Eco‐friendly synthesis of 3,4‐dihydroquinoxalin‐2‐amine,diazepine‐tetrazole and benzodiazepine‐2‐carboxamide derivatives with the aid of MCM‐48/H5PW10V2O40

A heterogeneous material composed of MCM‐48/H₅PW₁₀V₂O₄₀ was produced and used as an efficient, eco‐friendly and highly recyclable catalyst for the one‐pot and multicomponent synthesis of 3,4‐dihydroquinoxalin‐2‐amine, diazepine‐tetrazole and benzodiazepine‐2‐carboxamide derivatives in aqueous media and at room temperature with high yields in short reaction times (40–60 min). The recoverable catalyst was easily recycled at least five times without any loss of catalytic activity. The structures of obtained products were confirmed using ¹H NMR and ¹³C NMR spectra.     

金鸡纳碱衍生物修饰的负载铱催化剂催化芳香酮不对称加氢

以金鸡纳碱衍生物作为手性修饰剂, 研究了三苯基膦稳定的Ir/SiO₂催化剂催化芳香酮多相不对称加氢. 通过电感耦合等离子体原子发射发谱(ICP-AES)、高分辨透射电镜(HRTEM)、X 射线光电子能谱(XPS)、Brunauer-Emmett-Teller (BET)比表面积测试等固体表面分析手段对负载铱催化体系进行了表征; 利用红外(IR)光谱、固体核磁共振(NMR)等分析手段初步表征了负载铱多相催化体系中手性修饰剂-金属-稳定剂在载体上的相互作用; 利用“均相与多相催化体系的对比”、“催化剂稳定性实验”、“汞中毒实验”等方法阐明了手性修饰的负载铱催化体系是多相催化体系. 还考察了稳定剂种类、修饰剂种类、金属负载量、溶剂、碱添加剂种类等因素对不对称加氢反应的影响. 结果表明, 金鸡纳碱衍生物对Ir/SiO₂催化剂具有较好的修饰作用, 在优化反应条件下苯乙酮及其衍生物加氢反应的对映选择性为52%-96%, 4-乙酰基吡啶、2-乙酰基噻吩及2-乙酰基呋喃加氢反应的对映选择性可分别达到74%、75%及63%.     

Ag-single atoms modified S1.66-N1.91/TiO2-x for photocatalytic activation of peroxymonosulfate for bisphenol A degradation

In this study,Ag_0.23/(S_1.66-N_1.91/TiO_2-x) single-atom photocatalyst was synthesized by in-situ photoreducing of silver on S,N-TiO_2-x nanocomposite and used to degrade bisphenol A（BPA） through heterogeneous activation of potassium peroxymonosulfate（PMS） under visible-light illumination.The structure,physicochemical property,morphology,and electronic property were evalutated by X-ray diffraction（XRD）,Raman spectrum,X-ray photoelectron spectra（...     

SO42-/SnO2-Fe2O3固体酸催化下的环酮Baeyer-Villiger氧化反应及缩合反应

采用共沉淀的方法制备了不同Fe 掺杂量的SO₄^2-/SnO₂-Fe₂O₃固体超强酸催化剂. 利用傅里叶变换红外(FTIR)光谱, 粉末X射线衍射(XRD), N₂吸附-脱附实验(BET), 热重(TG)分析和扫描电镜(SEM)等方法对样品进行了表征. 考察了所得催化剂对4-叔丁基环己酮与乙二醇缩合反应的催化性能. 实验结果表明, 与未经过掺杂改性的SO₄^2-/SnO₂固体酸催化剂相比, 改性后催化剂的催化性能得到了改善. 研究了以Fe/Sn 摩尔比为0.5的SO₄^2-/SnO₂-Fe₂O₃固体酸为催化剂, 部分醛酮类化合物与乙二醇及1,2-丙二醇的缩合反应. 考察了反应时间、催化剂用量等因素对反应的影响. 同时, 将所得催化剂应用于环酮Baeyer-Villiger 氧化反应中, 催化剂表现出良好的催化活性, 且催化剂具有一定的循环使用性.     

