Rapid Reaction Rate Research Articles

Understanding the role of oxidants for enhanced remediation of groundwater nitrate: An insight into surface modification

Rapid urbanization and excessive agricultural runoff caused nitrate levels in groundwater to exceed permissible limits, making drinking water toxic and unsafe for consumption. Numerous physicochemical and biological treatment methods have been explored to remove nitrate from water; however, adsorption, a surface phenomenon, has a wide range of applications because of its rapid rate of reaction, recyclability, and environmentally friendly synthesis method. In this direction, this study aimed to unravel the role of oxidants in the facile synthesis of a competent zirconium-based adsorbent to remove nitrate from groundwater. The wet oxidative method, a facile chemical synthesis process requires an oxidant, which adds the oxidative functionalities on the surface of the adsorbent, which offers excessive anchorage to the transition metal on the surface of the adsorbent during synthesis. The batch experiments were conducted to evaluate the effectiveness of the adsorbents in treating nitrate. The maximum adsorption capacity of competent adsorbent was 113.97 mg/g at 300 K, which is considerably high compared to 62.83 mg/g of raw activated carbon and other existing adsorbents. The sorption capacity is reduced with an increase in temperature, which favors adsorption at lower temperatures. Adsorbents were successfully applied to test the groundwater samples showing increased removal efficiency. About 97 % desorption was obtained using 0.5 M NaOH, which facilitates the adsorbents for reuse. The developed adsorbent shows promising effectiveness in removing nitrate and could be used at a large scale.

Multicomponent Synthesis of Structurally Diverse Spiroheterocycles using Bio-organic Catalyst in Aqueous Medium

Background: MCRs are one of the most significant tools in the synthesis of organic compounds. MCR is a rapid chemical technique that uses three or more reactants to produce products that sustain all structural and substructural properties of the initial components. MCRs are useful in all fields of synthetic chemistry because of their rapid rate of reaction, simple procedure and excellent yields. We reported an efficient and environmentally friendly domino approach for the synthesis of spiroheterocycles spiro annulated with indeno[1,2-b]quinoline. Method: The spiroheterocycles with privileged heterocyclic substructures have been synthesized using taurine (2-aminoethanesulfonic acid) as a green, sustainable, bio-organic and recyclable catalyst in a three-component reaction of isatins, 1,3-diketones, and 1-napthylamine in aqueous media. The present synthetic method is probably the first report to synthesize spiroheterocycles, spiroannulated with indeno[1,2-b]quinoline. Furthermore, the approach is valuable because of the excellent yield that results from the reaction in 15-20 min. Result: The optimization of reaction conditions is an important case of efficient synthesis. The solvent, temperature, time and catalyst loading were all examined. The reusability of the catalyst was also investigated experimentally. The used catalyst taurine has a high activity as well as good reusability. The present synthetic protocol will be extended to synthesise a library of hybrid compounds. The present synthetic approach is cost-effective, and time-efficient with an easy-workup methodology that gives outstanding yields (80–95%) in 15–20 min. Conclusion: Taurine-catalyzed multicomponent reaction is a novel and efficient method for the synthesis of spiroannulated indeno[1,2-b]quinolines. The high catalytic activity of taurine as a catalyst with water as a green solvent makes the process environmentally friendly. The special features of the synthetic protocol include synthetic efficiency, operational simplicity, and reusability of the catalyst and it is expected to make significant contributions not only to drug discovery studies but also to pharmaceutical and therapeutic chemistry in view of introducing molecular diversity in the synthesized molecules.

