Showing papers on "Reagent published in 2019"
TL;DR: It is found that a combination of triphenylphosphine and sodium iodide under 456-nanometer irradiation by blue light–emitting diodes can catalyze the alkylation of silyl enol ethers by decarboxylative coupling with redox-active esters in the absence of transition metals.
Abstract: Most photoredox catalysts in current use are precious metal complexes or synthetically elaborate organic dyes, the cost of which can impede their application for large-scale industrial processes. We found that a combination of triphenylphosphine and sodium iodide under 456-nanometer irradiation by blue light–emitting diodes can catalyze the alkylation of silyl enol ethers by decarboxylative coupling with redox-active esters in the absence of transition metals. Deaminative alkylation using Katritzky’s N-alkylpyridinium salts and trifluoromethylation using Togni’s reagent are also demonstrated. Moreover, the phosphine/iodide-based photoredox system catalyzes Minisci-type alkylation of N-heterocycles and can operate in tandem with chiral phosphoric acids to achieve high enantioselectivity in this reaction.
435 citations
TL;DR: In vitro and in vivo results illustrate the designed benign and self-activated cascade reagent possesses a robust antibacterial effect with negligible biotoxicity.
Abstract: Metal–organic frameworks (MOFs)-based peroxidase mimics have been seldom applied in the biomedical field, especially in vivo. One of the main reasons is their optimum reactions occur in strong acidic environments with a pH of 3–4, severely limiting their applications in living systems where neutral pH is usually required. Other types of peroxidase mimics also suffer such a fatal defect. Additionally, the direct introduction of the relatively high concentrated and toxic reaction reagent H2O2 would induce undesired damage to normal tissues. Herein, a MOF-based hybrid nanocatalyst as a benign and self-activated cascade reagent has been constructed. Owing to better catalytic performance compared with three-dimensional bulk MOF, an ultrathin two-dimensional (2D) MOF (2D Cu-TCPP(Fe)) nanosheet is chosen as a model of peroxidase mimic to physically adsorb glucose oxidase (GOx) for fabricating such a hybrid nanocatalyst. Nontoxic glucose can be continuously converted into abundant gluconic acid and H2O2 by GOx, a...
304 citations
TL;DR: A single-atom catalyst of isolated single atom cobalt incorporated into Bi3O4Br atomic layers is successfully prepared, which can perform light-driven CO2 reduction with a selective CO formation rate and stabilize the COOH* intermediates.
Abstract: The design of efficient and stable photocatalysts for robust CO2 reduction without sacrifice reagent or extra photosensitizer is still challenging. Herein, a single-atom catalyst of isolated single atom cobalt incorporated into Bi3O4Br atomic layers is successfully prepared. The cobalt single atoms in the Bi3O4Br favors the charge transition, carrier separation, CO2 adsorption and activation. It can lower the CO2 activation energy barrier through stabilizing the COOH* intermediates and tune the rate-limiting step from the formation of adsorbed intermediate COOH* to be CO* desorption. Taking advantage of cobalt single atoms and two-dimensional ultrathin Bi3O4Br atomic layers, the optimized catalyst can perform light-driven CO2 reduction with a selective CO formation rate of 107.1 µmol g−1 h−1, roughly 4 and 32 times higher than that of atomic layer Bi3O4Br and bulk Bi3O4Br, respectively. While the conversion of CO2 to high-value products provides a promising means to remove and utilize atmospheric carbon, few materials can do so without wasteful, sacrificial reagents. Here, authors prepare single-atom Co on Bi3O4Br nanosheets as CO2 reduction catalysts using water and light.
296 citations
TL;DR: The molybdenum-catalysed reduction of nitrogen to ammonia is achieved under ambient conditions, using samarium(ii) diiodide in combination with either simple alcohols or water as the proton source.