Magnetic NiFe2O4 nanoparticles: efficient,heterogeneous and reusable catalyst for synthesis of acetylferrocene chalcones and their anti‐tumour activity

A robust synthesis of magnetic NiFe₂O₄ nanoparticles via a hydrothermal technique was investigated. The prepared magnetic NiFe₂O₄ nanoparticles were characterized using powder X‐ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM), high‐resolution TEM, energy‐dispersive X‐ray spectroscopy, thermogravimetric analysis, infrared spectroscopy and vibrating sample magnetometry. XRD and TEM analyses confirmed the formation of single‐phase ultrafine nickel ferrite nanoparticles with highly homogeneous cubic shape and elemental composition. Moreover, the prepared magnetic NiFe₂O₄ nanoparticles were used as an efficient, cheap and eco‐friendly catalyst for the Claisen–Schmidt condensation reaction between acetylferrocene and various aldehydes (aromatic and/or heterocyclic) yielding acetylferrocene chalcones in excellent yields, with easy work‐up and reduced reaction time. The products were purified via crystallization. The structures of the produced compounds were elucidated using various spectroscopic analyses (¹H NMR, ¹³C NMR, GC–MS). The catalyst is readily recovered by simple magnetic decantation and can be recycled several times with no discernible loss of catalytic activity. Furthermore, the prepared chalcone derivatives were evaluated for their anti‐tumour activity against three human tumour cell lines, namely HCT116 (colon cancer), MCF7 (breast cancer) and HEPG2 (liver cancer), and showed a good activity against colon cancer. Copyright © 2016 John Wiley & Sons, Ltd.     

Environmentally friendly synthesis of Ag/SiO2 nanoparticles using Thymus kotschyanus extract and its application as a green catalyst for synthesis of spirooxindoles

Today, plant extracts based on synthetic procedures have drawn consideration over conventional methods like physical and chemical procedures to synthesize nanomaterials. Green synthesis of nanomaterials has become an area of interest because of numerous advantages such as non-hazardous, economical, and feasible methods with a variety of applications in biomedicine, nanotechnology and nano-optoelectronics and as catalysts for various organic transformations. In this research, silver nanoparticles were deposited on the surface of nano-silica spheres by an in-situ reduction of Ag⁺ ions using an aqueous extract of Thymus kotschyanus aerial parts as a natural reducing and a capping agent. The result recorded from ultraviolet–visible (UV–Vis) spectrometer, Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDS) and X-ray powder diffraction supports the biosynthesis and characterization of Ag/SiO₂ nanoparticles. The results indicated that the average size of Ag/SiO₂ nanoparticles is 25–60 nm. The Ag/SiO₂ nanoparticles act as an environmentally friendly heterogeneous catalyst in the synthesis of spirooxindoles via the three-component condensation reaction of isatins, activated methylene reagents, and 1,3-dicarbonyl compounds in aqueous media, and the desired products were obtained with yields ranging from 90 to 98%. The catalyst can be recovered easily and used repetitively without significant loss of catalytic activity.

Graphical abstract

     

Heterogeneous catalytic solvent-free synthesis of 3,3,5-trimethyl cyclohexyl anthranilic acid esters via transesterification

The transesterification of anthranilates with both mixtures of cis and trans and pure trans 3,3,5-trimethyl cyclohexanol was studied using ‘calcium-oxide- and magnesium-oxide’-based catalysts under ‘solvent-free’ conditions. The catalysts were characterized by XRD, CO₂-TPD, BET-surface area, and FEG–SEM analysis. Pure calcium oxide was found to be the most effective heterogeneous catalyst. Pure ‘calcium-oxide’-based catalyst was recycled five times without appreciable loss in the catalytic activity. The TOF after five recycles was 10.7 mol/mol of catalyst/h. The study was further extended for the synthesis of new anthranilates. The synthesized pure esters have been characterized by UV–Vis, IR-, ¹H NMR-, and ¹³C NMR spectroscopies and mass spectrometry.     

Imidazolium-Based Ionic Network as a Robust Heterogeneous Catalyst in Synthesis of Phenacyl Derivatives

A new imidazolium-based poly(ionic liquid) has been synthesized and used as a robust heterogeneous catalyst for the preparation of phenacyl derivatives by an S_N2 reaction of different phenacyl bromides with a broad range of nucleophiles. The products are obtained in high yields under mild conditions. The catalyst can be recycled efficiently.

     

Application and developing of iron‐doped multi‐walled carbon nanotubes (Fe/MWCNTs) as an efficient and reusable heterogeneous nanocatalyst in the synthesis of heterocyclic compounds

Iron‐doped multi‐walled carbon nanotubes (Fe/MWCNTs) is an efficient, ecofriendly and reusable heterogeneous nanocatalyst for the one‐pot synthesis of heterocyclic compounds including bis‐spiro piperidines, piperidines, dihydro‐2‐oxopyrroles, pyrazoles and diazepines at room temperature with good to excellent yields. The heterogeneous nanocatalyst was fully characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), inductively coupled plasma (ICP) and FT‐IR analysis. Also, the structures of all prepared compounds were characterized by ¹H NMR, ¹³C NMR, FT‐IR, mass spectrometry (MS) and elemental analysis. The major advantages of these protocols are mild and green reaction conditions, short reaction times, clean reaction, operational simplicity, easy purification and good to excellent yields with the reusable heterogeneous nanocatalyst. The catalyst was ten recycled without significant loss of activity.     