Functionalized polyacrylonitrile nanofiber membranes with carbonic anhydrase for enhanced carbon dioxide capture and conversion: A performance study

As industrial activity rises, atmospheric carbon dioxide levels have significantly contributed to global warming and climate change. Developing effective carbon dioxide capture technologies is imperative to mitigate these effects. Carbonic anhydrase (CA) enzymes represent one of the most promising solutions due to their rapid reaction rates, environmental safety, and efficiency in facilitating CO2 conversion. This study takes a novel approach by investigating the immobilization of CA on functionalized polyacrylonitrile (PAN) nanofiber membranes to enhance CO2 conversion and mineralization. PAN nanofibers were fabricated via electrospinning and chemically modified to introduce carboxylic groups, resulting in NM-COOH nanofiber membranes. In addition, amine groups from chitosan (CS) were incorporated to form NM-COOH-CS nanofiber membranes. The immobilization of CA on these membranes revealed that covalent attachment through NM-COOH significantly enhances catalytic activity compared to physical attachment methods. The NM-COOH-CA membrane exhibited superior performance, achieving efficient conversion of CO2 into HCO3− and promoting CaCO3 mineralization. It reached a precipitation efficiency of 11.77 mg CaCO3 per gram of membrane-active unit (WAU) and maintained 63.12 % of its initial CaCO3 production over five cycles over five weeks. This study presents a novel, eco-friendly approach to greenhouse gas reduction, emphasizing the effectiveness of CA-immobilized nanofiber membranes. The findings mainly highlight the advantages of carboxylic functional groups in enhancing CA performance, paving the way for future research in carbon capture technologies.

Rapid Synthesis of Self‐Healing, pH‐Responsive IA‐Based Hydrogels via Frontal Polymerization

ABSTRACTSelf‐healing polymeric gels have emerged as a promising class of materials due to their ability to repair damage autonomously, offering significant advantages for various applications. Nevertheless, a major hurdle to their widespread practical use lies in their often‐compromised mechanical strength and long reaction time. Herein, we present the synthesis of a new type of self‐healing hydrogels using poly(itaconic acid‐co‐hydroxypropyl alcohol‐co‐acrylic acid), also known as poly(IA‐co‐HPA‐co‐AAc), by a frontal polymerization (FP) method. The rapid reaction rate of FP facilitates the swift and energy‐efficient synthesis of the hydrogels within 10 min, eliminating the need for prolonged reaction times. Additionally, the results revealed that the synthesized hydrogels exhibited pH‐dependent responsiveness, robust mechanical integrity, and autonomous self‐healing capabilities, obviating the requirement for external stimuli. The exceptional self‐healing properties can be attributed to the extensive hydrogen bonding network between the polymer chains, enabling them to recover up to 80% of their original mechanical strength. Rheological analysis confirmed the presence of a robust and stable gel network, evidenced by high storage modulus (G′) values across the entire frequency and strain sweep tests. This research addresses a significant knowledge gap in IA‐based hydrogels by introducing a rapid, optimized method for constructing self‐healing materials through hydrogen bonding interactions.

Anion substitution strategy for constructing abundant oxygen vacancies in perovskites enables efficient nitrate electroreduction

Perovskite oxides have emerged as promising candidates for electrocatalytic nitrate reduction (ERN) catalysts due to their unique electronic structures and tunable chemical compositions. In this work, we employed a fluorine ion substitution strategy to modulate the oxygen site of LaCoO3 (LCO), resulting in the construction of F-substituted LaCoO3 (LCOF0.5) catalyst for efficient ERN. The incorporation of fluorine ions leads to a weakening of the hybridization between the O 1 s orbital and Co 3d orbital of the catalyst, thereby inducing an increase in oxygen vacancies. The abundant oxygen vacancies can facilitate the electron transfer and surface adsorption energy of the ERN reaction intermediates. This leads to a reduction in the energy barriers for both the reduction of *HNO3 to *NO2 and the reduction of *HNO2 to *NO, thereby enhancing the performance of ERN. As excepted, LCOF0.5 exhibits a rapid reaction rate of k = 5.48 × 10−3 min−1, which is 1.70 times faster than that of pristine LCO, and its catalytic activity approaches that of the state-of-the-art electrocatalysts for ERN. Applying this strategy to LaFeO3 and LaMnO3 also yields similar results, demonstrating its general applicability. The F-anion substitution strategy offers new opportunities for significantly enhancing ERN performance.