Abstract: The production of ammonia from nitrogen gas is one of the most important industrial processes, owing to the use of ammonia as a raw material for nitrogen fertilizers. Currently, the main method of ammonia production is the Haber–Bosch process, which operates under very high temperatures and pressures and is therefore very energy-intensive1. The transition-metal-catalysed reduction of nitrogen gas2–6 is an alternative method for the formation of ammonia. In these reaction systems, metallocenes or potassium graphite are typically used as the reducing reagent, and conjugate acids of pyridines or related compounds are used as a proton source. To develop a next-generation nitrogen-fixation system, these reagents should be low cost, readily available and environmentally friendly. Here we show that the combination of samarium(ii) diiodide (SmI2) with alcohols or water enables the fixation of nitrogen to be catalysed by molybdenum complexes under ambient conditions. Up to 4,350 equivalents of ammonia can be produced (based on the molybdenum catalyst), with a turnover frequency of around 117 per minute. The amount of ammonia produced and its rate of formation are one and two orders of magnitude larger, respectively, than those achieved in artificial reaction systems reported so far, and the formation rate approaches that observed with nitrogenase enzymes. The high reactivity is achieved by a proton-coupled electron-transfer process that is enabled by weakening of the O–H bonds of alcohols and water coordinated to SmI2. Although the current reaction is not suitable for use on an industrial scale, this work demonstrates an opportunity for further research into catalytic nitrogen fixation. The molybdenum-catalysed reduction of nitrogen to ammonia is achieved under ambient conditions, using samarium(ii) diiodide in combination with either simple alcohols or water as the proton source.
275 citations
TL;DR: D density functional theory calculation was in good agreement with the experimental results, which proved that the Fe2+/OA/CaO2 could improve the circulation between Fe2- and Fe3+, promoting the oxygen reactive species generation and pollutant removal.
164 citations
TL;DR: A general, practical, and scalable means of preparing deuterated aldehydes from aromatic and aliphatic carboxylic acids with D2 O as an inexpensive deuterium source is reported.
Abstract: We report a general, practical, and scalable means of preparing deuterated aldehydes from aromatic and aliphatic carboxylic acids with D2 O as an inexpensive deuterium source. The use of Ph3 P as an O-atom transfer reagent can facilitate the deoxygenation of aromatic acids, while Ph2 POEt is a better O-atom transfer reagent for aliphatic acids. The highly precise deoxygenation of complex carboxylic acids makes this protocol promising for late-stage deoxygenative deuteration of natural product derivatives and pharmaceutical compounds.
140 citations
TL;DR: This review presents the impressive breakthroughs achieved mainly in the past decade in the development of new catalytic reactions for the formation of C-C, C-N, and C-S bonds using α-keto acids.
Abstract: A significant number of important acyl-transfer reactions, such as direct acylation, ortho acylation, heteroatom acylation, and a diversity of cyclization reactions using the title compound as a key starting material, have been described in recent years. Just like a sleeping beauty, α-oxocarboxylic acids were awakened from a 17-year sleep to become important reagents in classical and new acylation reactions. The greener characteristic of the coproduct formed in reactions using α-keto acid (only CO2), together with its versatility as a building block in catalytic organic synthesis, accredit it as a candidate to green acylating agent, an alternative to acyl chloride, and other acyl-transfer reagents. This review presents the impressive breakthroughs achieved mainly in the past decade in the development of new catalytic reactions for the formation of C–C, C–N, and C–S bonds using α-keto acids.
124 citations
TL;DR: An environmentally benign electrochemical method is reported which enables the oxidative coupling between thiols and amines, two readily available and inexpensive commodity chemicals.
Abstract: Sulfonamides are key motifs in pharmaceuticals and agrochemicals, spurring the continuous development of novel and efficient synthetic methods to access these functional groups. Herein, we report an environmentally benign electrochemical method which enables the oxidative coupling between thiols and amines, two readily available and inexpensive commodity chemicals. The transformation is completely driven by electricity, does not require any sacrificial reagent or additional catalysts and can be carried out in only 5 min. Hydrogen is formed as a benign byproduct at the counter electrode. Owing to the mild reaction conditions, the reaction displays a broad substrate scope and functional group compatibility.
