Reaction Of Acetate Research Articles

Preparation of cellulose acetate based flexible separator and its application in zinc–air batteries

Flexible solid-state zinc–air batteries as a wearable energy storage device with great potential, and their separators, which control ion permeability, inhibit zinc dendrite generation, and regulate catalytic active sites, have been developed as gel electrolyte separators with high retention of electrolyte uptake. However, the gel electrolyte separator still has problems such as poor affinity with the electrolyte and poor ionic conductivity, which limits its further application. In order to further improve the electrolyte absorption, ionic conductivity and mechanical strength of cellulose acetate(CA)/polyvinyl alcohol (PVA) nanofibers, TiO2 was added to CA/PVA to increase the porosity, and glutaraldehyde (GA) was used to modify the CA/PVA/TiO2 separator by acetal reaction with CA and PVA to make the molecules closely linked. The results shows that the optimal mass fractions of TiO2 and GA were 2% and 5%, respectively. At this time, the porosity and absorption rate of the separator increased from 48% to 68.2% and 142.4% to 285.3%, respectively. The discharge capacity reached 179 mA cm−3, and the cycle stability rate was 89% after 7 stable constant current charge/discharge cycles.

Schiff Base Complex of Copper Immobilized on Core-Shell Magnetic Nanoparticles Catalyzed One-Pot Syntheses of Polyhydroquinoline Derivatives under Mild Conditions Supported by a DFT Study.

We synthesized a stable and reusable Schiff base complex of copper immobilized on core-shell magnetic nanoparticles [Cu(II)-SB/GPTMS@SiO2@Fe3O4] with simple, efficient, and available materials. A variety of characterization analyses including Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA), X-ray diffraction (XRD), vibrating-sample magnetometry (VSM), energy-dispersive X-ray spectrometry (EDX), and inductively coupled plasma (ICP) confirm that our synthesized nanocatalyst was obtained. The particle size distribution from the TEM image was obtained in the range of 42-55 nm. The existence of cupric species (Cu2+) in the catalyst was determined with XPS analysis and clearly indicated two peaks at 933.7 and 953.7 eV for Cu 2p3/2 and Cu 2p1/2, respectively. BET results showed that our catalyst synthesized with a mesoporous structure and with a specific area of 48.82 m2 g-1. After detailed characterization, the resulting nanocatalyst exhibited excellent catalytic performance for the explored catalytic reactions in the one-pot synthesis of polyhydroquinoline derivatives by the Hantzsch reaction of dimedone, ethyl acetoacetate, ammonium acetate, and various aldehydes under sustainable and mild conditions. The corresponding products 5a-l are achieved in yields of 88-97%. Additionally, density functional theory (DFT) calculations were carried out to investigate the electrostatic potential root (ESP), natural bond orbital (NBO), and molecular orbitals (MOs), drawing the reaction mechanism using the total energy of the reactant and product and the study of structural parameters.

An elegant approach for the synthesis of multisubstituted imidazole via FeCl3/SiO2 catalyzed activation of acetals: a photophysical study of an imidazole-carbazole hybrid.

A simple and solvent-free catalytic system was developed for the direct conversion of multisubstituted imidazoles through the reaction of acetals and benzils with ammonium acetate/amines as the source of nitrogen. The reaction occurred under mild and benign conditions using FeCl3/SiO2 as a heterogeneous catalyst without the requirement of any toxic organic solvents. The easy preparation and recyclability of the catalyst allows the reaction to be simple and highly efficient, resulting in very good yields of imidazoles. Novel imidazole-carbazole hybrid compounds were also synthesised by adopting the present methodology. Single crystal X-ray diffraction study indicated the presence of a CH⋯π supramolecular interaction that renders effective molecular packing in the solid state. The steady-state and spectro-dynamic behaviours of these hybrid molecules were investigated, and it was revealed that a solvent-dependent excimer-coupled ICT phenomenon guided excited state photophysics. Very unusual excimer lifetime was noticed in the solid state of this bis-heterocyclic compound owing to the stacking of molecules via CH⋯π interaction, as evident from the X-ray studies.

