β-Silyl ketones reacted with aldehydes by treatment with KMMDS in the presence of 18-crown-6 to give β,γ-unsaturated ketones accompanied with a skeletal rearrangement. The reactions proceeded by aldol reaction of β-silyl ketones with aldehydes followed by [1,4]-Brook rearrangement and intramolecular 1,2-addition to form cyclopropanol derivatives, in which carbon-carbon bond cleavage took place to afford β,γ-unsaturated ketones. The β,γ-unsaturated ketones were prepared in a one-pot manner by conjugate addition of silyl anions to α,β-unsaturated ketones followed by reactions with aldehydes. The Brook rearrangement proceeded with complete inversion of configuration at the carbon center.
Crystal structure, optical properties, mobility, and photoelectric performance of [PEA]3[Bi2I9]
![Crystal structure, optical properties, mobility, and photoelectric performance of [PEA]3[Bi2I9]](https://onlinelibrary.wiley.com/cms/asset/f2de4750-9cfb-4245-aada-58eb41c69ad7/aoc7245-toc-0001-m.png)
We synthesized [PEA]3[Bi2I9] single crystals, and their crystal structure was analyzed. The spectroscopy data of the ground state and excited state show that the band gap is 2.048 eV. [PEA]3[Bi2I9] thin film has been proven to be an n-type semiconductor and has good coverage on the ITO interdigital electrode. The ITO interdigital electrode can effectively confirm the photoelectric conversion properties of [PEA]3[Bi2I9] thin film. The photocurrent density-time curves of the photodetector based on [PEA]3[Bi2I9] SC under different voltages (0.5, 1, 1.5, 2, and 2.5 V) at 386 nm with 30 W m−2 light intensity indicate the photocurrent density changes regularly with turning-on/off of the light. These methods provide ideas for screening lead-free optoelectronic material.
Lead halide-based salts exhibit good photoelectric properties; however, the use, leakage, and recovery of toxic lead require careful consideration. Therefore, developing a lead-free optoelectronic material conveniently and quickly is very important. Moreover, there is relatively little research on the salts of bismuth halides. In this study, we synthesized [PEA]3[Bi2I9] single crystals (SC) by volatilizing N,N-dimethylformamide (DMF) solvent at 70°C. The crystal system and spatial group of [PEA]3[Bi2I9] are monoclinic and P21/n, respectively. The Tauc plot reveals the optical band gap of the [PEA]3[Bi2I9] SC at 2.048 eV. The carrier mobility of [PEA]3[Bi2I9] SC is 47.4 cm2 V−1 s−1. Steady-state fluorescence and time-resolved fluorescence spectrum indicate that there are four fluorescence peaks and about 7 μs lifetime, respectively. The photodetector based on [PEA]3[Bi2I9] SC under different voltages (0.5, 1, 1.5, 2, and 2.5 V) exhibits stability and regularity with turning-on/off of the light. In addition, thermogravimetric analysis (TGA) tests indicate that [PEA]3[Bi2I9] SC has considerable thermal stability at temperatures up to 260°C, showing promise for becoming a high temperature resistant and nontoxic sensor with good application prospects.
Catalytic Conversion of Cellulose to 5‐Hydroxymethylfurfural: Advancements in Heterogeneous Catalysts and Cutting‐Edge Hydrolysis Strategies
This review examines the potential of converting cellulose into valuable 5-hydroxymethylfurfural (HMF) for sustainable chemical production. Catalyst types, hydrolysis strategies, and reactor systems are explored for their contributions to improving cellulose-to-HMF conversion. The review also covers challenges, future perspectives, and development directions.
Abstract
The catalytic conversion of lignocellulose-derived carbohydrates, particularly cellulose, into 5-hydroxymethylfurfural (HMF), holds significant potential as a crucial step in the sustainable production of valuable platform chemicals. This review presents the remarkable progress made in the field, with a specific emphasis on the role of heterogeneous catalysts, innovative methods for accelerating cellulose hydrolysis, and the design of flow reactor technologies. The distinctive properties and surface functionalities of catalysts facilitate the efficient breakdown of cellulose's intricate structure, thereby promoting selective hydrolysis leading to HMF formation. Therefore, this review comprehensively examines various categories of heterogeneous catalysts, including metal oxides/phosphates, zeolites, functionalized silica/carbon-based materials, heteropolyacids (HPAs), and metal-organic frameworks (MOFs), highlighting their unique mechanisms and performance in cellulose conversion. Furthermore, the review describes the intriguing progress in hydrolysis strategies (pretreatment techniques and advanced heating systems) that have been crucially involved in overcoming the challenges associated with cellulose recalcitrance and achieving enhanced HMF yields. The synergistic interactions between catalysts and innovative hydrolysis methods have played a central role in the breakthroughs within cellulose conversion technology. Another aspect covered in this work is the advancement in using fixed-/fluidized-bed reactors and slug microreactors for the continuous production of HMF. Lastly, the current challenges and future perspectives are presented to propose the dilemma and development direction for efficient cellulose-to-HMF conversion.
