Acid Anhydride Research Articles

The effect of composite curing agent ratio on the photooxidative aging behavior of epoxy asphalt based on molecular dynamics simulation

In order to explore the effect of composite curing agent ratio on the photooxidative aging behavior of epoxy asphalt with an acidic composite curing system, three curing agent ratios of epoxy asphalt were prepared to obtain different cross-linking network densities. The prepared epoxy asphalt was subjected to photooxidation aging for 240 h at 60 ℃. Fourier transform infrared (FTIR) and elemental analysis tests were conducted to determine the evolution of chemical components during photooxidative aging. Based on the chemical components before and after aging, molecular models of photooxidation aged epoxy asphalt with different curing agent ratios were constructed. The mean square displacement (MSD) of oxygen atoms and the oxygen uptake of each component were calculated to study the diffusion behavior of oxygen atoms and the oxidation degree of each component under various cross-linking networks. Glass transition temperature (Tg) and interaction energy were determined to characterize the thermodynamic properties and interaction between asphalt phase and epoxy resin phase of epoxy asphalt before and after aging. The radial distribution function (RDF) was determined to simulate the distribution of asphaltene and epoxy resin crosslinked networks in different cross-linking networks. The results show that the formation of carbonyl groups, alcohol hydroxyl groups, and the fracture of methylene groups was observed during the photooxidative aging process of epoxy asphalt. The rise in the proportion of anhydride curing agents improved the stability of the chemical components in epoxy asphalt under photooxidation aging. High cross-linking density and methylene fracture weakened the diffusion ability of oxygen atoms in epoxy asphalt due to a reduction in free volume. In addition, photooxidation aging had a negative impact on the low-temperature performance and interaction between asphalt phase and epoxy resin phase of epoxy asphalt. However, a high content of acid anhydride alleviated the damage of photooxidation aging to low-temperature performance. Photooxidation aging developed the polar functional groups of epoxy asphalt, promoting the stacking of asphaltene under a high content of dicarboxylic acid curing agent, while breaking the stacking of asphaltene under a high content of acid anhydride curing agent.

SYNTHESIS AND PROPERTIES OF BROMINE-CONTAINING BICYCLIC UNSATURATED POLYESTERS

A method for obtaining bromine-containing bicyclic unsaturated polyesters by the interaction of 1,4,5,6,7,7-hexabromobicyclo-[2,2,1]-hept-5-ene-2,3-dicarboxylic acid anhydride, propanetriol and maleic anhydride was developed. It was found that unsaturated polyethers synthesized by a two-step method have a higher molecular weight (3130), density (1.461 g/cm3), viscosity (105 St) and ether number (400 ml KOH/g). It was found that the compositions of epoxy resin ED-20 with unsaturated polyether obtained by method III possess higher tensile strength (90 MPa), higher relative elongation (9%), higher Vicat resistance (2500C) than unmodified epoxy resin. It was shown that in comparison with pure epoxy resin ED-20, its composition with unsaturated polyester synthesized by method I and cured in the presence of polyethylene polyamine (ED-20: unsaturated polyester: polyethylene polyamine), has flame retardant properties, high tensile strength, higher relative elongation and thermal resistance by Vicat. The best results are achieved when the content of unsaturated polyester in the composition is 20%

Palladium-catalyzed synthesis of carboxylic acid anhydrides from alkenes

Hydrocarbonylation of alkenes with nucleophiles – water, alcohols and amines, is widely studied and implemented in synthesis of fine chemicals and natural products. Here, an efficient and additive-free palladium-catalyzed hydrocarbonylation reaction of alkenes is described using carboxylic acids as the nucleophile, by which acid anhydrides are obtained in moderate to excellent yields. The relative concentrations of substrate and reagents play an important role in driving the reaction forward, which reaches an equilibrium at equimolar concentrations under a given CO pressure. A ligand-screening study revealed the use of electron-poor phosphine ligands to be crucial for obtaining higher rates of the catalytic reaction. Several substrates including unactivated alkenes were successfully converted to the corresponding symmetric as well as mixed anhydrides. An additional advantage of our synthetic procedure is that the obtained anhydrides can be converted to (primary) amides, thioesters or esters in situ via a simple one-pot derivatization reaction, since acid anhydrides are prone to degradation on isolation.

