BrØnsted Reusable Acidic Ionic Liquids Catalyzed Biginelli Reaction under Solvent-Free Conditions

Abstract

2-Pyrrolidonium hydrogensulfate, N-methyl-2-pyrrolidonium hydrogensulfate, and N-methyl-2-pyrrolidonium dihydrogenphosphate as Brønsted reusable acidic ionic liquids (ILs) catalyzed the preparation of 3,4-dihydropyrimidin-2(1H)-one (thione) derivatives from ethyl/methyl acetoacetate, urea/thiourea, and aromatic aldehydes under thermal solvent-free conditions.     

Hollow-Fiber-Based LPME as a Reliable Sampling Method for Gas-Chromatographic Determination of Pharmacokinetic Parameters of Valproic Acid in Rat Plasma

A sensitive and simple method based on two-phase liquid-phase microextraction in porous hollow fiber followed by gas chromatography-flame ionization detection was developed for quantification and pharmacokinetic study of valproic acid (VPA, an antiepileptic drug) in rat plasma after oral administration of pure sodium valproate (25 mg kg^?1). Some parameters such as type of organic solvent, pH of sample solution, stirring speed, salt addition, extraction time, and volume of sample that affected extraction efficiency of VPA were optimized. Under optimized microextraction conditions, VPA was extracted with 10 μL 1-octanol from 0.5 mL rat plasma previously diluted with 4.5 mL acidified and salinated water (pH 2) using 1-octanoic acid as internal standard. The limit of detection was 17 ng mL^?1 with linear response over the concentration range of 50–10,000 ng mL^?1 with correlation coefficient higher than 0.998. The developed method was successfully applied to determination of pharmacokinetic parameters such as t _max (peak time in concentration–time profile), C _max (peak concentration in concentration–time profile), t _1/2 (elimination half-life), AUC_0–t (area under the curve for concentration versus time), clearance, and apparent distribution volume in rats following oral administration of VPA.     

In Situ Synthesis and Characterization of Nano ZnO on Wool: Influence of Nano Photo Reactor on Wool Properties

This study has been carried out to synthesize nano ZnO on wool fabric and also to investigate influences of nano photo reactors on wool fabric characteristics. Zinc acetate has been used as a precursor and the synthesis process has been done in water and water/ethanol media. The treated wool fabrics were heated at 80°C for 10 h to dehydrate Zn(OH)₂ obtaining ZnO. The fabric samples were then subjected to daylight for 7 days to examine the influence of nano ZnO photo reactor on the fabric properties. SEM images revealed the embedding of ZnO nanoparticles on the fabrics and X‐ray diffraction verified the nanoparticles composition. The Yellowness Index (YI) of the fabrics was measured with Color Eye XTH that has been reduced with increasing pH, Zn(CH₃COO)₂ concentration, ethanol and heating. The lower water contact angle and time of water absorption confirmed higher hydrophilic properties of the treated fabrics. Interestingly, a higher tensile strength obtained on the wool fabrics proved the interaction of ZnO with protein chains of wool, which was verified through lower alkali solubility of treated fabric with nano ZnO and confirmed more benefits of the in situ synthesis process.     

One-Pot Synthesis and X-Ray Structure of New,Stable Tetrahydropyrrolo [1,2-a][1,10]phenanthrolines with Four Diastereoisomeric Centers

1,10-Phenanthrolinium N-ylides react with ethyl cyanoacetate and aromatic aldehydes via a domino-Knoevenagel cyclization to produce a new class of tetrahydropyrrolo [1,2-a][1,10] phenanthrolines with four diastereoisomeric centers as stable helical compounds in a simple, mild, and efficient protocol in excellent yields. Explicit structural elucidation of compounds was accomplished by single-crystal x-ray diffraction.     

