1‐Butyl‐3‐methylimidazolium Hydrogen Sulfate [Bmim]HSO4: An Efficient Reusable Acidic Ionic Liquid for the Synthesis of 1,8‐Dioxo‐Octahydroxanthenes

1‐Butyl‐3‐methylimidazolium hydrogen sulfate [bmim]HSO₄ as an acidic ionic liquid was prepared and used as a catalyst for the synthesis of 1,8‐dioxo‐octahydroxanthenes in excellent yields and short reaction times at 80 °C. The ionic liquid was easily separated from the reaction mixture by water extraction and was recycled four times without any loss in activity.     

Surfactant‐directed one‐pot preparation of novel Ti‐containing mesomaterial with improved catalytic activity and reusability

Titanium was incorporated in ionic liquid based periodic mesoporous organosilica to prepare a nanostructured catalyst (Ti@PMO‐IL) with high activity. Procedure for the synthesis of Ti@PMO‐IL was followed according the simultaneous hydrolysis and condensation of alkylimidazolium ionic liquid, tetramethoxysilane (TMOS) and tetrabutylorthotitanate (TBOT) where a surfactant template was used together with a simple acid‐based catalytic aproach. N₂ adsorption isotherm of the Ti@PMO‐IL was studied to measure its mean pore volume, pore size distribution and specific surface area. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy was applied to identify the chemical bonds present in Ti@PMO‐IL. The morphology of this nanomaterial was investigated by scanning electron microscopy (SEM). Transmission electron microscopy (TEM) image was used to study mesoporosity and structure order of the catalyst. The catalytic activity of Ti@PMO‐IL was then studied and found to be efficient and reusable to catalyze Hantzsch reaction.     

Ordered Mesoporous Organosilica with Ionic‐Liquid Framework: An Efficient and Reusable Support for the Palladium‐Catalyzed Suzuki–Miyaura Coupling Reaction in Water

The preparation of a novel palladium‐supported periodic mesoporous organosilica based on alkylimidazolium ionic liquid (Pd@PMO‐IL) in which imidazoilium ionic liquid is uniformly distributed in the silica mesoporous framework is described. Both Pd@PMO‐IL and the parent PMO‐IL were characterized by N₂‐adsorption–desorption, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), TEM, and solid‐state NMR spectroscopy. We have demonstrated that Pd@PMO‐IL is an efficient and reusable catalyst for the Suzuki–Miyaura coupling reaction of various types of iodo‐, bromo‐, and even deactivated aryl chlorides in water. It was also found that although the PMO‐IL nanostructure acts as reservoir for soluble Pd species, it can also operate as a nanoscaffold to recapture the Pd nanoparticles into the mesochannels thus preventing extensive agglomeration of Pd. This observation might be attributed to the isolated ionic liquid units that effectively control the reaction mechanism by preventing Pd agglomeration and releasing and recapturing Pd nanoparticles during the reaction process. The catalyst can be recovered and reused for at least four reaction cycles without significant loss of activity.     

Study on One‐pot Biginelli‐like Synthesis of Pyrazolo[3,4‐d]pyrimidines in Bronsted Acidic Ionic Liquid Under Sonication and its Mechanism

Pyrazolo[3,4‐d]pyrimidine derivatives were synthesized using ionic liquid, 1‐butylimidazolium tetrafluoroborate, under ultrasound irradiation at ambient condition without any added catalyst. Mechanistic pathway based on the catalytic role of ionic liquid has been proposed. This method offers the advantages of simple procedure, milder reaction condition, easier workup and improved yield over the conventional method. The ionic liquid could be recycled at least three times with marked retention in its activity.     

Clean Procedure for the Synthesis of Α‐Aminophosphonates Catalyzed by Choline‐Based Ionic Liquid

A sulfated choline‐based ionic liquid [Ch‐OSO₃H] was prepared and used as a novel catalyst for the synthesis of α‐aminophosphonates via a one‐pot three‐component reaction with aldehydes, amines, and triethyl phosphite/diethyl phosphite at room temperature under solvent‐free conditions or in aqueous media. The reaction was completed in short times and products could be simply separated from the reaction mixture in good to excellent yields. The catalyst could be recycled and reused for several times without noticeably reducing catalytic activity.     

