Novel ferrocene-based ionic liquid supported on silica nanoparticles as efficient catalyst for synthesis of naphthopyran derivatives

We report synthesis of silica nanospheres containing ferrocene-tagged imidazolium acetate (SiO₂@Im-Fc[OAc]) as efficient heterogeneous nanocatalyst for synthesis of naphthopyran derivatives under solvent-free conditions, based on modification of nano SiO₂ by ionic liquid with ferrocene tags and subsequent anion metathesis reaction. The synthesized novel nanocatalyst (SiO₂@Im-Fc[OAc]) was systematically characterized using Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, and field-emission scanning electron microscopy. The catalytic activity of (SiO₂@Im-Fc[OAc]) was tested in one-pot three-component reaction of aromatic aldehydes, malononitrile, and 2-naphthol for facile synthesis of naphthopyran derivatives. To achieve high catalytic efficacy, the effects of various reaction parameters such as temperature, amount of catalyst, type of solvent, etc. were investigated. Furthermore, recovery and reuse of the nanocatalyst several times was demonstrated without appreciable loss in catalytic activity. The presented protocol offers several advantages, including green and ecofriendly nature, operational simplicity, higher yield, and easy recovery and reuse of the nanostructured catalyst. The workup of these very clean reactions involves only recrystallization of the product from ethanol and recovery of the catalyst by filtration.     

Sequential Ugi Four‐Component Reaction (4‐CR)/CH Activation Using (Diacetoxyiodo)benzene for the Synthesis of 3‐(Diphenylmethylidene)‐2,3‐dihydro‐1H‐indol‐2‐ones

A sequential Ugi four‐component reaction (4‐CR)/C? H activation using (diacetoxyiodo)benzene is reported. This process is a five‐component reaction of aromatic aldehydes, aniline derivatives, isocyanides, phenylpropiolic acid (3‐phenylprop‐2‐ynoic acid), and (diacetoxyiodo)benzene for the synthesis of 3‐(diphenylmethylidene)‐2,3‐dihydro‐1H‐indol‐2‐ones. This procedure offers several advantages such as good yields, high bond‐forming efficiency, selectivity, and short reaction times.     

Composite of conducting polyaniline-isobutylated urea formaldehyde: Preparation and characterization

Composite of conductive polyaniline-isobutylated urea formaldehyde have been prepared by chemical oxidative emulsion polymerization of aniline in the presence of isobutylated urea formaldehyde resin (BUFR) in toluene-water solvents at room temperature. The mass loading of polyaniline was controlled by varying the BUFR/aniline charging ratio as well as oxidant (ammonium persulfate)/aniline molar ratio. Some factors capable of affecting the yield and conductivity of composite, such as amount of the oxidant, type of the dispersants (span-80 and span-20), and amount of resin and organic acid (para-toluene sulfonic acid) were investigated. The prepared composites were characterized by FTIR spectroscopy and scanning electron microscopy (SEM).     

Effect of Aqueous Ablation Environment on the Characteristics of ZnO Nanoparticles Produced by Laser Ablation

Effect of ablation environment on the nature of ZnO nanoparticles produced by laser ablation method in liquid medium is investigated experimentally. High purity Zn plate was irradiated by the fundamental beam of a Q-switch Nd-YAG laser in cetyltrimethylammonium bromide (CTAB), acetone, sodium dodecyl sulfate and water. Produced nanoparticles were characterized by UV–Vis absorption spectroscopy, transmission electron microscopy, scanning electron microscopy, X-ray diffraction spectrum, and fourier transform infrared spectroscopy. Results show that the highest rate of ablation occurs in CTAB. Largest nanoparticles are produced in acetone, and crystallinity of nanoparticles produced in CTAB is higher than other samples. CTAB surfactant changed the morphology of ZnO nanoparticles.     

Hydrodynamics and oxygen mass transfer in a packed bed split-cylinder airlift reactor containing dilute alcoholic solutions

In this article, the influences of alcohols on the hydrodynamics and oxygen mass transfer characteristics in an airlift reactor equipped with packing were investigated. The hydrodynamic parameters and mass transfer coefficient in 1 % (v/v) aqueous solutions of four aliphatic alcohols were tested. It was concluded that alcohols addition increased gas holdup and gas–liquid mass transfer coefficient. The packing installation increased mass transfer coefficient, gas holdup and liquid circulation velocity, as well.     

Photoluminescence of ZnO nanoparticles generated by laser ablation in deionized water

Zinc oxide (ZnO) nanoparticles were synthesized using pulsed laser ablation of a Zn metal plate in deionized water without using surfactant. The beam of a Q-switched Nd:YAG laser of 1064-nm and 532-nm wavelengths at 6-ns pulse width and different fluences is employed to irradiate the solid target in water. Transmission electron microscopy images revealed that the size of the ZnO nanoparticles formed by the 532-nm wavelength laser beam is smaller than that of the nanoparticles generated by the 1064-nm wavelength laser beam. The room-temperature photoluminescence spectra of the ZnO nanoparticles show intense violet emission along with emission in blue and green bands. The excellent ultraviolet emission indicates that the ZnO nanostructures have a low defect concentration.     

Selective separation of yttrium(III) through a liquid membrane system using 2-thenoyltrifluoroacetone as an extractant carrier

2-Thenoyltrifluoroacetone has been offered as a mobile carrier in organic phase for the transport and selective separation of yttrium from aqueous media using a liquid membrane system. Perceivably, the use of n-propylamine (PA) in the source phase enhances the transport of yttrium ions. The extraction and stripping conditions have entirely been evaluated and explained. The suggested method has been utilized for the separation of yttrium(III) from its binary mixtures with strontium(II) and some other cations such as Ni²⁺, Co²⁺, Ag⁺, Fe²⁺, Al³⁺, Cu²⁺, Hg²⁺and Cs⁺ in aqueous solutions of pH 5.4 in the presence of PA, while 1 M nitric acid was acting as a stripping agent in the receiving division. Cyanide ion and 5-sulfosalicylic acid have been used as masking agents to minimize the interferences from different transition metal ions and Al³⁺ in the source phase, respectively. ⁹⁰Y in secular equilibrium with ⁹⁰Sr in the source phase, was transferred to receiving phase and separated completely from its long-lived parent isotope. The activity of the transported ⁹⁰Y was found to decay with a half-life 64.17 ± 0.05 h. The purity of yttrium-90 was comparable or better than the other applied liquid membrane systems for purification of yttrium-90.     

Practical and efficient synthesis of tetrahydrobenzo[<Emphasis Type="Italic">b</Emphasis>]pyran using caffeine supported on silica as an ionic liquid solid acid catalyst

The new catalyst silica-caffeine hydrogen sulfate [SiO₂-caff.]HSO₄ was conveniently prepared from commercially available 3-chloropropyltriethoxysilane via immobilization on silica followed by reaction with caffeine. The catalyst prepared was then characterized by the FT-IR spectroscopy, TGA, EDX, and SEM techniques. It was found that this heterogeneous catalyst was a highly efficient one for the synthesis of tetrahydrobenzo[b]pyrans in good-to-high yields, and could be recovered by a simple filtration of the reaction solution and reused for five consecutive runs. The attractive features of this method are simple procedure, clean reaction, easy work-up, use of a reusable catalyst, and performing a multi-component reaction.     

An efficient one-pot synthesis of tetra-substituted pyrroles

The three-component reaction of primary amines, dialkyl acetylenedicarboxylates and β-nitrostyrene derivatives in the presence of Iron(III) chloride afforded 1,2,3,4-tetra-substituted pyrroles in high yields. These reactions could precede via domino Michael addition/cyclization process.