Hollow-Fiber-Based LPME as a Reliable Sampling Method for Gas-Chromatographic Determination of Pharmacokinetic Parameters of Valproic Acid in Rat Plasma

A sensitive and simple method based on two-phase liquid-phase microextraction in porous hollow fiber followed by gas chromatography-flame ionization detection was developed for quantification and pharmacokinetic study of valproic acid (VPA, an antiepileptic drug) in rat plasma after oral administration of pure sodium valproate (25 mg kg⁻¹). Some parameters such as type of organic solvent, pH of sample solution, stirring speed, salt addition, extraction time, and volume of sample that affected extraction efficiency of VPA were optimized. Under optimized microextraction conditions, VPA was extracted with 10 μL 1-octanol from 0.5 mL rat plasma previously diluted with 4.5 mL acidified and salinated water (pH 2) using 1-octanoic acid as internal standard. The limit of detection was 17 ng mL⁻¹ with linear response over the concentration range of 50–10,000 ng mL⁻¹ with correlation coefficient higher than 0.998. The developed method was successfully applied to determination of pharmacokinetic parameters such as t _max (peak time in concentration–time profile), C _max (peak concentration in concentration–time profile), t _1/2 (elimination half-life), AUC_0–t (area under the curve for concentration versus time), clearance, and apparent distribution volume in rats following oral administration of VPA.

     

Kinetics and mechanism of naringenin reaction with Ce(IV) in different aqueous solutions of dimethylsulfoxide

The reaction of naringenin with Ce(IV) was studied in different aqueous solutions of DMSO (50–80% v/v) and various sulfuric acid concentrations using a spectrophotometric method. The reaction was arranged to be under pseudo‐first‐order condition with respect to Ce(IV). It was found that 1 mol of Ce(IV)sulfate on average has consumed by about 2 mol of naringenin to complete the reaction. To determine the stoichiometric ratios of metal ion and the ligand in the formed complex species, the continuous variation method has been used. The results showed that pseudo‐first‐order rate constants increase with increasing naringenin concentration and decrease by increasing the amount of DMSO and sulfuric acid in solution. The rate constant (k₁) was measured at different conditions. Finally, a mechanism consistent with the observed results has been proposed and discussed at various aqueous DMSO solutions. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 715–724, 2011     

Reversible tuning of the wettability of carbon nanotube arrays: the effect of ultraviolet/ozone and vacuum pyrolysis treatments

Among diverse types of synthetic materials, arrays of vertically aligned carbon nanotubes have attracted the most attention, mainly because of their exceptional mechanical, electrical, optical, and thermal properties. However, their wetting properties are yet to be understood. In this present study, oxygenated surface functional groups have been identified as a vital factor in controlling the wetting properties of carbon nanotube arrays. The results presented herein indeed show that a combination of ultraviolet/ozone and vacuum pyrolysis treatments can be used to vary the surface concentration of these functional groups such that the carbon nanotube array can be repeatedly switched between hydrophilic and hydrophobic.     

Designing a sequential Ugi/Ullmann type reaction for the synthesis of indolo[1,2-a]quinoxalinones catalyzed by CuI/l-proline

An efficient strategy for the one-pot syntheses of indolo[1,2-a]quinoxalinones catalyzed by CuI have been developed. The procedures combine the Ugi four-component reaction of aldehydes, 2-iodoaniline, 2-indole carboxylic acid, and isocyanides followed by the copper-catalyzed intramolecular N-arylation of the Ugi product in one-pot procedure, which afford the desired products in good to very good yields.     

Palladium catalyzed stereoselective synthesis of 3-(anilinoarylmethylene)-2-oxindoles as Hesperadin analogoues

Potentially bioactive 3-(anilinoarylmethylene)-2-oxindoles as Hesperadin analogoues have been synthesized via a two-step procedure: (a) an Ugi-4MCR and (b) reaction of the Ugi adduct with aniline in the presence of a palladium catalyst via domino Heck/Buchwald reaction. In all cases, a single isomer with the Z-configuration was obtained in good to high yields.     

Granulated copper oxide nanocatalyst: a mild and efficient reusable catalyst for the one-pot synthesis of 4-amino-5-pyrimidinecarbonitriles under aqueous conditions

Abstract  

An efficient method for the synthesis of 4-amino-5-pyrimidinecarbonitriles by the three-component reaction of malononitrile, aldehydes, and N-unsubstituted amidines under aqueous conditions using CuO microspheres as catalyst is reported. The catalyst exhibited remarkable reusable activity.