Modified banana peel biochar-based green nanocatalyst for biodiesel production and its utilization to improve diesel engine performance and emission

This study introduces the integration of catalyst green, waste oil, and ultrasonication procedure for biodiesel synthesis, thereby addressing existing gaps in the present paper. In this scientific research, an efficient modified banana peel green catalyst was prepared via the pyrolysis procedure and utilized for biodiesel production from waste edible oil (WEO). Various analyses, including XRD, FTIR, FESEM, EDX/mapping, CO2-TPD, TEM, and BET-BJH were conducted to evaluate the catalyst structure. The results reveled that modified banana peel have spherical shaped particles with surface area of 127.56 m2g−1 and the size of the particle is <50 nm with basic sites of 206.4 µmol/g indicating suitable as catalyst for transesterification process. The highest biodiesel yield of 97.13 % was achieved under optimum conditions (ultrasonication time of 32.53 min, catalyst dosage of 3.23 wt%, methanol to WEO molar ratio of 11.51 and reaction temperature of 63.41 °C). Besides, the reusability of the modified banana peel nanocatalysts was demonstrated through multiple reuse stages, indicating high stability and consistent biodiesel yield over seven cycles (87.65 %) with biodiesel yield reduction of 9.48 %. Furthermore, the study investigated the effects of incorporating 20 % biodiesel into diesel (B20) and the presence of modified banana biochar in B20 on a compression-ignition diesel engine. The results revealed positive impacts on reducing CO (26.08 %) and UHC (25 %) emissions compared to diesel fuel and enhancing engine parameters using B20 with 80 ppm banana peel biochar. Moreover, the activation energy and exponential factor for the conversion of WEO to biodiesel are reported as 45.58 kJ/mol and 7.97×105 min−1, respectively. In summary, the modified banana peel nanocatalyst emerges as a standout option for biodiesel production, offering outstanding reusability, rapid reaction rates, and significant biodiesel efficiency attained within a quick reaction time.

SuFEx Chemistry Enables Covalent Assembly of a 280-kDa 18-Subunit Pore-Forming Complex.

Proximity-enhanced chemical cross-linking is an invaluable tool for probing protein-protein interactions and enhancing the potency of potential peptide and protein drugs. Here, we extend this approach to covalently stabilize large macromolecular assemblies. We used SuFEx chemistry to covalently stabilize an 18-subunit pore-forming complex, CsgG:CsgF, consisting of nine CsgG membrane protein subunits that noncovalently associate with nine CsgF peptides. Derivatives of the CsgG:CsgF pore have been used for DNA sequencing, which places high demands on the structural stability and homogeneity of the complex. To increase the robustness of the pore, we designed and synthesized derivatives of CsgF-bearing sulfonyl fluorides, which react with CsgG in very high yield to form a covalently stabilized CsgG:CsgF complex. The resulting pores formed highly homogeneous channels when added to artificial membranes. The high yield and rapid reaction rate of the SuFEx reaction prompted molecular dynamics simulations, which revealed that the SO2F groups in the initially formed complex are poised for nucleophilic reaction with a targeted Tyr. These results demonstrate the utility of SuFEx chemistry to structurally stabilize very large (here, 280 kDa) assemblies.

Unveiling the carbonation behavior of T-C3S and M-C3S: A comparative investigation

