Organic Reactions Research Articles

Sustainable Design and Revolutionary Synthesis of Highly Recyclable Sulfonic Acid–Based Magnetic Nanoparticles as a Solid Acid for Synthesis of 2‐Substituted Benzimidazole and Bis Indole Methane Derivatives

ABSTRACTConcerning the objectives of green chemistry, silica‐coated magnetite nanoparticles provide a new way to implement an efficient and effective system for assisting catalyst recovery across multiple organic reactions. With Fe3O4 spheres serving as the core shell, the synthesis of sulfonic acid‐functionalized silica‐coated magnetic nanoparticles is presented in this paper. FTIR, PXRD, SEM, TEM, EDX, TGA, XPS, and VSM techniques were used to assess the prepared catalyst. The proposed nanocatalyst was employed to produce biological relevance 2‐substituted benzimidazole and bis indole methane derivatives. High yield, quick reaction time, soothing reaction conditions, extended functional group tolerance, and an accessible workup approach are the main advantages of synthesized nanoparticles. Furthermore, the present nanocatalyst may be recovered using an external magnet and retaining its effectiveness for up to six cycles. These are distinctive functions of the present approach.

Lone Pair-π Interactions in Organic Reactions.

Noncovalent interactions between a lone pair of electrons and π systems can be categorized into two types based on the nature of π systems. Lone pair-π(C═O) interactions with π systems of unsaturated, polarized bonds are primarily attributed to orbital interactions, whereas lone pair-π(Ar) interactions with π systems of aromatic functional groups result from electrostatic attractions (for electron-deficient aryls) or dispersion attractions and Pauli repulsions (for electron-rich/neutral aryls). Unlike well-established noncovalent interactions, lone pair-π interactions have been comparatively underappreciated or less used to influence reaction outcomes. This review emphasizes experimental and computational studies aimed at integrating lone pair-π interactions into the design of catalytic systems and utilizing these interactions to regulate the reactivity and selectivity of chemical transformations. The role of lone pair-π interactions is highlighted in the stabilization or destabilization of transition states and ground-state binding. Examples influenced by lone pair-π interactions with both unsaturated, polarized bonds and aromatic rings as π systems are included. At variance with previous reviews, the present review is not structured according to the physical origin of particular classes of lone pair-π interactions but is divided into chapters according to ways in which lone pair-π interactions affect kinetics and/or selectivity of reactions.

Modulating the band structure of two-dimensional black phosphorus via electronic effects of organic functional groups for enhanced hydrogen production activity.

Electronic effects of organic functional groups play a fundamental role in determining the rate and/or direction of organic chemical reactions. The implementation of this concept in selective organic catalysis is achieved by tuning the electronic effects of organic functional groups to alter the corresponding reactivity. However, this approach has hardly been applied to modulate the band structure of inorganic materials. Here, we show that modulating the electronic band structure of two-dimensional black phosphorus (BP) is possible via the electronic effects of organic functional groups covalently modified on its surface. Organic functional group can either donate or withdraw charge density from BP surface, which will alter the bonding/anti-binding orbitals occupancy and thus shift the band-edge positions of functionalized BP downward/upward. Therefore, the valence-band maxima and the conduction-band minima of functionalized BP can be continuously tuned by changing the binding group with different Hammett parameters. Finally, unexpectedly high hydrogen evolution reaction rates under visible light are achieved using functionalized BP heterojunctions as photocatalysts. This work underscores the significant role of electronic effects in chemically controlling BP's band structure, offering greater flexibility and affordability beyond physical method limits.

