Facile One‐pot Synthesis of Substituted Dihydropyrrol‐2‐ones via Four‐component Domino Reaction of Amines,Dialkyl Acetylenedicarboxylates and Formaldehyde

A mild and efficient method for the one‐pot synthesis of substituted dihydropyrrol‐2‐one derivatives is described via four‐component domino reaction of amines, dialkyl acetylenedicarboxyaltes and formaldehyde in the presence of 1‐methyl‐2‐oxopyrrolidinium hydrogen sulfate ([Hpyro][HSO₄]) as ionic liquid catalyst. This facile approach proceeded smoothly in good to high yields and pure products are separated from the reaction mixture by simple filtration.     

Determination of pKa values for (E)-2-hydroxy-5-(aryldiazenyl) benzaldehydes in dimethyl sulfoxide: Cyclic voltammetry and density functional theory calculations

The (E)-2-hydroxy-5-(aryldiazenyl) benzaldehydes (azo dyes 1–4 ) were synthesized in high purity. As they are insoluble in water, the usual analytical methods cannot be utilized to determine their pK_a values. Cyclic voltammetry was experimentally used to determine their pKa values in DMSO solvent. In addition, computational methods and a conductor-like screening model (COSMO) were used to calculate the solvent effect. , , K_exchange, and pK_a values were estimated for the azo dyes being studied using the BP86, TPSS, B3LYP, PBE0, TPSSh, and PW6B95 density functionals in def2-TZVP basis sets. The obtained mean absolute deviations (MADs) indicate that the results of BP86, PBE0, and PW6B95 functionals are in good agreement with experimental values.     

Synthesis of a nano‐sized chiral imprinted polymer and its use as an (S)‐atenolol carrier in the bulk liquid membrane

In this work, nanosized chiral imprinted polymers containing (S)‐atenolol ((S)‐ATN) selective sites were synthesized by using suspension polymerization in silicon oil. (S)‐ATN, methacrylic acid, and ethylene glycol dimethacrylate were used as enantiomerically pure template, functional monomer, and cross‐linker, respectively. The prepared chiral imprinted polymers were used as the carrier elements in a bulk liquid membrane (BLM). (S)‐ATN transport capability of the chiral imprinted polymers was compared with that of the nonimprinted polymer. It was shown that chiral imprinted polymers could transport (S)‐ATN through the BLM more effectively than (R)‐ATN, whereas no difference in the facilitated transport was observed between (R)‐ATN and (S)‐ATN when using nonimprinted polymer particles as the carrier element in the BLM. A kinetic model was proposed for the transportation of (S)‐ATN through the chiral imprinted polymers based BLM. It was found that the extraction of ATN from the source to the membrane controls the chiral separation process. It was also found that the pH of source and receiving phases as well as the racemic ATN concentration in source phase had very crucial effect on the chiral separation efficiency.     

An Efficient One‐pot Access to Substituted Dihydropyrrol‐2‐one Derivatives Using Sucrose as Natural,Biodegradable and Inexpensive Catalyst

An efficient and simple procedure for the synthesis of highly substituted dihydropyrrol‐2‐ones has been developed via one‐pot four‐component condensation of amines, dialkyl acetylenedicarboxyaltes and formaldehyde in the presence of sucrose as an organocatalyst. The salient advantages of this method are using a natural, biodegradable and commercial available catalyst, good yields, short reaction times, simple work‐up and lack of need for column chromatography.     

Atomic absorption spectrometric determination of trace zinc in alloys and biological samples after preconcentration with [1-(2-pyridylazo)-2-naphthol] on microcrystalline naphthalene

An atomic absorption spectrometric method for the determination of trace amounts of zinc after adsorption of its [1-(2-pyridylazo)-2-naphthol] complex on microcrystalline naphthalene has been developed. This complex is adsorbed on microcrystalline naphthalene in the pH range 3.5-7.5 from large volumes of aqueous solutions of various alloys and biological samples with a preconcentration factor of 40. After filtration, the solid mass consisting of the zinc complex and naphthalene was dissolved with 5 ml of dimethylformamide and the metal was determined by flame atomic absorption spectrometry. Zinc can alternatively be quantitatively adsorbed on [1-(2-pyridylazo)-2-naphthol]-naphthalene adsorbent packed in a column and determined similarly. About 0.5 ng of zinc can be concentrated in a column from 200 ml of aqueous sample, where its concentration is as low as 2.5 pg ml-1. The calibration curve is linear in the range 0.1-6.5 ng ml-1 in dimethylformamide solution. Eight replicate determinations of 2 ng ml-1 of zinc gave a mean absorbance of 0.145 with a relative standard deviation of 1.5%. The sensitivity for 1% absorption was 0.061 ng ml-1. Various parameters, such as the effect of pH and the interference of a number of metal ions on the determination of zinc, have been studied in detail to optimize the conditions for the determination of zinc in various standard complex materials.     

