Search

Abstract: An efficient methodology employing copper nanoparticles for the preparation of 2-naphthol condensed 1,3-oxazinone derivatives employing one-pot condensation reaction in the presence of K2CO3 and copper nanoparticles in PEG-400 is described which offers several advantages, viz. high yields, clean reaction, short reaction times, recyclability of the catalyst and simple workup procedure. PEG-400 was found to be the best solvent out of a range of solvents examined for this scheme. Moreover, PEG could stabilize the nanoparticles from oxidation and thus could increase the catalyst efficiency by escalating the TON (Turn over Number) and TOF (Turn over Frequency) of the catalyst, making the protocol greener, eco-friendly and environmentally benign. [Copyright &y& Elsevier]

Abstract: Nanoparticles of MgO, Al2O3, CaO and SiO2 were synthesized using aerogel route, and characterized by N2-BET, SEM, TEM, XRD, TGA and FT-IR techniques. Characterization indicated 2–75nm diameter nanoparticles with 135–887m2/g surface area and microporous–mesoporous characteristics. Prepared nanoparticles were tested for their adsorptive potential by conducting studies on kinetics of adsorption of diethylchlorophosphate under static conditions. The kinetic parameters such as equilibration constant, equilibration capacity, diffusional exponent and adsorbate–adsorbent interaction constant have been determined using linear driving force model and Fickian diffusion model. AP-MgO and AP-CaO showed the maximum (1011mg/g) and minimum (690mg/g) uptake of DEClP, respectively. All nanoparticles showed the values of diffusional exponent to be >0.5, indicating the diffusion mechanism to be anomalous. Hydrolysis reaction (identified using GC/MS technique) was found to be the route of degradation of DEClP. [Copyright &y& Elsevier]

Abstract: Nanoparticles of AP-Al2O3 (aero-gel produced alumina) have been produced by an alkoxide based synthesis involving aluminum powder, methanol, toluene and water. Thus produced alumina nanoparticles were characterized and the data indicated the formation of nanoparticles of alumina in the size range of 2–30nm with high surface area (375m2/g). Thereafter, these nanoparticles were impregnated with reactive chemicals. Adsorptive removal kinetics for DEClP (diethylchlorophosphate) and GB (isopropylmethylphosphonofluoridate, sarin) was monitored by GC–FID (gas chromatograph coupled with flame ionization detector) technique and found to be following pseudo first order reaction kinetics. Among impregnated AP-Al2O3 nanoparticles based sorbent systems AP-Al2O3 impregnated with 9-molybdo-3-vanadophosphoric acid (10%, w/w) was found to be the most reactive with least half-life values of 7 and 30min for the removal of DEClP and GB, respectively, whereas unimpregnated AP-Al2O3 nanoparticles showed the best adsorption potential among all studied systems. In addition to this, hydrolysis reaction {identified using GC/MS (gas chromatograph coupled with mass spectrometer) technique} was found to be the route of degradation of DEClP and GB on impregnated alumina nanoparticles. [Copyright &y& Elsevier]

Abstract: Alumina nanoparticles in the size range of 2–30nm and surface area 375m2/g were synthesized using aerogel route and then characterized using N2–BET, SEM, TEM, XRD, FTIR and TGA techniques. Thereafter, these were impregnated with reactive chemicals and tested for their potential by conducting studies on kinetics of adsorption of 2-chloroethylethylsulphide (2-CEES) under static conditions. Kinetics was studied using linear driving force and Fickian diffusion model. The kinetics parameters such as equilibration constant, equilibration capacity, diffusional exponent and adsorbate–adsorbent interaction constant were also determined. AP-Al2O3 with 10% impregnation of MoVPA (V3) and NaOH showed the maximum (574mg/g) and minimum (88mg/g) uptake of 2-CEES among impregnated systems respectively. All impregnated systems except NaOH impregnation showed the values of diffusional exponent to be <0.5, indicated the diffusion mechanism to be Fickian, whereas AP-Al2O3 with and without NaOH impregnation showed the diffusional mechanism to be anomalous. Hydrolysis and dehydrohalogenation reactions (identified using GC/MS technique) were found to be the route of degradation of 2-CEES. [Copyright &y& Elsevier]

