Study on synergistic leaching of potassium and phosphorus from potassium feldspar and solid waste phosphogypsum via coupling reactions

To achieve the resource utilization of solid waste phosphogypsum(PG)and tackle the problem of utilizing potassium feldspar(PF),a coupled synergistic process between PG and PF is proposed in this paper.The study investigates the features of P and F in PG,and explores the decomposition of PF using hydrofluoric acid(HF)in the sulfuric acid system for K leaching and leaching of P and F in PG.The impact factors such as sulfuric acid concentration,reaction temperature,reaction time,material ratio(PG/PF),liquid–solid ratio,PF particle size,and PF calcination temperature on the leaching of P and K is systematically investigated in this paper.The results show that under optimal conditions,the leaching rate of K and P reach more than 93%and 96%,respectively.Kinetics study using shrinking core model(SCM)indicates two significant stages with internal diffusion predominantly controlling the leaching of K.The apparent activation energies of these two stages are 11.92 kJ·mol^(-1)and 11.55 kJ·mol^(-1),respectively.

Metal-organic-framework-derived copper-based catalyst for multicomponent C-S coupling reaction

Copper-based metal-organic frameworks(Cu-MOFs)are a promising multiphase catalyst for catalyzing C-S coupling reactions by virtue of their diverse structures and functions.However,the unpleasant odor and instability of the organosulfur,as well as the mass-transfer resistance that exists in multiphase catalysis,have often limited the catalytic application of Cu-MOFs in C-S coupling reactions.In this paper,a Cu-MOFs catalyst modified by cetyltrimethylammonium bromide(CTAB)was designed to enhance mass transfer by increasing the adsorption of organic substrates using the long alkanes of CTAB.Concurrently,elemental sulfur was used to replace organosulfur to achieve a highly efficient and atom-economical multicomponent C-S coupling reaction.

Pyroelectricity effect on photoactivating palladium nanoparticles in PbTiO3 for Suzuki coupling reaction

Combining microwave radiation with photocatalytic systems is a promising method to inhibit photogenerated electron-hole recombination and enhance the photocatalytic reaction performance. In this study, we have designed Pd/Pb TiO3 catalysts that can use both microwave fields and photocatalysis. Benefiting from the synergistic effect of microwave field and UV light, the Pb TiO3 crystals convert thermal energy into electrical energy via the pyroelectricity effect, generating positive and negative charges(q+ and q-), while Pd nanoparticles significantly improve the quantum efficiency of the photocatalytic process. The composite catalyst significantly enhances the reaction rate and selectivity of the model Suzuki coupling reaction performed with bromobenzene. Microwave fields can directly act on chemical systems, promoting or changing various chemical reactions in unique ways.

Rapid synthesis of Pd single‐atom/cluster as highly active catalysts for Suzuki coupling reactions

Palladium(Pd)‐based catalysts are essential to drive high‐performance Suzuki coupling reactions,which are powerful tools for the synthesis of functional organic compounds.Herein,we developed a solution‐rapid‐annealing process to stabilize nitrogen‐mesoporous carbon supported Pd single‐atom/cluster(Pd/NMC)material,which provided a catalyst with superior performance for Suzuki coupling reactions.In comparison with commercial palladium/carbon(Pd/C)catalysts,the Pd/NMC catalyst exhibited significantly boosted activity(100%selectivity and 95%yield)and excellent stability(almost no decay in activity after 10 reuse cycles)for the Suzuki coupling reactions of chlorobenzenes,together with superior yield and excellent selectivity in the fields of the board scope of the reactants.Moreover,our newly developed rapid annealing process of precursor solutions is applied as a generalized method to stabilize metal clusters(e.g.Pd,Pt,Ru),opening new possibilities in the construction of efficient highly dispersed metal atom and sub‐nanometer cluster catalysts with high performance.

Cu(I)/Diamine-catalyzed Aryl-alkyne Coupling Reactions

CuI/ethylene diamine/K2CO3/dioxane is shown to be a useful system for the cross coupling reactions of various aryl iodides and bromides with aryl and alkyl alkynes. Compared to the conventional Sonogashira reactions, the new procedure is free of palladium and phosphines.