Influence of PVA resin and cross-linking agent on the structure and properties of semi-refined carrageenan-based packaging films

For the high content of carrageenan in some seaweed and the low cost and easy availability of semi refined carrageenan (SRC), SRC resin powder was selected as our research object. Due to its water solubility, a solution casting method was adopted to form film, hoping to prepare food packaging materials that partially replace petroleum based resin. The pure SRC resin casting film is very brittle and cannot be formed. Therefore, 40wt% glycerol was added to the formula to plasticize and improve the flexibility and demoulding ability of SRC. The plasticized SRC film still has limitations. Soluble petroleum based polymer poly(vinyl alcohol) (PVA) resin was used as a blending modifier, cinnamaldehyde (CIN) as a crosslinking agent for acetal reaction with hydroxyl groups, boric acid (BA) as a provider of acidic environment and an auxiliary agent for generating partial hydrogen bonds with hydroxyl groups. Eight experimental research formulas were designed and FTIR, XRD, thermodynamic properties and mechanical properties of the modified films were analyzed. Both microscopic and macroscopic analyses have shown that under the acidic conditions of BA, CIN undergoes an acetal reaction with SRC and PVA, therefore mass ratio of the formula that SRC/glycerol/PVA/CIN/BA is 100/40/33.3/10/10, the film has the best tensile strength of 34.85Mpa, higher than that of other films. It has been proven that CIN does indeed act as a crosslinking agent in the formula, forming a network structure that enhances it.

Improvement and Expansion of the Experiment for Determining the Rate Constant of the Saponification Reaction of Ethyl Acetate

Improvement and Expansion of the Experiment for Determining the Rate Constant of the Saponification Reaction of Ethyl Acetate

Accelerated synthesis of 1,8-dioxo-octahydroxanthene and 1,8-dioxo-decahydroacridine derivatives using dendritic mesoporous nanosilica functionalized by hexamethylenetetramine: a novel nanocatalyst.

Xanthene and acridine derivatives are interesting organic compounds that are used in different research fields like biomedicine and pharmaceutical science. However, applied catalysts for their synthesis have some limitations such as long reaction times, the need for harsh conditions and low yield. So, discovery of novel catalysts for the synthesis of xanthene and acridine derivatives is highly demanded. To overcome the limitation of previous methods on the efficient synthesis of 1,8-dioxo-octahydroxanthene and 1,8-dioxo-decahydroacridine derivatives, a green heterogeneous organic nano-catalyst (Cu@KCC-1-nPr-HMTA) was synthesized by covalent attachment of hexamethylenetetramine to the cavities and channels of dendritic mesoporous nanosilica (KCC-1). The prepared nano-catalyst was identified using various spectroscopic and microscopic methods including scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), X-ray energy diffraction (EDX), EDX mapping and nitrogen adsorption-desorption analysis (BET-BJH). The prepared green nano-catalyst showed a spherical and dendritic structure with a surface area of 65.699 m2 g-1, average pore size of 40.78 nm and pore volume of 0.66 cm3 g-1. Also, Cu@KCC-1-nPr-HMTA has many chemo-active sites for the condensation reaction and was used as an efficient nano-catalyst towards one-step synthesis of 1,8-dioxo-decahydroacridine and 1,8-dioxo-octahydroxanthene derivatives from the reaction of aromatic aldehydes, dimedone, and ammonium acetate under solvent-free conditions. Short reaction times of 1 to 5 minutes for 1,8-dioxo-decahydroacridine and 30 to 55 minutes for 1,8-dioxo-octahydroxanthene derivatives, high yields and mild reaction conditions are advantages of the proposed synthetic method. It is hoped that the engineered nano-catalyst will be used for the synthesis of other organic compounds in the future.

High value-added fuel additive production from waste bio-glycerol over a versatile nanohybrid catalyst

This study presents a pioneering nanohybrid catalyst featuring hierarchically porous dual-functional (acid–base) active sites, which is a versatile catalyst for the crucial bio-glycerol acetalization reaction.

Synthesis and Characterization of the Trichlates [N(CH3)4][Cl3CSO3], [NH4][Cl3CSO3], and the Dichlate [NH4][Cl2CHSO3

The reaction of ammonium acetate, [NH4][CH3OO], and tetra‐methylammonium hydroxide, [N(CH3)4](OH), respectively, with (H5O2)[Cl3CSO3] in aqueous solution leads to the trichloromethanesulfonates (“trichlates”) [NH4][Cl3CSO3] (orthorhombic, Pnma, Z = 8, a = 2361.0(3), b = 996.1(1), c = 624.95(7) pm) and [N(CH3)4][Cl3CSO3] (orthorhombic, Pnma, Z = 4, a = 1020.59(9), b = 909.7(1), c = 1205.8(1) pm). Both compounds contain the rarely described trichlate anion, [Cl3CSO3]‐ in staggered conformation. The trichlates have been characterized by IR spectroscopy and thermal analyses. The dichloromethanesulfonate (“dichlate”) [NH4][Cl2CHSO3] (monoclinic, P21/c, Z = 4, a = 1219.75(6), b = 594.52(3), c = 953.54(5) pm, β = 106.487(2)°) has been obtained accidentally as a by‐product in the reaction of Ba(OH)2 and (H5O2)[Cl3CSO3] in aqueous NH3‐containing solution.