116 citations
TL;DR: Electrochemical fluoromethylation triggered lactonizations of alkenes were achieved under chemical oxidant-, catalyst- and additional supporting electrolyte-free conditions.
Abstract: An electrochemical difluoromethylation triggered lactonization of alkenes was developed for the first time. This protocol employs readily prepared CF2HSO2Na as the difluoromethylating reagent, affording unprecedented CF2H-containing lactones in moderate yields. Moreover, with CF3SO2Na as the trifluoromethylating reagent, a wide array of CF3-containing lactones were obtained under additional supporting electrolyte- and catalyst-free conditions.
98 citations
TL;DR: A new trifunctional cross-linking reagent, termed PhoX, which is decorated with a stable phosphonic acid handle, which makes the cross-linked peptides amenable to the well-established immobilized metal affinity chromatography (IMAC) enrichment.
Abstract: Chemical cross-linking mass spectrometry is rapidly emerging as a prominent technique to study protein structures. Structural information is obtained by covalently connecting peptides in close proximity by small reagents and identifying the resulting peptide pairs by mass spectrometry. However, substoichiometric reaction efficiencies render routine detection of cross-linked peptides problematic. Here, we present a new trifunctional cross-linking reagent, termed PhoX, which is decorated with a stable phosphonic acid handle. This makes the cross-linked peptides amenable to the well-established immobilized metal affinity chromatography (IMAC) enrichment. The handle allows for 300× enrichment efficiency and 97% specificity. We exemplify the approach on various model proteins and protein complexes, e.g., resulting in a structural model of the LRP1/RAP complex. Almost completely removing linear peptides allows PhoX, although noncleavable, to be applied to complex lysates. Focusing the database search to the 1400 most abundant proteins, we were able to identify 1156 cross-links in a single 3 h measurement.
91 citations
TL;DR: Difluoromethylation of alkenes, isonitriles and aryl bromides promoted by photoredox catalysis is described together with a non-catalytic photoinduced system.
Abstract: Recently, photoinduced radical difluoromethylation has emerged as a step-economical synthetic method of CHF2-containing compounds. In this article, difluoromethylation of alkenes, isonitriles and aryl bromides promoted by photoredox catalysis is described together with a non-catalytic photoinduced system. Representative reactions will be discussed for each highlighted difluoromethylating reagent. In addition, related monofluoromethylation with their corresponding monofluoromethylating reagents is also discussed.
TL;DR: In this article, a self-sacrificing ionic liquid was used to construct carbonized polymer dots (CPDs)/PbBiO2Br heterojunction photocatalysts.
Abstract: The semiconductor-mediated solar-driven the conversion of CO2 into the value-added fuels is considered as an ideal strategy for sustainable development. However, conventional semiconductors usually suffer from unsatisfactory photocatalytic performance due to the low efficiency of photo-induced carrier separation and sluggish interface adsorption/desorption equilibrium of reactants/products. Herein, novel carbonized polymer dots (CPDs)/PbBiO2Br heterojunction photocatalysts have been prepared via self-sacrificing ionic liquid, which not only act as the template and reactant to induce the formation of PbBiO2Br material, but also act as the glue to in situ anchor CPDs on the surface of PbBiO2Br material to form composites through hydrogen bond. Without sacrificial reagent, the obtained CPDs/PbBiO2Br materials synthesized with ionic liquid exhibit a high selectivity, stability and enhanced CO evolution rate in water. The introduction of CPDs not only effectively promote the light absorbance and separation efficiency of photogenerated electrons, but also adjust the adsorption/desorption equilibria of reactants/products on the CPDs/PbBiO2Br catalyst surface, such as boosting CO2 adsorption capacity, proton affinity and CO liberation. The reaction mechanism has been proposed with in situ FT-IR spectrometry. The strategy for the preparation of high-performance CO2 photoreduction catalysts can be extended to design and tune other advanced photocatalytic materials.
TL;DR: It is demonstrated that hydrogen bonding phase-transfer catalysis with KF provides access to valuable β-fluoroamines in high yields and enantioselectivities.