Abstract: High surface area (887.3m2/g) silica nanoparticles were synthesized using aerogel route and thereafter, characterized by N2-Brunauer–Emmet–Teller (BET), SEM and TEM techniques. The data indicated the formation of nanoparticles of silica in the size range of 24–75nm with mesoporous characteristics. Later, these were impregnated with reactive chemicals such as N-chloro compounds, oxaziridines, polyoxometalates, etc., which have already been proven to be effective against sulphur mustard (HD). Thus, developed novel mesoporous reactive sorbents were tested for their self-decontaminating feature by conducting studies on kinetics of adsorptive removal of HD from solution. Trichloroisocyanuric acid impregnated silica nanoparticles (10%, w/w)-based system was found to be the best with least half-life value (t 1/2 =2.8min) among prepared systems to remove and detoxify HD into nontoxic degradation products. Hydrolysis, dehydrohalogenation and oxidation reactions were found to be the route of degradation of HD over prepared sorbents. The study also inferred that 10% loading of impregnants over high surface area and low density silica nanoparticles enhances the rate of reaction kinetics and seems to be useful in the field of heterogeneous reaction kinetics. [Copyright &y& Elsevier]

Abstract: Nanoparticles of AP–Al2O3 (aerogel produced alumina) have been produced by an alkoxide based synthesis involving aluminum powder, methanol, toluene and water. Thus produced alumina nanoparticles were characterized by N2-BET, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transformed infra-red spectroscopy and thermogravimetry techniques. The data indicated the formation of nanoparticles of alumina in the size range of 2–30nm with high surface area (375m2/g) and microporous–mesoporous characteristics. Thereafter, these nanoparticles were impregnated with polyoxometalates and other reactive chemicals, which have already proven to be effective against sulphur mustard (HD). Adsorptive removal kinetics for HD was monitored by GC–FID (gas chromatograph coupled with flame ionization detector) technique and found to be following pseudo first order reaction kinetics. Among polyoxometalates impregnated alumina nanoparticles based novel mesoporous reactive sorbent systems AP–Al2O3 impregnated with 9-molybdo-3-vanadophosphoric acid (10%, w/w) was found to be the most reactive with least half life value (214min). In addition to this, degradation products of sulphur mustard on prepared mesoporous reactive sorbents were identified using GC/MS technique. Hydrolysis, dehydrohalogenation and oxidation reactions were found to be the route of degradation of sulphur mustard. [Copyright &y& Elsevier]

In this study, liver-directed gene transfer in rats with calcium phosphate (CaP) nanoparticles and the effect of the route of administration and surgical manipulations on transfection efficiency is reported. Formulations of CaP nanoparticles entrapping plasmid DNA (pDNA) were prepared by the reverse micellar method using two different surfactants. Transmission electron microscopy, scanning electron microscopy and dynamic light scattering were used to characterize the CaP–DNA nanocomposites. The morphological characteristics of the formulations showed a strong dependency on temperature. Gel electrophoresis experiments indicated that there was no degradation of the encapsulated pDNA, and in vitro cell transfection in HEK-293 and primary hepatocytes from rats as well as in vivo intraductal delivery experiments suggested that CaP nanoparticles led to significant and prolonged transgene expression. Therefore, our methodology gives a stable and viable formulation for hepatic gene therapy. Low-DNA dosage entrapped in CaP nanoparticles makes it an effective gene delivery system for clinical applications. [ABSTRACT FROM AUTHOR]