Electrocatalytic determination of L-cysteine using a modified carbon nanotube paste electrode:Application to the analysis of some real samples

The electrooxidation of L-cysteine(L-Cys) was studied using a benzoylferrocene(BF) modified multi-wall carbon nanotube paste electrode(BFCNPE) using cyclic voltammetry(CV),square wave voltammetry(SWV) and chronoamperometry(CHA).Under optimum pH in CV the oxidation of L-Cys occurs at a potential about 215 mV less positive than that at the surface of unmodified carbon paste electrode.The catalytic oxidation peak currents were dependent on the L-Cys concentration and a linear calibration curve was obtained in the range 0.7-350.0 mmol/L of L-Cys with SWV method.The detection limit(3s) was determined as 0.1 mmol/L.This method was also used for the determination of L-Cys in some real samples.     

Synthesis and Crystal Structure Study of Diethyl Aryl(benzo[d]thiazol‐2‐ylamino)methyl Phosphonates

A three‐component synthesis of α‐aminophosphonate is described from a reaction between aldehydes, 2‐aminobenzothiazole, and triethyl phosphite in the presence of InCl₃ as a catalyst under solvent‐free conditions for the generation of the particular α‐aminophosphonates. These products have two potentially biologically active parts, aminophosphonate and benzothiazole. This method offers advantages such as short reaction times, good yields, solvent‐free conditions, and easy workup with the green aspects by avoiding toxic catalysts and solvents. The crystal structure of 4b has been determined by X‐ray crystallography. This compound crystallizes in the monoclinic space group C2/c with cell parameters a = 21.9285(5) Å, b = 10.3221(2) Å, c = 18.5979(5) Å, β = 108.759(3)°, V = 3985.99(18) ų, D_calc = 1.301 mg m⁻³, and Z = 8. The final R value is 0.0501 for 3741 reflections. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 24:58–65, 2013; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21063     

Solvent-Free Conditions as an Eco-Friendly Strategy for Synthesis of Organophosphorus Compounds

A series of diverse NH- and CH-acids are used for a one-pot synthesis of stable phosphorus ylides and 1,4-diionic organophosphorus compounds by trapping of the zwitterionic intermediate from the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates under solvent-free conditions. The structural geometry for one of the products was confirmed by single crystal X-ray diffraction analysis.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Facile and Convenient Synthesis of 5-Arylalkylidenerhodanines by Electrocatalytic Crossed Aldol Condensation

Abstract

An electrochemically induced catalytic crossed Aldol condensation of one equivalent of rhodanine with various aromatic aldehydes and ketones in ethanol in an undivided cell in the presence of sodium bromide as an electrolyte results in the formation of the corresponding 5-arylalkylidenerhodanines in 80–96% yield with reactions in 40 min.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Toluene chemiresistor sensor based on nano-porous toluene-imprinted polymer

In this work, the application of molecularly imprinted polymer (MIP) as the recognition element of a chemiresistor sensor was introduced. Toluene-imprinted polymer and non-imprinted polymer (NIP) were synthesized and then mixed with carbon black powder in the presence of melted n-eicosane as the binder agent. The obtained composites were applied for the construction of chemiresistor sensors. The sensor, fabricated with toluene-imprinted polymer, showed a significant response towards toluene. Moreover, the response of the NIP-based (polymer synthesized without solvent) chemiresistor sensor was very small and negligible. The components of the MIP-based sensing composite were found to strongly influence the sensor sensitivity. Response surface experimental design methodology was applied to optimize the important parameters of the proposed sensor. Cross-sensitivity of the MIP-based chemiresistor sensor for different vapours was investigated and a satisfactory result was found for toluene vapour recognition. It was shown that the sensor response to toluene concentration in air was linear in the concentration range of 3.8 to 46.4?ppm. The detection limit and relative standard deviation (for five separate determinations) of the designed sensor were calculated equal to 0.8?ppm and 5.6%, respectively.