Utilized the (maleic) acid anhydride grafted cellulose to sorption of Cu(II), Mn(II), Cd(II), Fe(III) and Pb(II) in water sample

Utilized the (maleic) acid anhydride grafted cellulose to sorption of Cu(II), Mn(II), Cd(II), Fe(III) and Pb(II) in water sample

One-pot strategy to enhance nanofibrillation and esterification of cellulose using ternary deep eutectic solvent

Establishing green and efficient method for the nanofibrillation and modification of cellulose is the foundation to prepare the cellulose functional material. Herein, we provided a "one-pot " strategy to achieve the high-efficiency nanofibrillation and esterification of nanocellulose using the ternary deep eutectic solvents (DESs). The widths of cellulose nanofiber (CNF) with 18.9 ± 2 nm were successfully prepared by swelling with maleic acid/choline chloride (MA/ChCl) DES at 100 °C for 3 h, followed by mechanical colloid milling. The corresponding acid anhydrides maleic anhydrides (MAH) was added to form MAH/MA/ChCl DES for enhanced esterification of nanocellulose. As a result, the nanocellulose achieved a high degree of substitution (DS) of up to 0.84. The feasibility of "one-pot " strategy based on other ternary DESs (acetic anhydride/acetic acid/choline chloride (AAH/AA/ChCl), succinic anhydride/succinic acid/choline chloride (SAH/SA/ChCl) as representative) was further studied to fibrillate and esterify nanofibers, demonstrating it is an efficient method for the nanofibrillation and modification of cellulose.

T3P®-Assisted cascade synthesis of N-acyl α-cyanoamines, cyanoaryl amides and N-acyl cyanoarylamines: Application in making three pharmaceutically important molecules

Organic compounds possessing N-acyl α-cyanoamine function shows numerous pharmaceutical and medicinal properties, however, their synthesis require multiple steps. This article describes a novel and sustainable one-pot construction of N-acyl α-cyanoamines from α-amino amides and acids via propanephosphonic acid anhydride (T3P®)-assisted cascade strategy. A variety of chiral α-amino amides were conveniently transformed to N-acyl α-cyanoamine derivatives (15) by reacting with carboxylic acids using current protocol. The products are formed in 81–94% in 12 h at room temperature. Additionally, this method was also extended to the synthesis of cyanoaryl amides (18) (from 4-((aminooxy)carbonyl)benzoic acid and primary/secondary amines) and N-acyl cyanoarylamines (20) (from 3-aminobenzamide and carboxylic acids) with 83–95% yields in 2 h at 70 °C. The developed strategy has also been utilized successfully for the synthesis of DPP-4 inhibition agent, 2, intermediate, 4 of SphK1 inhibitor, and clinical agent of COVID-19, 10. These procedures are step-as well as pot-economic, which saves the reagents, solvents and separation agents required for the multiple steps that are associated with the reported routes.

UNIVERSAL ELECTROCATALYTIC SYSTEM FOR CONVERSION OF ALCOHOLS INTO CARBONYL COMPOUNDS AND CARBOXY ACID FUNCTIONAL DERIVATIVES

A universal catalytic system 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxyl/KI/pyridine base for the conversion of alcohols into carbonyl compounds and derivatives of carboxylic acids has been developed. The use of pyridine, 2,6-lutidine or collidine made it possible to obtain carbonyl compounds (yield up to 100%) after 2-2.2 F/mol. In the presence of pyridine, aliphatic alcohols are converted to esters (yield up to 35%) after 3-4 F/mol. Acid anhydrides (yield up to 80%) are formed using 2,6-lutidine or collidine after 5-6 F/mol. Nitriles were obtained in the presence of 2,6-lutidine and a source of nitrogen (yield up to 99%) after 3-4 F/mol.