Ferrocene‐tagged ionic liquid stabilized on silica‐coated magnetic nanoparticles: Efficient catalyst for the synthesis of 2‐amino‐3‐cyano‐4H‐pyran derivatives under solvent‐free conditions

An advanced novel magnetic ionic liquid based on imidazolium tagged with ferrocene, a supported ionic liquid, is introduced as a recyclable heterogeneous catalyst. Catalytic activity of the novel nanocatalyst was investigated in one‐pot three‐component reactions of various aldehydes, malononitrile and 2‐naphthol for the facile synthesis of 2‐amino‐3‐cyano‐4H‐pyran derivatives under solvent‐free conditions without additional co‐catalyst or additive in air. For this purpose, we firstly synthesized and investigated 1‐(4‐ferrocenylbutyl)‐3‐methylimidazolium acetate, [FcBuMeIm][OAc], as a novel basic ferrocene‐tagged ionic liquid. This ferrocene‐tagged ionic liquid was then linked to silica‐coated nano‐Fe₃O₄ to afford a novel heterogeneous magnetic nanocatalyst, namely [Fe₃O₄@SiO₂@Im‐Fc][OAc]. The synthesized novel catalyst was characterized using ¹H NMR, ¹³C NMR, Fourier transform infrared and energy‐dispersive X‐ray spectroscopies, X‐ray diffraction, and transmission and field emission scanning electron microscopies. Combination of some unique characteristics of ferrocene and the supported ionic liquid developed the catalytic activity in a simple, efficient, green and eco‐friendly protocol. The catalyst could be reused several times without loss of activity.     

Self‐assembled Pd nanoparticle‐containing ionic liquid: Efficient and reusable catalyst for the Heck reaction in water

A self‐assembled Pd nanoparticle‐containing ionic liquid as metal–organic polymer was successfully prepared. The structure of the catalyst was characterized using Fourier transform infrared and ¹H NMR spectroscopies, scanning electron microscopy and elemental analysis. The catalyst was effectively employed in the palladium‐catalyzed Heck reaction in water as a green solvent. Moreover, due to its stability the catalyst can be recovered simply and effectively and reused nine times without much loss of activity.     

Chloroaluminate ionic liquid‐modified silica‐coated magnetic nanoparticles: Efficient and reusable catalyst for selective synthesis of mono‐ and bis‐dihydropyrano[3,2‐b]chromenediones

The synthesis, characterization and catalytic activity of chloroaluminate ionic liquid‐modified silica‐coated magnetic nanoparticles ([SiPrPy]AlCl₄@MNPs) are described. The prepared magnetic nanocatalyst was characterized using Fourier transform infrared spectroscopy, elemental analysis, vibrating sample magnetometry, scanning and transmission electron microscopies, X‐ray diffraction and inductively coupled plasma analysis. The results showed that the ionic liquid had been successfully immobilized onto the magnetic support, and the resulting nanoparticles exhibited high catalytic activity for the synthesis of a diverse range of dihydropyrano[3,2‐b ]chromenediones via a one‐pot, three‐component and solvent‐free reaction of aromatic aldehydes, 1,3‐diones and kojic acid. This catalytic system also showed excellent activity in the selective synthesis of mono‐ and bis‐dihydropyrano[3,2‐b ]chromenediones from dialdehydes. The procedure gave the products in excellent yields and in very short reaction times. Moreover, the catalyst could be reused eight times without loss of its catalytic activity.     