Numerous studies have investigated the carbonation process of tricalcium silicate (C3S). However, research on the carbonation of its different crystal forms remains relatively limited. This study explored the effects of accelerated carbonation on the performance and microstructure of T-C3S and M-C3S. The findings indicated that both T-C3S and M-C3S exhibited a rapid carbonation reaction rate during the initial 12 h, which subsequently declined gradually. The carbonation products of T-C3S and M-C3S primarily consisted of calcite, with T-C3S also containing a proportion of aragonite calcium carbonate. The decomposition peak temperature of calcium carbonate weight loss increased with prolonged carbonation time for both C3S crystal forms. Prismatic or cubic morphology calcite formed in T-C3S and M-C3S during the initial carbonation stages, leading to a denser microstructure. As the carbonation duration increased, the particle size of calcite also grew, displaying a more irregular morphology. Furthermore, needle-like or rod-like aragonite calcium carbonate was observed in T-C3S. T-C3S exhibited superior compressive strength compared to M-C3S at all stages of carbonation. Additionally, a relationship was established between compressive strength, calcium carbonate content, and CO2 uptake. This study provided evidence that the crystal structure of C3S not only influenced the rate of the carbonation reaction but also impacted the type and morphology of calcium carbonate products and the development of compressive strength.

Experimental constraints on barium isotope fractionation during adsorption–desorption reactions: Implications for weathering and erosion tracer applications

Constraining the processes that fractionate barium isotopes is essential for utilising barium isotope ratios as environmental tracers. Barium concentration measurements from soils, rivers, and estuaries demonstrate that adsorption–desorption reactions significantly influence the distribution of fluid–mobile barium at the Earth’s surface, potentially driving isotopic fractionation. To quantify the direction and magnitude of isotopic fractionation resulting from these reactions, a riverine and an estuarine series of batch experiments were conducted using environmentally important adsorbent minerals and surface waters. Himalayan river sediment and water samples were used to validate the experimental results.Adsorption–desorption reactions were found to be rapid, relative to the average transit time of sediment and water in catchments, and largely reversible. The direction and magnitude of isotopic fractionation in the riverine experiment series were consistent with the riverine field samples (preferential adsorption of the lighter isotopes). The reaction rate, reversibility, and magnitude of isotopic fractionation were found to depend primarily on the mineral. Experiments performed with iron oxyhydroxides (goethite and ferrihydrite) resulted in a greater degree of fractionation compared to clay minerals (kaolinite and montmorillonite). Estuarine experiments, designed to simulate sediment passage through a salinity gradient, demonstrated a high degree of reversibility, with 77% to 94% of adsorbed barium desorbed upon the addition of seawater to freshwater-equilibrated clay minerals.The results of the estuarine experiments suggest that barium isotope ratios measured in marine paleo-archives (e.g., corals) will reflect both the adsorbed and dissolved freshwater barium inputs to the ocean. The combined findings of this study indicate that the chemical and isotopic behaviour of barium differs from more conventional group 1 and 2 metal isotope systems due to a significant proportion of barium released from bedrock dissolution partitioning to mineral surfaces, rapid reaction rates between fluid–mobile phases, and a high degree of reaction reversibility. Consequently, riverine barium isotope ratios are likely to provide unique insights into the complex array of terrestrial weathering and erosion processes that sustain life on Earth.

DNA nanosensor based on bipedal 3D DNA walker-driven proximal catalytic hairpin assembly for sensitive and fast TK1 mRNA detection.

Hyperproliferative diseases are the first step for tumor formation; thymidine kinase 1 (TK1) mRNA is closely related to cell proliferation. Therefore, the risk of malignant proliferation can be identified by sensitively detecting the variance in TK1 mRNA concentration, which can be used for tumor auxiliary diagnosis and monitoring tumor treatment. Owing to the low abundance and instability of TK1 mRNA in real samples, the development of a sensitive and fast mRNA detection method is necessary. A DNA nanosensor that can be used for detecting TK1 mRNA based on bipedal 3D DNA walker-driven proximal catalytic hairpin assembly (P-CHA) was developed. P-CHA hairpins were hybridized to a linker DNA strand coupled with magnetic nanoparticles to increase their local concentrations. The bipedal DNA walking on the surface of NPs accelerates reaction kinetics using the proximity effect. Taking advantage of the signal amplification of P-CHA as well as the rapid reaction rate of the DNA walker in 80min, the proposed sensor detects TK1 mRNA with a low detection limit of 14pM and may then be applied toclinical diagnosis.