Abstract: Use of highly monodispersed, easily recyclable and cheap nickel nanoparticles for oxidative coupling of aliphatic, aromatic, cyclic and heteroaromatic thiols to their corresponding disulfides has been reported. Ni-nanoparticles act as a green catalyst that can selectively catalyse oxidative coupling of thiols to disulfides without producing any over-oxidized products. The catalytic reaction occurred at room temperature with excellent yield under air atmosphere and high TON and TOF value could be achieved. Effect of solvent polarity and size distribution of the Ni-nanoparticles on the catalytic efficiency have been investigated. Nickel nanoparticles could be easily recovered by mild centrifugation. [Copyright &y& Elsevier]

Abstract: In principle, the technique of gene delivery involves taking complete or parts of genes that can code specific message and delivering them to selected cells in the body. Such a transfer of plasmid DNA into mammalian cells has posed major challenges for gene therapy. This study shows the encapsulation of a plasmid DNA in cross-linked polyvinylpyrrolidone (PVP) nanoparticles of size less than 100nm. This kind of encapsulation provides complete protection to the plasmid DNA from external DNase environment and generates the hope that the resulting formulation can be developed into a potential vector for effective gene delivery. In order to check this potentially, the reporter gene pSVβ-gal was encapsulated and in vitro transfection efficiency of this system was found to be nearly 80% compared to the commercially available transfection reagent PolyfectR. Further, in vivo biodistribution studies indicated that this system could be used safely for effective gene delivery. [Copyright &y& Elsevier]

A significant quantity of hydrocarbons remains in the reservoir after production using primary and secondary techniques. Traditional recovery techniques produce about 33 % of the original oil in place. However, the utilization of chemicals such as surfactants and polymers facilitate the additional recovery of one‐third of this oil. Researchers are currently aiming at mixing surfactant and nanoparticles for their potential applications in petroleum industry. In this work, authors claimed to be the first to study usage of synthesized Mesoporous Silica Nanoparticles (MSN) with Sodium Dodecyl Sulphate (SDS) surfactant to understand its applicability in Chemical Enhanced Oil Recovery through evaluation of the surface tension & Interfacial tension, surfactant adsorption, contact angle, and core flooding experiments. Surface tension studies revealed a synergistic interaction between MSN and anionic surfactant molecules. With the introduction of 2500 ppm of anionic surfactant, the surface tension of deionized water reduces to 34.5 mN/m from 72.4 mN/m. The surface tension of the mixture was further lowered by ∼9.8 % with the addition of 300 ppm MSN. The Interfacial Tension results also showed the same trend. When 300 ppm of MSN was introduced, then IFT values decreases from 8.13 mN/m to 3.91 mN/m at 2500 ppm of anionic surfactant. Contact angle measurements after MSN injection went from 77.98° for SDS (2500 ppm) to 73.36°, 66.54°, and 41.95° for 100, 200, and 300 ppm of MSN, respectively. This demonstrates that the shift toward water‐wet behavior increased along with the MSN concentration. Additionally, adding 300 ppm of MSN lowered surfactant adsorption by ∼80 % at a surfactant concentration of 2500 ppm. Up to 72.27 % of the OOIP could be recovered using the chemical slug made of SDS surfactant, polymer, and MSN. The research data suggests that the MSN can increase the effectiveness of the chemical injection approach, which can be used to recover more oil. [ABSTRACT FROM AUTHOR]

Surfactant flooding is a prolific enhanced oil recovery technique. It alters the rock fluid interfacial interactions between reservoir fluids and rocks. However, a pair of impeding factors often limit the economic viability of the process and need to be optimized. The first is the surfactant loss on the adsorbent surface due to adsorption making it a potential environmental problem. The second is the Critical Micelle Concentration (CMC) which governs the amount of surfactant pumped. This study aimed to minimize the surfactant loss and the CMC, thereby optimizing the flooding efficiency and reducing the environmental concerns for nanoparticle applications. To achieve this, Silicon Carbide nanoparticles (SCN) were employed as additives to the surfactant solution. It was observed that the use of SCN reduces the surfactant adsorption by as much as 44 % and the critical micelle concentration by 14 %. The studies also observed that the concentration of SCN required to get these results is dramatically (more than 25 times) lower than previously reported literature on other nanoparticles. To adsorption isotherm studies provide an insight into the type of adsorption taking place. The adsorption isotherm follows the Langmuir model. [ABSTRACT FROM AUTHOR]