Catalytic Enantioselective [4+2] Cycloadditions of Salicylaldehyde Acetals with Enol Ethers.

A readily accessible conjugate-base-stabilized carboxylic acid (CBSCA) catalyst facilitates highly enantioselective [4+2] cycloaddition reactions of salicylaldehyde-derived acetals and cyclic enol ethers, resulting in the formation of polycyclic chromanes with oxygenation in the 2- and 4-positions. Stereochemically more complex products can be obtained from racemic enol ethers. Spirocyclic products are also accessible.

Acetal Formation of Flavoring Agents with Propylene Glycol in E-Cigarettes: Impacts on Indoor Partitioning and Thirdhand Exposure.

The widespread use of flavored e-cigarettes has led to a significant rise in teenage nicotine use. In e-liquids, the flavor carbonyls can form acetals with unknown chemical and toxicological properties. These acetals can cause adverse health effects on both smokers and nonsmokers through thirdhand exposure. This study aims to explore the impacts of these acetals formed in e-cigarettes on indoor partitioning and thirdhand exposure. Specifically, the acetalization reactions of commonly used flavor carbonyls in laboratory-made e-liquids were monitored using proton nuclear magnetic resonance (1H NMR) spectroscopy. EAS-E Suite and polyparameter linear free energy relationships (PP-LFERs) were employed to estimate the partitioning coefficients for species. Further, a chemical two-dimensional partitioning model was applied to visualize the indoor equilibrium partitioning and estimate the distribution of flavor carbonyls and their acetals in the gas phase, aerosol phase, and surface reservoirs. Our results demonstrate that a substantial fraction of carbonyls were converted into acetals in e-liquids and their chemical partitioning was significantly influenced. This study shows that acetalization is a determinant factor in the exposure and toxicology of harmful carbonyl flavorings, with its impact extending to both direct exposure to smokers and involuntary exposure to nonsmokers.

Solventless autothermic production of energy-intensive furanic biofuels expedited by photothermal effect

Driving C-C coupling reactions to produce biofuels is usually energy-consuming and requires well-tailored catalysts. Herein, a novel photothermal catalytic strategy was developed to be highly efficient for cascade hydroxyalkylation-alkylation (HAA) of various biomass-derived aldehydes/ketones with 2-methylfuran or acetalization of different bioalcohols with furfural to exclusively afford furanic biofuel molecules (up to 94.8 % yield). The developed bio-based SO3H-functionalized graphene-like catalyst (GLB-SO3H-700) could complete the HAA and acetalization reactions in 10 min under solvent-free and room-temperature conditions. Infrared thermal imaging revealed that the local photothermal effect of interfacial solar heating could in-situ remove water co-product, thereby improving the reaction selectivity and rate as evidenced by kinetic study. Moreover, the GLB-SO3H-700 catalyst exhibited good stability and recyclability. The developed SO3H-functionalized graphene-like photothermal materials hold great potential for catalytic upgrading of biomass into high-quality biofuels under mild conditions.

Effect of Support on Oxidative Esterification of 2,5-Furandiformaldehyde to Dimethyl Furan-2,5-dicarboxylate

One-step oxidative esterification of 2,5-furandiformaldehyde (DFF) derived from biomass to prepare Dimethyl Furan-2,5-dicarboxylate (FDMC) not only simplifies the catalytic process and increases the purity of the product, but also avoids the polymerization of 5-hydroxymethylfurfural (HMF) at high-temperature conditions. Gold supported on a series of acidic oxide, alkaline oxide, and hydrotalcite was prepared using colloidal deposition to explore the effect of support on the catalytic activities. The Au/Mg3Al-HT exhibited the best catalytic activity, with 97.8% selectivity of FDMC at 99.9% conversion of DFF. This catalyst is also suitable for oxidative esterification of benzaldehyde and furfural. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and CO2 temperature programmed desorption (CO2-TPD) were performed to characterize the catalysts. The results indicated that the medium and strong basic sites in the catalysts benefited for the absorption of intermediate agents and facilitated the oxidative esterification of aldehyde groups, while neutral or acidic supports tended to produce an acetal reaction. It is worth noting that basicity on the support surface reduced the electronic state of the Au nanoparticle (Auδ−) and, thus, enhanced the catalytic selectivity of oxidative esterification. This finding demonstrated that the support plays a crucial role in oxidative esterification.