The Application of Suzuki Coupling Reaction on the Preparation of Carbosilane Dendrimers with 4-(Naphthalen-1-yl)phenyl Core

Carbosilane dendrimers with p-bromophenyl core were synthesized by alternating Grignard and hydrosilylation reaction. And the α-naphthalenyl was connected to the core by the Suzuki coupling reaction. A new carbosilane dendrimer with big π-conjugated structure [4-（naphthalen-l-yl）phenyl core] was given. It shows Suzuki coupling reaction is an effective and powerful core-functionalization method and the satisfactory result can be obtained through prolonging the reaction time with the increase of the generation of dendrimer.

Sm/TiCl_4 (cat.) system-mediated intermolecular and intramolecular reductive coupling reactions of ketones with esters

Sm/TiCl4 system could well integrate the high reactivity of samarium（Ⅱ） and high deoxygenation capacity of low valent titanium within one system. In this paper, the intermolecular and intramolecular reductive coupling reactions of ketones with esters mediated by metallic samarium （Sm） and a catalytic amount of titanium tetrachloride （TiCl4） were successfully developed. A series of substituted ketones and cyclic β-keto-esters were prepared in moderate to good yields under reflux and neutral conditions.

An Efficient System TiCl_4-Al for the Homocoupling Reaction of Aromatic Aldehydes

The reduction of TiCl4(THF)2 with Al in CH2Cl2 gave a green solution of [Ti2(μ-Cl)2Cl4· (THF)4] (1) which was found to promote the reductive homocoupling of aromatic aldehydes to yield symmetrical 1, 2-diols with high diasterepselectivities.

Well-dispersed Palladium Nanoparticles Catalysts Prepared by Wood Nanomaterials for Suzuki Coupling Reaction

Herein, well-dispersed Palladium(Pd) nanoparticles(NPs) with good catalytic activities were prepared using a wood nanomaterial(WNM) as a reductant and a supporting agent. Various factors that influenced the NP morphologies, including reaction time, temperature, and precursor concentration were studied. The as-prepared Pd NPs/WNM showed good catalytic performance for Suzuki coupling reactions.

An Efficient Palladium-catalyzed Coupling Reaction for the Preparation of Biaryls and Polyaryls

In the case of Pd(PPh3)4 as catalyst and toluene as reaction solvent, the desired biaryls and polyaryls were synthesized in excellent yield and on a large scale.

A facile approach to asymmetrical biaryls via coupling reaction of aryl halides with sodium tetraphenylborate catalyzed by MCM-41-supported sulfur palladium(0) complex

Various functionalized asymmetrical biaryls can be synthesized in high to excellent yields via coupling reaction of aryl iodides or bromides with NaBPh4 catalyzed by MCM-41-supported sulfur palladium（0） complex. This palladium complex can be easily recovered and reused many times without loss of activity.

Oxygen-vacancy-anchoring Ni_(x)O_(y) loading towards efficient hydrogen evolution via photo-thermal coupling reaction

Oxygen vacancy(Vo)is a significant component in defect engineering.The present work reports the anchoring effects of initial Vo for further loading modifications and the reducing capacity of photoinduced Vo for pure water splitting.Herein,we propose Ni-loaded Cu-doped TiO_(2)(NCT)materials by successive doping and loading.The continuously added Ni ions should accumulate around the Vos and gradually grow into complete nickel oxide crystals,achieving a higher average valence state of the Ni species.NiO crystals can be detected on a 0.5%NCT sample,while the structure of Ni_(2)O_(3) has been confirmed with a higher nickel mass ratio.Moreover,the introduction of nickel oxide effectively improves the photochemical and electrochemical performance by the interface charge separation,finally reaching an H2 yield of 30.6 pmol/g-cat on 0.5%NCT for Vo-based photo-thermal coupling reaction,which consists of Vo generation in photo and Vo consumption in thermal environment.In situ infrared spectroscopy further indicated that the presence of high valence state nickel oxide hindered the H2 formation but effectively promoted the conventional oxidizing reaction,with an H2 yield of 20.6 mmol/g-cat in a methanol-water reaction on the 2.0%NCT material.In summary,Vo controls the morphological structure of Ni loading and produces diverse effects for reactions with dissimilar mechanisms,which provides a novel way to design modifications for promoting various chemical reactions.