Modulating the band structure of two‐dimensional black phosphorus via electronic effects of organic functional groups for enhanced hydrogen production activity

Electronic effects of organic functional groups play a fundamental role in determining the rate and/or direction of organic chemical reactions. The implementation of this concept in selective organic catalysis is achieved by tuning the electronic effects of organic functional groups to alter the corresponding reactivity. However, this approach has hardly been applied to modulate the band structure of inorganic materials. Here, we show that modulating the electronic band structure of two‐dimensional black phosphorus (BP) is possible via the electronic effects of organic functional groups covalently modified on its surface. Organic functional group can either donate or withdraw charge density from BP surface, which will alter the bonding/anti‐binding orbitals occupancy and thus shift the band‐edge positions of functionalized BP downward/upward. Therefore, the valence‐band maxima and the conduction‐band minima of functionalized BP can be continuously tuned by changing the binding group with different Hammett parameters. Finally, unexpectedly high hydrogen evolution reaction rates under visible light are achieved using functionalized BP heterojunctions as photocatalysts. This work underscores the significant role of electronic effects in chemically controlling BP’s band structure, offering greater flexibility and affordability beyond physical method limits.

Recent Advances in Rechargeable Zn-Air Batteries

Rechargeable Zn-air batteries are considered to be an effective energy storage device due to their high energy density, environmental friendliness, and long operating life. Further progress on rechargeable Zn-air batteries with high energy density/power density is greatly needed to satisfy the increasing energy conversion and storage demands. This review summarizes the strategies proposed so far to pursue high-efficiency Zn-air batteries, including the aspects of the electrocatalysts (from noble metals to non-noble metals), the electrode chemistry (from the oxygen evolution reaction to the organic oxidation reaction), electrode engineering (from powdery to free-standing), aqueous electrolytes (from alkaline to non-alkaline) and the battery configuration (from liquid to flexible). An essential evaluation of electrochemistry is highlighted to solve the challenges in boosting the efficiency of rechargeable metal-air batteries. In the end, the perspective on current challenges and future research directions to promote the industrial application of rechargeable Zn-air batteries is provided.

FeOOH Quantum Dots Assembled MXene-Decorated 3D Photothermal Evaporator for Synergy Application in Solar Evaporation and Fenton Degradation.

Solar-driven water evaporation is considered as the sustainable approach to alleviate freshwater resource crisis through direct use of solar energy. However, it is still challenging to achieve the multifunctional solar evaporators equipped with both high evaporation and purification performance to handle practical complex wastewater. Here, a simple and cost-effective multifunctional 3D solar evaporator is prepared by alternately decorating the commercial sponge with FeOOH quantum dots (FQDs) supported MXene sheets composites and chitosan hydrogel coatings for enabling the solar water evaporation and organic wastewater photodegradation simultaneously. MXene composites allow the solar evaporator with excellent photothermal conversion performance, the hydrophilic chitosan hydrogel coated interconnecting skeleton structures of sponge serve as the mass transfer and water transport channels. The Fenton-catalytic FQDs anchored on the MXene sheets surface accept the photo-generated electrons of MXene sheets to induce the organic pollutant photo-Fenton degradation reaction under sunlight irradiation. The resulting evaporator possesses both excellent water evaporation rate of 2.54kg m-2h-1 and high degradation efficiency (99.24% for methylene blue), coupled with durable salt-resisting performance during long-term seawater desalination (20 wt.% NaCl). This work provides a simple and feasible strategy for designing multifunctional solar evaporators to meet the potential application scenarios in practice.

Pressure enabled organic reactions via confinement between layers of 2D materials.

Confinement of reactants within nanoscale spaces of low-dimensional materials has been shown to provide reorientation of strained reactants or stabilization of unstable reactants for synthesis of molecules and tuning of chemical reactivity. While few studies have reported chemistry within zero-dimensional pores and one-dimensional nanotubes, organic reactions in confined spaces between two-dimensional materials have yet to be explored. Here, we demonstrate that reactants confined between atomically thin sheets of graphene or hexagonal boron nitride experience pressures as high as 7 gigapascal, which allows the propagation of solvent-free organic reactions that ordinarily do not occur under standard conditions. Specifically, we show that cyclodehydrogenation of hexaphenylbenzene without catalysts as a proof of concept and oxidative polymerization of dopamine into sheet-like crystalline structure are enabled by the effective high pressure experienced by the reactants between the graphene layers. Our results demonstrate a facile, general approach for performing high-pressure chemistry based on confinement of reactants within two-dimensional materials.