Solid‐State Electrolyte‐Based Electrochemical Conversion of Carbon Dioxide: Progress and Opportunities
Progress and opportunities related to the application of SSEs as central compartments for electrochemical catholyte-free CO2RR have been described, with key parameters such as SSE type, product carrier, ion exchange membrane, and catalyst hydrophilicity, which affect the performance parameters, to produce a pure product with a high concentration.
Abstract
Research on electrocatalytic CO2 reduction reaction (CO2RR) has been growing rapidly owing to the urgent requirement of sustainable renewable energy. However, several obstacles hinder the application of liquid salt electrolytes in CO2RR, such as high costs, low concentrations of the product, and low purity due to the separation process of the product. Solid-state electrolytes (SSEs) have been introduced as viable alternatives to liquid electrolytes and their salts to address this challenge. Here, we summarize the recently demonstrated studies and opportunities related to catholyte-free CO2RR using SSEs. The recent studies are classified based on the product, including the CO2RR electrolyzer performance. Different SSEs are briefly discussed to highlight the new opportunities in CO2RR application. We also describe the basic operation parameter of the catholyte-free CO2RR using SSE, which has been studied before as the key variable of the reactor. This review provides insights on minimizing the use of salt electrolytes for CO2RR and reveal opportunities for using this technique to improve the efficiency of CO2RR on a large scale. The exploration of utilizing solid-state electrolytes (SSE) on a scale-up production has been pursued to showcase their viability in integrating them into commercial CO2RR technology.
Rh(II)‐Catalyzed Denitrogenative Reaction of N‐Sulfonyl‐1,2,3‐triazoles with Quinolones and Isoquinolones
An operationally facile O−H insertion followed by intramolecular rearrangement was illustrated with Rh-azavinyl carbenes to access biologically relevant 2-aminoquinolines and 1-aminoisoquinolines.
Abstract
Herein, we developed an efficient approach to access biologically relevant 2-aminoquinolines and 1-aminoisoquinolines from readily available N-sulfonyl-1,2,3-triazoles and 2-quinolones or 1-isoquinolones. This transformation involves the selective O−H insertion of these derivatives onto the in situ generated Rh-azavinyl carbenes (Rh-AVC) followed by rearrangement. The reaction proceeds smoothly under operationally simple conditions and the protocol was found to be scalable.
Electrochemical Properties of BaTaO2N Photocatalyst with Visible‐Light‐Driven Water Splitting Capability
Specific nitridation conditions produced distinct types of BaTaO2N (BTON) particles, one type with overall water splitting activity (Active-BTON) and the other without this activity (Inactive-BTON). Electrochemical and photoelectrochemical properties of the Active- and Inactive-BTON were investigated using the particulate photoelectrodes. Enhanced photocurrent generation by Active-BTON is due to the better semiconducting properties, such as lower carrier concentration related to defects and impurities within BTON particles.
Abstract
A BaTaO2N (BTON) particulate photocatalyst enables solar water splitting in response to visible light irradiation at wavelengths of up to 640 nm. The specific nitridation conditions produced distinct types of BTON particles with the capability of one-step overall water splitting (Active-BTON) and without the overall water splitting activity (Inactive-BTON). Unveiling the intrinsic differences between the active- and inactive-BTON particles is crucial for obtaining more in-depth information about the water splitting activity. Herein, we investigated the electrochemical (EC) and photoelectrochemical (PEC) properties of these BTON photocatalysts using the particulate-based photoelectrodes for water splitting. EC measurements, including Mott–Schottky analysis, revealed that the flat band potential of Active-BTON is located at a potential that is more positive than that of Inactive-BTON, whereas the carrier concentration of Active-BTON is one-tenth lower than that of Inactive-BTON. Irrespective of the pH value of the 1.0 M potassium phosphate aqueous solution, the Active-BTON-based photoelectrodes showed a higher photocurrent than that of Inactive-BTON under simulated AM 1.5G solar illumination. The PEC performance of the BTON was found to be limited by the electrocatalytic activity of the CoO x co-catalyst, specifically the electrolyte pH.