Synthesis and comparative study of catalytic activity between Pd-metallodendrimer and Pd/Cu-bimetallodendrimer nanoparticle-based on triazine

Triazine-based heterogeneous Pd/Cu-bimetallodendrimer Nanoparticle (Pd/Cu-BMDNP) has been synthesized by sequential loading method from palladium containing metallodendrimer (Pd-MD) which was prepared by the reaction of 2,4,6-Triamine-1,3,5-triazine (melamine) with substituted benzoyl chloride using (Ph₃P)₂PdCl₂ in DMSO at 90 °C. SEM and EDX of Pd/Cu-BMDNP showed the nanosized aggregated spherical surface morphology and the presence of Palladium and copper of the NP. Also, the phase was detected as Face Centered Cubic (FCC) structure by XRD analysis. In addition, the average particle size of Pd/Cu bimetallic catalyst was identified as 12–13 nm by TEM investigation. Greater thermal stability of Pd/Cu-BMDNP than Pd-MD was detected from TG and DSC experiments. The Pd-metallodendrimer has been also characterized by IR, ¹H NMR, ¹³C NMR, SEM, EDX, Mass, TG and DSC techniques. The simple recoverability, high reusability, low amount of catalyst loading, negligible amount of catalyst leaching of the heterogeneous Pd/Cu-BMDNP have made more effective catalyst than homogeneous Pd-metallodendrimer for the C–C cross-coupling reaction such as Heck, Glaser, Sonogashira and Suzuki-Miyaura in excellent yields.     

Peroxidase/H2O2 catalyzed oxidative oligomerization of 1-aminopyrene

A new florescent oligo(aminopyrene) (OAP) was successfully synthesized by enzymatic approach. For this, H₂O₂ and Horse Radish peroxidase (HRP) were used as catalyst and oxidant, respectively. The structures of monomer and oxidation product were confirmed by NMR, FT-IR and UV-Vis measurements. The oxidation product was characterized by gel permeation chromatography (GPC), thermogravimetry (TG), differential scanning calorimetry (DSC), cyclic voltammetry (CV), photoluminescence (PL) and scanning electron microscopy (SEM) analyses. OAP was soluble in a wide range of organic solvents. UV-Vis spectrum of the OAP showed a dramatic red shift compared to that of the monomer. The optical and electrochemical band gaps of OAP were found to be 1.65 and 1.56 eV, respectively. OAP emitted turquoise color in THF and green color in toluene. SEM observations indicated the presence of a heterogeneous cauliflower like morphology.     

Phosphomolybdic acid supported on Schiff base functionalized graphene oxide nanosheets: Preparation,characterization, and first catalytic application in the multi‐component synthesis of tetrahydrobenzo[a]xanthene‐11‐ones

New Schiff base (SB) functionalized graphene oxide (GO) nanosheets containing phosphomolybdic counter‐anion H₂PMo₁₂O₄₀^¯ (H₂PMo) were successfully prepared by grafting of 3‐aminopropyltriethoxysilane (APTS) on GO nanosheets followed by condensation with benzil and finally reaction with phosphomolybdic acid (H₃PMo₁₂O₄₀, denoted as H₃PMo) and characterized using Fourier transform infrared (FT‐IR) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), particle size distribution, energy‐dispersive X‐ray (EDX) analysis, EDX elemental mapping, and inductively coupled plasma optical emission spectrometry (ICP‐OES). The prepared new nanomaterial, denoted as GO‐SB‐H₂PMo, was shown to be an efficient heterogeneous catalyst in one‐pot, three‐component reaction of β‐naphthol, aldehydes, and dimedone, giving high yields of tetrahydrobenzo[a]xanthene‐11‐ones within short reaction times. The catalyst is readily recovered by simple filtration and can be recycled and reused several times with no significant loss of catalytic activity.     