Catalyst-free and wavelength-tuned glycosylation based on excited-state intramolecular proton transfer

The chemoselectivity of organic reactions is a fundamental topic in organic chemistry. In the long history of chemical synthesis, achieving chemoselectivity is mainly limited to thermodynamic conditions by an exogenous activation strategy. Here, we design an endogenous activation method, which can be used to control the chemoselectivity of phenol and naphthol through the photo-induced excited-state intramolecular proton transfer (ESIPT). A wavelength-tuned glycosylation is developed to showcase the penitential of this new strategy. Traditionally, an exogenous activator (electrophilic promoters) is essential to induce the cleave of a polar single bond, and this strategy has been extensively studied and used in the glycosylation chemistry, for the formation of oxocarbenium cation intermediate. In our systems, the oxocarbenium cation intermediates can be selectively formed from glycosyl donors bearing tunable chromophoric groups under mild conditions of acid-base free and redox neutrality, which enables continuous synthesis of oligosaccharides.

Patterns in Explanations of Organic Chemistry Reaction Mechanisms: A Text Analysis by Level of Explanation Sophistication

Patterns in Explanations of Organic Chemistry Reaction Mechanisms: A Text Analysis by Level of Explanation Sophistication

Recent Progress in Situ Application of H2O2 Produced via Catalytic Synthesis.

Industrial production of H2O2 requires lots of energy and causes environmental pollution. Moreover, in subsequent applications, much economic loss could be produced during the transportation process of H2O2 and its dilution process. Therefore, it is highly desirable for in situ application of H2O2. In recent years, catalytic synthesis of H2O2, e. g., direct catalytic synthesis, electrocatalytic synthesis, and photocatalytic synthesis, has attracted more and more attention because the continuous and low-concentration H2O2 produced by catalytic synthesis can be directly used for the oxidation of organic compounds, effectively avoiding the shortcomings of the current industrial route. Here, we briefly reviewed the latest processes for the catalytic production of H2O2 via various routes. On this basis, we summarized and discussed the in situ application of H2O2 in typical organic conversion reactions, including the ammoximation of ketones, the oxidation of alcohols, the oxidation of C-H bonds, and the oxidation of olefins. Some in situ coupling reactions have shown excellent performance with high conversion and selectivity, and the economic cost has been significantly reduced. Finally, the shortcomings of the in situ utilization of H2O2 in coupling reactions were analyzed, and some strategies for promoting the efficiency of the H2O2 application in organic synthesis were proposed.

31P Nuclear Magnetic Resonance Spectroscopy for Monitoring Organic Reactions and Organic Compounds.

31P NMR spectroscopy is a consolidated tool for the characterization of organophosphorus compounds and, more recently, for reaction monitoring. The evolution of organic synthesis, mainly due to the combination of elaborated building blocks with enabling technologies, generated great challenges to understand and to optimize the synthetic methodologies. In this sense, 31P NMR experiments also became a routine technique for reaction monitoring, accessing products and side products yields, chiral recognition, kinetic data, intermediates, as well as basic organic parameters, such as acid-base and hydrogen-bonding. This review deals with these aspects demonstrating the essential role of the 31P NMR spectroscopy. The recent publications (the last ten years) will be explored, discussing the experiments of 31P NMR and the strategies accomplished to detect and/or quantify distinct organophosphorus molecules, approaching reaction mechanism, stability, stereochemistry, and the utility as a probe.