Design and synthesis of п-conjugated aromatic heterocyclic materials with dual active sites and ultra-high rate performance for aqueous zinc-organic batteries

Acid anhydride cathode materials garner considerable interest for aqueous zinc ion batteries (AZIBs) due to ideal specific capacity and structural diversity, however, serious solubility leads to capacity degradation. Herein, 1,4,5,8-naphthalene tetracarboxylic acid dianhydride − 2,3-diamino phenothiazine (NTDP) featuring multiple active sites (6 with CN and 2 with CO) and large π-conjugated backbone, was designed and synthesized utilizing solid-phase method. The smallest energy gap (ΔE) and the lowest LUMO levels (against monomers) induced by multiple active sites and п-conjugated backbone with high aromaticity, NTDP exhibited excellent specific capacity (307.5 mA h g−1 under 0.05 A/g), ultrahigh rate performance (194.9 mA h g−1 under 20 A/g) and impressive cycling stability (190.0 mA h g−1 over 9000 cycles with a capacity retention of 91.2 % at 15 A/g). The reversible Zn2+ insertion/removal mechanism on multiple active centers (CO and CN) was proposed through XPS, FT-IR, and Raman. The specific capacity of the NTDP//zinc flexible cell was 112.6 mA h g−1 at 3 A/g under various folding angles (45°, 90°, 135°, and 180° bends), suggesting its practical potential for flexible devices. This work will offer opportunities for the rational design of battery structures.

Hydrophobic Bombyx mori Silk Fibroin: Routes to Functionalization with Alkyl Chains

AbstractBombyx mori silk fibroin (SF) is a very versatile biopolymer due to its biocompatibility and exceptional mechanical properties which make possible its use as a functional material in several applications. SF can be modified with a large variety of chemical approaches which endow the material with tailored chemical–physical properties. Here, a systematic investigation of different routes is reported to graft long alkyl chains on SF based on both liquid‐ and solid‐phase, aiming to modulate its hydrophobic behavior. The liquid phase method involves direct activation of SF tyrosine residues via diazo coupling and cycloaddition reactions, generating hydrophobic materials insoluble in any common solvent. The solid phase approach consists of the chemical modification of drop‐casted SF films by esterification of hydroxyl groups of serine, threonine, and tyrosine SF residues with acyl chlorides of fatty acids. For the solid‐state functionalization, a new class of hydrophobic pendant groups is synthesized, based on triple esters of gallic acid anhydrides, that are reacted with the biopolymer to further enhance its resulting hydrophobic features.

Synthesis of N-alkoxycarbonyl Pyrroles from O-Substituted Carbamates: A Synthetically Enabling Pyrrole Protection Strategy.

The condensation of readily available O-substituted carbamates with 2,5-dimethoxytetrahydrofuran gives N-alkoxycarbonyl pyrroles in a single step and in good yield. By this method, several common amine protecting groups can be introduced on the pyrrole nitrogen. With the exception of N-Boc, N-alkoxycarbonyl groups have seen only minimal use for protection of the pyrrole nitrogen to date. Here, we show that N-alkoxycarbonyl protection can endow pyrrole with distinct reactivity in comparison with N-sulfonyl protection, for example, in a pyrrole acylation protocol employing carboxylic acids with a sulfonic acid anhydride activator.