基于TiO2的绿色多相催化剂催化CO2与环氧化合物偶联反应

金属离子掺杂纳米TiO2(M-TiO2,M=Zn2+,Cu2+,Co2+,Mn2+,Ni2+)在CO2与环氧化合物的偶联反应中表现出较高的催化活性.反应以四正丁基碘化铵(TBAI)为共催化剂,在无溶剂条件下进行.考察了反应温度、反应时间和CO2压力在Zn-TiO2/TBAI体系中对反应性能的影响.作为无毒的多相催化剂,Zn-TiO2可循环使用5次,其催化活性没有明显降低.     

Polystyrene bis[N-(2-pyridyl) sulfonamide] palladium(II): Synthesis,characterization as a catalyst for coupling reactions

The [N-(2-pyridyl)] para-styrene sulfonamide (PSS) was prepared as a monomer, from the reaction of para-styrene sulfonyl chloride and 2-amino pyridine in the presence of potassium hydroxide solution 0.5 M as a base, and CH₃Cl. Polystyrene [N-(2-pyridyl) sulfonamide] (PPSS) was synthesized from the polymerization of [N-(2-pyridyl)] para-styrene sulfonamide (PSS). The Polystyrene bis [N-(2-pyridyl) sulfonamide] palladium (II) as a polymer- supporting palladium complex was also prepared from the reaction of PdCl₂ (CH₃CN)₂ with PPSS in the presence of KOH 0.5 M. Polystyrene bis [N-(2-pyridyl) sulfonamide] palladium (II) is produced as a novel heterogeneous catalyst for coupling reactions for C-C bond formation. This method includes higher yield and has an easier work-up procedure. The structures of the monomer, polymer and its Pd complex were confirmed by using FT-IR and ¹H-NMR spectroscopy. Elemental analysis of Pd by inductively coupled plasma (ICP) technique and hot filtration test showed loading of the metal into solution from the catalyst The heterogeneous catalyst was recycled without any loss in its properties.     

WO3–SiO2 nanomaterials synthesized using a novel template-free method in supercritical CO2 as heterogeneous catalysts for epoxidation with H2O2

A series of tungsten oxide-silica (WO₃–SiO₂) composite nanomaterials were synthesized through a novel, template-free sol-gel method, in which supercritical-CO₂ (scCO₂) was utilized as synthesis medium. The efficacy of the synthesis method stems from a tailored reactor design that allows the contact of the reactants only in the presence of scCO₂. Selected synthetic parameters were screened with the purpose of enhancing the performance of the resulting materials as heterogeneous catalysts in epoxidation reactions with H₂O₂ as environmentally friendly oxidant. A cyclooctene conversion of 73% with epoxide selectivity of > 99% was achieved over the best WO₃–SiO₂ catalyst under mild reaction conditions (80 °C), equimolar H₂O₂ amount (1:1) and low WO₃ loading (~2.5 wt%). The turnover number achieved with this catalyst (TON = 328), is significantly higher than that of a WO₃–SiO₂ prepared via a similar sol-gel route but without supercritical CO₂, and that of commercial WO₃. A thorough characterization with a combination of techniques (ICP-OES, N₂-physisorption, XRD, TEM, STEM-EDX, SEM-EDX, FT-IR and Raman spectroscopy, XPS, TGA and FT-IR analysis of adsorbed pyridine) allowed correlating the physicochemical properties of the WO₃–SiO₂ nanomaterials with their catalytic performance. The high catalytic activity was attributed to: (i) the very high surface area (892 m²/g) and (ii) good dispersion of the W species acting as Lewis acid sites, which were both brought about by the synthesis in supercritical CO₂, and (iii) the relatively low hydrophilicity, which was tuned by optimizing the tetramethyl orthosilicate concentration and the amount of basic solution used in the synthesis of the materials. Our optimum catalyst was also tested in the reaction of cyclohexene with H₂O₂, resulting in cyclohexane diol as main product due to the presence of strong Brønsted acid sites in the catalyst, whereas the reaction with limonene yielded the internal epoxide as the major product and the corresponding diol as side product. Importantly, the catalyst did not show leaching and could be reused in five consecutive runs without any decrease in activity.     

An efficient and convenient protocol for the synthesis of quinoxalines and dihydropyrazines via cyclization-oxidation processes using HClO4·SiO2 as a heterogeneous recyclable catalyst

A convenient and straightforward method has been developed for the synthesis of quinoxalines and dihydropyrazines (DHPs) using α-bromo ketones and 1,2-diamines in the presence of silica supported perchloric acid (HClO₄·SiO₂) at room temperature. The quinoxalines and DHPs were presumably formed via cyclization-oxidation. The catalyst works under heterogeneous conditions and can be recycled.     

