Alkaline Hydrolysis Reaction Research Articles

Photocurrent enhancement in dye-sensitized solar cells by polyimide covalent organic frameworks decorated with silver nanoparticles

Covalent organic framework (COF), featuring in highly ordered conjugated hexagonal array architecture, gains much attention due to their application potential in emerging energy and optoelectronic technologies. Polyimide-based COF (PI-COF) has alkaline-hydrolyzable imide units that can serve as adsorption sites for the anchorage of metallic nanoparticles, particularly eye-catching for multifunctionality. In this study, Ag nanoparticles (Ag NPs) sizing 5 to 20 nm are evenly attached on the surface of spherical PI-COFs through alkaline hydrolysis, ion exchange, and reduction reactions. The Ag-decorated COF (COF@Ag) are doped into the titania photoelectrode of dye-sensitized solar cell (DSSC) to explore its multifunctionality for the photovoltaic performance. The DSSC with the doping of COF@Ag exhibits a power conversion efficiency of 8.03 % under simulated one sun illumination, outperforming that without the doping of COF@Ag (6.86 %) by an enhancement in the photocurrent from 15.14 mA cm−2 to 17.31 mA cm−2. Comprehensive analyses including dye loading, electrochemical impedance, electron kinetics, and light absorption confirms the multifunctionality of COF@Ag. Localized surface plasmon resonance (LSPR) of Ag NPs enhances the photocurrent, and host–guest interaction of COFs facilitates the charge injection and suppresses the charge recombination.

Octocrylene carboxylate as an antenna in a luminescent Europium(III) complex: Experimental and theoretical insights

A new carboxylic acid, 2-cyano-3,3-diphenyl-2-propenoic acid, CLN, a chromophore ligand, was obtained by an alkaline hydrolysis reaction from the octocrylene, a commercial type B ultraviolet (UVB) radiation absorber. The CLN structure was elucidated by single-crystal X-ray diffraction (SCXRD) as being tetragonal with space group P4‾21/c and the presence of a carboxylic acid group was confirmed by mass, infrared (IR), and proton nuclear magnetic resonance (1H NMR) spectroscopy. In this way, coordination compounds were developed between CLN and Ln(III), Ln = being Gadolinium (Gd) and Europium (Eu), with a stoichiometry of 4:13 metal:ligand, confirmed by thermal and elemental analyses, corroborating with the metal cluster predicted by Sparkle/AM1 semi-empirical model. Photoluminescence data indicated that Eu(III) is efficiently sensitized by CLN due to its triplet excited state, determined using the emission spectrum of the Gd(III) mimic complex (T = 25,477 cm−1), being suitable for this purpose. Therefore, the emission spectrum of the Eu(III) complex exhibited a 5D0 → 7FJ transitions characteristic of the lanthanide ion. Furthermore, the Judd-Ofelt intensity parameters, the radiative and non-radiative decay rates, and the intrinsic quantum yield evaluated using the software LUMPAC software were in good agreement with the experimental values.

Eurochevalierines A-I, Sesquiterpene Alkaloid Hybrids with Anti-Triple Negative Breast Cancer Activity from Penicillium sp. HZ-5.

Nine new sesquiterpene alkaloids, eurochevalierines A-I (1-9), were separated from the rice cultures of the endophytic fungus Penicillium sp. HZ-5 originated from the fresh leaf of Hypericum wilsonii N. Robson. The structures' illumination was conducted by single-crystal X-ray diffraction, extensive spectroscopic analysis, alkaline hydrolysis reaction, and Snatzke's method. Importantly, the antitumor activities screen of these isolates indicated that 1 could suppress triple negative breast cancer (TNBC) cell proliferation and induce apoptosis, with an IC50 value of 5.4 μM, which is comparable to the positive control docetaxel (DXT). Flow cytometry experiments mentioned that compound 1 significantly reduced mitochondrial membrane potential (MMP) of TNBC cells. In addition, 1 could activate caspase-3 and elevated the levels of reactive oxygen species (ROS) and expressions of suppressive cytokines and chemokines. Further Western blot analysis showed that 1 could selectively induce mitochondria-dependent apoptosis in TNBC cells via the BAX/BCL-2 pathway. Remarkably, these finding provide a new natural product skeleton for the treatment of TNBC.