Efficient removal of amoxicillin, ciprofloxacin, and tetracycline from aqueous solution by Cu-Bi2O3 synthesized using precipitation-assisted-microwave

This study investigates the synthesis and characterization of Cu-Bi2O3 for degradation of antibiotics AMX, CIP, and TC using precipitation-assisted-microwave method at varying concentrations of Cu at 0%, 2%, 4%, 6%, and 8%. The effect of Cu concentration on the structural, morphological, and optical properties were studied by XRD, UV-Vis, and SEM-EDX. The optimal results were obtained by adding 4% Cu to the Bi2O3 matrix. With an energy band gap of 2.32 eV, a crystal size of 37.04 nm, and ?-Bi2O3 and CuBi2O4 phases. The removal efficiency of each antibiotic using the photocatalytic method varies, with AMX at 52.06%, CIP at 61.72%, and TC at 69.44%. Cu-Bi2O3 degraded TC-type antibiotics more rapidly. The high removal efficiency and rapid reaction rate indicate that Cu-Bi2O3 is an effective antibiotic removal agent. This further confirms the fact that the addition of Cu to Bi2O3 material can increase its ability to degrade antibiotics more effective.

Amphichdiral enhancement on singlet oxygen generation and stable thallium immobilization using iron-driven copper oxide

Thallium (Tl) as a prominent priority contaminant in aquatic environment necessitates rigorous regulation. However, limited horizon devotes the impact of selective oxidation on the process of thallium purification. In this study, selective active radical of singlet oxygen (1O2) was continually generated for Tl(Ⅰ) oxidation accomplished with efficient Tl(Ⅲ) immobilization using iron-driven copper oxide (CuFe)/peroxymonosulfate (PMS). Fe-doping changed the active center of electronic structure for enhancing the catalytic and adsorptive reactivities, and installed magnetism for solid-liquid separation. Rapid reaction rate (0.253 min−1) coupled with vigorous elimination efficiency (98.32%) relied on electrostatic attraction, surface complexation, and H-bond interaction. EPR and XPS analyses demonstrated that the synergistic effects of ≡ Cu(Ⅰ)/≡Cu(Ⅱ) and ≡ Fe(Ⅲ)/≡Fe(Ⅱ) redounded to the sustained generation of 1O2 through the pathway of PMS → •O2− → 1O2, and 1O2 exploited an advantage to selectively oxidize Tl(Ⅰ) to Tl(Ⅲ). 3D isosurface cubic charts revealed that the immobilizing ability of Tl(Ⅲ) hydrate for CuFe was notably superior to that of Tl(Ⅲ) hydrate for CuO and Tl(Ⅰ) hydrate for CuO/CuFe, which further attested surface reactivity promoted stable immobilization form. This work develops the continuous generation of 1O2 and stable immobilization with the goal of efficiently cleansing Tl-containing wastewater.

Enantioselective synthesis of chiral amides by carbene insertion into amide N–H bond

Chiral amides are important structure in many natural products and pharmaceuticals, yet their efficient synthesis from simple amide feedstock remains challenge due to its weak Lewis basicity. Herein, we describe our study of the enantioselective synthesis of chiral amides by N-alkylation of primary amides taking advantage of an achiral rhodium and chiral squaramide co-catalyzed carbene N–H insertion reaction. This method features mild condition, rapid reaction rate (in all cases 1 min) and a wide substrate scope with high yield and excellent enantioselectivity. Further product transformations show the synthetic potential of this reaction. Mechanistic studies reveal that the non-covalent interactions between the catalyst and reaction intermediate play a critical role in enantiocontrol.