Fe3O4@SiO2@Im‐bisethylFc [HC2O4] as a novel recyclable heterogeneous nanocatalyst for synthesis of bis‐coumarin derivatives

Nanomagnetic bisethylferrocene‐containing ionic liquid supported on silica‐coated iron oxide (Fe₃O₄@SiO₂@Im‐bisethylFc [HC₂O₄]) as a novel catalyst was designed and synthesized. The described catalyst was recycled and used without change in the time and efficiency of the condensation reaction. The Fourier transform‐infrared spectroscopy (FT‐IR), scanning electron microscopy images, X‐ray diffraction patterns, energy‐dispersive X‐ray spectroscopy, transmission electron microscope and vibrating‐sample magnetometer results confirmed the formation of Fe₃O₄@SiO₂@Im‐bisethylFc [HC₂O₄] magnetic nanoparticle. The novel bis‐coumarin derivatives were identified by ¹H‐NMR, ¹³C‐NMR, FT‐IR and CHNS analysis.     

Synthesis of Pb(OH)2/rGO Catalyst for Conversion of Sugar to Lactic Acid in Water

Conversion of sugars from biomass to platform chemicals or fuels is an attracting topic for the utilization of biomass. Pb²⁺ ion is an efficient catalyst for the degradation of sugar to lactic acid, and it will be better to fix lead on a solid catalyst to reduce the risk of exposure of Pb²⁺ to environment. Here, a simple method has been developed to prepare a composite catalyst of Pb(OH)₂/rGO, where the nanoparticles of Pb(OH)₂ in size of 2-5 nm were prepared and fixed over the as-prepared reduced graphene oxide (rGO) nanosheets. The as-obtained catalyst showed an efficient catalytic activity to degrade glucose, fructose, and cellulose in aqueous solution, and the major product is lactic acid. The yield of lactic acid reached 58.7% when fructose was used as the feedstock (433 K and 2.5 MPa N₂), and the catalyst can be recycled with high activity. Cellulose can also be directly converted into lactic acid in aqueous solution over the catalyst without extra acid or alkali, and the maximum yield of lactic acid is 31.7%.     

Synthesis,characterization and catalytic application of a new organometallic oligomer based on polyhedral oligomeric silsesquioxane

Although homogeneous catalysts provide high performance and selectivity, the difficulty of separation and recycling of these catalysts has bothered the scientific community worldwide. Therefore, the demand for heterogeneous catalysts that possess the advantages of homogeneous ones, with ease of separation and recyclability remains a topic of major impact. The oligomeric catalyst synthesized in this work was characterized using elemental analysis, Fourier transform infrared, ¹³C NMR, ²⁹Si NMR and energy‐dispersive X‐ray spectroscopies, X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy and Brunauer–Emmett–Teller analysis and compared to its homogeneous counterpart [W(CO)₃Br₂(ATC)] in the epoxidation of 1‐octene, cyclooctene, (S )‐limonene, cis ‐3‐hexen‐1‐ol, trans ‐3‐hexen‐1‐ol and styrene. The results showed that the percentage conversion for the homogeneous species [W(CO)₃Br₂(ATC)] was slightly higher than for the oligomeric catalyst (POSS‐ATC‐[W(CO)₃Br₂]). Furthermore, the selectivity for epoxide of the oligomeric catalyst was greater than that of the homogeneous catalyst by about 25% when (S )‐limonene was used. Great conversions (yields) of products were obtained with a wide range of substrates and the catalyst was recycled many times without any substantial loss of its catalytic activity.     

Vinyl polymerization of norbornene catalyzed by 2‐Py‐amidine Ni(II) complex/methylaluminoxane systems

Two 2‐Py‐amidine ligands (2‐Py―NH―C(Ph)═N―Ar, Ar = 2,6‐Me₂C₆H₃ and 2,6‐ⁱPr₂C₆H₃) and the corresponding Ni(II) complexes ( 1 and 2 ) were synthesized and characterized using elemental analysis and FT‐IR, UV–visible, ¹H NMR and ¹³C NMR spectroscopies. X‐ray crystal structures indicate that the chelate ring conformation of the less bulky complex 1 is relatively planar compared with that of the bulky complex 2 . Paramagnetic ¹H NMR and ¹³C NMR studies show that, in solution, the time‐average structures of complexes 1 and 2 have mirror symmetry. Both complexes 1 and 2 were used as catalyst precursors for norbornene polymerization with methylaluminoxane as a co‐catalyst. The effects of Al/Ni ratio, temperature and structure of precursors on the catalytic performance were investigated. Copyright © 2014 John Wiley & Sons, Ltd.