Optimization of Pressurized Alkaline Hydrolysis for Chemical Recycling of Post-Consumer PET Waste.

Addressing the environmental impact of poly(ethylene terephthalate) (PET) disposal highlights the need for efficient recycling methods. Chemical recycling, specifically alkaline hydrolysis, presents a promising avenue for PET waste management by depolymerizing PET into its constituent monomers. This study focuses on optimizing the pressurized alkaline hydrolysis process for post-consumer PET residues obtained from packaging materials. Post-consumer PET packaging waste was chemically recycled by means of an alkaline hydrolysis reaction in a 2 L pressurized reactor under varying conditions of the NaOH/PET ratio and temperature. The reaction's progress was monitored by sampling the liquid phase hourly over a four-hour period. The obtained products were purified, with a focus on isolating terephthalic acid (TPA). Higher temperatures (150 °C) resulted in superior TPA yields (>95%) compared to lower temperatures (120 °C). The NaOH/PET ratio showed minimal influence on the TPA yield. The optimal conditions (T = 150 °C; NaOH:PET = 2) were identified based on TPA yield and reaction cost considerations. This study demonstrates the feasibility of pressurized alkaline hydrolysis for PET recycling, with optimized conditions yielding high TPA purity and efficiency.

Granular aqueous suspensions with controlled interparticular friction and adhesion.

We present a simple route to obtain large quantities of suspensions of non-Brownian particles with stimuli-responsive surface properties to study the relation between their flow and interparticle interactions. We perform an alkaline hydrolysis reaction on poly(methyl methacrylate) (PMMA) particles to obtain poly(sodium methacrylate) (PMAA-Na) particles. We characterize the quasi-static macroscopic frictional response of their aqueous suspensions using a rotating drum. The suspensions are frictionless when the particles are dispersed in pure water. We relate this state to the presence of electrosteric repulsion between the charged surfaces of the ionized PMAA-Na particles in water. Then we add monovalent and multivalent ions (Na+, Ca2+, La3+) and we observe that the suspensions become frictional whatever the valency. For divalent and trivalent ions, the quasi-static avalanche angle θc at large ionic strength is greater than that of frictional PMMA particles in water, suggesting the presence of adhesion. Finally, a decrease in the pH of the suspending solution leads to a transition between a frictionless plateau and a frictional one. We perform atomic force microscopy (AFM) to relate our macroscopic observations to the surface features of the particles. In particular, we show that the increase in friction in the presence of multivalent ions or under acidic conditions is driven by a nanoscopic phase separation and the bundling of polyelectrolyte chains at the surface of the particle. Our results highlight the importance of surface interactions in the rheology of granular suspensions. Our particles provide a simple, yet flexible platform to study frictional suspension flows.

UPLC-MS/MS Method for Detection of Etomidate and Its Metabolite Etomidate Acid Quantity in Blood.

To establish a method for the simultaneous quantitative analysis of etomidate and its metabolite etomidate acid in blood, and to discuss its application value in actual cases. Acetonitrile precipitate protein method was used, and C18 column was selected. Gradient elution was performed with acetonitrile and 5 mmol/L ammonium acetate within 6 min. Electrospray ionization source in positive ion mode was used. The internal standard etomidate acid-d5 was obtained by etomidate-d5 alkaline hydrolysis reaction. Ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used for quantitative analysis. The methodological verification was conducted. Etomidate and etomidate acid in blood showed good linear relationship in the quantitative linear range (r>0.999), with the lower limit of quantification was 2.5 ng/mL and 7.5 ng/mL, respectively. The accuracy, precision, recovery rate, and matrix effect of the method met the professional verification standards. The practical application results showed that etomidate and etomidate acid could be detected in the blood of the abusers, and their mass concentrations ranged from 17.24 to 379.93 ng/mL. The method established in this study can simultaneously quantify etomidate and etomidate acid in blood, which is simple and convenient to operate with accuracy. It can meet the detection needs of actual cases and provide technical support for law enforcement to crack down on etomidate abuse.