Abstract: Potassium fluoride (KF) is an ideal reagent for fluorination because it is safe, easy to handle and low-cost. However, poor solubility in organic solvents coupled with limited strategies to control its reactivity has discouraged its use for asymmetric C–F bond formation. Here, we demonstrate that hydrogen bonding phase-transfer catalysis with KF provides access to valuable β-fluoroamines in high yields and enantioselectivities. This methodology employs a chiral N-ethyl bis-urea catalyst that brings solid KF into solution as a tricoordinated urea-fluoride complex. This operationally simple reaction affords enantioenriched fluoro-diphenidine (up to 50 g scale) using 0.5 mol % of recoverable bis-urea catalyst.
TL;DR: A metal-free synthesis of α-ketothioester reagents via the combination of an α-hydroxyl ketone, elemental sulfur and a benzyl halide is reported, which are used for N- or C-dicarbonyl bond formation.
Abstract: The 1,2-dicarbonyl motif is vital to biomolecules, especially natural products and pharmaceuticals. Conventionally, 1,2-dicarbonyl compounds are prepared via an α-keto acyl chloride. Based on the methods used in nature, a transition-metal-free approach for the synthesis of an α-ketothioester reagent via the combination of an α-hydroxyl ketone, elemental sulfur and a benzyl halide is reported. Mechanistic studies demonstrate that the trisulfur radical anion and the α-carbon radical of the α-hydroxy ketone are involved in this transformation. The dicarbonylation of a broad range of amines and amino acids, and importantly, cross couplings with aryl borates to construct dicarbonyl-carbon bonds are realized under mild conditions by employing this stable and convenient α-ketothioester as a 1,2-dicarbonyl reagent. The dicarbonyl-containing drug indibulin and the natural product polyandrocarpamide C, which possess multiple heteroatoms and active hydrogen functional groups, can be efficiently prepared using the designed 1,2-dicarbonyl reagent.
TL;DR: Cu xP is proposed as a solid reagent that can activate dioxygen to generate reactive oxygen species in ambient aqueous condition, which is more facile to handle and store than liquid/gas reagents (e.g., H2O2, Cl2, O3).
Abstract: Copper phosphide (Cu xP) was synthesized and tested for its reactivity for generating H2O2 through spontaneous reduction of dioxygen under ambient aqueous condition. The in situ generated H2O2 was subsequently decomposed to generate OH radicals, which enabled the degradation of organic compounds in water. The oxygen reduction reaction proceeded along with the concurrent oxidation of phosphide to phosphate, then copper ions and phosphate ions were dissolved out during the reaction. The reactivity of Cu xP was gradually reduced during 10 cycles with consuming 8.7 mg of Cu xP for the successive removal of 17 μmol 4-chlorophenol. CoP which was compared as a control sample under the same experimental condition also produced H2O2 through activating dioxygen but did not degrade organic compounds at all. The electrochemical analysis for the electron transfers on Cu xP and CoP showed that the number of electrons transferred to O2 is 3 and 2, respectively, which explains why OH radical is generated on Cu xP, not on CoP. The Cu+ species generated on the Cu xP surface can participate in Fenton-like reaction with in situ generated H2O2. Cu xP is proposed as a solid reagent that can activate dioxygen to generate reactive oxygen species in ambient aqueous condition, which is more facile to handle and store than liquid/gas reagents (e.g., H2O2, Cl2, O3).
TL;DR: This review presents the recent developments of I2 -catalyzed C-C, C-N,C-O, and C-S/C-Se bond-forming reactions for the synthesis of various important organic molecules by cross-dehydrogenative coupling.