Studies on the Preparation of Bioactive Oligomerstilbene by Oxidative Coupling Reaction(Ⅰ)-Preparation of Shegansu B using Silver Oxide as Oxidant

篢he oxidative coupling reaction of isorhapontigenin using sliver oxide as oxidant afforded a major product, named shegansu B（2）， which was isolated from the roots of Belamcanda chinensis (L．)DC. Both the natural and synthetic Shegansu B have the same potent antagonism activities of leukotriene B4，D4 receptor．

Pinacol Coupling Reactions Catalyzed by Active Zinc

Pinacol coupling reactions catalyzed by active zinc revealed high activity and extensive suitability. The efficiency of the reaction was improved apparently owing to decreasing reductive potential of zinc. In addition, the results indicated that the zinc activity has a direct relation to the coupling reactivity compared to untreated zinc or other general active zinc.

Nickel Chloride Promoted Glaser Coupling Reaction in Hot Water

A Glaser coupling reaction of terminal alkynes in the presence of nickel chloride without any organics and bases in hot water has been developed, which produces the corresponding homo-coupling products in good yields.

Role of Reduced Defects for Coupling Reactions of Acetaldehyde on Anatase TiO2（001）-（1×4） Surface

The chemistry of acetaldehyde (CH3CHO) adsorbed on the anatase TiO2(001)-(1×4) surface has been investigated by temperature-programmed desorption (TPD) method. Our experimental results provide the direct evidence that the perfect lattice sites on the anatase TiO2(001)-(1×4) surface are quite inert for the reaction of CH3CHO, but the reduced defect sites on the surface are active for the thermally driven reductive carbon-carbon coupling reactions of CH3CHO to produce 2-butanone and butene. We propose that the coupling reactions of CH3CHO on the anatase TiO2(001)-(1×4) surface should undergo through the adsorption of paired CH3CHO molecules at the reduced defect sites, since the existing reduced Ti pairs provide the suitable adsorption sites.

Photo-induced Coupling Reaction of 1,1-Diphenyl-2,2-dicyanoethylene with 10-Methyl-9,10-dihydroacridine

Diphenyl-2, 2-dicyanoethylene reacts with 10-methyl-9, 10-dihydroacridine in deaerated acetonitrile under irradiation with l>320 nm to give the coupling product 1, 1-diphenyl-1-(10-methyl-9-acridinyl)-2, 2-dicyanoethane, which has been characterized by X-ray crystallographic, MS and NMR analyses.

THE INTRAMOLECULAR COUPLING REACTION OF 2-NITROETHYL-1, 3-DICARBONYL COMPOUND INDUCED BY LOW-VALENT TITANIUM

Low-valent titanium reagent prepared in situ from TiCl_4 and Zn was employed to induce the intramolecular coupling of nitro group with carbonyl group to give substituted hydroxyl pyrrolines, pyrroles and lactam in good yields.

Coupling reaction mechanism of 2-(2-bromo-4-fluorophenyl)-1-cyclohexen-1-yl trifluoromethane-sulfonate

The detailed mechanism of CuI-catalyzed C-O intramolecular coupling reaction of 2-（2-bromo-4-fluoro-phenyl）-l- cyclohexen-1-yl trifluoromethane-sulfonate was studied with the density functional theory （DFT）. The geometries of the reactants, transition states, intermediates and products were optimized at the B3LYP/6-31 ＋G＊ level. Meanwhile, the single point energy of species involved in gas and solvent at B3LYP/6-31 I＋G＊ level was individually investigated. Polarizable continuum models （PCM） were applied to the dioxane and water solutions at the same level, respectively. Results show that the rate-limiting step, M3→TS3, does not change in different solutions. However, the activation energy in a dioxane solution is lower than that in water, which explains the previous experimental results. Compared with the non-catalyzed reaction process, the activation energy of the rate- limiting step is reduced by 56.53 kJ mo1-1 in gas and 44.84 kJ mol-l in solvent, demonstrating a high catalytic efficiency of CuI.

Low-valent Titanium Induced Reductive Coupling Reaction of Aryl Sulfonyl Chlorides with α,β-Unsaturated Esters

The reductive coupling reactions of aryl sulfonyl chloride induced by (TiCl4-Zn) reagent affords diaryl disulfide. However, reaction of aryl sulfonyl chloride with α,β-unsaturated ester under the same condition affords β-arylsulfo ester.