Nano-Fe3O4@SiO2–TiCl3 as a novel nano-magnetic catalyst for the synthesis of 4H-pyrimido[2,1-b]benzothiazoles

Research on Chemical Intermediates - Fe3O4@SiO2–TiCl3 NPs, a novel core shell catalyst, was synthesized via preparing Fe3O4@SiO2 as a magnetic support followed by treatment with titanium...     

A green one-pot three-component synthesis of α-aminophosphonates under solvent-free conditions and ultrasonic irradiation using Fe3O4@SiO2-imid-PMAn as magnetic catalyst

An efficient and environment friendly process for the synthesis of α-aminophosphonates has been devised. Through a one-pot three-component condensation of various aldehydes, amines, and triethyl phosphite in the presence of Fe₃O₄@SiO₂-imid-PMAⁿ nanoparticles as magnetic catalysts under solvent-free conditions and ultrasonic irradiation, α-aminophosphonates were obtained with excellent yields. The reactions under solvent-free conditions at room temperature are compared with the ultrasonic-assisted reactions. This new procedure has notable advantages such as short reaction time, excellent yields, easy purification, and the absence of any tedious workup or purification. The aforementioned catalyst could be easily recovered by an external magnetic field and can be reused for six consecutive reaction cycles without significant loss of activity. In addition, SEM and DLS of the catalyst after the reaction cycle were investigated.     

Ultrasound-assisted one-pot multi-component synthesis of 2-pyrrolidinon-3-olates catalyzed by Co3O4@SiO2 core–shell nanocomposite

2-pyrrolidinon-3-olates were synthesized via one-pot four-component reaction of 2-aminobenzothiazole, aromatic aldehydes, dimethyl acetylenedicarboxylate and morpholine/piperidine in the presence of Co₃O₄@SiO₂ core–shell nanocomposite as catalyst under ultrasound irradiation. The protocol offers several such advantages as high yields, short reaction time and mild reaction conditions with reusability of the catalyst. The core–shell nanocomposite was also prepared using ultrasound irradiation and the structure and magnetic properties were fully characterized by TEM, FE-SEM, XRD, EDX, FT-IR and VSM analysis.     

Fe3O4@SiO2-polymer-imid-Pd magnetic porous nanosphere as magnetically separable catalyst for Mizoroki–Heck and Suzuki–Miyaura coupling reactions

The activity of palladium nanoparticles supported on poly (N-vinylpyrrolidone) grafted Fe₃O₄@SiO₂ was investigated in the cross-coupling reactions. We have applied this catalyst under low loading of the supported palladium nanoparticles for the coupling of aryl halides with alkenes (Mizoroki–Heck reaction) and organoboronic acids (Suzuki–Miyaura reaction) in the absence of phosphorous ligands. Short reaction times and excellent yields of the products express the effectiveness of this catalyst. The nanocatalyst can be separated from the reaction mixture by applying a permanent magnet externally and can be reused for six times without appreciable change in catalytic activity. Also, the amount of leaching of Pd nanoparticles has been determined by ICP analysis and results showed low leaching of the metal into solution from the supported catalyst.     

Fe3O4@SiO2@ADMPT/H6P2W18O62: a novel Wells–Dawson heteropolyacid-based magnetic inorganic–organic nanohybrid material as potent Lewis acid catalyst for the efficient synthesis of 1,4-dihydopyridines

A novel Wells–Dawson heteropolyacid-based magnetic Inorganic–organic nanohybrid, Fe₃O₄@SiO₂@ADMPT/H₆P₂W₁₈O₆₂, was fabricated and used as a green, efficient, eco-friendly, and highly recyclable catalyst for the one-pot and multi-component synthesis of 1,4-Dihydopyridine (1,4-DHP) derivatives from the reaction of various aromatic aldehydes with ethyl acetoacetate and ammonium acetate with good to excellent yields and in a short span of time. The nanohybrid catalyst was prepared by the chemical anchoring of Wells–Dawson heteropolyacid H₆P₂W₁₈O₆₂ onto the surface of functionalized Fe₃O₄ nanoparticles with 2,4-bis(3,5-dimethylpyrazol)-triazine (ADMPT) linker. These nanocatalysts were identified by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), infrared spectroscopy (IR) and vibrating sample magnetometer (VSM). This protocol is developed as a safe, cost-effective and convenient alternate method for the synthesis of 1,4-DHP derivatives utilizing an eco-friendly, and a highly reusable catalyst.     