Abstract: The development of ecofriendly methods for carbon-carbon (C-C) and carbon-heteroatom (C-Het) bond formation is of great significance in modern-day research. Metal-free cross-dehydrogenative coupling (CDC) has emerged as an important tool for organic and medicinal chemists as a means to form C-C and C-Het bonds, as it is atom economical and more efficient and greener than transition-metal catalyzed CDC reactions. Molecular iodine (I2 ) is recognized as an inexpensive, environmentally benign, and easy-to-handle catalyst or reagent to pursue CDCs under mild reaction conditions, with good regioselectivities and broad substrate compatibility. This review presents the recent developments of I2 -catalyzed C-C, C-N, C-O, and C-S/C-Se bond-forming reactions for the synthesis of various important organic molecules by cross-dehydrogenative coupling.
30 May 2019
TL;DR: In this paper, light has emerged as a promising new reagent in chemical reactions, especially in enhancing the performance of metal nanoparticle catalysts, and certain metal nanoparticles support localized surface pl...
Abstract: Light has emerged as a promising new reagent in chemical reactions, especially in enhancing the performance of metal nanoparticle catalysts. Certain metal nanoparticles support localized surface pl...
TL;DR: A resource saving protocol for the synthesis of 5-fluoromethyl-2-oxazolines by using electrochemistry offering a sustainable alternative over conventional reagent-based pathways is realized.
TL;DR: A ketone synthesis that couples two different carboxylic acid esters, N-hydroxyphthalimide esters and S-2-pyridyl thioesters, to form aryl-alkyl and dialkyl ketones in high yields is demonstrated.
Abstract: Synthesis of the C-C bonds of ketones relies upon one high-availability reagent (carboxylic acids) and one low-availability reagent (organometallic reagents or alkyl iodides) We demonstrate here a ketone synthesis that couples two different carboxylic acid esters, N-hydroxyphthalimide esters and S-2-pyridyl thioesters, to form aryl alkyl and dialkyl ketones in high yields The keys to this approach are the use of a nickel catalyst with an electron-poor bipyridine or terpyridine ligand, a THF/DMA mixed solvent system, and ZnCl2 to enhance the reactivity of the NHP ester The resulting reaction can be used to form ketones that have previously been difficult to access, such as hindered tertiary/tertiary ketones with strained rings and ketones with α-heteroatoms The conditions can be employed in the coupling of complex fragments, including a 20-mer peptide fragment analog of Exendin(9-39) on solid support
TL;DR: The new exchange reagent sBu2 Mg⋅2 LiOR (R=2-ethylhexyl) further increases the rate of the halogen-magnesium exchange allowing one to perform a chlorine-mag magnesium exchange for aromatic chlorides bearing an ortho-methoxy substituent in toluene.
Abstract: This Minireview describes the scope of the halogen-magnesium exchange It shows that the use of the turbo-Grignard reagent (iPrMgCl⋅LiCl) greatly enhances the rate of the Br- and I-Mg exchange Furthermore, this magnesium reagent allows the performance of a fast sulfoxide-magnesium exchange Also, the use of sBuMgOR⋅LiOR (R=2-ethylhexyl) enables a Br-Mg exchange in toluene leading to various Grignard reagents in toluene Additionally, the new exchange reagent sBu2 Mg⋅2 LiOR (R=2-ethylhexyl) further increases the rate of the halogen-magnesium exchange allowing one to perform a chlorine-magnesium exchange for aromatic chlorides bearing an ortho-methoxy substituent in toluene
TL;DR: In this paper, a unique visible-light-induced method for the organochalcogenation of the sp2 C-H bonds of indoles and aniline has been presented using diaryl dichalcogens (S, Se, and Te) and oxygen as an oxidant avoiding a photocatalyst, base, catalyst, and reagent in acetone at room temperature.
TL;DR: In this paper, a novel removal process of elemental mercury (Hg0) from gas using Cu2+-enhanced Fenton system in a bubble column reactor was developed, where experiments were conducted to explore the influence of several factors (concentrations of H2O2, Fe2+ and Cu2+, reagent pH, reaction temperature, concentrations of Hg0, NO and SO2) on removal.
TL;DR: An efficient and reliable electrochemical generator of hypervalent iodine reagents has been developed and the combination of electrochemical and flow-chemistry advantages largely improves the ecological footprint of the overall process compared to conventional approaches.