Heuristic-Based Alkaline Hydrolysis Mechanism of Nitrate Ester (Nitrocellulose Monomer) and Nitroamine (Hexogen) Compounds: Electrostatic Attraction Effect of the Nitro Group

The alkaline hydrolysis reaction of energetic materials is important and complex. With improved performance, AMK_Mountain was used to systematically study the alkaline hydrolysis of the nitrocellulose monomer and hexogen. The reaction pathways showed that the nitrocellulose monomer produces the nitrate anion and nitrite anion differently, while hexogen only produces the nitrite anion. Electronic structure results at the M06-2X/6-311G(d,p)/PCM(Pauling) level showed that the nitrocellulose monomer and hexogen have a similar pathway in their main energy-releasing process (nitrite anion production): with electrostatic attraction effects after proton transfer, the nitrite anion dissociates from the original structure with a low barrier. Moreover, during the alkaline hydrolysis of the nitrocellulose monomer, the metastable intermediates after proton transfer may be directly generated following transition states that, structurally, tend to produce nitrite anions "proximal" to the proton transfer site and produce nitrate anions "distal" to the proton transfer site. Electronic structure analysis showed that representative metastable intermediates revealed that the charge transfer caused by electrostatic attraction may be the direct cause of these reactions.

Glycoluril and Its Chemical Properties

In the chemistry of heterocyclic compounds, bicyclic bisureas — glycolurils, have a special place. Glycolurils are used as a basis for the industrial production of substances that have found application in many areas of human life. The variety of glycoluril derivatives and their properties is primarily due to various substituents in the bicyclic structure. In this review, 2,4,6,8-tetraazabicyclo[3.3.0.]octane-3,7-dione (glycoluril), as the main representative of bicyclic bisureas, its physico-chemical properties, and methods for the synthesis of derivatives based on it are considered. In particular, the main physico-chemical characteristics of glycoluril and the data obtained from its spectral analysis by IR, NMR spectroscopy and X-ray diffraction analysis are presented and discussed. The paper briefly outlines the known methods for the synthesis of glycolurils and related compounds, also highlights the chemical properties of glycoluril and its derivatives, as well as the ways to modify them. Coordination compounds based on N-alkylglycolurils as ligands are briefly considered. The reaction products of N-halogenation and N-acylation of glycolurils are presented and discussed. Reactions for obtaining phosphorus-, nitro- and nitroso derivatives of glycolurils; alkylation methods, Mannich reactions, thionization, alkaline hydrolysis and reduction reactions at the carbonyl group of glycolurils are also shown. There is a discussion of the macromolecules formation in the condensation reaction of glycoluril with formaldehyde as precursors for the synthesis of cucurbit[n]urils.

Enhanced Hemocompatibility of Lysine Grafted Polyacrylonitrile Electrospun Nanofiber Membranes as a Potential Bilirubin Adsorption in Hemoperfusion

Hyperbilirubinemia is one of most severe clinical diseases, which is caused by the accumulation of unconjugated bilirubin. Electrospun nanofiber membranes used as highly efficient bilirubin adsorbents have been applied to remove the extra bilirubin in hemoperfusion for their high surface area and easy functionalized properties. In this work, Lysine (Lys) grafted polyacrylonitrile (PAN) electrospun nanofiber membranes doped with organic Hectorite (OHec) (Lys-HPAN@OHec) have been fabricated via a series of modified process, including pore forming, alkaline hydrolysis and grafting reaction. The obtained Lys-HPAN@OHec nanofiber membranes have been analyzed in detail and investigated the adsorption capacity for bilirubin. Compared with original PNA membranes, Lys-HPAN@OHec nanofiber membranes show an excellent bilirubin adsorption capacity and more stable rejection rate of bovine serum albumin (BSA). The maximum adsorption capacity of Lys-HPAN@OHec membranes for bilirubin is 64 mg/g, the adsorption process of Lys-HPAN@OHec membranes matched the Langmuir model well. In addition, dynamic adsorption reveals that the adsorption equilibrium time of Lys-HPAN@OHec membranes is about 2 h. Significantly, Lys-HPAN@OHec membranes have excellent biocompatibility and hemocompatibility. This study demonstrates that the novel Lys-HPAN@OHec membranes may provide a new way to treat hyperbilirubinemia.