Construction of a screening system for lipid-derived radical inhibitors and validation of hit compounds to target retinal and cerebrovascular diseases

Recent studies have highlighted the indispensable role of oxidized lipids in inflammatory responses, cell death, and disease pathogenesis. Consequently, inhibitors targeting oxidized lipids, particularly lipid-derived radicals critical in lipid peroxidation, which are known as radical-trapping antioxidants (RTAs), have been actively pursued. We focused our investigation on nitroxide compounds that have rapid second-order reaction rate constants for reaction with lipid-derived radicals. A novel screening system was developed by employing competitive reactions between library compounds and a newly developed profluorescence nitroxide probe with lipid-derived radicals to identify RTA compounds. A PubMed search of the top hit compounds revealed their wide application as repositioned drugs. Notably, the inhibitory efficacy of methyldopa, selected from these compounds, against retinal damage and bilateral common carotid artery stenosis was confirmed in animal models. These findings underscore the efficacy of our screening system and suggest that it is an effective approach for the discovery of RTA compounds.

14C-Isotope Use to Quantify Covalent Reactions between Flavor Compounds and β-Lactoglobulin.

A 14C-based method was developed to study the rate and extent of covalent bond formation between β-lactoglobulin and three model flavor compounds: a ketone (2-undecanone UDO), an aldehyde (decanal DAL), an isothiocyanate (2-phenylethyl isothiocyanate PEITC), and an unreactive "methods blank" (decane DEC). Aqueous protein solutions with one of the 14C-labeled model flavor compounds were placed in water baths at 25, 45, and 65 °C for 4 weeks measuring the amount of flavor: protein reaction at 1, 3, 7, 14, 21, and 28 days. UDO showed lowest reactivity (max of 0.9% of added compound reacted), DAL (max of 16.4% reacted), and PEITC (max of 71.8% reacted). All compounds showed a rapid initial reaction rate which slowed after ca. 7 days. It appears that only PEITC (at 65 °C) saturated all potential protein-reactive sites over the storage period.

Unlocking the magnetic potential of Fe2O3 nanoparticles by single-step synthesis of cobalt-infused nanomaterials for chromium removal

The study optimized the chromium removal capacity of Fe2O3 nanoparticles through the infusion of cobalt using a single-step synthesis method. This approach not only enhanced their magnetic properties but also employs less-chemical synthesis techniques, ultimately yielding highly magnetic CoFe2O4 nanoparticles and less impurities. The prepared materials underwent comprehensive testing, encompassing examinations of their optical properties, structure, chemical composition, and surface characteristics using various analyticals methods. In a span of 90 min under visible light exposure, CoFe2O4 nanoparticles exhibit the ability to remove more that 90% of chromium. This was corroborated through analysis using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). Moreover, the study illustrates that increased temperatures amplify the endothermic process of chromium adsorption. Positive ΔH°, negative ΔS°, and heightened Cr(IV) adsorption are linked to the temperature effects on solubility, mobility, and dissolved oxygen. Both Langmuir (R2 = 0.95, RL = 0.055) and Freundlich models (R2 = 0.98, n = 0.69) suggest favorable adsorption. The efficient Cr(IV) adsorption by CoFe2O4 nanocomposite is attributed to a rapid reaction rate and substantial capacity, following pseudo-second order kinetics (rate constant 0.01 g mg−1 min−1, R2 = 0.99).Graphical abstract

Self-assembly of hyperbranched DNA network structure for signal amplification detection of miRNA

Catalytic hairpin assembly (CHA) and hybridization chain reaction (HCR) can achieve the high sensitivity and rapid reaction rate in detecting miRNA. However, the amplification efficiency by these methods are limited. Herein, an enzyme-free and label-free hyperbranched DNA network structure (HDNS) was designed, in which localized catalytic hairpin assembly (LCHA) and hybridization chain reaction occurred in the horizontal axis and longitudinal axis, respectively, exhibiting intensive signal dual-amplification. miRNA-122 was selected as the target on behalf of miRNA to design the HDNS sensor. The fluorescence signal change of HDNS showed good linearity for detecting miRNA-122 in the concentration range from 0.1 nM to 60 nM with a limit of detection (LOD) at 37 pM which was lower than those of the sensors based on separate CHA or HCR. Afterwards, the HDNS sensor was applied to detect miRNA-122 in serum samples with the recovery rate in the range of 97.2 %–107 %. The sensor could distinguish different kinds of miRNAs, even the family members with high sequence homology, exhibiting excellent selectivity. This method provided a novel design strategy for improving the sensitivity and selectivity of DNA sensor for miRNA detection.