Synthesis of New Spiropyrrolo[3,4-b]Pyridine Derivatives Employed Multicomponent Reactions

In this research, novel derivatives of spiropyrrolo[3,4-b]pyridine derivatives were synthesized in high yields by using multicomponent reaction (MCR) of ninhydrin, ammonium acetate, ethyl 2,4-dioxo-4-arylbutanoates, primary amines, methyl propiolate, and triethyl amine (Et3N) in aqueous media. The antioxidant activity of new synthesized spiropyrrolo[3,4-b]pyridine derivatives is due to having OH group which was evaluated by two procedures. This employed procedure for preparation of spiropyrrolo[3,4-b]pyridine derivatives conveys benefits including reaction with low time, products with high yields, and easy separation of products using an easy procedure.

One-pot synthesis of MoO3-ZrO2 solid acid catalyst for solvent-free solketal production from glycerol

Glycerol acetalization to solketal is a promising method of increasing the additional value of glycerol, which is a by-product in biodiesel industry. In this work, a series of mesoporous x-MoO3-ZrO2 (x = Mo/Zr) solid acid catalysts with controllable Mo contents were designed and synthesized for the acetalization of glycerol. As important influence factors of solid acid catalysts, the mesoporous structure and existential state of Mo species were systematically investigated. Results show that Mo species were introduced as planned and existed in a homogeneously dispersed state in MoO3-ZrO2 materials. The acidic properties of MoO3-ZrO2 were explored through NH3-TPD and pyridine-chemisorbed FT-IR spectroscopy, and the formation of Brønsted and Lewis acid sites was confirmed by density functional theory calculations. Given their excellent acidity, MoO3-ZrO2 catalysts were employed for the acetal reaction of glycerol. Among the tested catalysts, the 20 %-MoO3-ZrO2 catalyst exhibited the optimal catalytic performance and reusability, achieving a conversion of 89 % for glycerol and a selectivity of 97 % for solketal. Consequently, MoO3-ZrO2 is a green solid acid catalyst with promising applications in solvent-free solketal production from glycerol.

Construction of Marigold-like Poly(vinyl alcohol) Microspheres for Catalytic Microreactors.

It has long been pursued to develop polymer microspheres with various special morphologies and structures for better results in applications such as catalysis, drug delivery, and bioscaffolds. However, it remains a challenge to develop a facile method to produce poly(vinyl alcohol) (PVA) microspheres with special morphologies. Herein, a micron-sized marigold-like poly(vinyl alcohol) (CE-PVATPA) microsphere was engineered and fabricated by a feasible strategy, that is, emulsification-cross-linking, freeze-drying, and secondary acetal reaction steps. The morphological evolution of microspheres was systematically investigated under different conditions, and the procedure of constructing PVA microspheres with stabilizing marigold-like structures was proposed. More importantly, a specially structured PVA microsphere microreactor synergistically loading palladium metal nanoparticles (CE-PVATPA@Pd) for the heterogeneous catalyst 4-nitrophenol (4-NP) could be further demonstrated, which indicated high catalytic activity and excellent recyclability. The resultant stabilized fabricating method is promising to provide valuable guidance for the design and fabrication of a high-performance PVA microsphere microreactor.

Competition between C-C and C-H Bond Fluorination: A Continuum of Electron Transfer and Hydrogen Atom Transfer Mechanisms.

In 2015, we reported a photochemical method for directed C-C bond cleavage/radical fluorination of relatively unstrained cyclic acetals using Selectfluor and catalytic 9-fluorenone. Herein, we provide a detailed mechanistic study of this reaction, during which it was discovered that the key electron transfer step proceeds through substrate oxidation from a Selectfluor-derived N-centered radical intermediate (rather than through initially suspected photoinduced electron transfer). This finding led to proof of concept for two new methodologies, demonstrating that unstrained C-C bond fluorination can also be achieved under chemical and electrochemical conditions. Moreover, as C-C and C-H bond fluorination reactions are both theoretically possible on 2-aryl-cycloalkanone acetals and would involve the same reactive intermediate, we studied the competition between single-electron transfer (SET) and apparent hydrogen-atom transfer (HAT) pathways in acetal fluorination reactions using density functional theory. Finally, these analyses were applied more broadly to other classes of C-H and C-C bond fluorination reactions developed over the past decade, addressing the feasibility of SET processes masquerading as HAT in C-H fluorination literature.