[Emim][BF4]: An Efficient Green Protocol for the Synthesis of Bioactive 2‐(5‐(substituted)‐2,6‐dioxo‐1,2,5,6‐tetrahydropyrimidin‐4‐yl)‐2,3‐dihydrophthalazine‐1,4‐dione Derivatives

The present study is designed to synthesize the 2‐(5‐(substituted)‐2,6‐dioxo‐1,2,5,6‐tetrahydropyrimidin‐4‐yl)‐2,3‐dihydrophthalazine‐1,4‐diones and investigate their anticancer activity. This is the first example of the condensation reaction of a series of phthalhydrazide derivatives in ionic liquid. In this investigation, the titled compounds syntheses were carried out by simple and efficient three component coupling of phthalhydrazide, aldehydes, and barbituric acid in the presence of [Emim][BF₄] ionic liquid. This methodology was provided and promotes the higher product yields in shorter reaction times and mild reaction conditions. The title compounds were tested for their anticancer activity. Some of them were shown the significant cytotoxic activity against the selected cancer cell lines.     

CuI/Fe3O4 NPs@Biimidazole IL‐KCC‐1 as a leach proof nanocatalyst for the synthesis of imidazo[1,2‐a]pyridines in aqueous medium

In the present work, an innovative leach proof nanocatalyst based on dendritic fibrous nanosilica (DFNS) modified with ionic liquid loaded Fe₃O₄ NPs and CuI salts was designed and applied for the rapid synthesis of imidazo[1,2‐a]pyridines from the reaction of phenyl acetylene, 2‐aminopyridine, and aldehydes in aqueous medium. The structure of the synthesized nanocatalyst was studied by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared (FT‐IR), flame atomic absorption spectroscopy (FAAS), energy‐dispersive X‐ray (EDX), and X‐ray diffraction (XRD), vapor–liquid–solid (VLS), and adsorption/desorption analysis (Brunauer–Emmett–Teller [BET] equation) instrumental techniques. CuI/Fe₃O₄NPs@IL‐KCC‐1 with high surface area (225 m² g^?1) and porous structure not only exhibited excellent catalytic activity in aqueous media but also, with its good stability, simply recovered by an external magnet and recycled for eight cycles without significant loss in its intrinsic activity. Higher catalytic activity of CuI/Fe₃O₄NPs@IL‐KCC‐1 is due to exceptional dendritic fibrous structure of KCC‐1 and the ionic liquid groups that perform as strong anchors to the loaded magnetic nanoparticles (MNPs) and avoid leaching them from the pore of the nanocatalyst. Green reaction media, shorter reaction times, higher yields (71–97%), easy workup, and no need to use the chromatographic column are the advantages of the reported synthetic method.     

Ionic Liquid‐coordinated Ytterbium(III) Sulfonate Catalyzed Michael Addition of Indoles to Electron‐deficient Nitroolefins

The Michael addition of indoles to electron‐deficient nitroolefins was effectively catalyzed by an ionic liquid‐coordinated ytterbium(III) sulfonate catalyst. The recycling procedure of the catalyst was very simple without extraction with water, and the catalyst was reused for five times without any loss of its catalytic activity. Furthermore, to demonstrate the application of this methodology, the Pictet‐Spengler reaction was chosen and successfully carried out in the mixture of Br?nsted‐acidic ionic liquid and [bmim]BF₄.     

Ionic‐Liquid‐Grafted Rigid Poly(p‐Phenylene) Microspheres: Efficient Heterogeneous Media for Metal Scavenging and Catalysis

Novel guanidinium ionic liquid‐grafted rigid poly(p‐phenylene) (PPPIL) microspheres have been developed for metal scavenging and catalysis. The noble‐metal nanoparticles supported on the microspheres surface can be used as efficient heterogeneous catalysts. The combination of nanoparticles and ionic liquid fragments on the microsphere surfaces enhance the activity and durability of the catalyst. The PPPIL ? Pd⁰ catalyst has been tested in the Suzuki cross‐coupling reaction, and exhibits much higher catalytic activity than Pd catalysts supported on porous polymer matrices. The PPPIL ? Pd⁰ catalyst can be recycled at least for nine runs without any significant loss of activity. The present approach may, therefore, have potential applications in transition‐metal‐nanocatalyzed reactions.     