Experimentally monitoring of the rapid biomolecular hydrolysis reaction with optical weak measurement

The real-time measurement of optical activity is of great significance for studying the chemical reactions of chiral molecules. In this study, we have built a set of linear common path optical weak measurement chiral sensor system in frequency domain, and the optical sensitivity of the system feasibly reaches 1524 for activity. Using this system, we have realized the state measurement of the ultrafast alkaline hydrolysis reaction of gluconolactone under different concentrations of catalyst. This study shows that the optical weak measurement chiral sensor can well monitor and compare the degree of hydrolysis reaction, and partly reflect the approximate change of the optical rotation in the real-time process of hydrolysis. Optical weak measurement chiral sensing does not require separation and labeling molecules, and has great application potential for the production and development of chiral compounds, especially chiral drugs.

Novel α-Aminophosphonates and α-Aminophosphonic Acids: Synthesis, Molecular Docking and Evaluation of Antifungal Activity against Scedosporium Species.

The Scedosporium genus is an emerging pathogen with worldwide prevalence and high mortality rates that gives multidrug resistance to antifungals; therefore, pharmacological alternatives must be sought for the treatment of diseases caused by this fungus. In the present project, six new α-aminophosphates were synthesized by the Kabachnik–Fields multicomponent reaction by vortex agitation, and six new monohydrolyzed α-aminophosphonic acids were synthesized by an alkaline hydrolysis reaction. Antifungal activity was evaluated using the agar diffusion method as an initial screening to determine the most active compound compared to voriconazole; then it was evaluated against 23 strains of the genus Scedosporium following the M38-A2 protocol from CLSI (activity range: 648.76–700 µg/mL). Results showed that compound 5f exhibited the highest antifungal activity according to the agar diffusion method (≤1 mg/mL). Cytotoxicity against healthy COS-7 cells was also evaluated by the MTT assay and it was shown that compound 5f exhibits a lower toxicity in comparison to voriconazole at the same concentration (1000 µM). A docking study was conducted afterwards, showing that the possible mechanism of action of the compound is through the inhibition of allosteric 14-α-demethylase. Taking these results as a basis, 5f is presented as a compound with attractive properties for further studies.

Humic Acids Aggregates as Microheterogeneous Reaction Media: Alkaline Hydrolysis Reactions

The influence of humic aggregates in a water solution upon the chemical stability under basic conditions of different substrates was reviewed. The kinetic behavior of each substrate was modeled in terms of a micellar pseudophase model.

Nucleophilic Substitution at Tetracoordinate Phosphorus. Stereochemical Course and Mechanisms of Nucleophilic Displacement Reactions at Phosphorus in Diastereomeric cis- and trans-2-Halogeno-4-methyl-1,3,2-dioxaphosphorinan-2-thiones: Experimental and DFT Studies.

Geometrical cis- and trans- isomers of 2-chloro-, 2-bromo- and 2-fluoro-4-methyl-1,3,2-dioxaphosphorinan-2-thiones were obtained in a diastereoselective way by (a) sulfurization of corresponding cyclic PIII-halogenides, (b) reaction of cyclic phosphorothioic acids with phosphorus pentachloride and (c) halogen–halogen exchange at PIV-halogenide. Their conformation and configuration at the C4-ring carbon and phosphorus stereocentres were studied by NMR (1H, 31P) methods, X-ray analysis and density functional (DFT) calculations. The stereochemistry of displacement reactions (alkaline hydrolysis, methanolysis, aminolysis) at phosphorus and its mechanism were shown to depend on the nature of halogen. Cyclic cis- and trans-isomers of chlorides and bromides react with nucleophiles (HO−, CH3O−, Me2NH) with inversion of configuration at phosphorus. DFT calculations provided evidence that alkaline hydrolysis of cyclic thiophosphoryl chlorides proceeds according to the SN2-P mechanism with a single transition state according to the potential energy surface (PES) observed. The alkaline hydrolysis reaction of cis- and trans-fluorides afforded the same mixture of the corresponding cyclic thiophosphoric acids with the thermodynamically more stable major product. Similar DFT calculations revealed that substitution at phosphorus in fluorides proceeds stepwise according to the A–E mechanism with formation of a pentacoordinate intermediate since a PES with two transition states was observed.