Synthesis and characterization of Fe3O4@SiO2–polymer-imid–Pd magnetic porous nanospheres and their application as a novel recyclable catalyst for Sonogashira–Hagihara coupling reactions

We demonstrate herein the modification of magnetic nanoparticles and their use as a magnetic nanocatalyst in direct coupling reactions of aryl halides with terminal alkynes. Magnetite particles were prepared by simple co-precipitation method in aqueous medium, and then Fe₃O₄@ SiO₂ nanosphere was synthesized by using nano-Fe₃O₄ as the core, TEOS as the silica source and PVA as the surfactant. Fe₃O₄@SiO₂ was coated with polymeric N-heterocyclic carbene/Pd. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, thermogravimetric analysis, vibration sample magnetometer and N₂ adsorption–desorption isotherm analysis. Poly (N-vinyl imidazole) functionalized Fe₃O₄@SiO₂ nanoparticle was found to be an efficient nanocatalyst in Sonogashira–Hagihara cross-coupling reactions. The nanocatalyst can be easily recovered by a magnetic field and reused for six runs without appreciable loss of its catalytic activity.     

Green and highly efficient approach for the reductive coupling of nitroarenes to azoxyarenes using the new mesoporous Fe3O4@SiO2@Co–Zr–Sb catalyst

Research on Chemical Intermediates - Efficient, green, simple and environmentally friendly approach for the straightforward reductive coupling of nitroarenes to the corresponding azoxyarenes has...     

Hydrotalcite-bound ruthenium as a multifunctional heterogeneous catalyst for one-pot synthesis of α-alkylated nitriles and quinolines

This article reviews our recent progress in one-pot syntheses of α-alkylated nitriles and quinolines by heterogeneous catalysis with hydrotalcite-bound ruthenium based on cooperative action between cationic Ru species and the base sites of the hydrotalcite surface.     

CoFe2O4–SiO2–SO3H nanocomposite as a magnetically recoverable catalyst for oxidative bromination of alkynes

A hybrid catalyst has been prepared by incorporating sulfonic acid onto cobalt ferrite magnetic nanoparticles. The catalyst was successfully applied for rapid (20?min) synthesis of α,α-dibromoketones directly from alkynes and NBS. The reaction works well in the presence of 10?wt% of the catalyst at room temperature to produce the desired products in high yield. The catalyst could be recovered using an external magnet and reused without appreciable change in activity.     

Preparation and characterization of SO4 2−/Fe2O3–TiO2–Nd2O3 catalyst

This paper reports on the preparation of SO₄ ^2?/Fe₂O₃–TiO₂–Nd₂O₃ (SFTN) by combustion method. The effect of Nd content on catalytic activity was investigated. The prepared materials doped and undoped by Nd were compared by means of TG-DTG, XRD, FT-IR, NH₃-TPD and TEM techniques. Results indicated that the introduction of Nd improved the catalytic activities of the catalysts. Catalytic activity of SFTN was the highest with 98.3 % menthol conversion when Nd content was at 2 wt%. The introduction of Nd stabilized the coordination bond between the sulfate irons and the metallic oxides, helping in the formation of solid acid sites, enhancing the dispersion of catalyst particles, and inhibiting the growth of catalyst particles under heating.     

CeCl_3·7H_2O as an efficient catalyst for one-pot synthesis of β-amino ketones by three-component Mannich reaction

<正>Cerium trichloride heptahydrate(CeCl_3·7H_2O) was found to be an efficient and recyclable catalyst for the three-component direct Mannich reaction of anilines and benzaldehydes with acetophenone.This protocol has advantages of high yield,no environmental pollution,mild condition,and simple work-up procedure.     

多功能Fe3O4@SiO2 Janus颗粒

采用溶剂热法和溶胶-凝胶法制备了顺磁性Fe₃O₄@SiO₂颗粒,以Pickering乳液界面保护法实现颗粒表面分区获得Fe₃O₄@SiO₂ Janus颗粒,进一步选区复合生长Pt或Ag纳米颗粒制备Fe₃O₄@SiO₂-Pt和Fe₃O₄@SiO₂-Ag Janus颗粒.Fe₃O₄@SiO₂-Pt Janus颗粒的Pt一侧进行催化过氧化氢的反应,具有自驱动功能.因其顺磁性和两亲性,Fe₃O₄@SiO₂-Ag Janus颗粒能够作为磁响应颗粒乳化剂稳定油水乳液,并将Ag的催化功能引入界面.     

Fe3O4@SiO2–NH2 core-shell nanocomposite as an efficient and green catalyst for the multi-component synthesis of highly substituted chromeno[2,3-b]pyridines in aqueous ethanol media

ABSTRACT

An efficient and green approach for synthesizing chromeno[2,3-b]pyridine derivatives through one-pot three-component reactions of salicylaldehydes, thiols, and malononitrile has been developed by Fe₃O₄@SiO₂–NH₂ nanocatalyst in aqueous ethanol media under re?ux conditions. The present procedure provides several advantages such as environmentally benign, straightforward, excellent yields, short reaction times, cost-effective, good recyclability, little catalyst loading, and facile catalyst separation for the preparation of chromeno[2,3-b]pyridines as important privileged medicinal scaffold. In addition, aminopropyl-coated Fe₃O₄@SiO₂ nanoparticles were fully characterized by scanning electron microscopy, X-ray diffraction, energy dispersive analysis of X-ray, vibrating sample magnetometer, and FT-IR analysis.     