Abstract: An efficient and reliable electrochemical generator of hypervalent iodine reagents has been developed. In the anodic oxidation of iodoarenes under flow conditions to hypervalent iodine reagents the use of electricity replaces hazardous and costly chemical oxidants. Unstable hypervalent iodine reagents can be prepared easily and coupled with different substrates to achieve oxidative transformations in high yields. The unstable electrochemically generated reagents can also easily be transformed into classic bench stable hypervalent iodine reagents via ligand exchange. The combination of electrochemical and flow chemistry advantages largely improves the ecological footprint of the overall process compared to conventional approaches.
TL;DR: In this paper, Oxalate has been identified as a sustainable reagent for metal recovery and separation processes from a mixture of valuable metals are vital to the metallurgy and recycling industries.
Abstract: Energy-efficient metal recovery and separation processes from a mixture of valuable metals are vital to the metallurgy and recycling industries. Oxalate has been identified as a sustainable reagent...
TL;DR: The coupling of anodic oxidation reactions with the production of hydrogen gas for use as a reagent in remote, Pd-catalyzed hydrogenation and hydrogenolysis reactions is examined.
Abstract: While the majority of reported paired electrochemical reactions involve carefully matched cathodic and anodic reactions, the precise matching of half reactions in an electrolysis cell is not generally necessary. During a constant current electrolysis almost any oxidation and reduction reaction can be paired, and in the presented work we capitalize on this observation by examining the coupling of anodic oxidation reactions with the production of hydrogen gas for use as a reagent in remote, Pd-catalyzed hydrogenation and hydrogenolysis reactions. To this end, an alcohol oxidation, an oxidative condensation, intramolecular anodic olefin coupling reactions, an amide oxidation, and a mediated oxidation were all shown to be compatible with the generation and use of hydrogen gas at the cathode. This pairing of an electrolysis reaction with the production of a chemical reagent or substrate has the potential to greatly expand the use of more energy efficient paired electrochemical reactions.
TL;DR: In this paper, the authors developed a method for facile, scalable, and efficient synthesis of Zr(IV)-based MOFs with high-performance hydrolysis by imparting enriched active sites to the catalysts, as well as to examine its feasibility using the combination of UiO-66 with the organic bases including 4-ethylmorpholine (4-EM) and linear/ branch-type polyethyleneimine (PEI).
Abstract: A catalytic hydrolysis rate of nerve agents can be a significant issue because of their severe toxicity which can lead to severe damage to human life. Regarding the issue, much effort has been given rise to the development of the various design of Zr(IV)-based MOF catalysts so that high catalytic performance. However, we still have feasibility issues. To this end, we turned our attention to develop the method for facile, scalable, and efficient synthesis of Zr(IV)-based MOFs (UiO-66) with high-performance hydrolysis by imparting enriched active sites to the catalysts, as well as to examine its feasibility using the combination of UiO-66 with the organic bases including 4-ethylmorpholine (4-EM) and linear-/ branch-type polyethyleneimine (PEI). The modulated UiO-66 catalysts were synthesized by varying the total reaction concentration. The synthesized three different UiO-66 catalysts were characterized and then applied for hydrolysis rates of the methylparaoxon (MPO) nerve agent simulant. From these investigations, we found that the highest concentration led to the smallest particle size (ca. 100 nm) and highest defect density (1.8 per cluster), resulting in 3-times higher catalytic activity (0.548 s−1) in turnover frequency (TOF) relative to that of the uncontrolled UiO-66 (ca. 580 nm and 1.6 per cluster) (0.188 s−1) which is prepared by the reported procedure. In addition, the reaction process significantly influenced on the catalytic activity of UiO-66, in which the simple change of the reagent mixing method led to a ca. 182-times difference in the catalytic activity for MPO hydrolysis despite using the same reagents including catalysts and bases. Importantly, we found that the reaction process-dependent catalytic activity of UiO-66 can be significantly associated with the chelation of Zr(IV) Lewis acidic active sites by base materials of 4-EM and PEI (Lewis base). Furthermore, the solid-state catalytic system based on the polymer composite of UiO-66S/LPEI10k on the cotton fabric was also examined for MPO hydrolysis at various relative humidity and temperature conditions to create actual atmosphere conditions, which gave the possibility for actual military applications such as protective suits and equipment. In addition, we schematically demonstrated the loss of active sites on UiO-66 by chelation effects based on experimental and density functional theory (DFT)-derived computational simulation because it is highly correlated to the feasibility of Zr(IV)-based MOF catalysts for detoxification of nerve agents. In addition, we carefully propose a plausible reaction mechanism step on the nucleophilic attack by hydroxide group on the basis of the computational simulation.