Ir‐Catalyzed B(3)‐Amination of o‐Carboranes with Amines via Acceptorless Dehydrogenative BH/NH Cross‐Coupling
By employing an acceptorless BH/NH dehydrocoupling strategy, regioselective B(3)-amination of o-carboranes with amines has been achieved via iridium catalysis, offering an array of B(3)-aminated-o-carboranes in one-pot process.
Abstract
An efficient and convenient strategy for Ir-catalyzed selective B(3)-amination of o-carboranes with amines via acceptorless BH/NH dehydrocoupling was developed, affording a series of B(3)-aminated-o-carboranes in moderate to high isolated yields with H2 gas as a sole by-product. Such an oxidant-free system endues the protocol sustainability, atom-economy and environmental friendliness. A reaction mechanism via an Ir(I)-Ir(III)-Ir(I) catalytic cycle involving oxidative addition, dehydrogenation and reductive elimination was proposed.
Synthesis of 2,3‐Diaminoindoles via a Copper‐Iodine Co‐catalytic Strategy
A one-pot synthesis of vicinal diamines using indoles, azoles and phenothiazines in a tandem multi-component reaction is developed.
Comprehensive Summary
A one-pot synthesis of vicinal diamines using indoles, azoles and phenothiazines in a tandem multi-component reaction is developed. The utilization of a copper-iodine co-catalytic system enables the generation of a diverse range of vicinal diaminoindoles with good selectivity and moderate to good yields. An attractive aspect of this method is that it can be conducted under mild and environmentally friendly conditions, showcasing its potential as an alternative approach for synthesizing vicinal diamines. Moreover, the use of a multicomponent tandem reaction highlights the power and versatility of such strategies in synthetic chemistry.
Nickel‐Catalyzed Cross‐Electrophile Coupling of Triazine Esters with Aryl Bromides
An efficient nickel-catalyzed cross-electrophile coupling of triazine esters with aryl bromides in the presence of magnesium powder and lithium chloride in THF is reported. The cross-coupling reactions proceeded smoothly at room temperature to afford a variety of structurally diverse diaryl ketones in moderate to good yields with wide functional group tolerance.
Comprehensive Summary
Cross-electrophile coupling of triazine esters with aryl bromides could be facilely accomplished by employing nickel as catalyst, magnesium as metal mediator, and lithium chloride as additive. The reactions proceeded efficiently in THF at room temperature through C—O bond activation to afford an array of structurally different diaryl ketones in moderate to good yields with wide functional group tolerance. Control experiments showed that nickel, magnesium, lithium chloride, and THF are all indispensable for the good performance of the coupling reaction. Preliminary mechanistic exploration indicated that in situ formed arylmagnesium reagent by the insertion of magnesium into aryl bromide might serve as the key intermediate of the cross-coupling. The method which avoids the utilization of moisture-labile and relatively difficult-to-obtain organometallics is step-economical, cost-efficient, and operationally simple, potentially serving as an attractive alternative to documented methods.
Iron‐Catalyzed Alkenylzincation of Internal Alkynes
The first iron-catalyzed alkenylzincation of internal alkynes featuring mild conditions, simple operation, broad substrate scope, excellent functional group tolerance, and high activity has been developed, which provides an efficient access to multi-substituted conjugated olefins.
Comprehensive Summary
The alkenylzincation of internal alkynes is an effective method for the synthesis of multi-substituted conjugated dienes; however, the current catalytic systems for this reaction are limited in terms of substrate scope and selectivity control, which restricts its practical applications. Herein, we report the first iron-catalyzed alkenylzincation of internal alkynes, which features mild conditions, simple operation, broad substrate scope (including aryl/alkyl, diaryl, and dialkyl acetylenes), excellent functional group tolerance (tolerating highly active functional groups such as ester, methylthio, amide, sulfonyl, cyano, etc.), and high activity (with a turnover number of up to 11500, the highest record for carbometallation reactions). Notably, the catalytic system described in this article also realized the highly selective vinylzincation of unfunctionalized internal alkynes as well as the alkenylzincation of unsymmetrical diarylacetylenes and dialkyl acetylenes, which have not been achieved with other catalytic systems reported in the literatures. The current study provides a highly selective access to synthetically important multi-substituted conjugated dienes.