Steering the reaction kinetics of the MgO-V2O5 system toward selective synthesis of magnesium vanadates

Magnesium vanadates (MgV2O6, Mg2V2O7 and Mg3V2O8) are common redox catalysts for organic reactions and excellent energy storage materials. However, due to the diversity of magnesium vanadates and their interconvertibility, it is difficult to accurately synthesize a species of magnesium vanadate or control its stability during functioning. Herein, the reaction kinetics of MgO-V2O5 system was studied for controllable synthesis of magnesium vanadates. The MgO-V2O5 diffusion couples were prepared to explore the interface reaction characteristics of the MgO-V2O5 system at different reaction time. During reaction, the thickness of the diffusion layer and diffusion coefficient gradually increased and reached a maximal value of 29.55 μm and 6.06×10-11 cm2·s−1 at 10 h, which diffusion is faster than that of CaO-V2O5 system. Additionally, the interconvertible mechanisms of different magnesium vanadates were investigated using XRD and SEM/EDS techniques. MgV2O6 was produced during the synthesis of Mg2V2O7 in the initial 4 h, which converted into Mg2V2O7 at a longer synthesis time. Mg2V2O7 was found during the generation process of Mg3V2O8; with abundant MgO, Mg2V2O7 converted into Mg3V2O8. These findings provide important insights into the accurate control of magnesium vanadate synthesis and even the vanadium extraction process.

Dealuminated H–Y zeolites generate, stabilize and catalytically insert carbenes from diazocarbonyl compounds

Carbenes are among the most powerful reactants in organic synthesis, with capacity to insert into a variety of otherwise stable bonds, and generate two new bonds in a straightforward manner. However, the intrinsic instability of such carbenes makes them to be catalytically generated, in–situ, from precursors such as diazocarbonyl compounds, and the catalyst, in turn, also controls the subsequent insertion reaction. The catalyst is generally a metal complex in solution, mainly Cu, Ag or Rh, but also others, including protons in rare cases. Here we show that carbenes are generated, stabilized and inserted into C–C, C–H, O–H, N–H, Si–H and O–O bonds after reacting diazocarbonyl compounds with catalytic amounts of metal–free, commercially available dealuminated H–Y zeolites. These results open the way to design carbene–mediated organic reactions on readily available and reusable catalytic solids without involving metals.

Designing Sustainable Copper‐Based Hybrid Framework Catalysts for One‐Pot Multicomponent Organic Reactions

AbstractThe recent breakthroughs in heterogeneous catalysis emphasize the need for novel materials capable of driving organic transformations. The present study explores two copper phosphonate hybrid framework materials, 2D Cu3[(Hhedp)2(C4H4N2)].2H2O (Cu(II)Pyz‐P) and 3D Cu3[(H3hedp)2(C4H4N2)4(SO4)].2H2O (Cu(I/II)Pyz‐P), as single crystals isolated via hydrothermal synthetic strategy using H4hedp (1‐hydroxyethane 1,1‐diphosphonic acid) and N‐donor secondary ligand (Pyrazine; C4H4N2). Cu(II)Pyz‐P contains exclusively +2 oxidation state of copper, while Cu(I/II)Pyz‐P is characterized by a mixed oxidation state, where copper +2 phosphonate is embedded within the network formed by copper +1 state. Moreover, magnetic study elucidates the distinct oxidation states of both compounds by showing deviations from each other. The aforementioned compounds are exceedingly effective for catalyzing multicomponent reactions, that is, A3 coupling reaction and click reaction. Cu(I/II)Pyz‐P ensures the regioselective synthesis of triazole with high purity, while A3 coupling reaction is facilitated by both the compounds. Solvent‐ and additive‐free efficient multicomponent reactions are explored for the first time in the copper phosphonate hybrid framework structures. The present study reveals the promise of copper‐based hybrid phosphonate frameworks as durable and efficient catalysts for organic synthesis, providing cost‐effective and sustainable ways for advanced catalytic transformations.