TL;DR: An environmentally friendly method for the clean preparation of various quinolin-2-yl substituted ureas in water under mild and toxic reagent-, base-, and organic solvent-free conditions was established in this article.
Abstract: An environmentally-friendly method for the clean preparation of various quinolin-2-yl substituted ureas in water under mild and toxic reagent-, base-, and organic solvent-free conditions was established. In the large-scale synthesis, the products could be rapidly collected via simple filtration and washing with ethanol. The usage of readily available raw materials, 100% atom economy, high yield, and excellent regioselectivity enhanced the practicability of this protocol.
TL;DR: In this paper, the dominant techniques for the beneficiation of low-grade phosphate ores are introduced and the factors that affect the flotation of phosphate ore, including the properties of mineralogy, flotation reagents (depressants and collectors) and flotation medium, were systematically analyzed.
Abstract: Phosphate ore is an important raw material for manufacturing fertilizers and phosphorous chemical products. While most of the phosphate resources cannot be directly treated as feed stock due to the low grade of P2O5 and high content of impurities. In order to obtain a qualified phosphate concentrate, the beneficiation of the low-grade phosphate ore is, hence, of great necessity. Many beneficiation techniques can be employed to upgrade the P2O5 grade of phosphate ores based on their characteristics in chemical composition and texture. The flotation process is most widely applied to balance the P2O5 recovery ratio and cost. In this review, the dominant techniques for the beneficiation of phosphate ores are introduced. Moreover, the factors that affect the flotation of phosphate ore, including the properties of mineralogy, flotation reagents (depressants and collectors) and flotation medium, were systematically analyzed.
TL;DR: A Ni-catalyzed reductive coupling for the synthesis of benzonitriles from aryl (pseudo)halides and an electrophilic cyanating reagent, 2-methyl-2-phenyl malononitrile (MPMN), which suggests that NaBr plays a role in facilitating oxidative addition with substrates.
Abstract: Herein, we report a Ni-catalyzed reductive coupling for the synthesis of benzonitriles from aryl (pseudo)halides and an electrophilic cyanating reagent, 2-methyl-2-phenyl malononitrile (MPMN). MPMN is a bench-stable, carbon-bound electrophilic CN reagent that does not release cyanide under the reaction conditions. A variety of medicinally relevant benzonitriles can be made in good yields. Addition of NaBr to the reaction mixture allows for the use of more challenging aryl electrophiles such as aryl chlorides, tosylates, and triflates. Mechanistic investigations suggest that NaBr plays a role in facilitating oxidative addition with these substrates.
TL;DR: A broad range of functional groups are tolerated, and a correspondingly large collection of derivatization reactions are possible on the products, including substitution at sulfur, conjugate addition, and N‐functionalization, suggest that this method could find new applications in chemical biology.
Abstract: A series of low-molecular-weight, compact, and multifunctional cyclic alkenylsulfonyl fluorides were efficiently prepared from the corresponding alkenyl triflates. Palladium-catalyzed sulfur dioxide insertion using the surrogate reagent DABSO effects sulfinate formation, before trapping with an F electrophile delivers the sulfonyl fluorides. A broad range of functional groups are tolerated, and a correspondingly large collection of derivatization reactions are possible on the products, including substitution at sulfur, conjugate addition, and N-functionalization. Together, these attributes suggest that this method could find new applications in chemical biology.