Mass balance and elimination mechanism of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) during the kraft pulping process

Papermaking raw materials are usually digested by NaOH and Na2S solution. The fate of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) during the kraft pulping process is still poorly known. In this study, a comprehensive investigation was conducted on the variation in PCDD/Fs in the kraft pulping section of 3 modern non-wood pulp mills adopting elemental chlorine-free (ECF) bleaching technology. Similar dioxin homologue profiles, dominated by Cl1−3DF and Cl2DD homologues, were observed in the raw materials, black liquors and brown pulps; and the partitioning behaviors of dioxin congeners between black liquor and brown pulp were found to be partly dependent on their octanol-water partitioning coefficients. Dioxin mass flow analysis indicated that the raw materials contributed more than 95 % to the dioxins entering the pulping section. Approximately 7 − 30 % of the input dioxins were exported by black liquor, and the brown pulp carried 44 − 51 % of the input dioxins into the subsequent bleaching section. The kraft pulping process caused a 40 − 48 % reduction in input dioxins. Alkaline hydrolysis and coupling reaction between dioxins and the aromatic fragments of lignin were proposed as two most possible mechanisms for dioxin elimination. In general, modern pulp mills have actually become industrial plants that eliminate environmental dioxins.

Detailed modeling of the kraft pulping chemistry: carbohydrate reactions

AbstractThe article introduces a detailed model for carbohydrate chemistry in kraft pulping. This article is continuation to the modeling work carried out for hot water extraction and chemical pulp bleaching. The model includes galactoglucomannan, xylan, and cellulose acid–base equilibria, in addition to peeling, stopping, and alkaline hydrolysis reactions of the same carbohydrates, as well as hexenuronic acid formation and degradation reactions. The Arrhenius parameters were applied from the literature or regressed against experimental data in the present study. The model is very successful in predicting the experimental data of carbohydrate reactions during kraft pulping. Many features of the pulping‐related model can be applied to specific fractionation chemistry considerations. The detailed knowledge on carbohydrates composition at any stage of pulping gives possibility for further development of biorefinery cases based on kraft pulping, such as biofuel and chemicals production.

Efficient and Adhesiveless Metallization of Flexible Polyimide by Functional Grafting of Carboxylic Acid Groups.

Surface metallization of polyimide (PI) is the key process for the preparation of flexible printed circuit boards (FPCBs). To meet the miniaturization demand, the ultrathinness of FPCB by the removal of the intermediate adhesive layer is imperative. The common adhesiveless process relies on the surface activation of hydrophobic PI through alkaline hydrolysis to generate the hydrophilic carboxylate anion sites for the metallic deposition. However, the alkaline hydrolysis process involves the imide ring cleavage caused by the attack of a strong nucleophile (OH-), resulting in mechanical destruction and surface coarseness of PI. In this study, a new PI is synthesized with the grafting of carboxylic acid groups as the active sites to intrinsically activate PI for efficient metallization. The surface activation is accomplished through an acid-base neutralization reaction in a dilute alkaline environment, which can suppress the alkaline hydrolysis reaction. The attenuated total reflection Fourier transform infrared spectroscopy analysis confirms a significant reduction of the extent of the imide ring cleavage in the carboxylic acid-grafted PI films. According to the microstructural examination using transmission electron microscopy, the deposited metal film adheres firmly to the carboxylic acid-grafted PI films through an interlocking effect of a broccoli bud-shaped nanocluster layer.

Reaction yield model of nitrocellulose alkaline hydrolysis.