Chayote Root Starch Modified with Acyl and Acetyl Groups: Synthesis, Characterization, and Preparation of Edible Films

AbstractChemical modification of starch from the chayote root (Sechium edule Jacq) is carried out with lauric acid and acetic anhydride. The modified starch is characterized by Fourier‐transform infrared spectrometry (FTIR), X‐ray diffraction (XRD), and Differential Scanning Calorimetry (DSC) and used to formulate edible films. The developed edible films are characterized based on their physicochemical and mechanical properties. The physicochemical and functional properties of starch are affected by the incorporation of the acyl and acetyl group. Both starches exhibit a significant decrease in solubility. Starch modified by the incorporation of the acyl group (lauroyl) has higher thermal stability than starch modified by the incorporation of the acetyl group. The first shows an increase in emulsifying and foaming capacity, as well as water‐ and oil‐retention capacity, while the second exhibits adequate edible film‐forming properties. The edible films develop with modified starch with acetyl group has a homogeneous surface and exhibit a higher percentage of elongation at break when they are stored at a water activity of 0.561. In accordance with the above, it is concluded that the chayote root starch modified has physicochemical and functional properties that indicate their potential utility in the food industry.

Conformational analysis of carboxylic acid anhydrides: A microwave and computational study

The microwave spectra of four carboxylic acid anhydrides, RCOOCOR′, (R,R′) = (CH3,CF3), (C(CH3)3,CF3), (C6H5, CF3) and (CH3, C(CH3)3), have been observed in a supersonic jet. Calculations at the M06-2X/6-311++G(d,p) and MP2/6-311++G(d,p) levels of theory predict the lowest energy conformations for all four species to be nonplanar cis structures, i.e., conformations in which the C=O groups point in approximately the same direction, but are twisted out of a coplanar orientation. The observed spectra are consistent with these predictions. In addition, for all but the (R,R′) = (CH3, C(CH3)3) species, higher energy nonplanar trans conformers are also predicted, typically within 1–2 kcal/mole the nonplanar cis form. For (R,R′)= (C(CH3)3, CF3), extensive isotopic substitution has enabled a determination of most of the (non-fluorine) heavy atom structural parameters. Excellent agreement with the DFT and MP2 structures was obtained, thus validating the theoretical methods used. A strong correlation is found between the calculated O=C⋯C=O dihedral angle and the average of the vapor phase C=O stretching frequencies of RCOOH and R′COOH.

Study on the Migration Behaviors of Magnesium Oxysulfate Nano-Whiskers in Polypropylene Composites with Surface Modification.

In this study, surface modification aimed to enhance the compatibility between a hydrophilic inorganic filler and polypropylene (PP) matrix using hydrophobic treatment. Lauric acid, butyl acrylate, and maleic anhydride were employed to modify the filler surface. After treatment, inorganic filler/PP composites were produced using melt-mixing and extrusion-injection molding processes. The study focused on investigating compatibility and migration behavior between the filler and matrix. The findings indicated that hydrophobic modification, specifically with butyl acrylate and maleic anhydride, improved migration issues in nano-whisker, while maintaining favorable mechanical properties even under accelerated thermal aging. However, excessive hydrophobicity induced by superhydrophobic treatment using lauric acid led to reduced compatibility with the matrix, compromising its effectiveness. Consequently, the study revealed the potential of surface modification to enhance interfacial properties and mitigate migration concerns in PP composites for automotive applications.

Electrical Properties of Alicyclic Epoxy Resins for Application to Varnish of Rotating Machine Winding

Epoxy resins (EP) are commonly used to power apparatus due to their excellent electrical, thermal, and mechanical properties. Two types of EP resins were prepared to develop the varnishes for a rotating machine winding. A bifunctional alicyclic EP were used as an EP main resin, and an acid anhydride [mixture of hexahydro phthalic anhydride and methyl hexahydro phthalic anhydride (HHPA), or methyl nadic anhydride (NMA)] were used as a curing agent. The DC and impulse breakdown strengths of the EP‐HHPA were higher than that of EP‐NMA regardless of the applied voltage waveform and the temperature. The PDIV of the twisted pair sample coated with EP‐HHPA under the surge voltage application was also higher than that of twisted pair sample without the coating with EP resin and that with EP‐NMA. Furthermore, the transferred and/or accumulated charge amount of the EP‐HHAP on bulk and surface properties at high temperatures were superior to that of EP‐NMA. From these results, it is considered that EP‐HHPA may be preferable varnishes materials than EP‐NMA for a rotating machine winding. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Insights into non-crystalline structure of solid solution Ce-Mn co-oxide nanofibers for efficient low-temperature toluene oxidation.

