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Hot‐water‐soluble starch (HWSS) was employed as binder for fabrication of a composite from magnetite and Ag nanoparticles (NPs). Electron microscopy images showed a good dispersion of magnetite NPs in the matrix of HWSS. This observation indicates that HWSS tends to coat the maximum surface of magnetite by encapsulation of individual magnetite NPs, leading to disassembly of their aggregates. The HWSS‐coated magnetite NPs were employed as nano‐support for immobilization of fine Ag NPs generated in situ via reduction of Ag+ cations by glucose. Monitoring of the formation and growth of Ag NPs by UV–Vis spectroscopy made it possible to set up an optimal condition for fabrication of the nano‐composite and to verify the supremacy of HWSS‐coated magnetite NPs over bare magnetite NPs as support in this new protocol. Valuable insights into the texture of the nano‐composite were obtained by VSM, FT‐IR and XRD studies. The bio‐derived nano‐composite displayed an interesting magnetic property and an efficient catalytic activity in the three‐component synthesis of pyrano[2,3‐d]pyrimidines. It is a robust heterogeneous catalyst and can be simply retrieved from reaction mixtures by magnetic separation method. [ABSTRACT FROM AUTHOR]

This study explored the efficacy of a cost-efficient activated carbon (AC) derived from natural bitumen through chemical activation with phosphoric acid. The objective was to evaluate bitumen-based activated carbon (AC) potential as a novel adsorbent by integrating Cu (NO3)2.3H2O onto AC for the removal of harmful dyes from water-based solutions. Assessments of the adsorption capabilities of Cu@AC were conducted using representative samples of cationic and anionic dyes, namely methylene blue (MB) and methyl orange (MO). The incorporation of Cu onto the AC, leading to the formation of Cu@AC, resulted in a significant enhancement of the adsorption capacity of AC. The adsorption capacity of Cu@AC was measured using Brunauer-Emmett-Teller (BET) and iodine number measurements, with the most optimal Cu@AC sample exhibiting a BET surface area of 611 m²/g. Surface chemical properties were analyzed through FT-IR spectroscopy, while the microstructure of the produced Cu@AC was examined using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The efficiency of the adsorption process was influenced by factors such as pH, initial dye concentration, adsorbent dosage, and contact time. The most effective processing conditions for dye removal were determined as pH 11 for MB and pH 5 for MO, with an initial concentration of 25 mg/L, a 0.5 g/L adsorbent dosage, and a temperature of 333 K for a duration of 90 min. Under these optimized conditions, removal efficiencies exceeded 90% for MO and 80% for MB. The results demonstrated that Cu@AC has the potential to function as a cost-effective alternative to commercially available activated carbons for efficiently eliminating dyes from contaminated water. [ABSTRACT FROM AUTHOR]

The reaction of dry and pulverized rice husk with alkaline CS2 followed by treatment of the resulting xanthate derivative with zirconyloxychloride at room temperature led to functionalization of the xanthated biomass with sodium zirconate grouping. The as-prepared sodium salt of the rice-husk xanthatozirconate was characterized physicochemically and found to be an efficient, robust, and recyclable catalyst for the three-component synthesis of some spiro[4H-pyran-4,3′-indoline]s in water. [ABSTRACT FROM AUTHOR]

Fairly high yields of 2-aryl-3-nitrodibenzo[e,g] indoles were synthesized via a hitherto unreported domino-reaction of 9,10-phenanthrenequinone, ammonium acetate and β-nitrostyrenes in one pot. This novel three-component synthetic route is efficaciously catalysed by the carboxylated multiwalled carbon nanotubes equipped with superparamagnetic amylose-coated magnetite nanoparticles. This reaction seems to proceed via a Robinson-like annulation of in situ generated phenanthrenequinone imine and presents a novel nitroolefin-based route for annulation of the indole ring. Our experiments display that the internal charge transfer between the aryl group and the indole nucleus of the products can be reversed based on the electronic nature of the aryl group and undergoes a wavelength shift in both absorption and fluorescence emission by changing the pH of the medium. These photophysical properties make the products interesting candidates for application in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Benzylation of DBU followed by anion exchange of the resulting salt with trifluoroacetate gave nearly quantitatively the ionic liquid [Bn-DBU][TFA]. It is shown here to be an efficient catalyst for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones via the three-component reaction of phthalhydrazide, aromatic aldehydes, and active α-methylene nitriles. DFT calculations at the B3LYP/SVP level and the experimental results are in agreement with a three-step mechanism for this reaction. Based on the DFT calculations, the catalytic effect largely arises from the intrinsic ionic properties of the ionic liquid rather than its action as a simple base. These calculations also predict the existence of two close-in-energy activated complexes whose rate determining roles and energies depend on their interaction with the anionic component of the ionic liquid, as [Bn-DBU][TFA] has shown a higher catalytic activity than [Bn-DBU][OAc]. This mechanistic approach opens up new and promising insights into the rational design of ionic liquid catalysts for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones. The synthetic method presented here has several prominent advantages. [ABSTRACT FROM AUTHOR]