Military nitrocellulose waste is flammable and explosive, and thus requires safe disposal and resource utilization. The alkaline hydrolysis process is a potential treatment method for nitrocellulose waste. In this study, a reaction yield model of nitrocellulose alkaline hydrolysis reaction was studied. For this purpose, a theoretical reaction yield model of nitrocellulose alkaline hydrolysis was developed based on Fick's law and scanning electron microscopy analysis. Additionally, the reaction yield model was experimentally validated. The results revealed a linear relationship between the nitrocellulose alkaline hydrolysis rate of xNC and the reaction time of t, which is given by t/tf = xNC. The limiting step of the alkaline hydrolysis of nitrocellulose is the rate of diffusion of OH- through the large pore channels. Accordingly, the reaction rate of the nitrocellulose alkaline hydrolysis can be increased by increasing the KOH concentration, reaction temperature, and reducing the size of the nitrocellulose granules. Thus, this model provides theoretical and technical support for the safe disposal and resource utilization of nitrocellulose waste.

3G2-C6 4',4"-ジアセチルフェノールフタレインのアルカリ加水分解反応における速度論的解析(教材開発,一般研究,学びの原点への回帰-学習の質を高める科学教育研究-)

3G2-C6 4',4"-ジアセチルフェノールフタレインのアルカリ加水分解反応における速度論的解析(教材開発,一般研究,学びの原点への回帰-学習の質を高める科学教育研究-)

Reactivity differences of O‐aryl O‐(4‐nitrophenyl) thionocarbonates versus their homolog carbonates: Micellar catalysis in hydrolysis reactions

AbstractThe alkaline hydrolysis reaction of O‐(4‐cyanophenyl), O‐(4‐methylphenyl), and phenyl O‐(4‐nitrophenyl) thionocarbonates (1, 2, and 3, respectively) and O‐(4‐cyanophenyl) and phenyl O‐(4‐nitrophenyl) carbonates (4 and 5, respectively) has been spectrophotometrically studied in aqueous borate buffer media, in the presence of the cationic surfactant CTAB. The pseudophase model successfully explained the results obtained, in the presence of this cationic micelle, and various kinetic parameters were determined. Results show that the catalytic efficiency increases in carbonates and thionocarbonates. In fact, a catalytic efficiency ( ) of 485‐fold was found in the hydrolysis reaction of thionocarbonate 1, while in the carbonate homolog 4, the effect was of 146‐fold. In addition, we found that at the same experimental conditions (Borate buffer pH = 9.0 and 25°C), an increase in the concentration of the buffer led to a decrease of the hydrolysis rate.

Synthesis and Metal‐Complexation Ability of Cross‐Linking Materials Containing Noria‐Templated Cavities with Pendant Carboxylic Acid Groups

AbstractWe synthesized noria‐containing cross‐linking materials, Cross(Noria‐MA‐co‐DM[n]m), by radical polymerization of a noria derivative with pendant methacryloyl groups (noria‐MA) and α, ω‐alkanedimethacrylamides (DM[n], n=3, 6, 12) at feed ratios of noria‐MA/DM[n]=1/2.4, 1/12, and 1/24 (m=2.4, 12. and 24). Alkaline hydrolysis reaction of Cross(Noria‐MA‐co‐DM[n]m) removed the noria moieties to give corresponding cross‐linking materials, Cross‐COOH‐DM[n]m, containing noria‐templated fixed cavities with pendant carboxylic acid groups. Among the noria‐containing cross‐linking materials, Cross(Noria‐MA‐co‐DM[6]24) showed the greatest extent of removal of noria upon hydrolysis. Nitrogen and carbon dioxide absorption studies indicated that Cross(Noria‐MA‐co‐DM[6]24) contains fixed cavities, whereas Cross‐COOH‐DM[6]24 does not in the solid (unswollen) state. Examination of the inclusion‐complex‐forming ability of the synthesized cross‐linking materials using aqueous solutions of metal ions revealed that Cross‐COOH‐DM[6]24 has the greatest absorption capacity. These results indicate that Cross‐COOH‐DM[6]24 indeed contains noria‐templated cavities that can accommodate metal ions in aqueous solution.