Base Promoted Three‐component Reaction for Efficient Construction of Spiro[indoline‐3,3′‐quinoline]‐2,5′‐dione

AbstractA convenient synthetic protocol for the construction of spiro[indoline‐3,3′‐quinoline]‐2,5′‐dione motifs was successfully developed by base promoted one‐pot three‐component reaction. In the presence of piperidine, three‐component reaction of ammonium acetate, aromatic aldehydes and the in situ generated 3‐isatyl 1,4‐dicarbonyl compounds, which were derived from base mediated addition of dimedone to 3‐methyleneoxindoles, resulted in two diastereoisomers of spiro[indoline‐3,3′‐quinoline]‐2,5′‐dione derivatives in good yields and with good diastereoselectivity. The stereochemistry of the reaction was clearly elucidated by isolation of two diastereomers and determination of several single crystal structures.

Influence of sulphonation on Al-MCM-41 catalyst for effective bio-glycerol conversion to Solketal

Al-MCM-41 and sulphate modified Al-MCM-41 catalysts with variable sulphate loadings (0.25-1SAM) were synthesized through sol-gel and impregnation techniques respectively for the transformation of glycerol into solketal, a fuel additive via acetalization reaction. The mesoporous structure, surface morphologies, composition and porosity of the prepared catalysts were subjected to characterization by Low angle XRD, SEM-EDAX, TEM, FT-IR, XPS and BET-surface area studies. The strength and quantification of acid sites were obtained from TPD of NH3. Pyridine-adsorbed FTIR and 27Al MAS NMR data distinguished Lewis and Brønsted acid sites present on the catalysts. Among the synthesized catalysts, 1 N sulphated Al-MCM-41 was a better catalyst that promotes a higher solketal formation rate of 23.5 mmol h−1g cat−1 by the acetalization of glycerol. This is much higher in comparison to 4 times lesser activity of 6.1 mmol h−1gcat−1 exhibited by the parent Al-MCM-41. This catalyst further showed consistent activity and reusability up to 5 cycles. Large surface area, total acidity, strong Lewis acid sites, compatible surface characteristics of 1 N sulphated Al-MCM-41 endorse the higher acetalization activity of the catalyst. As a result, these parameters have been regarded as crucial considerations in designing a better catalyst in the effective conversion of glycerol to solketal.

Electrochemical Radical Reaction Construction of C-C Bonds: Access to 1,4-Dicarbonyl Compounds from Enol Acetates and 1,3-Diketones.

As important substrates for the construction of heterocycles, a simple and efficient approach for synthesis of 1,4-diones is highly desirable. In this work, novel and efficient electrochemical radical reactions of enol acetates and 1,3-diketones have been developed to successfully achieve 1,4-diketones under catalyst-free and oxidant-free conditions. The wide range of substrates, good group tolerance, and simple operation process make the approach have important practical value. Moreover, the obtained 1,4-diketones can be easily further transformed to pyrrole and furan derivatives.

Neighboring-Group Participation by C-2 Acyloxy Groups: Influence of the Nucleophile and Acyl Group on the Stereochemical Outcome of Acetal Substitution Reactions.

A single acyloxy group at C-2 can control the outcome of nucleophilic substitution reactions of pyran-derived acetals, but the extent of the neighboring-group participation depends on a number of factors. We show here that neighboring-group participation does not necessarily control the stereochemical outcome of acetal substitution reactions with weak nucleophiles. The 1,2-trans selectivity increased with increasing reactivity of the incoming nucleophile. This trend suggests the intermediacy of both cis-fused dioxolenium ions and oxocarbenium ions in the stereochemistry-determining step. In addition, as the electron-donating ability of the neighboring group decreased, the preference for the 1,2-trans products increased. Computational studies show how the barriers for the ring-opening reaction on the dioxolenium ions and the transition states to provide the oxocarbenium ions change with the electron-donating capacity of the C-2-acyloxy group and the reactivity of the nucleophile.