The controllable preparation of efficient non-crystalline solid solution catalysts is a great challenge in the catalytic oxidation of volatile organic compounds. In this work, series non-crystalline solid solution structured Ce-Mn co-oxide nanofibers were creatively prepared by adjusting Ce/Mn molar ratios using electrospinning. 0.20CeMnOx (the ratio of Ce to Mn was 0.2) displayed an outstanding low-temperature toluene oxidation activity (T90 = 233 °C). The formation of the amorphous solid solution and the unique nanofiber structure both contributed to a large specific surface area (S = 173 m2 g-1) and high adsorbed oxygen content (Oads/O = 41.3%), which enhanced the number of active oxygen vacancies. The synergies between non-crystalline structure and active oxygen species markedly improved oxygen migration rate as well as redox ability of the catalysts. Additionally, in situ diffuse reflectance infrared Fourier transform spectra showed that the absorbed toluene could be completely oxidized to CO2 and H2O with benzyl alcohol, benzaldehyde, benzoic acid, and maleic anhydride as intermediates. In summary, this study provided an alternative route for the synthesis of non-crystalline metal co-oxide nanofibers.

Optimizing the Spatial Density of Single Co Sites via Molecular Spacing for Facilitating Sustainable Water Oxidation.

Advances in single-atom (-site) catalysts (SACs) provide a new solution of atomic economy and accuracy for designing efficient electrocatalysts. In addition to a precise local coordination environment, controllable spatial active structure and tolerance under harsh operating conditions remain great challenges in the development of SACs. Here, we show a series of molecule-spaced SACs (msSACs) using different acid anhydrides to regulate the spatial density of discrete metal phthalocyanines with single Co sites, which significantly improve the effective active-site numbers and mass transfer, enabling one of the msSACs connected by pyromellitic dianhydride to exhibit an outstanding mass activity of (1.63 ± 0.01) × 105 A·g-1 and TOFbulk of 27.66 ± 1.59 s-1 at 1.58 V (vs RHE) and long-term durability at an ultrahigh current density of 2.0 A·cm-2 under industrial conditions for oxygen evolution reaction. This study demonstrates that the accessible spatial density of single atom sites can be another important parameter to enhance the overall performance of catalysts.

Recyclability and catalytic characteristics of copper oxide nanoparticles derived from bougainvillea plant flower extract for biomedical application

Abstract This work aims to investigate the environmentally sustainable technique to synthesize the copper nanoparticles using bougainvillea flower ethanolic extract at ambient temperature. Copper nanoparticles have considerable potential for reducing the environment’s harmful pigments and nitrogen contaminants. The oxidized copper nanoscale catalysts are enclosed inside nanomaterial, which work as a benign and sustainable resource for capping agents. Ultraviolet spectroscopic, transmission electron microscopy (TEM), and X-ray crystallography (XRD) techniques were used to evaluate the produced oxidized copper nanocrystals. The particles produced have been very robust, are cylindrical in form, and have an outer diameter of 12 nm. Furthermore, under normal conditions, copper oxide (CuO) nanomaterials demonstrated strong photocatalytic efficiency in liquid media for the oxidation of Congo red, bromothymol blue, and 4-nitrophenol in an acidic solution acetic anhydride. Moreover, the CuO nanocrystalline enzyme could be readily vortexed or used for five cycles with an exchange rate of even over 90%. The evaporation process caused around 18% of the loss of weight between 25°C and 190°C, while soil organic breakdown caused almost 31% of the loss of weight around 700°C. As a result, the little reduction in enzymatic effectiveness of the recoverable multilayer CuO substrate might be attributed to catalytic degradation throughout spinning and processing.