Preparation and characterization of Fe3O4@Cu-β-CD as a hybrid magnetic catalyst for the synthesis of dihydropyrano[2,3-c]pyrazoles in H2O

Research on Chemical Intermediates - Fe3O4@Cu-β-CD is a hybrid composite with high catalytic activity. Easy separation with an external magnet and recyclability are the advantages of this...     

Nano TiO_2 as a heterogeneous catalyst in an efficient one-pot three-component Mannich synthesis of β-aminocarbonyls

TiO₂ nanoparticles（TiO₂ NPs） worked as an efficient heterogeneous catalyst in a one-pot,three-component,and solvent free Mannich reaction;producing variousβ-aminocarbonyls in good yields,and with good stereoselectivities.The catalyst was easily separated from the reaction mixture and was recycled four times with no significant loss of its catalytic activity.     

Solvent-free one-pot synthesis of 4-aryl-3,5-dimethyl-1,4,7,8-tetrahydrodipyrazolo[3,4-b:4′,3′-e]pyridines using Fe3O4@SiO2@(BuSO3H)3 catalytic Fe3+ system as selective colorimetric

Research on Chemical Intermediates - The synthesis of 4-Aryl-(3,5-dimethyl-1,4,7,8-tetrahydro-dipyrazolo[3,4b:4′,3′e]pyridine derivatives was accomplished using Fe3O4@SiO2@(BuSO3H)3...     

Magnetic core–shell Fe3O4@C-SO3H nanoparticle catalyst for hydrolysis of cellulose

Catalytic hydrolysis of cellulose over solid acid catalysts is one of efficient pathways for the conversion of biomass into fuels and chemicals. High catalytic activity and easy separation from reaction media are two important factors for evaluating the performance of the solid acid catalysts for the cellulose hydrolysis. In this study, we report a core–shell Fe₃O₄@C-SO₃H nanoparticle with a magnetic Fe₃O₄ core encapsulated in a sulfonated carbon shell, as recyclable catalyst for the hydrolysis of cellulose. The sulfonated carbon shell shows a good activity, presenting 48.6 % cellulose conversion with 52.1 % glucose selectivity under the moderate conditions of 140 °C after 12 h reaction. Importantly, the magnetic Fe₃O₄ core makes the catalysts easily separated from reaction mixtures by using the externally applied magnetic field. In addition, the Fe₃O₄@C-SO₃H nanoparticle catalyst shows a high stability in the activity and magnetization during recycling tests, suggesting it a promising solid acid catalyst for the hydrolysis of cellulose.     

α-Fe_2O_3 immobilized benzimidazolium tribromide as novel magnetically retrievable catalyst for one-pot synthesis of highly functionalized piperidines

Nanostructured α-Fe_2O_3 were prepared by precipitation followed by calcination method.Cetyltrimethylammonium bromide(CTAB) was used as surfactant.The nano α-Fe_2O_3 was then silanized with(3-chloropropyl)-triethoxysilane(CPTES) by room temperature mixing of α-Fe_2O_3 and CPTES to produce silane coated α-Fe_2O_3(ClPr-Si@Fe_2O_3).As-synthesized ClPr-Si@Fe_2O_3 was functionalized via covalent grafting of benzimidazole to produce 3-(l-benzimidazole)Pr-Si@Fe_2O_3.This was further reacted with bromine to afford α-Fe_2O_3 immobilized benzimidazolium tribromide(α-Fe_2O_3-BIM tribromide).This ionic liquid(IL)α-Fe_2O_3 BIM tribromide was characterized by FT-IR,XRD,TEM,SEM,TGA,VSM,EDX and BET analysis.The as-synthesized IL tribromide was used as catalyst for one-pot synthesis of highly substituted piperidines.The method is greener in terms of solvent selection,recovery of the catalyst and efficiency.     

Alum： An efficient catalyst for one-pot synthesis of α-aminophosphonates

Alum (KAl(SO ₄) ₂·12H ₂O) is an inexpensive, efficient, non-toxic and mild catalyst for the one-pot synthesis of α-aminophosphonates.A three component reaction of an aldehyde/ketone, an amine and triethyl phosphite was carried out under solvent-free conditions to afford the corresponding a-aminophosphonates in short reaction times and high yields with the green aspects by avoiding toxic catalysts and solvents.     

Facile one-pot synthesis of 5-amino-1H-pyrazole-4-carbonitriles using alumina–silica-supported MnO2 as recyclable catalyst in water

Research on Chemical Intermediates - A novel, facile, one-pot, multicomponent protocol for the synthesis of 5-amino-1H-pyrazole-4-carbonitrile derivatives has been developed using...