The synthesis of spiro[chromeno[4,3- b ]pyrazolo[4,3- e ]pyridine-7,3ʹ-indoline]s is achieved via three-component reactions of 5-amino-3-methylpyrazole, 4-aminocoumarin, and isatin derivatives. This protocol provides expedient synthesis of 10-unsubstituted derivatives of the parent heterocyclic spiro framework and does not lead to coumarin ring opening. The synthesis is highly convergent as no by-products are present in the reaction mixtures. The spiro products show violet fluorescence emissions depending on the nature of their substituents. [ABSTRACT FROM AUTHOR]

A nearly neutral but protic chiral ionic liquid was prepared via neutralization of (1 S)‐(+)‐camphor‐10‐sulfonic acid with N,N‐dimethyl‐n‐octylamine. The structure of this room temperature ionic liquid was confirmed by NMR spectroscopy. It was proved to be an efficient mild promoter for the synthesis of some novel spiro‐oxindoles. The ionic liquid has shown a high asymmetric induction potential, as the spiro‐oxindoles were obtained in high optical purities. All the synthesized spiro‐compounds are new. [ABSTRACT FROM AUTHOR]

Bis-coumarins and xanthenes are privileged compounds with diverse pharmaceutical activities. Hence, we introduce here an efficient synthesis of 3,3′-arylmethylene-bis-(4-hydroxycoumarin-3-yl) and 1,8-dioxooctahydroxanthenes under the soft catalytic activity of magnetite encapsulated hot-water-soluble starch nanoparticles. The greater catalytic efficiency of the bio-derived nano-composite in these syntheses over magnetite and hot-water-soluble starch was ascribed to cooperation of its two components in proton exchange with the reactants. The enhanced proton exchange of the nano-composite was better interpreted as being conducted by its bioorganic shell through switching between the covalent and the coordination bonds it forms with the magnetite core. Application of a nontoxic and superparamagnetic bio-consistent catalyst, simple work-up procedure, and short reaction times are the prominent advantages of the synthetic methods presented here. The nano-catalyst is stable, as it can be recycled in the model reactions at least four times without appreciable decrease in its catalytic activity. [ABSTRACT FROM AUTHOR]

A novel and green synthesis of 2-((2-aryl-3-oxoisoindolin-1-yl)methyl)quinazolin-4(3 H )-one is described. The one-pot three-component reaction between 2-methylquinazolin-4(3 H )-ones, aryl amines and 2-formylbenzoic acid, through a sequential condensation, sp 3 C H bond functionalization and cyclization reactions in aqueous media leads to formation of desired compounds in good to excellent yields. [ABSTRACT FROM AUTHOR]

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A nano‐magnetic core‐shell composite fabricated of a unique zwitterionic chitosanderived coating and cobalt ferrite core was found to be a green and reusable heterogeneous catalyst for efficient synthesis of pyrano[3,2‐c]quinoline and spiro‐oxindole derivatives in high to excellent yields. Due to having negative charges at its outermost layer and a high magnetization, the catalyst is finely dispersed in ethanol and can be easily separated from reaction mixtures by using a simple external magnet. It is reasonably stable as can be reused several times without appreciable loss of catalytic activity. [ABSTRACT FROM AUTHOR]

Novel pyrazole-fused spiro[4H-pyridine-oxindoles] were synthesized under the catalysis of the binary ionic liquid mixture [1,1,3,3-tetramethylguanidinium chloride][1-methylimidazolium-3-sulfonate] in solvent-free conditions. The hitherto unreported binary ionic liquid (BIL) was synthesized via an acid–base reaction and has a melting point much lower than that of the moderate temperature ionic liquid, [1,1,3,3-tetramethylguanidinium chloride], it is made from. The synthesis of the spiro-products was realized via a thermodynamically-favored three-component domino reaction between isatins, 1-phenyl-1H-pyrazol-5(4H)-ones, and 4-aminocoumarin. The domino reaction was highly convergent and functional group tolerant, providing a rapid route to synthesize spiro[4H-pyridine-oxindoles] in fairly high yields from simple bench-stable starting materials. No by-products could be resolved from the reaction mixtures under the optimized conditions. [ABSTRACT FROM AUTHOR]

Several bio-composites of chitosan (CS), as the hydrophilic natural polymer, were prepared by composition with 2, 5, 10 and 15 wt% of rice husk ash (RiHA), as the bio-based filler, via solution casting. These composites were obtained with the aim to improve the hydrophobicity, thermal stability, and degradation mechanism of pure chitosan. The resulting bio-composites were characterized by scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and FT-IR spectroscopy as well as XRD analysis. The SEM images showed amorphous morphology, irregular shape, and the number averaged size of 32 µm for the RiHA particles dispersed in the composites. Investigation of thermal properties of the RiHA-reinforced chitosan composites by TGA/DTG and DSC measurements has revealed some improvements in the thermal behavior of chitosan by the RiHA filler. For instance, the composite made of 15 wt% filler was found to be thermally more stable as it degrades at significantly higher temperatures than the composites containing other portions of the filler. Unlike the other samples that are degraded in three-steps, the weight loss of the composite having 15 wt% of RiHA occurs in two steps. Additional experiments showed that the composites are more hydrophobic than virgin chitosan and the hydrophobicity of the samples is increased by increasing their RiHA component. [ABSTRACT FROM AUTHOR]