Biocompatible coatings based on photo-crosslinkable cellulose derivatives

Materials derived from renewable resources have great potential to replace fossil-based plastics in biomedical applications. In this study, the synthesis of cellulose-based photoresists by esterification with methacrylic acid anhydride and sorbic acid was investigated. These resists polymerize under UV irradiation in the range of λ = 254 nm to 365 nm, with or, in the case of the sorbic acid derivative, without using an additional photoinitiator. Usability for biomedical applications was demonstrated by investigating the adhesion and viability of a fibrosarcoma cell line (HT-1080). Compared to polystyrene, the material widely used for cell culture dishes, cell adhesion to the biomaterials tested was even stronger, as assessed by a centrifugation assay. Remarkably, chemical surface modifications of cellulose acetate with methacrylate and sorbic acid allow direct attachment of HT-1080 cells without adding protein modifiers or ligands. Furthermore, cells on both biomaterials show similar cell viability, not significantly different from polystyrene, indicating no significant impairment or enhancement, allowing the use of these cellulose derivatives as support structures for scaffolds or as a self-supporting coating for cell culture solely based on renewable resources.

Electrochemical biosensor for highly sensitive detection of cTnI based on a dual signal amplification strategy of ARGET ATRP and ROP

Cardiac troponin I (cTnI), a gold biomarker for the diagnosis of acute myocardial infarction (AMI), plays a vital role in the early diagnosis, treatment and prognosis analysis of AMI. In this paper, an electrochemical biosensor for the highly sensitive determination of cTnI was fabricated based on the dual signal amplification strategy of electron transfer atom transfer radical polymerization (ARGET ATRP) and ring-opening polymerization (ROP) for the first time. Briefly, the thiolate cTnI-aptamer 1, which was bonded to the electrode via Au–S bonds, specifically captured cTnI to the electrode surface. Then, cTnI-aptamer 2 (Apt2) was successfully introduced to the electrode surface to form Apt-cTnI-Apt sandwich structure. Subsequently, the initiator BIBB was connected to Apt2 through bromination reaction, and then the resulting ATRP polymer was employed as a macromolecular initiator for the succeeding reaction. Next, the monomers, α-amino acid-N-carboxylic acid anhydride ferrocene derivatives (NCA-Fc), used for the ROP reaction produced numerous electroactive polymers on the electrode surface. The dual action of ARGET ATRP and ROP significantly improved sensitivity of cTnI biosensor assay, the prepared biosensor displayed a wide linear detection range from 100 fg mL−1 to 100 ng mL−1, with a detection limit of 32.24 fg mL−1. The method exhibited favorable selectivity, simple operation and excellent stability. Furthermore, the biosensor still rendered satisfactory analytical performance in the detection of clinical serum samples, indicating the application potential in clinical diagnosis.

Response surface methodology based on the Box‐Behnken design for optimizing the synthesis of symmetrical anhydrides from acid chlorides using cerium (III) as a homogeneous catalyst

AbstractHere we report the synthesis of symmetrical carboxylic acid anhydrides from acid chlorides using cerium (III) as a homogeneous catalyst. The optimal experimental conditions (temperature at 40 °C, catalyst loading at 30 mg, 1.5 equivalents of base, and solvent volume at 1 mL) for the preparation of benzoic anhydride2 awere obtained using the Box‐Behnken design in combination with the response‐surface methodology. The analysis of variance showed that the presented quadratic model successfully performed the experimental data with coefficients of determination of R2=0.99. The predicted yield of synthesized anhydride2 aobtained from the RSM under optimal conditions was 98.63 %. A confirmation test of the optimal conditions proved the viability of the model and gave a yield of 97.27 %. Under the optimal conditions, the resulting synthesized anhydrides2 a–gwere obtained with good isolated chemical yields of 60 %<yield<96 %.