We report here a method by which Ni-nanoparticles can be used efficiently to catalyze the acetylation of a variety of amines and thiols under ambient conditions at room temperature. However in a competitive reaction, the thiol was acetylated selectively while the amine remained almost unaffected. The demonstrated chemoselectivity could have multiple potential synthetic applications. Some of the major advantages of this method are high yields, selectivity, short reaction times (<40 min), ease of operation, and compatibility with other protecting groups. Additionally, the process reported is environmentally benign. [ABSTRACT FROM AUTHOR]

We recently reported a novel synthesis of copper nanoparticles from copper sulphate utilizing the charge-compensatory effect of ionic liquid [bmim]BF4 and ethylene glycol. The nanoparticles were characterized and found to be stable for one year. Here we hypothesize that the stabilized nanoparticles should be able to catalyze one-pot multicomponent organic reactions. We show that the nanoparticles catalyzed Biginelli reaction at room temperature to give the product 3,4- dihydopyrimidinone (.90% yield in ,15 minutes) from aldehydes, β-diketoester (ethylacetoacetate) and urea (or thiourea). ). Remarkably, such high yields and rapid kinetics was found to be independent of the electronic density on the reactant aryl-aldehyde. This was probably because even the surface-active particles reacted faster in the presence of ionic liquid as compared to conventional methods. The heterocyclic dihydropyrimidinones (DHPMs) and their derivatives are widely used in natural and synthetic organic chemistry due to their wide spectrum of biological and therapeutic properties (resulting from their antibacterial, antiviral, antitumor and anti-inflammatory activities. Our method has an easy work-up procedure and the nanoparticles could be recycled with minimal loss of efficiency. [ABSTRACT FROM AUTHOR]

In this work, we present a novel method for the synthesis of copper nanoparticles. We utilize the charge compensatory effect of ionic liquid [bmim]BF4 in conjunction with ethylene glycol for providing electro-steric stabilization to copper nanoparticles prepared from copper sulphate using hydrazine hydrate as a reducing agent. The formed copper nanoparticles showed extended stability over a period of one year. Copper nanoparticles thus prepared were characterized by powder X-ray diffraction measurements (pXRD), transmission electron microscopy (TEM) and quasi elastic light scattering (QELS) techniques. Powder X-ray diffraction (pXRD) analysis revealed relevant Bragg's reflection for crystal structure of copper. Powder X-ray diffraction plots also revealed no oxidized material of copper nanoparticles. TEM showed nearly uniform distribution of the particles in methanol and confirmed by QELS. Typical applications of copper nanoparticles include uses in conductive films, lubrication and nanofluids. Currently efforts are under way in our laboratory for using these nanoparticles as catalysts for a variety of organic reactions. [ABSTRACT FROM AUTHOR]

Abstract: Recyclable Ni-nanoparticles provides an efficient, economic and rapid method for catalyzing Knoevenagel condensation of aldehydes with an active methylene compound at room temperature. The method offers high yield preferably in case of aromatic aldehydes and proceed well in neutral medium. This method provides a wide range of substrate applicability and simple workup procedure. The products need no further purification and the process is environmentally benign. [Copyright &y& Elsevier]