Methanol, ethylene glycol, and glycerol photoelectrochemical oxidation reactions on BiVO4: Zr,Mo/Pt thin films: A comparative study

The green H2 production plays a key role in the energy transition, however it still needs improvements to be applied in a large scale. The water oxidation reaction, as an anodic process to provide both protons and electrons for H2 production, possesses kinetic limitations. Therefore, the use of an alternative process like the oxidation of biomass-derivative species is extremely desired to replace water oxidation during H2 production. In this work, we provide a comparative study of different small organic molecules (methanol, ethylene glycol (EG), and glycerol) as alternatives to water oxidation at pristine BiVO4, Mo-Zr dopped BiVO4, and Pt co-catalyst BiVO4 photoanodes in neutral media. While the band energy diagram and surface morphology are similar for the distinct materials, the presence of Zr-Mo increases the charge carriers density. The presence of Pt acts as co-catalyst for the organic molecules. Regardless of the material employed, the activity order for each organic molecule reaction was: jwater< jmethanol < jEG < jglycerol affeered by both linear potential sweep and chronoamperometry at 1.23 V vs RHE. The presence of both Zr-Mo and Pt increases the photoactivity for the alcohol's oxidation, however the presence of Pt is more advantageous for glycerol oxidation than for other species, maintaining 80 % of activity after 24 h electrolysis. The reactivity of alcohols can be tentatively explained by the greater stability of radicals formed from larger molecules.

A Cytochrome P450 TxtE Model System with Mechanistic and Theoretical Evidence for a Heme Peroxynitrite Active Species

AbstractThe cytochrome P450 homolog, TxtE, efficiently catalyzes the direct and regioselective aromatic nitration of the indolyl moiety of L‐tryptophan to 4‐nitro‐L‐tryptophan, using nitric oxide (NO) and dioxygen (O2) as co‐substrates. Pathways for such direct and selective nitration of heteroaromatic motifs present platforms for engineering new nitration biocatalysts for pharmacologically beneficial targets, among a medley of other pivotal industrial applications. Precise mechanistic details concerning this pathway are only weakly understood, albeit a heme iron(III)‐peroxynitrite active species has been postulated. To shed light on this unique reaction landscape, we investigated the indole nitration pathway of a series of biomimetic ferric heme superoxide mimics, [(Por)FeIII(O2−⋅)], in the presence of NO. Therein, our model systems gave rise to three distinct nitroindole products, including 4‐nitroindole, the product analogous to that obtained with TxtE. Moreover, 15N and 18O isotope labeling studies, along with meticulously designed control experiments lend credence to a heme peroxynitrite active nitrating agent, drawing close similarities to the tryptophan nitration mechanism of TxtE. All organic and inorganic reaction components have been fully characterized using spectroscopic methods. Theoretical investigation into several mechanistic possibilities deem a unique indolyl radical based reaction pathway as the most energetically favorable, products of which, are in excellent agreement with experimental findings.

Two-Dimensional Covalent Organic Frameworks with Carbazole-Embedded Frameworks Facilitate Photocatalytic and Electrocatalytic Processes.

Catalytic technologies are pivotal in enhancing energy efficiency, promoting clean energy production, and reducing energy consumption in the chemical industry. The pursuit of novel catalysts for renewable energy is a long-term goal for researchers. In this work, we synthesized three two-dimensional covalent organic frameworks (COFs) featuring electron-rich carbazole-based architectures and evaluated their catalytic performance in photocatalytic organic reactions and electrocatalytic oxygen reduction reactions (ORRs). Pyrene-functionalized COF, termed as FCTD-TAPy, demonstrated excellent photocatalytic performance for amino oxidation coupling and showed a remarkable preference for substrates with electron-withdrawing groups (up to >99% Conv. and >99% Sel). Furthermore, FCTD-TAPy favored a four-electron transfer pathway during the ORR and exhibited favorable reaction kinetics (51.07 mV/dec) and a high turnover frequency (0.011 s-1). In contrast, the ORR of benzothiadiazole-based FCTD-TABT favored a two-electron transfer pathway, which exhibited a maximum double-layer capacitance of 14.26 mF cm-2, a Tafel slope of 53.01 mV/dec, and a hydrogen peroxide generation rate of 70.3 mmol g-1 h-1. This work underscores the potential of carbazole-based COFs as advanced catalytic materials and offers new insights into the design of metal-free COFs for enhanced catalytic performance.

High-Energy Ball Milling Enables an Ultra-Fast Wittig Olefination Under Ambient and Solvent-free Conditions.