Site-Selective Polyfluoroaryl Modification and Unsymmetric Stapling of Unprotected Peptides.

Peptide stapling is recognized as an effective strategy for improving the proteolytic stability and cell permeability of peptides. In this study, we present a novel approach for the site-selective unsymmetric perfluoroaryl stapling of Ser and Cys residues in unprotected peptides. The stapling reaction proceeds smoothly under very mild conditions, exhibiting a remarkably rapid reaction rate. It can furnish stapled products in both liquid and solid phases, and the presence of nucleophilic groups other than Cys thiol within the peptide does not impede the reaction, resulting in uniformly high yields. Importantly, the chemoselective activation of Ser β-C(sp3)-H enables the unreacted -OH to serve as a reactive handle for subsequent divergent modification of the staple moiety with various therapeutic functionalities, including a clickable azido group, a polar moiety, a lipid tag, and a fluorescent dye. In our study, we have also developed a visible-light-induced chemoselective C(sp3)-H polyfluoroarylation of the Ser β-position. This reaction avoids interference with the competitive reaction of Ser -OH, enabling the precise late-stage polyfluoroarylative modification of Ser residues in various unprotected peptides containing other highly reactive amino acid residues. The biological assay suggested that our peptide stapling strategy would potentially enhance the proteolytic stability and cellular permeability of peptides.

Base‐Promoted Structural Rearrangement of Ynamide and Simultaneous N‐Desulfonylation

AbstractHerein, we describe a base‐promoted regioselective and chemoselective cascade cyclization, ynamide N−Csp bond cleavage, selective intramolecular 1,3‐migration, and simultaneous N‐desulfonylation strategy for the synthesis of 2‐phenyl‐3‐(phenylethynyl)‐1H‐indole derivatives. We observed multiple bond breaking (−N−Ts, and Csp2−Ts, Csp2−I/Csp2−SePh) from (E)‐3‐(1‐iodo‐2‐phenyl‐2‐tosylvinyl)‐2‐phenyl‐1‐tosyl‐indole/(E)‐2‐phenyl‐3‐(2‐phenyl‐1‐(phenylselanyl)‐2‐tosylvinyl)‐1‐tosyl‐indole derivatives to prepare 2‐phenyl‐3‐(phenylethynyl)‐1H‐indole in 15–60 min using our standard reaction conditions. A gram‐scale experiment as well as postsynthetic transformations of the synthesized 2‐phenyl‐3‐(phenylethynyl)‐1H‐indole were performed to exhibit the advantages of this synthetic methodology.

Thermodynamic Behavior of Pyrite and Arsenopyrite in Preoxidation for Chlorination Leaching of Refractory Gold Concentrate

Recently, preoxidation is an effective pretreatment method of refractory gold ore, which has been widely used due to the high desulfurization, arsenic removal, low environmental pollution, and rapid reaction rate. In this paper, we describe the thermodynamic considerations of preoxidation of pyrite and arsenopyrite, the main minerals of the refractory gold ore, and the effect of the pressure oxidation, one of the preoxidation processes on the chlorination leaching. The thermodynamic results indicated that arsenopyrite under acidic conditions is easier to oxidize compared to pyrite and the oxidation decomposition of pyrite and arsenopyrite-type gold ore can be considered mainly for pyrite. The experiment has shown that the arsenic removal rate was higher than the desulfurization rate; it is confirmed that the thermodynamic conclusion of the oxidation of pyrite and arsenopyrite was correct. Comparing the XRD, SEM, and EDX analyses of gold concentrate and pressurized oxidation residue, it can be seen that the surface of pressurized oxidation residue is a fine porous structure and the dense and durable structure of sulfide ore is mainly destroyed.