An efficient method for the preparation of 1,3-dithiolanes of aliphatic and both activated and deactivated aromatic carbonyl compounds with 1,2-ethanedithiol in the presence of a catalytic amount of inexpensive, easily recyclable, monodispersed, chemoselective Ni-nanoparticles having high TON and TOF is reported. An efficient method for the chemoselective thioacetalization of ketones in the presence of aldehydes using Ni-nanoparticles is also reported in this article. Our reaction is kinetically controlled and the method is relatively expedient, avoids the use of cost-prohibitive reagents, high temperatures and leads to excellent yield. Selective Protection of Carbonyl Compounds Over Nano-sized Nickel Catalysts Ajeet Kumar,a Santosh Kumar,a Amit Saxena,a Arnab De,b Subho Mozumdara* aDepartment of Chemistry, University of Delhi, Delhi, 110007, India; b Department of Chemistry, Indiana University, Bloomington, USA; subhoscom@yahoo.co.in An efficient method for the preparation of 1,3-dithiolanes of aliphatic and both activated and deactivated aromatic carbonyl compounds with 1,2-ethanedithiol in the presence of a catalytic amount of inexpensive, easily recyclable, monodispersed, chemoselective Ni-nanoparticles having high TON and TOF is reported. We report an efficient method for the chemoselective thioacetalization of ketones in the presence of aldehydes using Ni-nanoparticles. Our reaction is kinetically controlled and the method is relatively expedient, avoids the use of cost-prohibitive reagents, high temperatures and leads to excellent yield. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: Biologically active quinoxalines were efficiently synthesized in excellent yields and in less reaction time using inexpensive, monodispersed and easily recyclable Ni-nanoparticles. In order to elucidate the role of the Ni-nanoparticles, a control reaction was conducted using glyoxal and o-phenylenediamine in acetonitrile in the absence of Ni-nanoparticles. Quinoxaline was formed in around 10h with a 30% yield. However, the same reaction carried out in acetonitrile using 10mol% of Ni- nanoparticles (14–18nm) at 25°C and stirred under N2 gave quinoxaline in quantitative yield in 10min. The separation of the product was facile and the catalyst could be separated and recycled by mild centrifugation. Our method is very quick, avoids the use of expensive reagents, high temperatures (our reaction takes place at room temperature) and leads to excellent yield. [Copyright &y& Elsevier]

Abstract: Cu-Nanoparticles provide an efficient catalysis for the synthesis of 2-arylbenzoxazoles by the coupling of aromatic or heteroaromatic aldehydes with 2-aminophenol though the oxidative cyclization of the Schiffs’ bases using 10mol% of the Cu-nanoparticles in the presence of K2CO3 in MeOH. This method avoids the use of metal oxide or organic oxidizing agents, namely, DDQ or strong acids such as polyphosphoric acid or boric acid. [Copyright &y& Elsevier]

Abstract: A novel method for reduction of aromatic and heteroaromatic aldehydes with ammonium formate using Ni-nanoparticles is described. The Ni-nanoparticles act as a green catalyst for selective reduction of the aldehydic group in the presence of other functional groups, viz.: –NO2, –CN and alkenes to give the corresponding alcohols in excellent yields. [Copyright &y& Elsevier]

Abstract: Polymeric nanoparticles of AADG cross-linked with MBA encapsulating water soluble macromolecules such as FITC-Dextran have been prepared in the reverse micellar system. The particles obtained were of >85nm in diameter which were highly monodisperse. An optically clear solution was obtained on redispersing these nanoparticles in aqueous buffer. Size and morphology of the particles remains the same on re-dispersing the lyophilized powder of these nanoparticles in aqueous buffer. The size dependency of the particles on the monomer and surfactant concentration was observed. The average size of the nanoparticles as obtained from DLS studies ranges from 74 to 114nm in case 0.06M AOT and 62–104nm in case of 0.1M AOT concentration. FITC-Dextran was entrapped into nanoparticles with high efficiency (>70%). The pH dependent release of the entrapped molecules from these nanoparticles was also studied. At pH 5.0 solution, ∼43% of FITC-Dx was released and at pH 7.4 it was about 70%. [Copyright &y& Elsevier]

Abstract: A novel method for effecting the aza-Michael reactions of N-alkyl- and N-arylpiperazines with acrylonitrile using Cu-nanoparticles is described. The method features the use of 10mol% Cu (14–17nm) nanoparticles under mild reaction conditions to afford the addition products in good to excellent yields. The Cu-nanoparticles selectively catalysed the aza-Michael reaction of N-alkyl- and N-arylpiperazines in the presence of aromatic amino or aliphatic hydroxy groups. [Copyright &y& Elsevier]