Amino acid ionic liquid‐based titanomagnetite nanoparticles: An efficient and green nanocatalyst for the synthesis of 1,4‐dihydropyrano[2,3‐c]pyrazoles

The amino acid ionic liquid tetrabutylammonium asparaginate (TBAAsp) was immobilized on titanomagnetite (Fe_3?xTi_xO₄) nanoparticles in a facile one‐pot process using an organosilane compound (TMSP) as spacer. The modified Fe_3?xTi_xO₄@TMSP@TBAAsp magnetic nanoparticles were characterized using Fourier transform spectroscopy, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, vibrating sample magnetometry and thermogravimetric analysis. The resulting analytical data clearly verified the successful immobilization of the ionic liquid on the magnetic substrate. The magnetic ionic liquid‐based nanoparticles exhibited high catalytic activity in the synthesis of 1,4‐dihydropyrano[2,3‐c]pyrazole derivatives via a one‐pot three‐component reaction under mild reaction conditions. The catalyst was easily recycled and reused for at least six runs without any considerable loss of activity.     

New Hexanuclear Niobium Cluster Compounds with Perfluorinated Ligands Made Using Ionic Liquids

Three new hexanuclear niobium cluster compounds, which carry trifluoroacetate ligands on the exo sites of the metal atom octahedra, were synthesized and characterized. For the syntheses, the ionic liquid 1,1,3,3‐tetramethylguanidinium‐trifluoroacetat, (TMG‐H)TFA, was used as solvent as well as source for the ligands and cations. All three cluster compounds consist of the [Nb₆Cl₁₂(TFA)₆]^4– anion and (TMG‐H)⁺, (TMG‐H)⁺ + (TMGTFAA‐H)⁺, or (TMGTFAA‐H)⁺ cations [(TMGTFAA‐H)⁺ = 1,1,3,3‐tetramethylguanidine‐trifluoroacetamidinium]. TMGTFAA and the corresponding cation are obtained by either heating and/or by addition of TFA‐anhydrate to (TMG‐H)TFA in a slow chemical reaction. (TMGTFAA‐H)TFA comprises a second ionic liquid in this reaction system, which provides cations for two of the three characterized niobium cluster compounds. Structural details of the three new cluster compounds as well as of TMGTFAA were obtained by X‐ray diffraction experiments. With a melting point of approx. 145 °C the cluster compound with the (TMG‐H)⁺ cations almost can be called a “cluster ionic liquid“.     

An efficient and highly selective approach for the construction of novel dispiro heterocycles in guanidine-based task-specific [TMG][Ac] ionic liquid

A simple, efficient and highly selective one-pot approach for the synthesis of biologically important novel dispiro heterocycles assembling three pharmacophoric moieties such as piperidinone, 1,3-indanedione, and pyrrolidine in a single molecular framework by means of three-component reaction between ninhydrin, sarcosine, and 1-benzyl/methyl-3,5-bis[(E)-arylidene]-piperidin-4-one is reported in task-specific 1,1,3,3-tetramethylguanidine acetate [TMG][Ac] ionic liquid as a environmentally benign solvent in excellent yields without using any catalyst. The TMG-based ionic liquid could be recovered and used at least four times without considerable reduction in its activity and selectivity. Good functional group tolerance and broad scope of usable substrates are other prominent features of the present methodology with high degree of chemo-, regio-, and stereoselectivity. The structure and relative stereochemistry of final products were established by single crystal X-ray structure and spectroscopic techniques.     