The titled products comprising of two mutually merged bioactive nucleuses, 2-aminobenzo[ d]thiazole and 2,5-dihydropyrrole rings, were obtained from the reaction between dialkyl acetylenedicarboxylates and alkyl 2-(benzo[ d]thiazol-2-yl)amino-2-oxoacetates in the presence of triphenylphosphine at RT. [ABSTRACT FROM AUTHOR]

A class of sulfonic ionic liquids, with the supremacy of methylsulfonylimidazolium triflate hydrochloride, was found to be efficient for catalyzing the self-condensation of acetophenone derivatives and sulfonating the resulting condensates in a one-pot rapid reaction leading to the synthesis of 4,6-diaryl-1,2-oxathiine-2,2- dioxides (diaryl-δ-sultones). [ABSTRACT FROM AUTHOR]

The ionic liquid [BMIm]BF4 doped with LiBF4 was found to efficiently catalyze the three-component reaction between isocyanides, acetylenic esters and enols or phenols at room temperature, leading to rapid synthesis of 2-aminopyran-annulated systems in fairly high yields. Efficiency of this catalysis and its benefits in terms of improved yields and reaction times could be ascribed to involvement of relatively stable organolithium intermediates which make the reaction more feasible. The ionic solution tolerates a significant amount of dissolved LiBF4, while remaining fluid at room temperature to serve as solvent for the organic substrates. It retains its initial integrity after use and recovery, as it could be recycled several times without appreciable catalytic decrements. The catalytic activity of the ionic composite is completely lost in the absence of LiBF4. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of novel 4-substituted-3,4-dihydro-6H-pyrano[3,2-c]quinoline-2,5-diones was accomplished efficiently via a three-component reaction between 4-hydroxyquinoline-2-one, Meldrum’s acid, and an alkyl or arylaldehyde under catalysis by [Bmim]HSO4. The ionic liquid catalyst offers the advantage of realizing the synthesis of the title products at ambient temperature and widens the scope of the reactants to include aliphatic aldehydes with respect to the catalysts already applied for similar syntheses. [Copyright &y& Elsevier]

Abstract: A homogeneous ionic liquid made up of 0.5mol% Mg(BF4)2 doped in [BMIm]BF4 was obtained from a mixture of MgCl2 and [BMIm]Cl subjected to anion exchange with NaBF4. The ionic liquid efficiently catalyzes the synthesis of 1,8-dioxo-octahydroxanthenes, 14-aryl-14H-dibenzo[a,j]xanthenes, and 1,8-dioxo-decahydroacridines, giving excellent yields in short periods of time at 80°C. The integrity of the ionic liquid remains reasonably unchanged when it is separated from the reaction mixture by water extraction, as it can be recycled several times without any loss of activity in each of the title syntheses. Magnesium cation, though in low concentration, appeared as an essential element of this ionic liquid catalysis, perhaps due to its non-coordinated existence giving rise to a promoted Lewis acidic characteristic. Application of this new homogeneous catalyst system offered the advantages of high yields, short reaction times, and easy workup procedure compared to the conventional methods of the syntheses. [Copyright &y& Elsevier]

Abstract: A simple and efficient one-pot approach for assembling some fused spiro[4H-pyran-oxindole] heterocycles by means of three-component reactions between isatins, malononitrile or ethyl cyano-acetate, and 1,3-dicarbonyl compounds is reported. The combinatorial syntheses were achieved for the first time without applying extra activation energy at ambient temperature while making use of [BMIm]BF4 as an ionic liquid catalyst. Good functional group tolerance and broad scope of usable substrates are other prominent features of the present methodology. [Copyright &y& Elsevier]

An improvement in the rates of Morita-Baylis-Hillman reactions between isatin derivatives and acrylic esters or acrylonitrile under solvent-free conditions is presented. The reactions proceeded expediently at 0 °C under catalysis by 1,4-diazabicyclo[2,2,2]octane (DABCO) to afford the desired adducts. The optimized conditions are indicative of the presence of the more ordered transition states involved in these reactions, supporting the previously suggested mechanism for similar reactions. [ABSTRACT FROM AUTHOR]

An efficient one-pot synthesis of the biologically important spiro[dihydropyridine-oxindole] scaffold was accomplished simply by the reaction of isatin, 2H-indene-1,3-dione and naphthalen-2-amine in aqueous medium. The scope of this reaction was successfully extended by employing two other reactive ketones (acenaphthylene-1,2-dione and ninhydrin) in place of isatin to access the synthesis of corresponding spirocyclic derivatives. [ABSTRACT FROM AUTHOR]

A new method upon adopting a solid-phase strategy for synthesis of N-aryl succinimides is described here, using the silica-bound benzoyl chloride (SBBC) as dehydrating agent in reaction with N-arylsuccinamic acids. The main advantage of this method is the recyclability of SBBC. [ABSTRACT FROM AUTHOR]