30 Seconds to success!-The Wittig reaction, a fundamental and extensively utilized reaction in organic chemistry, enables the efficient conversion of carbonyl compounds to olefins using phosphonium salts. Traditionally, meticulous reaction setup, including the pre-formation of a reactive ylide species via deprotonation of a phosphonium salt, is crucial for achieving high-yielding reactions under classical solution-based conditions. In this report, we present an unprecedented protocol for an ultra-fast mechanically induced Wittig reaction under solvent-free and ambient conditions, often eliminating the need for tedious ylide pre-formation under strict air and moisture exclusion. A range of aldehydes and ketones were reacted with diverse phosphonium salts under high-energy ball milling conditions, frequently giving access to the respective olefins in only 30 seconds.

Exploration and Reflection on the Reform of the "Open Book Exam" in Organic Reactions for Drug Synthesis

Objective: In the era of big data, the traditional “memorization - repetition” learning method is inadequate for addressing the vast and ever - evolving knowledge in courses such as “Organic Reactions for Drug Synthesis”. This article aims to explore how to shift students from “memorization - repetition” to “understanding - application” through educational reform and changes in assessment mechanisms, enabling them to adapt to a rapidly changing knowledge system. Methods: The study analyzed examination data from 9 classes over three consecutive years to assess the impact of implementing “open - book exams” in the “Organic Reactions for Drug Synthesis” course. In the first and third years, a closed - book examination was employed, which is a traditional method that tests studentsʼ ability to recall and apply knowledge without external resources. The second year introduced an open - book examination, the exam allow students to consult materials, promoting a deeper understanding of concepts and the flexible application of knowledge to solve practical problems. Results: The analysis revealed that open - book exams positively influenced studentsʼ ability to understand and apply concepts, fostering greater learning autonomy and creativity. However, issues such as over - reliance on materials and insufficient mastery of basic knowledge were also identified. Conclusion: By examining the “successes” and “failures”, this article offers valuable insights for reforming assessment methods in courses like “Organic Reactions for Drug Synthesis”. Continuous exploration and practice can help educators develop teaching and assessment approaches better suited to the current era, ultimately enhancing studentsʼ comprehensive skills and innovative abilities.

Assessment of amoxicillin biodegradation using a fluidized bed reactor

In recent decades, emerging pharmaceutical contaminants, such as personal care items, pharmaceuticals, and disinfectants, have increased alarmingly in aquatic ecosystems. The efficacy of wastewater treatment plants in eliminating these contaminants has been demonstrated. This study aims to find an alternative method, such as using the fluidized bed reactor (FBR) with bacteria to remove amoxicillin from wastewater. The active bacteria Acinetobacter baumannii and Klebsiella pneumoniae were isolated from one of the pharmaceutical factories in Baghdad, Iraq, from Al-Jazeera wastewater, which was used in FBR technology to decompose the antibiotic amoxicillin. The study examined several operational parameters, including pH, total organic carbon (TOC), dissolved carbon dioxide (CO2) concentration, airflow rate, amoxicillin concentration, and bacterial number, while maintaining a constant temperature. High-performance liquid chromatography (HPLC) was used to find the reaction route. The maximum amoxicillin removal efficiency was 93% and 91% for Acinetobacter baumannii and Klebsiella pneumoniae, respectively. For both bacterial species, the pH decreased due to the formation of amino acids and CO2. The suitable operation condition was 5 mg/L of amoxicillin concentration, flow rate of 30 m/s, and the number of bacteria 47 x 105 cfm/mL and 40 x 105 cfm/mL for Acinetobacter baumannii and Klebsiella pneumoniae, respectively. After treatment, the number of bacteria increased due to the degradation of amoxicillin. The steady-state time is found at 64 hours. The organic matter reaction pathway ends at the aromatic amino acid lysine, which kills gram-negative bacteria. This method was found to be successful in removing amoxicillin in low concentrations by using Acinetobacter baumannii. In the future, treating amoxicillin in wastewater using FBR technology with gram-positive bacteria is recommended.