittance and absorbance in solar cell applications. In the present work, the band gap and reflectance were reduced through solvent engineering. We found that perovskite thin films produced using DMF (Dimethyl form amide) solvent had a band gap that was 0.24 eV less than those produced using IPA (Isopropyl Alcohol) solvent. Perovskite thin films produced using DMF solvent also exhibited considerably lower solar spectrum reflectance.

A highly selective and rapid solvatochromic material for amide solvent detection.

The detection of amide solvents is essential to human health due to their carcinogenicity. A simple, solvatochromic luminescent material is presented for quick and accurate detection of amides. The luminescence color variation from blue to yellow is ascribed to the amide-induced phase transformation from Cs2ZnBr4:Cu to CsBr:Cu+/Cu2+.

Metal-Free Photoredox-Catalyzed Hydrodefluorination of Fluoroarenes Utilizing Amide Solvent as Reductant.

A metal-free photoredox-catalyzed hydrodefluorination of fluoroarenes was achieved by using N,N,N',N'-tetramethyl-para-phenylenediamine (1) as a strong photoreduction catalyst. This reaction was applicable not only to electron-rich monofluoroarenes but also to polyfluoroarenes to afford non-fluorinated arenes. The experimental mechanistic studies indicated that the amide solvent NMP plays an important role for regeneration of the photocatalyst, enabling additive-free photoreduction catalysis.

Mechanism of Dehydrohalogenation of 2,2-Di(4-chlorophenyl)-1,1,1-trichloroethane in NaOH–N,N-Dimethylformamide System: A Quantum-Chemical Approach

The processes of alkaline hydrolysis of an amide solvent and the dehydrochlorination reaction of 2,2-di(4-chlorophenyl)-1,1,1-trichloroethane in NaOH–DMF system were simulated. A quantum-chemical analysis of the thermodynamic parameters of the processes proceeding with the participation of competing reagents such as the hydroxide anion and the intermediate anion of the DMF alkaline hydrolysis process in the system was carried out. The most probable dehydrochlorinating reagent and the reaction mechanism were proposed.