Protic Ionic Liquid Promoted One Pot Synthesis of 2‐amino‐4‐(phenyl)‐7‐methyl‐5‐oxo‐4H,5H‐pyrano[4,3‐b]pyran‐3‐carbonitrile Derivatives in Water and Their Antimycobacterial Activity

One pot three component reaction of 4‐hydroxy‐6‐methylpyran‐2‐one, 3‐methoxy benzaldehyde, and malononitrile in water using protic ionic liquid as a catalyst at room temperature afforded pyrano[4,3‐b]pyran derivatives. Protic ionic liquid has been proved to be an efficient and mild catalyst for the synthesis of pyrano[4,3‐b]pyran scaffolds due to their highly polar nature. The notable aspects of protic ionic liquid are easy availability, improved reaction rates, high product yields, simple workup procedure, recyclability, and reusability. Molecules docking studies have been performed on enzyme enoyl‐ACP‐reductase from Mycobacterium tuberculosis. The molecular docking simulation indicated plausible π‐alkyl and alkyl‐alkyl interactions between the amino acids and scaffolds. The synthesized derivatives have been evaluated for their in vitro antituberculotic activity against M. tuberculosis H₃₇RV strain using Microplate Alamar Blue Assay method. Together, biological activity data and docking data showed that the tested scaffolds exhibited excellent antituberculotic activity.     

Metal‐containing Ionic Liquid/Polyacrylonitrile‐derived Carbon Nanofibers for Oxygen Reduction Reaction and Flexible Zn–Air Battery

Practical applications of Zn–air batteries are usually limited by sluggish kinetics of oxygen reduction reaction. Replacing Pt‐based catalysts with convenient, efficient and low‐cost materials to boost oxygen reduction reaction is highly desirable. Herein, a class of Fe?N co‐doped carbon nanofibers is successfully synthesized by pyrolysis of polyacrylonitrile/metal‐containing ionic liquid‐based electrospun films. The ionic liquids act as porogen to provide multiscale pores as well as activator to bring carbon nanofibers active sites. The catalyst possessing appropriate active sites and unique 3D porous architecture exhibits remarkable long‐term stability and electrocatalytic activity. Particularly, the catalyst maintains a shape of membrane after carbonization, manifesting its direct use as air electrode without binders. It is notable that an all solid‐state Zn–air battery based on the carbon nanofibers exhibits good flexibility, indicating its promising application as wearable devices.     

Green route for selective gram‐scale oxidation of sulfides using tungstate/triazine‐based ionic liquid immobilized on magnetic nanoparticles as a phase‐transfer heterogeneous catalyst

Tungstate ions were successfully loaded onto triazine‐based ionic liquid‐functionalized magnetic nanoparticles through an anion exchange process. The use of triazine core for creating ionic liquid led to the immobilization of high amounts of WO₄^2?. The resulting catalyst showed high activity and selectivity in the oxidation of sulfides to sulfoxides with H₂O₂ as a green oxidant at room temperature. In addition, due to the presence of ammonium groups in the catalyst structure, water dispersibility of the catalyst was increased. More important, the catalyst was magnetically recovered and reused for up to six runs without any marked decrease of activity and selectivity. Finally, easy gram‐scale oxidation of methylphenyl sulfide as well as fast separation of catalyst and product makes the protocol economical and industrially applicable.     

Sonochemical synthesis of library benzodiazepines using highly efficient molecular ionic liquid supported on Fe‐MCM‐41 nanocomposites as a recyclable catalyst

In this study, library substituted benzodiazepines was synthesized using molecular ionic liquid supported on Fe‐MCM‐41 nanocomposites (Fe‐MCM‐41‐IL). This protocol using ultrasound provided advantages such as rapid, clean conversion and simplicity in experimental setup that led to rapid generation of benzodiazepines under mild condition. The catalyst can be easily isolated by using an external magnetic field and reused in the next reaction up to six cycles without obvious activity decreasing.     

A green approach for the synthesis of 2‐oxazolidinones using gold(I) complex immobilized on KCC‐1 as nanocatalyst at room temperature

A novel gold(I)‐containing ionic liquid‐based KCC‐1 catalyst was applied for the cyclization of propargylic amines with CO₂ to provide 2‐oxazolidinones. High catalytic activity and ease of recovery from the reaction mixture using an external magnet, and several recycle runs without significant loss in performance are additional eco‐friendly attributes of this catalytic system. Copyright © 2016 John Wiley & Sons, Ltd.